Brake booster

Detonator;
The Pantera used a Bonaldi booster as well as a Bonaldi master cylinder. Not sure that Ford has an exact cross reference to a vehicle. Since you are using Brembo brakes, it may be necessary to match your booster and master cylinder to the calipers and piston assemblies you are using. Possibly Brembo or a Brembo specialist would be helpful.

Thanks, I have the willwood master, the guys at the shop say the booster may be bad as the old master was leaking, Brembo says the stock master is fine so I don't know, proly just grab a new one.

I ended up going with the booster/master kit from http://precisionproformance.com they have a upgraded GM booster, but to finish this post off for anyone who might need the stock part number My Master Parts Catalog shows it as a "28195 Booster Assembly". The stock Pantera brake booster was a Bendix-Italia unit (Benditalia) also used in various '80 & up Ferrari 308 series. Info from Jack DeRyke, and Jim Nowlin.

As Detonator did, I replaced my leaking OEM with a Precision Pro-formance GM conversion assembly. Not quite a bolt-in since you must cut the ISO bubble-flairs off the stock hard lines and add SAE conical flairs to fit the GM master. And on early cars, there may be a small amount of interference from the slightly larger dia. booster can with the inner left fender and the front trunk floor. Both easily fixed with the requisite Big Ball-peen Hammer. And some clutch masters may touch the larger booster, also needing a bit of grinding or a small dent. I had none of these on our Sept '72-build Pantera but others have mentioned them.

On the positive side, the GM assembly uses a larger aluminum dual-diameter master cylinder piston (front OD is larger) that is rebuildable and a dual-diaphragm booster with a built-in residual pressure valve. Weight of the more effective converted GM is almost identical to the OEM. In addition, I've had nothing but praise for Precision Proformance and Bob's business practices. Good guy to deal with.

I have the same booster as Jack. See pic.
Wondering which is the front/rear brake connection and what size flare. The two connections are of different sizes. The smaller connection seems like a 3/16 brake line with double flare is correct. The larger connection I have no idea. Anyone know?

Hey Boss,

I was leaning towards getting one of these to replace my badly leaking Italian replacement master cylinder. Do you think this will work okay with stock brakes. I've removed the proportioning valve. I want to upgrade the calipers at some point but I don't have the money right now.

Steve

I've asked around a lot on the forums and this booster/master upgrade will supposedly make the brakes work very well with the stock calipers. That's what I'm hoping for once I figure out how to get it installed !!!

Sean,

Precision Proformance offers 3 version of this. Which did you get and did he tell you the difference? Are you going to need an after market proportioning valve? He lists them at $450.00, is that what you paid?

Steve

Got it from Hall last year. Think it was around $450. I saw PP had them too but maybe Hall was cheaper at the time. PP might have different bore sizes in their masters to compensate for their advertised racing systems.
I was planning on just leaving my stock proportioning valve in place cause that was easiest for me.

I'd say give Bob at PP a call he can answer all your questions.

This thread baffles me... The point of a different booster and different master cylinder bore sizes, is to increase line pressure while reducing leg effort. If the stock booster is good and the master isn't leaking, starting at the booster or master to increase performance is the wrong place to start.

By replacing the booster and master in an effort to increase brake performance is fine except, leaving the stock proportioning valve in the mix is actually lowering pressure to the front brakes. So your increasing master cylinder bore size to increase pressure, then you leave the proportioning valve in the circuit to reduce brake pressure. All for only $450.00. You could do the same thing by leaving the stock master and removing the stock proportioning valve for free!!! However, I wouldn't remove the proportioning valve if the rear brakes are still stock.

Trying to increase brake performance by replacing the master or booster FIRST is completely backwards!!!

If you are on a budget, the CHEAPEST way to get a HUGE performance upgrade is to simply upgrade the rear calipers and remove the proportioning valve. This change alone will pay HUGE dividends in braking performance.

Brake system changes should be done carefully or you will end up with an unbalanced and unsafe brake system.

Scott

I wonder if this Fiat Booster is something that will fit?

http://www.ebay.co.uk/itm/1507...e=STRK%3AMEBIDX%3AIT

There is also a lot of Brake Masters that looks very similar. I don't know if anyone has ever experimented with a suitable substitute from i.e. Fiat or Alfa. For sure they will be very interesting on the price ;-)

My old stock booster was not holding vacuum and my resevoir was leaking. Thats why I decided to replace it. I was leaving the p valve in place just for simplicity. I'm not very experienced with brakes so I appreciate all your input.

quote:

My old stock booster was not holding vacuum and my resevoir was leaking. Thats why I decided to replace it. I was leaving the p valve in place just for simplicity. I'm not very experienced with brakes so I appreciate all your input.

Hi Sean,

If your brake system is stock then leaving the proportioning valve in the system isn't a bad idea. I wouldn't recommend removing it until the rear calipers are upgraded.

Take care, Scott

This guy, Harmon Brakes, rebuilds them. He did one for my 68 Shelby. I spoke to him about the Pantera and he said they rebuild the same as US units and he has the parts and equipment to do them.

He advertises on ebay. I've dealt with him and can recommend him. He is very easy to talk to and guaranties his work.

It's about a 10 day turn around.

He doesn't substitute another unit for yours. He rebuilds yours and returns it to you.

Just tell him PanteraDoug in NY sent you. He's originally from about a mile a way from here before he got smart and moved to CA and left me in all of this ice, snow and sub zero winter weather.

I should go take a CA roadtrip but how do I get my car there? I don't think the CHiPs will like the flames coming out of my exhausts from the Webers?


http://www.ebay.com/itm/Midlan...em53fd2fdc84&vxp=mtr

Scott, can you tell what is going on with the master in the picture. Why one size connection is larger and tell what size/flare should connect there?

Doug your tip on Harmon Brakes is a FIND!!! Had no idea you could do a rebuild on the original booster, plus he's about 30 miles from me! Thanks

He really is. His name is George. Give him a call. He's a nice guy and very knowledgeable.

He isn't one of the NYers who screwed up Cali.

quote:

Scott, can you tell what is going on with the master in the picture. Why one size connection is larger and tell what size/flare should connect there?

All brake lines should be 3/16 in size. Even the metric lines are darn close and can be flared correctly.

Some masters use different size tube nuts so people don't hook them up backwards.

You can have a 3/16 line with a 3/8-24 tube nut (this is the most common). OR, like in your case, the larger hole is likely 7/16-24. So you would use a 7/16-24 tube nut that is made for a 3/16 brake line.

They have tube nuts in MANY sizes that will fit a 3/16 brake line. The double flare is the same no matter what size tube nut you are using.

Let me know if you need more help or if you have more questions.

Take care, Scott

quote:

There is also a lot of Brake Masters that looks very similar. I don't know if anyone has ever experimented with a suitable substitute from i.e. Fiat or Alfa. For sure they will be very interesting on the price ;-)

The Ferrari 308 master is nearly identical to the Pantera, with the exception that the outlets point out the opposite side. I used one on my car for a time. It also has a fluid level float switch in each cap, which can be a nice feature.

Yes I was just thinking the ferrari Master cylinders I have seen are around 300€ where the Fiats range from 30-100€ depending on the seller.
like this one
http://www.ebay.co.uk/itm/3707...e=STRK%3AMEBIDX%3AIT
or
http://www.ebay.co.uk/itm/New-...&hash=item5d46990a52

This is the Ferrari 308 and by judging on the the photos looks damn near close to the Fiats. But remains to tested.....

http://www.ebay.co.uk/itm/1107...e=STRK%3AMEBIDX%3AIT

The person who restored the Pantera that I bought recently put solid crowler cams and racing headers. Now, the vacuum at idle is only about 7 psi. I am thinking of adding an electric vacuum pump. What's the current thinking on this type of fix?

The ones I have seen/heard are noisy. Maybe there are some newer ones that are more silent. A diesel engine does not provide any vacuum either so they solve that problem various ways. Some has a mechanical Pump run on a Cam and some off them uses an Alternator that has a build on Vacuum pump at the shaft opposite the pulley (and thats what I think is interesting). And some also have an electrical pump. There must be some US diesel cars which had an Alternator with Pump that could easy be made to fit the Pantera? Other individual Pumps are so compact and with a pulley that I would almost think they could be fitted (depending on your setup) on your v-belt from the water pump and at the same time act as a tensioner pulley. (just a thought)

Of course the simplest way is to hook up an electrical Pump ;-)

I worked with an Opel once that had this one:

http://www.ebay.de/itm/Lichtma...&hash=item20e07cd775

quote:

Originally posted by goodroc:
The ones I have seen/heard are noisy. Maybe there are some newer ones that are more silent. A diesel engine does not provide any vacuum either so they solve that problem various ways. Some has a mechanical Pump run on a Cam and some off them uses an Alternator that has a build on Vacuum pump at the shaft opposite the pulley (and thats what I think is interesting). And some also have an electrical pump. There must be some US diesel cars which had an Alternator with Pump that could easy be made to fit the Pantera? Other individual Pumps are so compact and with a pulley that I would almost think they could be fitted (depending on your setup) on your v-belt from the water pump and at the same time act as a tensioner pulley. (just a thought)

Of course the simplest way is to hook up an electrical Pump ;-)

I worked with an Opel once that had this one:

http://www.ebay.de/itm/Lichtma...&hash=item20e07cd775

You would have to relocate the alternator. The alternator in the Pantera is right up against the cylinder head and there is no room for the vacuum pump there.

If you are going to start changing master brake cylinders irregardless of whether or not they bolt up (which they probably will) you must know the bore diameter of what you have and what you are putting in.

Like Scott said, you are changing the feel of the brake pedal.

That is a balance between output pressure to the brakes and leg effort.

I doubt that you will be happy by going larger than 1".

Most cars are going to like somewhere between 3/4" bore and 1".

If you go over 1" you increase the effort but not necessarily the pressure.


Race cars do that to reduce the tendency of locking up the brakes with too sensitive a brake pedal.

In the Pantera be careful about giving the rear brakes too much bite. If you increase the braking in the rear you need to increase the front braking proportionally or else the rear will be locking up too early and the rear will come around on you.

There is a reason Detomaso has those small calipers engineered into the car, and that is the reason why.

Mid engine cars need to be balanced in a way where anyone can drive them safely. It isn't anything to play around with unless you have a lot of knowledge and experience on brake systems.

Your car with those beautiful big brakes can suddenly be a dangerous unsafe monster.

Best to go with a system already engineered and tested under extreme conditions to work well. Scott has already done a lot of work on making kits available for the Pantera.


Bigger rear pads with more braking torque are going to need an adjustable brake proportioning valve to dial out a percentage of the torque you just put in. You are also going to need about a days work on a private tarmac somewhere to get the adjustment right. You can not do that on a public street safely and if you try you likely will get arrested for unsafe driving and endangering the public.

quote:

You would have to relocate the alternator. The alternator in the Pantera is right up against the cylinder head and there is no room for the vacuum pump there.

If you are going to start changing master brake cylinders irregardless of whether or not they bolt up (which they probably will) you must know the bore diameter of what you have and what you are putting in.

Like Scott said, you are changing the feel of the brake pedal.

That is a balance between output pressure to the brakes and leg effort.

I doubt that you will be happy by going larger than 1".

Most cars are going to like somewhere between 3/4" bore and 1".

If you go over 1" you increase the effort but not necessarily the pressure.


Race cars do that to reduce the tendency of locking up the brakes with too sensitive a brake pedal.

In the Pantera be careful about giving the rear brakes too much bite. If you increase the braking in the rear you need to increase the front braking proportionally or else the rear will be locking up too early and the rear will come around on you.

There is a reason Detomaso has those small calipers engineered into the car, and that is the reason why.

Mid engine cars need to be balanced in a way where anyone can drive them safely. It isn't anything to play around with unless you have a lot of knowledge and experience on brake systems.

Your car with those beautiful big brakes can suddenly be a dangerous unsafe monster.

Best to go with a system already engineered and tested under extreme conditions to work well. Scott has already done a lot of work on making kits available for the Pantera.


Bigger rear pads with more braking torque are going to need an adjustable brake proportioning valve to dial out a percentage of the torque you just put in. You are also going to need about a days work on a private tarmac somewhere to get the adjustment right. You can not do that on a public street safely and if you try you likely will get arrested for unsafe driving and endangering the public.

About the Vacuumpump on Alternator, I didn't actually say it was an easy option, just an option. We are all spending tons of hours of modifications with sometime minor benefits. Just because we like modifications and it makes us proud to achieve something cool (nerdy by someone) For example I did a lot of work and spend a (relatively) lot of $$$$$$ just to get the passenger backrest 1,5" further back. Does it make sense? don't know..... perhaps for my wife. But it is a cool mod!
About the Master cylinder, I couldn't agree more with what you say. Of course the bore must match or else other precautions should be taken so that the Brakes remains balanced. On the photo of the Fiat Master you will see it is 25,4mm = 1"

And btw here were I live NO person will ever get arrested for testing their Brakes on a remote piece of road (public) ;-) Not even by the meanest rookie cop.

PanteraDoug; I was just trying to help with options, whatever people do is their entire own responsibility, agree?

quote:

Originally posted by goodroc:

quote:

You would have to relocate the alternator. The alternator in the Pantera is right up against the cylinder head and there is no room for the vacuum pump there.

If you are going to start changing master brake cylinders irregardless of whether or not they bolt up (which they probably will) you must know the bore diameter of what you have and what you are putting in.

Like Scott said, you are changing the feel of the brake pedal.

That is a balance between output pressure to the brakes and leg effort.

I doubt that you will be happy by going larger than 1".

Most cars are going to like somewhere between 3/4" bore and 1".

If you go over 1" you increase the effort but not necessarily the pressure.


Race cars do that to reduce the tendency of locking up the brakes with too sensitive a brake pedal.

In the Pantera be careful about giving the rear brakes too much bite. If you increase the braking in the rear you need to increase the front braking proportionally or else the rear will be locking up too early and the rear will come around on you.

There is a reason Detomaso has those small calipers engineered into the car, and that is the reason why.

Mid engine cars need to be balanced in a way where anyone can drive them safely. It isn't anything to play around with unless you have a lot of knowledge and experience on brake systems.

Your car with those beautiful big brakes can suddenly be a dangerous unsafe monster.

Best to go with a system already engineered and tested under extreme conditions to work well. Scott has already done a lot of work on making kits available for the Pantera.


Bigger rear pads with more braking torque are going to need an adjustable brake proportioning valve to dial out a percentage of the torque you just put in. You are also going to need about a days work on a private tarmac somewhere to get the adjustment right. You can not do that on a public street safely and if you try you likely will get arrested for unsafe driving and endangering the public.

About the Vacuumpump on Alternator, I didn't actually say it was an easy option, just an option. We are all spending tons of hours of modifications with sometime minor benefits. Just because we like modifications and it makes us proud to achieve something cool (nerdy by someone) For example I did a lot of work and spend a (relatively) lot of $$$$$$ just to get the passenger backrest 1,5" further back. Does it make sense? don't know..... perhaps for my wife. But it is a cool mod!
About the Master cylinder, I couldn't agree more with what you say. Of course the bore must match or else other precautions should be taken so that the Brakes remains balanced. On the photo of the Fiat Master you will see it is 25,4mm = 1"

And btw here were I live NO person will ever get arrested for testing their Brakes on a remote piece of road (public) ;-) Not even by the meanest rookie cop.

PanteraDoug; I was just trying to help with options, whatever people do is their entire own responsibility, agree?

Sure I agree. I think the most likely solution in the Pantera to the low vacuum issue is a separate electric pump. That way you can find some room somewhere under there to put it in.

The pump on the back of the alternator is a fantastic idea if it would fit. I'd be out buying that alternator right now.

I'm pretty sure that is the same size bore as the stock Pantera master cylinder. It's about right to keep the brakes from locking up.

Police it Europe must be more sympathetic than here. Here there is no mercy by mindless Police.

Some are just plane antagonistic and confrontational.

None of them live in the same cities where the work. If they did they would actually have to show their faces on the street and face the people that they abuse.

NYC is the worst. They have stop and frisk rules there and you HAVE to carry identification. Very much a harbinger of the coming Police State here in the US.

Their excuse is it is for everyone's safety and security.

I suppose that's what the Nazi's told the German people in the beginning too?

Too bad. No one would suspect the US was going in that direction?

I wonder which country we will invade next?

I agree with you and I can't stand that Pack mentality exercised by any group. Wether it is the Police or the guys with long black Boots from the south who were mingling with the regular soldiers that invaded and occupied my country from April 9th 1940. Some of them was really nasty ;-(

Anyway to get back to the subject. If installing an electrical vacuum pump some people suggest that you install a vacuum reservoir (tank). Otherwise the pump will start/stop too often. I would go to the local junkyard and pick up an empty small fire extinguisher bottle (have seen them there) and use that or perhaps just buy one build for the purpose. (not the small ones for HVAC or Power locks) And of course a vacuum sensor switch to sense the system vacuum and control the Pump. You can still take advantage of the 7" of vacuum at your manifold as initial vacuum if you remember to add an additional check valve that shuts as the system vacuum goes below 7" generated by the vacuum pump.

quote:

Originally posted by goodroc:
I agree with you and I can't stand that Pack mentality exercised by any group. Wether it is the Police or the guys with long black Boots from the south who were mingling with the regular soldiers that invaded and occupied my country from April 9th 1940. Some of them was really nasty ;-(

Anyway to get back to the subject. If installing an electrical vacuum pump some people suggest that you install a vacuum reservoir (tank). Otherwise the pump will start/stop too often. I would go to the local junkyard and pick up an empty small fire extinguisher bottle (have seen them there) and use that or perhaps just buy one build for the purpose. (not the small ones for HVAC or Power locks) And of course a vacuum sensor switch to sense the system vacuum and control the Pump. You can still take advantage of the 7" of vacuum at your manifold as initial vacuum if you remember to add an additional check valve that shuts as the system vacuum goes below 7" generated by the vacuum pump.

I will be looking for a compact quiet vacuum pump soon. I don't want to give up on the power brakes yet.

Personally I'm running with 14in-hg at idle. With this cam, that's pretty good. There is good vacuum pressure but the Webers don't generate enough volume.

Just buy a vacuum reservoir can from Summit. They are cheap and compact one gallon sizes.


My difficulty at the moment is engineering in a PCV system with the Webers off of a vacuum manifold.

There isn't enough volume of vacuum left to pressurize the brake booster. Just getting the PCV system to work means finagling with internal restrictions in the line to the pcv and loosing 2 in-hg at idle.

Problem is there are no pcv valves that close 100% at idle. They are all open a little.

A few Pantera owners have installed this pump...

http://www.saccrestorations.ne...lectric-vacuum-pump/

I too have been thru this situation.
when we originally built the car I decided that the products and cost offered by the vendors for the brake booster and master cylinder were lets say un-necessary. I fitted a GM 7" booster and 1" master assembly used mostly for street rods. It costs a fraction of what the vendors are asking. The GM master works great especially coupled with SACC's brake upgrade kit for the stock rotors. Unfortunately once I got the car on the road found out that the engine did not always make the vacuum required. I installed an electric vacuum pump that I purchased from SACC. Scott if I'm not mistaken this is the fist one you sold. Any way the pump works well. Now the brakes work consistently well as opposed to sometime well and other times not so well depending on vacuum. The pump is loud but guess what my engine with the 180's is louder. So I guess it doesn't matter.

quote:

Originally posted by ZR1 Pantera:
A few Pantera owners have installed this pump...

http://www.saccrestorations.ne...lectric-vacuum-pump/

These pumps have a reputation for being noisy. Can you give me any feedback on that concern?

PanteraDoug, Hope you don't mind if I chime in some more on the pump. It is loud. I have mine mounted up front next to the battery. If I turn on the key I can clearly hear it. If the engine is running even at idle I can barely hear it. While driving the car I don't hear it. I did mount it on rubber isolators to help reduce vibration. Hope this describes it better for you.

quote:

Originally posted by ItalFord:
PanteraDoug, Hope you don't mind if I chime in some more on the pump. It is loud. I have mine mounted up front next to the battery. If I turn on the key I can clearly hear it. If the engine is running even at idle I can barely hear it. While driving the car I don't hear it. I did mount it on rubber isolators to help reduce vibration. Hope this describes it better for you.

Is it louder than an electric fuel pump?

It is a different sound than the fuel pump. A high capacity fuel pump is pretty loud but more high pitched. It sounds a lot like the air compressor used for the low rider air bag systems. Sorry but hard to describe.

quote:

Is it louder than an electric fuel pump?

http://www.youtube.com/watch?v=uUYM3wgk7g8

Here is a small clip from youtube. Might give you and idea of the noise level. I would say fit it somewhere in the right side of the Engine compartment in the area below the Starter Solenoid and hook it up to the original Vacuum Line via a T-joint (remember check valves). The original lines will also serve as a reservoir to some extend. I believe if it is hooked up directly in the front next to the Booster the noise will be really annoying in the long run.

That thing is ridiculously loud. It does sound like the portable compressor I use for my nail guns.

There has got to be one that is quieter?

It looks like the unit that is sold by Comp Cams.

Thanks for posting that. Looks like a Dartmouth Engineering undergraduate student?

quote:

That thing is ridiculously loud. It does sound like the portable compressor I use for my nail guns.

There has got to be one that is quieter?

It looks like the unit that is sold by Comp Cams.

Thanks for posting that. Looks like a Dartmouth Engineering undergraduate student?

Yes they are noisy I am just thinking that technically (if you dont have a/c) you can use your a/c compressor as a vacuum pump. It should be possible. I know of people who use them as AIR compressor for air-suspension. So I don't see why it should not be used as a vacuum pump. You will of course have to make sure that some oil remains in the compressor but that should not be a problem. You can use a vacuum switch to control your clutch-relay and if you use a 1 gallon reservoir as you suggested it will not engage very often.

just a thought!

quote:

Originally posted by PanteraDoug:
That thing is ridiculously loud. It does sound like the portable compressor I use for my nail guns.

There has got to be one that is quieter?

It looks like the unit that is sold by Comp Cams.

Thanks for posting that. Looks like a Dartmouth Engineering undergraduate student?

Many cars use vacuum pumps for brakes, mostly turbo cars. I bought a new pump from ebay that was from a VW 1.8T, it did not seem that loud on a test run on the bench.
I also bought a vac reservoir from http://evsource.com/tls_braking_system.php It has the gauge, one way valve and switch all included. I fitted one to my sons Saab which we upgraded the engine on and the vac pump did not work as we wanted. With the tank, the pump sometimes runs when you turn the car on then stops, pump the brakes a few times and the pump runs and turns off, much better brakes now.
I see this company also sell a quiet vac pump.

Since I have a newer kompressor Engine installed I solved the poor vacum by installing a hydroboost system since the new Engine came with a servopump already installed. When I was at it I also installed servosteering since the servopressure was already there.

The hydroboost.

quote:

Originally posted by PanteraDoug:
My difficulty at the moment is engineering in a PCV system with the Webers off of a vacuum manifold.

There isn't enough volume of vacuum left to pressurize the brake booster. Just getting the PCV system to work means finagling with internal restrictions in the line to the pcv and loosing 2 in-hg at idle.

Problem is there are no pcv valves that close 100% at idle. They are all open a little.

Doug, check out this product, http://mewagner.com
I also did not want to bleed off vac at idle because I have a large duration cam and I cannot find a "performance" pcv. I have bought quite a few, some have just a small hole and are rated at different vac levels. There are also people who threaded a screw on the top of a regular pcv valve to adjust it. I bought one of these valves but because of the cold weather and bolting on other parts, I am not sure when I will get to test it. Try it risk free for 30 days and you can get an inline adapter and it can be mounted in any direction / orientation.

quote:

Originally posted by bdud:

quote:

Originally posted by PanteraDoug:
My difficulty at the moment is engineering in a PCV system with the Webers off of a vacuum manifold.

There isn't enough volume of vacuum left to pressurize the brake booster. Just getting the PCV system to work means finagling with internal restrictions in the line to the pcv and loosing 2 in-hg at idle.

Problem is there are no pcv valves that close 100% at idle. They are all open a little.

Doug, check out this product, http://mewagner.com
I also did not want to bleed off vac at idle because I have a large duration cam and I cannot find a "performance" pcv. I have bought quite a few, some have just a small hole and are rated at different vac levels. There are also people who threaded a screw on the top of a regular pcv valve to adjust it. I bought one of these valves but because of the cold weather and bolting on other parts, I am not sure when I will get to test it. Try it risk free for 30 days and you can get an inline adapter and it can be mounted in any direction / orientation.

I already investigated this one. If you read the information you will note that they do no claim the valve to close 100% at idle. That is the issue for me.

What I currently have is an Allen set screw that is drilled with an orifice of .060" or so (maybe I used 2mm?) that is installed in line to the PCV valve.

What it does is instead of me having 14" at idle it reduces the leak to only 2". That leaves me with 12" at idle.


Considering that I have 74 degrees of overlap with this camshaft that is a very strong vacuum signal. Even 12" would be good.



IF there was a PCV valve that fully closed that would solve much of the problem. As far as I can determine there is not. These valves are $2 parts and the quality of the construction is as cheap as you can get. The design intent is there with them but the execution in building them is not.

The combination of low VOLUME of vacuum signal (not strength) created by the IR (individual runner) manifold and a 5/8" vacuum tube to the brake booster creates an issue that even a one gallon storage tank in line does not fix.

I am still in progress with this vacuum refinement. Too cold to run the engine right now. Got up to 18 this morning. Webers don't like that.

The issue was complicated by a non-functioning check valve at the booster. I've replaced that but still haven't pressure tested the booster itself to see if the internal diaphragm is shot (kaput). Considering this is the original booster to the car, that is a distinct possibility and if it is rotted out could be the problem right there?

I may have to take my own recommendation and send this booster to Harmon brakes and let him rebuild it?


At the moment, this is a very, very complicated issue and I need to backtrack to identify basic problems that I may have overlooked.

The availability of the vacuum pump is comforting and the fact that there is no one anywhere that I can find that has run a PCV system with a Weber set up makes me a trailblazer. That is a task which I detest but often find myself immersed in.

I thank everyone for the input. Hopefully I will be able to remember all of these options but I suspect that it may be just that scenario of the elephant hiding in the bowl of M&M's and everyone else sees it but me?

Confucius say, "never set a cannon to kill a mosquito!" Well ok, but he never said anything about a machine gun? Ask Ted Nugent.

I have a hard time grasping the concept of needing to add a vacuum pump, is the engine not a giant vacuum/air pump, I would think a check valve and manifold pressure would be all you need? what am I not understanding?
I am being serious what did I miss?

I am not sure what vacuum the dual valve uses at idle, it talks about adjusting it with a gauge and reading 0-1", but this might be the port for setting the valve up and not what the valve will allow at idle. They designed the valve to allow some vacuum at idle and increased flow at cruise.
I did use a GM truck pcv at one time which is just a small hole, not sure it helped.

quote:

Originally posted by Detonator:
I have a hard time grasping the concept of needing to add a vacuum pump, is the engine not a giant vacuum/air pump, I would think a check valve and manifold pressure would be all you need? what am I not understanding?
I am being serious what did I miss?

In order for the engine to be the vacuum pump itself that will operate vacuum accessories like the brake assist booster, it must provide 1) pressure to the intake manifold (source of vacuum). That pressure is measured in inches of mercury rather that in pounds per square inch.

The reason is it is a negative number if stated in psi and that confuses too many people 2) the engine needs to produce the pressure across a large enough hole in the intake manifold. In the case of the stock Pantera that hole is 5/8" and the minimum pressure is 15in-hg.

Camshaft timing, most specifically the overlap of the camshaft, i.e., the amount of time both the intake valve and the exhaust valve are open, effects how high the manifold pressure will be.

These engines when new and "stock" produced about 16 or 17in-hg.



When you change to a longer duration camshaft with more valve overlap, the pressure produced in the intake manifold drops. Almost always under 15. Sometimes as low as 7 or 8in-hg at idle.

That isn't enough pressure for the accessories to operate on.


In my case, the design of the intake manifold does not have a common plenum. Each runner to an intake manifold has it's own. It's own carburetor as well.

In order to get a reading of the combined vacuums being produced by each cylinder, the intake runners need to be connected together to each other in some way. Sometimes that connection of plumbing to which they all connect is called a vacuum manifold.

In the case of independent runner manifolds using carburetion, not fuel injection, you have to minimize the amount of pressure lost into that vacuum manifold to insure that you can still tune the strength of the fuel mixture, or more correctly stated, minimize the amount of leaning out of the mixture due to the interference of the leak of cylinder pressures into the vacuum manifold.

The vacuum manifold on mine, as with many with Webers is made from 1/4" od metal tubing, and is strung together in series like a Christmas Tree light bulb set.

So the pressure can be read accurately now with a vacuum gauge because of the vacuum manifold, but the quantity of vacuum (negative pressure) does not add up to the amount you get from the 5/8" inside diameter hose that would be connected to an intake manifold with one common plenum under one carburetor that would supply the entire engine with atomized fuel.

I've also introduced a PCV valve into the equation by connecting it to the vacuum manifold which equates to a 2in-hg loss, AND I had to restrict that to keep it at only a 2in-hg loss at idle. So now I have 12in-hg at idle. This is not enough pressure, and not enough volume of pressure to operate the brake booster.

So one possible solution is to use a vacuum pump to supply the accessories, in this case just the power brakes because it is not dependent upon the engine itself to produce the vacuum. It is a self propelled vacuum pump producing up to 22-23in-hg on demand.

Get it now at all?

Yes I can see how some special intake setups could cause a problem, guess I am just trying to wrap my head around it.

No problem. We are all, always learning something new.

When it isn't our field or avenue of expertize sometimes the learning curve feels unreasonably steep?

In my case it makes my head feel like it's full of molasses in the middle of a Canadian winter!

Yeah for me the V8 NA carbureted concept is somewhat new, spent most of my life building high HP 4cyl turbos, completely different concept with standalone ECU and boost.

quote:

Originally posted by Detonator:
Yeah for me the V8 NA carbureted concept is somewhat new, spent most of my life building high HP 4cyl turbos, completely different concept with standalone ECU and boost.

My son built a SC Contour SVT. 3.0Liter. Quite a handful to keep running at full boost. Supercharger keeps breaking. Very quick to 140. Dynos only at 285.

Never did turbos. Always wanted to do a Covair Spyder. Factory limited to 6psi. Had a '63. Car had other issues. Two piece flywheel riveted together. Came apart on me at about 100.

Probably what really got me interested in the mid-engine concept of the Pantera though.

Son #2 has an '02 Audi TT 1.8 Turbo. 6 speed. Very very quick under boost. Probably over 300 hp. Great straight line car. Quatro makes it go straight but not through the curves.

Can't handle though. Only good for 35-40 mph on an off ramp whereas my Taurus SHO (275dyno) is good for almost 70 and the Pantera spun out at 90. The SHO handles. The Pantera is just plain filthy. Pantera with Webers.

Two more stablemates. 68 Shelby GT350 347, 5 speed, 2x4 Holleys. 67 Shelby GT500.

6 cats. One retired Greyhound racer. Two outside cats. All interesting toys. Keeps me busy.

I probably learned the most by breaking them all (the cars) at one time or another and having to fix them all by myself. Some things come hard but you NEVER forget.

Cool stuff, yeah my last project was 91 turbo mr2 300whp fun at the auto cross.

quote:

Originally posted by Detonator:
Cool stuff, yeah my last project was 91 turbo mr2 300whp fun at the auto cross.

Sounds a lot like the Audi TT. Quatro keeps it from spinning the tires but doesn't help it handle until it's doing 90 to 100.

It's ironic though. Center of gravity is as low as the Pantera's and corners flat. It just doesn't bite in the turns.

I don't drive it enough and know that each car needs to driven one way to make it handle. The TT is still a mystery. Haven't found the secret yet.

This thread has gone far afield from a brake booster question, but I just have to comment on Audi TTs.......
I love mine!........That is all............

Way off-topic, Detonator, but superchargers may not be your best choice for a stock 351-C block due to the thin cylinder walls that flex under high boost- for a while. Then they crack, and good blocks are getting scarce. Nitrous is a little better since it's only a momentary overload, much like Corvair turbos which were originally meant as a sort of 'passing gear'. If big power with decent vacuum for brakes is what you want, I'd look at a big-block conversion in a Pantera. There are quite a few around. Some will pass smog tests while delivering scary power.

Way off topic? Why is everyone looking at me? Like nobody else has a Greyhound and a zillion cats? The Detomaso icon is Isis the Egyptian God of cats?

quote:

Originally posted by PanteraDoug:
The Detomaso icon is Isis the Egyptian God of cats?

(Just to get even further off topic) That's a first, but no Isis isn't the goddess of cats and just to rehash a very old topic the DT symbol is from the family's cattle brand. But you were just kidding, right?

I still have two 351c blocks n heads I am going to rebuild, one is the Australia block so that one for sure, nope no boost on this car the 351w made 500hp on the engine Dyno so I am good with that, I hope not to have vacuumed issues when everything is said and done, got STI for boost lol.

quote:

Originally posted by Detonator:
I still have two 351c blocks n heads I am going to rebuild, one is the Australia block so that one for sure, nope no boost on this car the 351w made 500hp on the engine Dyno so I am good with that, I hope not to have vacuumed issues when everything is said and done, got STI for boost lol.

You need to have the Australian block sonic tested. Apparently many of the cylinder bores are too thin to make them worthwhile to use.

That could be a reason someone along the line sold the thing to begin with. In my opinion from feedback I've heard on them, that is very likely.

The Australia block came out of the car, I plan to sleeve it anyway, I think my dad said it was 60 over last rebuild, that engine had a cracked piston so I took it out lol and ten years later here I am. The other block not sure what I plan to do with it.

I think I'd sleeve it too? Kind neat of a block to have. You wouldn't need to twist my arm to take one.