Single plane or dual plane?

Edelbrocks are not known as serious perforning manifolds.
Their intended scope is better then stock, but not all out performance.
What you describe is typical of them.

With 427 cubic inches, you can't be hurt with a single plane at all.

The main differences you will see is a little rougher idle and maybe a little flatter to 2500 or so but you will have top end to over 7000 rpm usually unless you don't have enough cam.

If you have a vacuum gauge hooked up you will probably see less idle vacuum but not to worry. 12 inches is enough. You can even get by with 10.

With a manifold like you have, you will probably not see less then 2 at WOT. Maybe not even lower then 3-4. With the single plane, you will.

A reading like that to me indicates there is restriction in the manifold at WOT. Again, typical of an Edelbrock.

Some have been able to port them for better results but that really depends on the manifold design.

Personally I have been playing with Clevelands since 1972. I have yet to find a dual plane FOR A CLEVELAND that will perform where it counts LIKE a single plane.

These are just my experiences and others may have different views and results, and as always, "your mileage may vary".

If I were you I'd ask Dan Jones if he has any specific manifold recommendations for you. He has dynoed quite a few on his 408. He could save you a lot of time and experimentation and put you right in the ballpark where you need to be.

The manifold you want may not be a current production one. I'm thinking it might be one of the discontinued Ford Motorsport/Racing units. There are a few of them. Dan has tested a few.

Your cubic inches will have different requirements then a 351 will.

Here are a couple links on the subject:

Intake Manifold List for Production 351C Cast Iron Cylinder Heads, by Dan Jones
http://mustangsandmore.com/ubb...ones351CIntakes.html

Optimizing the Blue Thunder Intake
http://www.network54.com/Forum...+Blue+Thunder+Intake

Mike Drew's Dyno Results, by Dan Jones
http://realbig.com/pipermail/d...2010-May/122577.html

D'oh! I totally missed that you need an intake for a Windsor. The links above are for Cleveland intakes. Oh well. I'll leave the links here for posterity.

Push, are you running Cleveland stagger-valve heads or straight-valve Windsor type heads on your 427? This will make quite a difference in what intake will be better.

Boss - yes, it's a winsor style block using winsor style heads - RHS aluminum 215 cc intake runner heads.

PanteraDoug and garth, thanks for sharing your thoughts

Price Performance makes a 2x4 dual plane intake for a 351w and uses Holley carbs. Out of the box the runners flow 285cfm.
I think this might be a good match for what you have.
It comes two ways. It comes with the angled carb base for a car like a Mustang and with flat carb bases for a car like the Pantera.

I don't know if it is low enough to fit under the screen AND under the deck without cutting it like you would do for Webers, but I can tell you that the set up works very well since the carbs are vacuum secondaries.

I have the Ford "over the counter" 289-302 Holley 2x4 "Trans-Am" manifold on my 68 GT350 with a 347 in it. It runs just plain old Holley 1850's. Nothing fancy. It is very similar.

It is amazingly torky right off of idle and the top end is absolutely amazing. You might want to consider it.

It positively kicks a ss. You'd love it.

I'm pretty sure DJ hasn't tested it as yet but I'm very sure I saw it on his list of "to do".

I am running a 408W with a bit more compression at 11:1 with the same RHS 215 heads. My cam is 236/248 duration and I made the switch from the RPM air Gap dual plane to a (ported) Victor Jr. single plane. If I lost anything on the low end, the seat of the pants dyno didn't notice but I did notice a pick up in the upper revs and wouldn't go back. Hope that helps!

Hi Kristian,

Single plane and 830 carb would be beneficial for those cubes.

That cam, however, will not let that extreme stroke breathe much beyond 5000rpm. I'd probably go for a major cam change first. Something like Lunati 20350518 or Comp 35-602-8. I'd probably take the comp for the narrower LSA. That stroke tames the cam quite a bit.

Then, I'd try the super victor and last change the carb.

I'm sure not everyone agrees though...

-Janne

The heads are the limiting factor with your setup. 215cc intakes are way too small for those cubes. This is a perfect example of where you would want the huge intake ports of the 351c 4v heads if you want top end over 7000rpm.

Unless you just want to tear the entire engine apart and start all over from the shortblock up, just go for more intake manifold and more carbureation.

Like I said, two 4v Holleys with vacuum secondaries and progressive mechanical linkage LIKE the Ford 427 medium riser set up is where you want to be.

That setup uses two 715cfm carbs where as the low riser uses two 652 carbs.

The beauty of the set up is that the engine will only take what it can use with the vacuum secondary carbs as opposed to the Carter/Edelbrock/AFB set up which has mechanical secondaries and open whether or not the engine needs it.

You can port out the Price 2x4 manifold to flow more with not much trouble but I would invest with a professional porter with a flow bench to get it as close to right as you can get.

You are already running a lot of cam to begin with. I don't know at what lift those heads develop maximum flow but your duration is ABOUT as much as you want for a strictly street car unless you want to idle at 1,200rpm or more?

It all depends on how much more work you want to put into this and what you are willing to put up with to max out the engine.

You really won't know that until you go to much. The engine will loose it's civility really fast and you will drastically shorten the engine life exponentially.

You asked for opinions. That's mine.

Plugging the ballpark engine specs to Pipemax, the cam is done by 5500rpm. Being big stroke, small bore and limited heads, it will fall quickly after that.
Improved intake and carb will help, whether single or dual, but wont do miracles, if the cam is not there. If you take a litre off that displacement, the sweet spot with the same cam will be at 5800 and it wont fall on it's face until 6500.

Now what comes to my cam suggestions, I'll take it back. You need more cam, the ones I mentioned are quite close to what you have now.

Guys - Thanks for your input. That's really useful.

I'm not looking for all out max power and 7000 rpms, I still wan't it to be streetable. With the current cam, although it's a bit rough, it's actually very streetable and idles nicely in the 1000-1200 rpm range.

It seems from your comments that a single plane, or the price 2x4 set-up (which indeed seems like a nice set-up - and expensive) wouldn't hurt the low-end too much, but move the power-band up and increase top-end while still maintaning reasonable good street manners.

A ported victor jr with a QF 830 may be the way to go then, as the super victor is too tall to fit under the screen.

Regarding the heads, it's possible that they are limiting for a 427?. These are the flow numbers for the heads: Cam lift is about .600 in/ex.

Flow in CFM
.050 in 26.5 ex 24.0
.100 in 60.0 ex 52.0
.200 in 116.0 ex102.0
.300 in 168.0 ex134.0
.400 in 217.0 ex172.0
.500 in 260.0 ex181.0
.600 in 292.0 ex190.0
.700 in 305.0 ex200.0

quote:

Originally posted by jannem:
Plugging the ballpark engine specs to Pipemax, the cam is done by 5500rpm. Being big stroke, small bore and limited heads, it will fall quickly after that.
Improved intake and carb will help, whether single or dual, but wont do miracles, if the cam is not there. If you take a litre off that displacement, the sweet spot with the same cam will be at 5800 and it wont fall on it's face until 6500.

Now what comes to my cam suggestions, I'll take it back. You need more cam, the ones I mentioned are quite close to what you have now.

This is absolutely correct. It is difficult to have both displacement and rpm capability.

Something like the Ford 427 medium riser would have both. However having driven a 427 Cobra at 8500 rpm in fourth gear on the track at Pocono I would caution anyone about it.

If there ever was a car that the driver needed to be "qualified" to drive at that speed (180mph), this would be it. It is not a car for a novice as compared to a Pantera in which seemingly anyone can get into and drive fast the first time, BUT that is with a 351 NOT a 427 medium riser.

These are choices that are made in selecting things like displacement, bore/stroke, cam profile and heads. Even so. No combination will be perfect.

Personally I like the rev-ability of the small block vs. the big block.

Limiting heads? I think that might just be a function of how the engine is equipped.
I am pretty sure that the hottest Cleveland heads flow in the 330 @ .600 lift range BUT I'm not sure that a 351 can use that. Flow isn't everything.

I think anything that flows 285 or better at 500 to 600 is pretty decent. Those were numbers that only serious race prepared engines were reaching 20 years ago.

I think you need to look at some engine dyno tests and see what the results suggest with different intake manifolds, cylinder heads and camshaft combinations.

What big cube engines do is put a mountain of torque right down off of idle.

I don't see how you could go with more cam. Induction would be your biggest choices at the moment.

As far as saying 2x4 Holley system doesn't work as well as a single Holley, that depends on your interpretation.

The advantage of a 2x4 Holley is that you are driving on a smaller set of primary throttles, in the primary carb, up to 3,000 rpm.

There the primaries on the secondary carb begin to open.

If you are using say 1850's, those are 600 cfm carbs. The primaries on them are smaller then the primaries on an 830cfm Holley and the better throttle response shows that as well as better overall milage.

The secondaries are vacuum operated and will open in unison to the vacuum demands the engine creates.

The 1850's are also a street, original equipment carb from Ford. I have run the pair with as small as 59 main jets and the plug colors are perfect with them. Try to run those jest with your 830, and you will put holes in your pistons.

The old numbers from Ford indicate that 2x4 carbs will make 50 hp more then a single carb.

I didn't understand all of that until I tried the system. Now I understand what they were talking about and the system is much crisper, has a tremendous top end, and gives about 4 mpg better around town then one big Holley.

Also keep in mind that two 4's was the system of choice in Trans-Am racing until the rules outlawed them. Not just one big monster single carb.Do you think there is a reason for that maybe?

In all fairness to accuracy on the subject though, what really makes the Ford system work is the design of the intake manifold. It just happens that the only combination they could make fit WORKS, and it makes the engineers look like geniuses.

Chevy's 2x4 don't work any near as well as the Ford design. Has to do with port layout, etc.

Also Bill Price really did a wild and crazy thing. He copied the manifold design of the 289-302 and extrapolated it up to a 351?

No they work and really quite well. Oh and not that I need to put icing on the cake but ever hear of the Ford GT40 MarkII and Mark IV? Those are the Ford 427's. Guess what induction system they ran in competition? You'll never guess? Hey Doug, what is this a conspiracy? Geez-us!

I understand Mr. Ferrari didn't like them either? Said they were irrigation engines? Imagine all those linguine wagons painted tomato sauce red beaten by a bunch of pion Americans with the irrigation engines they took off of the corn farm? Is there no God in Heaven?

I have Weber 48ida's also and they both seem to make about the same power on top, but with the 2x4's you can virtually pop the wheels off the ground in the front, the Webers won't.

The Webers have a better throttle response in the 5,000rpm range (around 100) but not by much. Webers have the reputation for having better throttle response in very high speed cornering and I think is well deserved.

In real driving both the 2x4 and the Webers will blow the single Holley away. No contest at all. On a dyno there may be different results, but I don't know how to drive a dyno on the street or even the race track. Do you?

It all depends on what kind of driving you do or how you drive the car.

The Price manifold is $450. Plus the 427 Ford throttle linkage at around $100, then the two Holleys. If you use 1850's you can find them "factory rebuilt" for about $150 each.

I don't think that's so bad? A 351c Weber manifold these days is $950 new, carbs $650 each. A Weber setup will cost you over $4,000 depending on the particulars.

BUT, and this is a big but, you already have a dual plane manifold and it shows signs of restriction. The point is you can get some more top end and basically keep the bottom end you have by going to a single plane manifold.

None of these are mistakes, they are choices that you have. Nothing has zero drawback. Some of the drawbacks you won't know of until you have a system running and drive the car.

If you don't like the drawbacks or limitations, then you go to plan "B"...whatever that is?

Try a single plane manifold first. Maybe it will be just what the doctor ordered?

quote:

Originally posted by Push1267:
Guys - Thanks for your input. That's really useful.

I'm not looking for all out max power and 7000 rpms, I still wan't it to be streetable. With the current cam, although it's a bit rough, it's actually very streetable and idles nicely in the 1000-1200 rpm range.

It seems from your comments that a single plane, or the price 2x4 set-up (which indeed seems like a nice set-up - and expensive) wouldn't hurt the low-end too much, but move the power-band up and increase top-end while still maintaning reasonable good street manners.

A ported victor jr with a QF 830 may be the way to go then, as the super victor is too tall to fit under the screen.

Regarding the heads, it's possible that they are limiting for a 427?. These are the flow numbers for the heads: Cam lift is about .600 in/ex.

Flow in CFM
.050 in 26.5 ex 24.0
.100 in 60.0 ex 52.0
.200 in 116.0 ex102.0
.300 in 168.0 ex134.0
.400 in 217.0 ex172.0
.500 in 260.0 ex181.0
.600 in 292.0 ex190.0
.700 in 305.0 ex200.0

Hi Kristian,

The challenge with the big stroker is that heads become the bottleneck. If you look at the port and valve sizes of 427's and 429cj's of the time there's a huge difference. I appreciate there are many aspects to this comparison, which are not ideal, but big bore, short stroke and big valve heads help the engine to hang on past peak with smaller cam.
You have a Windsor head, which limits options. You can do only so much before getting into the cam, but anything that helps the intake side would be good.

Easiest trial that can make a noticeable difference is the intake. You may change the carb if you like, but you can get a good idea just changing the intake. That may be just what you are looking for.

You could also get AFR225's. You would make noticeably more power everywhere, but still would not make a major difference in rev range. You already have a 2.08 valve (vs.2.1" of that AFR, less than 1mm difference), and if the valve curtain area goes to sonic choke, you need to begin changing lift and duration to make a difference in range.

You could talk to someone like Mike Jones (jonescams) to get a custom hydro roller that does what you want, without going miserable at part throttle.

As I recall, the 4v iron Cleveland heads "resemble" the BB Chevy rectangular port heads.

The 2.19 intake is a 427 size intake valve.

The Windsor heads are not as well suited to big cube engines as the Cleveland head is.

The big cube engine to build is a Cleveland, not a Windsor.

quote:

I'm sure not everyone agrees though...

Janne, nobody would be stupid enough to argue with the fastest duo on the LMC trip!

quote:

Say Hi to Helen.

Kind regards

Andy

Andy, I'm not sure what's being going on on that trip, but Helen is my wife, not Kristian's. I've noticed Kristian didn't correct you...

Say hello to Dawn/whoever...

And now to business.
Strange that anybody would put a dual plane on a 427 stroker. It sounds likely that it's a bottleneck, if so, going with single plane will of course help. If your heads are the bottleneck, you'll not see much difference obviously. But it's a cheap test.

Two carbs are IMHO more show than go. Yes, they can be made to idle fine. I had a tunnelram on a Camaro in the 80s, mostly because everybody said it wouldn't work, and while I liked looking at two carbs, it didn't give me noticeably more power.

quote:

Andy, I'm not sure what's being going on on that trip, but Helen is my wife, not Kristian's. I've noticed Kristian didn't correct you...

... well, just thought that I would call Helen to tell her that Andy said hallo . My wife btw was (well, still is) Trine .

I actually don't think the flow numbers for the RHS 215 heads are too bad - I've read posts on forums where they support 650+ HP.

The dual plane air gap manifold has tiny, tiny ports compared to the ports in my heads. No port work was done by the enginebuilder and it still came out with 525 HP which I think is not too bad.

I'm not going to make big changes to the motor this winter, so my plan is to start out with the dual plane, to which I now have done some quite extensive port-matching. I'm quite curious how porting, and solving the problem with the intake gaskets that was badly mismatched, will affect engine power and general behaviour.

Then I'll try out the victor jr or the equivalent ford motorsport V351 possibly with a doublepumper to feel the effect.

Regarding all the other suggestions - they will be considered for my next engine build - probably a Dart aluminum block based 438 clevor.

Sounds like a plan! It should keep you busy all winter for sure?

quote:

think you are lucky I can remember any names - the only time I was even slightly sober was when I was behind the wheel!

Ha !! I was sober behind the wheel too and while working out bugs on my car - consequently, I didn't have much time to drink !!

Below. Some where around Paris changing/cleaning plug no 2 due to bad intake gaskets.

Traffic light in a small village along the Loire river - failed throttle linkage bracket - spend two hours fixing a temp solution to get the car to the hotel

Then, fabrication of a throttle bracket at the hotel - THANKS guys. Note who's drinking the beers !!

My beer was placed on the ground while in your car. No decent cup holder...

Well.. There's nothing like accomplished craftsmen working on fine piece of equipment... and watching that with a beer in your hand. LOL.