Weber tuning frustration

quote:

Originally posted by PanteraDoug:
Mine look like that as well including in my 347 Windsor.

Your plugs would indicate to me that the idle is way to heavy on your induction. The light side is about right.

This dual reading happens because one side is facing the intake valve, the other is facing the exhaust valve.


One thing that you will find as helpful is indexing the plugs. All plugs should read equal and the defining line should be right down the middle of the plug.


I define that as, the tip of the plug needs to point directly at the intake valve. In order to do that you need to use shims under the plugs.


The racers that I know say this is MANDATORY to get the engine to operate properly and state that they have dyno proof of 15 to 20 hp differences between indexed and non-indexed plugs.


IF you are running Webers, try going to .60F/.80-.85-.90idle holders. The .70f are too heavy.

Excuse my bad English but the "tip" of the plug is the earth electrode?

Ngk bp6es but an Autolite 3923 works too if you cant fit the bigger size plug socket in.

This heat range works out to being hotter then the af32 but cooler then the af42.

my final Weber settings ended up this way. air corrector 210, main jet 150, f5 emulsion tube, 120 idle jet holder, 60 idle jet. mind you, I am running a mild cam and higher compression pistons but lost the specs some time ago. The car idles at nicely 900 rpm and runs very strong. I don't know how to post a video within the file size limit.

quote:

Originally posted by René #4406:

quote:

Originally posted by PanteraDoug:
Mine look like that as well including in my 347 Windsor.

Your plugs would indicate to me that the idle is way to heavy on your induction. The light side is about right.

This dual reading happens because one side is facing the intake valve, the other is facing the exhaust valve.


One thing that you will find as helpful is indexing the plugs. All plugs should read equal and the defining line should be right down the middle of the plug.


I define that as, the tip of the plug needs to point directly at the intake valve. In order to do that you need to use shims under the plugs.


The racers that I know say this is MANDATORY to get the engine to operate properly and state that they have dyno proof of 15 to 20 hp differences between indexed and non-indexed plugs.


IF you are running Webers, try going to .60F/.80-.85-.90idle holders. The .70f are too heavy.

Excuse my bad English but the "tip" of the plug is the earth electrode?

Today I was on Panonia Ring .
After about 18 mins on the track the engine lost a lot of power. So I make 2 slow turns and after that the power come back.
I do not know what this was.
The engine sounds ok.
No smoke at the exhausts or at the breathers.
Maybe a to lean air mixture ?
At full throttle the engine runns normaly great also at half.
But when I go back from full throttle to idle in race conditions I have a lot of backshouts in the exhaust system.
Is this normal ?
Thanks
Peter

Nice looking car!

Peter, it sounds a lot like you ran out of gas. I don't know what your engine uses, but be aware that if you're using stock Pantera fuel lines starting with the fuel tank pickup, they are too small in diameter to support much more than about 400 horsepower even if the tuneup is perfect. The carbs will literally run out of fuel after a few minutes (at high rpms) with all-stock lines, and it will happen quicker if you have used some sort of fuel pump pressure reduction for your Weber setup, along with a mechanical fuel pump. While Webers can be adjusted to run at 2-3 psi, a 351-C needs large amounts of volume! I once 'fixed' a real 289 Cobra at a track by simply removing the fuel pressure regulator- which was actually a fuel restrictor- and the car instantly gained 3000 rpms in top gear! I use a 3/8" OD fuel line on my altered Pantera's late fuel sender, in place of the less-than-5/16" OD stock setup. Big lines from pump to carb(s) is good but the engine needs big lines all the way to the fuel down in the tank. Just a suggestion-

I have to agree with BW. It sounds exactly like you ran out of gas. It's a little strange how it happened but has the out of gas symptoms.

The Shelby race Cobras never used a fuel pressure regulator at all. they ran the cars at 5-7 psi depending on what rpm the engine was at.

At 3500 rpm you would likely see 7 psi and at the red line, likely 5.

It is absolutely normal for these freakin' things to backfire through the exhaust when you suddenly close the throttle like you would decelerating going into a turn.

I never could figure out why but ALL of the
Weber equipped cars do AND if you are behind one you will see a small flame out through the exhausts.

Have someone start the car in the dark for you while you watch the velocity stacks. You will very clearly see flames in the carbs. It's really freaky.

My neighbors kids, when they were small always wanted to watch me start the car in the dark. They would start screaming in joy at seeing the exhaust flames.

The real danger of running dry on fuel is at wide open throttle. The engine will suddenly backfire violently and it's to the point that it will bend all of the throttle shafts.

My opinion is that when you are racing the car, your fuel supply should be unrestricted but no more then 7 psi.

You can do that by using a 7 psi electric fuel pump that feeds a Holley HP mechanical pump. Neither pump will give you more then 7psi either individually or together in tandem

On the street you are PROBABLY safer with a fuel pressure reducer? Probably. I have no way of proving that scientifically though.

If you haven't already installed glass ball inlet valves, you need to. It's not a bad idea to use the solid nitrofil floats either but you can only get them from one of the VW racing guys here in the US.

That way there is no way you can collapse the brass floats or overwhelm the original inlet valves. The original Weber ones were always questionable. I don't know what they were made out of but at least Holley uses Viton in their's.

The glass balls don't care about ethanol in the gas. The "rubber" ones do.

I love the picture of the car. Great shot.

I have not had the fuel starvation problem but flames through the exhaust was a constant condition in the early years. Scared my wife and the cat the first time it sent out foot long flames.Now that the car is mostly for show and road fun I have tuned it for that. Your car looks fine.

quote:

Originally posted by Tom Kuester:
I have not had the fuel starvation problem but flames through the exhaust was a constant condition in the early years. Scared my wife and the cat the first time it sent out foot long flames.Now that the car is mostly for show and road fun I have tuned it for that. Your car looks fine.

Spark Plug

More plugs

The color of the plug is good but according to my experience is too hot to run even on a street car.

I'm very surprised that you can use it.

Using the Ford Motorcraft chart as a reference, the coldest plug to run would be a 22. That plug will very quickly foul at idle. It would be useful for a track only plug and takes about 3500 rpm to clean them up.

The 32 is a good compromise and I have run them on the street with no problems and on the track to over 7,000 rpm.

The 42 is useful with something like aluminum heads and Webers IF you are having problems fouling the 32's.


I am using an NGK BP6ES. If you look at where the BP6ES NGK matches up to other plugs heat wise, it's hotter then the 32 but cooler then the 42 so it makes sense to me why it runs clean for me.


I suppose it is possible to come up with various alternatives but I stop when I find something that works.

An Autolite 3923 is in the 347 in my GT350. It's got AFR aluminum heads and two 600 cfm Holleys on a C60E Ford Trans Am intake. The plugs look about right so far. Cleaner then the Weber plugs but the same heat range.

That Autolite plug, 3923, will also work in a Cleveland with aluminum heads. It just uses a 5/8" spark plug socket rather then the 13/16" on the NGK.



IF you are using a high energy ignition system, there should be no need to increase the basic temperature of the spark plug.

Long ago I had tried to make MSD ignitions work and for the most part, they don't do what they are supposed to do and certainly are very unreliable.


The Ford solid state igition is a good system but it won't fire a fouled spark plug. With tuning Webers that often is a problem since it is so easy to go to over rich in just one jet change.


The best solution that I have found to use the the Pantera-electronics system since it will fire and then clean up fouled spark plugs. This helps tremendously with tuning a Weber carburetor system.


These are just my experiences, not necessarily a formula for anyone else to run. Obviously others have had different results.