Vintage GT350 Weber manifold with Webers

[6s2055]

When I bought CSX2192 in 1967 the Webers had a fuel log in front and each fuel line was black rubber.....gas line. No steel lines back then.

[shelbydoug]

When I bought CSX2192 in 1967 the Webers had a fuel log in front and each fuel line was black rubber.....gas line. No steel lines back then.

Yup. Everyone calls that the FIA fuel log now.

What's interesting with the factory Weber set up is that there was no fuel pressure regulator at all.

Whatever the fuel pump was kicking out is what the carbs got.

I would be interested to see how they dealt with isolating the carbs from engine heat.

It was similar to this one but just normal period fuel line connections to use with hose clamps. This one is Cobra Automotives to use with -6 AN fittings and hose.

The same basic concept though.

[Dan Case]

What's interesting with the factory Weber set up is that there was no fuel pressure regulator at all.

Whatever the fuel pump was kicking out is what the carbs got.

I would be interested to see how they dealt with isolating the carbs from engine heat.

It was similar to this one but just normal period fuel line connections to use with hose clamps. This one is Cobra Automotives to use with -6 AN fittings and hose.

The same basic concept though.

Most of the time SA just used and sold the thin off white celluloid paper gaskets made locally to SA by Miller Manufacturing. To me they were totally wrong gaskets as they were very weak. Strong suction pluses would literally pull the gaskets into the bores if the mounting nuts were not sufficiently tight. I have pictures I took of a system Bob Johnson used that sucked in two gaskets to create severe vacuum leaks. I have purchased two unrestored intact COBRA systems with early carburetors and Shelby race shop hardware. Both of them had at least one original Miller gasket sucked in. Look close, you can read Miller on the gasket. I contacted them years ago but they didn't have records going back into the 1960s.



SA and SA supported Cobra racers sometimes, but not always, used thick asbestos gaskets. I have one used original set and one new old stock factory set in my samples collection. Occasionally, SA used thick GT40 engineered material spacers and two thin gaskets on at least one team car.  (I have never had one in my hands but I am guessing a phenolic compound of some type.)

[shelbydoug]

One of the early stops alone the learning curve with Webers that I had was that the carbs had to have heat isolation or they would flood.

I don't even know how Bob Johnson could run the setup with those gaskets?

In fact in addition to the thick asbestos gaskets, the glass ball inlet valves were needed.

Johnson's set up is a contradiction of my known facts. That's a stunning revelation but actually disturbing to me. I'm afraid to start the car now? 

Thanks for posting the picture.

[Dan Case]

I would have to dig out the data but cylinders with sucked in gaskets on two works systems I took apart had very different jetting than the others so somebody knew something was wrong.
   

I had base gaskets made (water jet cut) by a local gasket, hose, and seal company that served many of the manufacturing plants in North Alabama. I chose an industrial gasket stock I used for decades in high pressure chemical processing. It worked for all kinds of harsh chemicals and could withstand 3,000 psig  or millions of cycles between 200 and 1,100 psig between bolted flanges as ring gaskets. It could also withstand vacuum.  Plus it is reusable as long as it was not cut or physically damaged. Since then I have seen others use the material in other rare systems like box ram intakes and gasket sets for AUTOLITE® in-line 4Vs.


Thermoseal® KLINGERSIL® C-4401

[shelbydoug]

I would have to dig out the data but cylinders with sucked in gaskets on two works systems I took apart had very different jetting than the others so somebody knew something was wrong.
   

I had base gaskets made (water jet cut) by a local gasket, hose, and seal company that served many of the manufacturing plants in North Alabama. I chose an industrial gasket stock I used for decades in high pressure chemical processing. It worked for all kinds of harsh chemicals and could withstand 3,000 psig  or millions of cycles between 200 and 1,100 psig between bolted flanges as ring gaskets. It could also withstand vacuum.  Plus it is reusable as long as it was not cut or physically  damaged. Since then I have seen others use the material in other rare systems like box ram intakes and gasket sets for Autolite in line 4Vs.

Does that material have heat isolating/transfer limiting properties?

I've only seen asbestos gaskets about 1/8" thick for IDA's.

Holleys are different. They are using some type of a compressed paper material with some type of a rubber/plastic compound" o-ring around the carb mounting studs.

They are not as good as the "Weber" materials and as I write this, are still causing heat riser/transfer issues.


Not to pick on even factory teams of the era, but there was a steep learning curve with likely very little development time available?

What you showed me from Bob Johnson's car just looks like a DNF across the board to me?


I was shown that car specifically when Ken Eber had it in his garage in Chappaqua. It had the early sand cast versions of the pre-IDA's on it.

CSX21?? something..."first Cobra to win a race!" etc, etc, etc. I know the number, just don't recall it at this moment?

I never heard it run.

Although I was allowed to look, there was real danger of having a stun gun used on me if I was deemed too close. 

[Dan Case]

I don't recall heat transfer data. I use to know during my former industrial work life.

If we go out for an hour or so, pull the top of the carburetor right next to the coolant expansion tank (the carburetor that gets the warmest), we find carburetor bodies relatively cool to the touch and fuel in the bowl around 85°F. It takes several minutes after shut down to reach boiling temperature, which at 5,400 feet is right around 115°F to 124° depending on brand and grade of fuel. For test session purposes, we use external gauges to watch fuel level before start cold, during start up, engine running, and what happens during heat soak after shut down. We worked the fuel level down until boiling at the worst period of heat soak wouldn't over run fuel out auxillary venturi passages and down the into the engine.  (The same post shut down fuel boiling was a problem in our car with a 4V and the solution was to lower running fuel levels just enough. Some of the folks around here with got fast cars only use electric pumps which they can shut off and run fuel out of their carburetors before shut down. Some others just converted to closed systems  fuel injection.)

I was concerned that main system start would be delayed too much but it was fine. Our mains are working by 30 mph in fourth as evidenced by changes in main fuel jet sizes result in the predicted changes in air fuel ratio (we have sensors in each header collector).

[shelbydoug]

You are trying to make my head explode aren't you?

[shelbydoug]

Weber insulating gasket. Looks mostly like an asbestos alloy. No way it can get sucked in. It's rigid material.

Now I need to put this back on my car. 


In my experience, you want to keep the fuel levels high, not low. IF you should have the misfortune of running the bowl dry under WOT, you will "backfire" through the exhaust.

IF you are LUCKY, you will just blow the muffler up, literally. IF NOT, you will punch a hole through the piston.


As was pointed out by Drew in regards to the Holleys, the float needs to drop a certain amount to open the valve completely. The only way you can do that is to keep the fuel level high enough to provide adequate float drop and consequently full valve opening.

So he is saying it "different but the same" (thanks for that phrase Bob) then me.


He also said something about so many Holleys having TOO MUCH fuel pressure, They only need 5 psi. The same is true of the Webers.

[98SVT - was 06GT]

Does he still have the Mini Lite wheels? I'd like another set of those. I let mine get away years ago.

[SFM5S000]

One of the early stops alone the learning curve with Webers that I had was that the carbs had to have heat isolation or they would flood.

I don't even know how Bob Johnson could run the setup with those gaskets?

In fact in addition to the thick asbestos gaskets, the glass ball inlet valves were needed.

Johnson's set up is a contradiction of my known facts. That's a stunning revelation but actually disturbing to me. I'm afraid to start the car now? 

Thanks for posting the picture.

Doug,

For a street driven car your comment regarding the necessity of a heat isolating gaskets definitely applies, but for a pure race car such as Bob Johnson's Cobra I can understand the paper thin gasket such as the photo Dan Case posted. The race car would be running flat out for 1 1/2-2 1/2 hours or however long the event would be. The car wouldn't sit long enough typically (except for an unusually long pit stop for some reason) ambient temperature fuel would be constantly running through the carburetors. That would be my explanation for the thin gaskets.

Cheers,
~Earl J

[Dan Case]

To the original poster. I apologize for hijacking your thread. You have a neat period accessory. I'll stop with this reply.
Dan

In my experience, you want to keep the fuel levels high, not low. IF you should have the misfortune of running the bowl dry under WOT, you will "backfire" through the exhaust.

Stock bore, ex-Le Mans Shelby team GT40 heads, Le Mans cam, headers, and 11.6:1 SCR.

12.7 - 13.1 AFR during a long WOT run and the fuel pressure only drops about the width of the pressure gauge needle so the stock pump keeps up just fine on a hot summer day.  Filling the bowls after an over night or longer dwell restart takes some seconds where there is only about 1 to 2  psig of fuel pressure at the fuel log indicated until the bowls fill so there is plenty of float drop. I am using 2.50 valves out of a SA customer's 1965 race engine.

Multiple issues can lead to high rpm WOT lean conditions, live running fuel level is just one. As long as the main starts as soon as you pass the last transition port and doesn't stop until throttles are closed again, that is all that is required and that is easy to check (oxygen sensors systems are real handy). 

I assisted two Cobra owners that were running out of fuel to the point of engines died over about 4,000 rpm and in both those cases they had kinks in the fuel line between the pump and engine and didn't know it.  Reworking the lines into long curves did the trick. When we bought out red car it would run out of fuel with a small 4V the first two drives around the neighborhood. You may have guessed, but a hose between the pressure regulator the former owner used and the carburetor was way too long and doubled into a kink against the left side inner panel.  Shortening that hose solve that one.


One of the most troublesome details about these carburetors is doing the bench needle valve and float settings E. Weber outlined only gets you running. The factory literature indicates that you were suppose to check the actual liquid level and adjust as required. Every 0.001 inch change in needle valve setting, gasket thickness, or float tang setting means a 0.005 inch change (in significant figures) in wet fuel level. I laid everything out in CAD to test the math and then we did of experiments with a carburetor in our car. It worked perfectly and made changing levels a math equation and a few minutes to make the changes and verify the results.

One day I weighed and measured  all the floats for three sets of carburetors. I tried to check the angles of brackets to floats the best I could. I picked the six closest to each other in every way and sequentially installed them into a single carburetor. The body had an external sight gauge installed. Surprise. The live fuel level with three floats was within experimental error the same. One float produced barley higher liquid level. One float provided slightly lower fuel level; I would not have tried to change it. One float allowed so much fuel in the sight gauge overflowed.  We made several repeats and even tried that wild float in the car. The wet fuel level range I could measure was 0.4 inch lowest to highest with six floats I tried to match by physical measurements.  One carburetor six floats and different results.  I suspect that is why the  E. Weber company recommended check actual fuel levels in the car.

I experimented with that wild float several hours one day. My conclusion was that the bracket attached to the float was bent a few arc seconds from where the other five were. I tried changing that angle a tiny amount but always over shot; one bend would make fuel level super low and the next might have fuel over flowing.  The only solution I could think of was design and build a fixture with jack screws to slowly adjust the angle until live fuel level matched the others.  Interesting idea but not a priority  to spend more time on as floats are cheap relatively speaking.



Bystanders around when we start the car are typically disappointed that the engine is easier to start cold or hot than most stock 289 powered cars of any kind, cold or hot the engine settles into a smooth idle quickly (no jabbing of the throttle or extra rpm required), and running at idle it is not as loud as most of the 1960s hot rodded cars they might know. The mechanical valve lifter and rocker arm sounds are the only clue the engine is not a demure stock 289 2V Fairlane engine. Some seem to be disappointed that leaving a parking place takes no more effort or created no more drama than leaving a parking spot in our 2015 Ford F150 pickup truck.  In all respects except fuel mileage the red car with 4-2V is much easier to use than the black car with 4V. I used to think the black car was quick. It would out run anything small block with fenders at Hallet except GT40s and a Genie sports racer somebody use to bring. The Pantera with Webers that showed up one year sounded good but it was not tuned well and I passed it. The red car with 4-2V makes the black car seem like a really old antique with a four cylinder engine. The red car is fun but took a lot of development and learning to get there for all around ease, great manners, and exciting acceleration. It was fun to experiment, develop, and learn. I don't know that I would do another engine though.  The plug and play fuel injection systems make life so much easier especially if you drive been near sea level and the top of the Rocky Mountains and use whatever fuel you can find on the road.


I tried using 4-2V just as SA put the systems in use. The engine was a fine on off switch but road manners were horrible. Right out of the box as new WOT was fine, every other situation left something to be desired. These systems won't be worth the effort to many people and they won't like the nasty manners they had as SA used them.

[shelbydoug]

I've never run these carbs under race type conditions so I'm not aware of the significance of this "issue".

I am constantly glared at by my 32 year old son who constantly tells me that carbs are BS and a total waste of time on this type of detail.

I do readily admit that I spend entirely too much time on trying to get float levels just right. Holleys are just the worst there is. You get them right, then the car sits a week and then the inlet valves stick...yet again.

That just doesn't happen with glass ball valves.


Earl, at some point the engine needs to be shut off and I would lay heavy money on these carbs as set up by the factory as erupting like Mt.Vesuvius but with gasoline.

Personally, my approach was always to make them safe to use in a street car and getting race performance out of them. That's just me.


At this point, exactly what the factory did to race them is purely accademic ALTHOUGH, yes Dan, I did write that I'd like to see the factory set up but frankly, "I wouldn't send a kid up in a crate like that".

With that remark, someone might say "you don't know anything". Fair enough but maybe the answer is I know too much?

[pbf777]

,,,,,,,,,, but for a pure race car such as Bob Johnson's Cobra I can understand the paper thin gasket such as the photo Dan Case posted. The race car would be running flat out for 1 1/2-2 1/2 hours or however long the event would be. The car wouldn't sit long enough typically (except for an unusually long pit stop for some reason) ambient temperature fuel would be constantly running through the carburetors.

Cheers,
~Earl J

      Actually, under any reasonable load to W.O.T. one would find that the carburetor(s) and intake manifold port runner castings will be found to be significantly cooler than the surrounding ambient air temperature as the combination of throttling, this creating the effect of expansion and reduction of density of the incoming atmosphere, and, this coupled to the vaporization process involved of the atomized fuel particles/droplets emanating from the carburetor(s) within this air stream these both creating a significant cooling effect.             

      Where's that airplane engine guy, John, he for sure understands about carburetor freezing/icing !         

      And with the above understood, and one look at the not so substantial  pair of ears of the intake to support the Weber's, then one is led to believe the original intention was to have a thin sealing gasket, not to permit the use of a thick pliable filler here, which even with instruction would inevitably be over torqued causing distortion to the ears, and failures in sealing or even casting breaks.  That is if one is going to attribute any foresight capacity to the designers anyway?           

      Scott. 

[shelbydoug]

The cooling effect is so good, that the carbs will ice up anytime under about 40 degrees.

Different considerations for street or race. "Necessity is the mother of invention". Street use requires "improved" engineering.