Correct Manifold for Comp Cars with Hi Rise Heads?

[richsd]

Originally Posted by Anthony

I believe this to be the correct carb, Holley list 3255-1 , 780 cfm, for ford 427 Hi-Riser race engine. The carb came as a vacuum secondary, although I know some were modified to be mechanical secondaries as raced by shelby. I don't know if they modified all carbs, some carbs, or only on a select few. They come up for sale on ebay every month or so.

Although many people think that the 780 cfm carb was used on comp cars this was actually not the case very ofter, 780s were used by some but more often a larger carb such as a 850 cfm was used on original comp cars.

[Byots]

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[FFR428]

[quote=Byots]Here is a picture of a high riser equipped engine in CSX3002 at Silverstone in late '64: http://www.clubcobra.com/photopost/s...0&ppuser=18204

Not to get to OT but...
What about that weber tunnelport intake in the next picture? I don't think I've ever seen a pic of that before! Do you know the history on those? That is just to cool.

G.

[Byots]

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[computerworks]

Dick Thompson ran the Essex car at Elkhart Lake USRRC in Sep. 1965, Laguna Seca USRRC in Sep. 1965 and Riverside L.A. Times GP in Oct. 1965...

...in OA class, not AP

[Cobra #3170]

Originally Posted by computerworks

Dick Thompson ran the Essex car at Elkhart Lake USRRC in Sep. 1965, Laguna Seca USRRC in Sep. 1965 and Riverside L.A. Times GP in Oct. 1965...

...in OA class, not AP

I looked at the car in 1965 at Laguna and it had a single 4 barrel, I was quite interested because I already had a deposit down on my car at the time. Although I am not positive, I think the car ran in both production and OA classes.

[Byots]

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[Anthony]

Originally Posted by Byots

Here is a picture of a high riser equipped engine in CSX3002 at Silverstone in late '64: http://www.clubcobra.com/photopost/s...0&ppuser=18204 The carb was an 850, as evident from the different shape of the airhorn relative to the 780. Period Ford documents list the 850 for the "7000 rpm" high riser.
.

What was (is) the Holey List # for the 850 cfm carb?

[Anthony]

Originally Posted by Byots

Here is a picture of a high riser equipped engine in CSX3002 at Silverstone in late '64: http://www.clubcobra.com/photopost/s...0&ppuser=18204 The carb was an 850, as evident from the different shape of the airhorn relative to the 780. Period Ford documents list the 850 for the "7000 rpm" high riser.
.

Well, obviously the air horn has been modified, as well as the choke plate removed. I believe a 850 holley carb has bigger throttle bores and plates compared to a 780, and I am wondering if the carb pictured is a "true" 850, with larger throttle bores/plates, or simply a modified 780 for greater airflow, being labeled as a 850, which would then not be a true 850, and probably not flow like a true 850.


I'll do alittle investigating.

[Byots]

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[Anthony]

Originally Posted by Byots

The choke plate was removed, as was on all comp car carbs, but that is not how the choke towers were milled when the carbs were modified. Here is an original period 850 comp car carburetor airhorn:







You can see how the original plating is still on the top edge of the airhorn, so it was not machined after original manufacture.

Nice close up shot. Obviously the carb was modified from a vacuum secondary to a mechanical secondary.

You wouldn't have a close up shot of the front of the carb? Showing the list #, date of manufacture ?

[PROFESSOR FATE]

I believe the number you're looking for is 2953. There's also a 2953-1. They were available in '65 and '66, respectively. They were probably intended for use on the 4V versions of the SOHC motors.

[Anthony]

Originally Posted by PROFESSOR FATE

I believe the number you're looking for is 2953. There's also a 2953-1. They were available in '65 and '66, respectively. They were probably intended for use on the 4V versions of the SOHC motors.

Thanks. You're right, holley did spec them at 850 cfm.

[computerworks]

Originally Posted by richsd

Although many people think that the 780 cfm carb was used on comp cars this was actually not the case very often, 780s were used by some but more often a larger carb such as a 850 cfm was used on original comp cars.

..can you share the data that backs that up? "More often" means more than 10 cars.

Very curious about that....

[richsd]

Originally Posted by computerworks

..can you share the data that backs that up? "More often" means more than 10 cars.

Very curious about that....

Well I am not a data collector so I don't know what to provide to back this up. 850 cfm carbs were the carb of choice for comp cars. This comes from people I know that worked on comp cars back in the day. The guy that does the work on my car and his father are examples. Their shop is full of a ton of Cobra racing history but it is not in the form of data that I can quote and post here. It is in the form of many parts from original comp cars, many stories, and many pictures. With each visit I make, I learn more about the reality of what was done on these cars in the 60s and during the racing days. If you would like to further your knowledge I would highly recommend a visit to them some day. You would see some pretty cool stuff, learn some new things, and likely hear some things that are not consistent with the typical views that have been posted more widely. Many of the guys that worked with the Cobras in the day have no interest at all in a forum such as this so the only way to learn from them is to talk to them in person.