the modified FI you have is this the dual air horn one or the older style that was cut down the middle and welded back together with the spaced out air horn?
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Questions on modified FI systems
I remember the dual air meter FI system on the Cheetahs. They started out with a '63 big plenum unit and installed two air meters (vertically) on a new top plate. The second (earlier) modified unit you mentioned doesn't ring a bell. Was it based on an earlier "small plenum" unit, and can you describe more precisely how it was modified? Also, what car(s) were these used on and are there any pictures published in the various books on Corvette racing?
Another question on the big plenum dual air meter unit from the Cheetahs. Airflow varies with the square of pressure differential, so by installing two air meters, the signal from each annualar venturi would only be one-quarter the single air meter signal at the same air flow rate. So what did they do on the fuel meter side to deliver the proper amount of fuel with the significantly reduced venturi signal?
Hope I didn't overload ya, Clem, but I know you've got too much information stored away in your mental achives for me to leave alone. Inquiring minds wanna know!
Duke -
Re: Questions on modified FI systems
the dual air horn ones were done at the old GULF research labs and the old style we split the dog house down the middle verticaly on a doall saw and ported the inside and the runners. we then welded it back togeather.spaced the air horn out for more air flow. the dual air horn job took a complete recalibration to adjust for the different air flow. this was done on the air flow bench and the chassis dynos at GULF.Comment
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Re: Questions on modified FI systems
the fuel flow was checked in a fixture on the beach that had 8 graduated clys that the nozzles shot into while applying vacuum and turning the pump with a external source.Comment
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Thanks! Question on Gulf.
I assume Gulf was involved because Gulf VP Grady Davis was and enthusiast/racer. Did Gulf get paid by GM for the R&D or was it strickly Grady who made the Gulf resources available to build better race cars?
DukeComment
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Re: Thanks! Question on Gulf.
there were GM engineers at GULF during some of the time. i do not know if they were working on the race program or just working on GM car projects. GULF did engine durability test for all car makers.Comment
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Re: Follow-up this Saturday
Great response! The unit that I am talking about was cut horizontally across the top and welded back on. It is a typical Model 320 C1 style flat-top. I don't have access to it until this Saturday so I will let you all know if there is an air spacer between the plenum and the SINGLE air horn. The weld itself is almost invisible, and when the unit was purchased in the early 70's at a swap meet, we were told it was modified by Mickey Thompson. I'll copy all the remaining part numbers for your interest.
LarryComment
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