DeTomaso Mailing List: February 98, Message #66
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RE>Intake manifold/carburettor 2/2/98 Cristiano, It would sound like you have a 73ish "spreadbore" intake manifold versus a "square bore" that would be found on earlier cars (70-72). As long as the secondary holes are larger than the carb bores, don't worry about it!..... If it was the other way around, then I'd be doing a die grinder thing or looking for a transitional spacer.... to deal with the port mismatch. If it really bugs you, find a spread bore Holley and be done with it.,.... You will see little difference..... except for at waaaaay top end operation! It has run until now, no reason to figure it would run any worse in the future... no? 03 Steve -------------------------------------- Date: 2/2/98 10:32 AM To: Steve Liebenow From: Cristiano Rossi I have on my car a standard cast iron intake manifold and a Holley 600 cfm type 4160. The carburettor has 4 venturies, each with a diameter of about 1.6". For the first time in the 14 years I have owned the car, I removed the carburettor from the manifold, mostly of curiosity. I discovered that the intake manifold has different sized holes. The two front holes are about 1.6" each in diameter, and the rear holes are about 2" each in diameter. The thick gasket under the carburettor is obviously made for the Holley carb., and the marks in the gasket show that the rear venturies are a little offset compared to the big rear holes in the manifold. My local "US Car Shop" says that they can provide a special spacer that is almost 1" thick to combine the manifold and the carburettor in a better way. If I buy this spacer, there will no more be room for my aircleaner under the cover. Questions: - Do I need this spacer? - How much extra power will it give me? - Since my car is a GTS, I have always thought that the Holley carb. was standard- mounted from the factory. Is it probable that the factory has mounted the carb. in the described way? Were the carb's on american cars (Mustangs etc.) also mounted this way? - Would it be an advantage - instead of installing the spacer - to install another carb. with 2" secondaries, which the manifold was obviously intended fore? Thanks for any advice. Cristiano Rossi thpnma 02869