Quote:
Originally Posted by brendonak
Ha, not for a driver! I think I'll stick with the carb, hei, intake, and headers for now. Reliability is key and based on your truck that should do the power department some good.
When changing the intake to an Offenhouser, do you need any special studs, gaskets, hardware? What about carb linkage to the 390? Anything special?
Some day maybe do the TBI conversion
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The Offy intake is an aluminum clone of the GM cast iron intake, so it fits in the same configuration. It does not have any fittings for carb linkage, however. When I ran the Holley 390 [on the old engine] I fabbed a boomerang-like bellcrank on a special pivot off the right rear carb stud connecting with the '68 accelerator rod coming out of the firewall. It was a Rube Goldberg-type operation and at times I couldn't get WOT. Other times it jammed or tiny cotter pins broke off and caused control failure. It even "carb-iced" up once. Before I swapped engines, I changed over to a '72-style gas pedal and pull-type throttle cable. Much more reliable. Also, after a hard life of 25 years, the Holley gave up the ghost -- I couldn't get it to set up right on the new engine, so I bought an Edelbrock 500 CFM [Edl-1404] copy of the old Carter AFB. Good carb after some teething troubles with the metering rod springs. Maybe a little rich, but it's got juice!
As far as mounting the carb on the Offy intake... It's just like any other 4 Bbl on a V8. Good base gasket [I wet it down with spray PAM or WD40] new carb studs and nuts. Don't tighten them on too hard and use a 'kittycorner' alternating pattern. I like to mount the carb "sidesaddle" on an L6 with the primaries outboard. That way cylinders 1-2-3 get the same air/fuel mix as 4-5-6 throughout the acceleration cycle. Some people [Brad?] will argue that it doesn't matter. With the AFB carb, it makes tuning easy with the mixture screws accessible from the drivers side fender. With the Holley, maybe not so much.
If you're converting from the stock configuration, you need to lose the mounting guide pins on the head at positions #1 and # 8. They will unscrew counterclockwise with vice grips and PB Blaster. Replace them with 3/8-16 UNC header bolts or studs 3/8-16--3/8-24 and stainless or Grade 8 3/8-24 nuts. I like to use studs at positions #1, #3,#4, +#8. That way it's easier to hang the headers when you're mounting the 2 header pieces and intake. You'll still wish you had 3 hands.
