Holley jetting recommendations

Ive got a question maybe someone has the answer for...


Ive got a 455 in a 71 GS. Its got a T/A 308S cam, 12.5-1's, race ported iron heads, T/A 1.6 rollers, single plane intake, Holley 850, 3500 stall converter and 3.73s.....all the good stuff. Im trying to dial in the carb and I wanted to find out what size jets/ power valves, etc.. I should be running. Whats the hot ticket for setting up a Holley on a 455 with this combo? Any tips would be appreciated!


Thanks,
Jason

 

Hey there Jim! Yes, carb is new. The carb has had the air horn milled off. But I know its a 0-4781. Im running annular boosters in it. Hope this helps.


Jason

 

Sure, its really just a weekend toy. I dont do any real bracket racing with it, but I do take it to the track occasionally. I was looking for some amount of street driveability, thats why I didnt go with a Dominator. When I was shopping for a carburetor, I told the carb shop what kind of setup I had, he recommended I get annular boosters. I think he said it was going to improve low to mid range throttle response. It did make a big difference over what I took off. I took off a 750 double pumper (0-4779) from my mildly cammed previous engine. Im sure theres alot more potential hiding in the 850. Im really more of a Quadrajet guy. Holleys are a bit of a tuning mystery to me. But Ive been learning (slowly). Mostly from my mistakes!

 

I dont recall offhand what the carb shop installed as far as jets. Im going to say 78 in the front and 80 in the rear (I should really write these things down). I would have to pop the bowls off to verify. There is a 3.5 power valve in the front because of the crappy vacuum at idle.

Jason