So I just got an 84 4x4 pickup. It had an 85 block with an 84 head so I got a used head, rebuilt it and put everything together with a pacesetter header, an offy dual-port intake, and a Holley 390CFM four barrel. The sheet with the header said that it should be paired with about a 235CFM carb (based on engine CID and max RPM). The carb comes with .050 jets, does anyone know what size jets I should put in it to get it to run right? I have the screws in almost all the way and it acts like it is still too rich.

 

the stock carb is 326 cfm i believe. i dont really think a performance part would call for a 33% smaller carb than stock...dont make sense. best thing you could do is buy an air fuel meter. at worst, tuning from that info that could be close to whay you need.

 

the 22R can't suck that much fuel unless it's got forced induction -- i think even in most cases if you're revving it to 7000 it can only ingest around 300cfm. still, doesn't mean you can't gain some benefits from some bigger carbs(a weber 32/36 flows around 325cfm, while the 38 flows 390cfm).

i don't know much about the 390(or most holleys in general), but i think some celica guys like them. i've got a bunch of 2 barrel holley tuning info though. i think that if you're running rich(checking your plugs? an O2 sensor ain't a bad idea either) you'll need to drop the size of your jets down. summit racing should sell jet kits for holleys, and most speed shops do as well.

 

Well, I found out that the electric fuel pump the guy before me put on pushes 10-14 psi. The Holley shouldn't get more than 7. Basically, the fuel was pushing past the floats and running REALLY rich. I got a regulator and set it at 5 psi, plus I replaced the original .050 jets with .048. It runs really well now sitting still. Still a little rich, but ALOT better. The real test will be on the road as soon as my carrier bearing comes in.

 

I haven't heard good things about the holley either... I think the circle track carbs are 500cfm 2bbls, however...
They run that 390 on the early Z-car also... So your mileage may vary..
Stock carb is under 250cfm.
I recommend the 32/36 also...