I have a Q- jet from a '79 truck with a 305 and have it on my 350 now. the car runs fine and even passes emissions. my question is if I put in a 454 or 502 would I be able to rejet the carb to work on the big block?

 

Well, that depends. The displacement of a 454 is quite a bit more than that of a 5.7 liter. I think it's almost 2 extra liters if my math is correct.

Find out what the CFM rate is of your current carburetor, and then go looking around on the internet for what a 454 would normally use. And then compare.

 

AFAIK, all the 454's from gm since the late 70's came with 795cfm Q-jets - which is what I have. I was wondering if it was a commonly known fact which jets and rods to use to emulate the stock 454 Q-jet.

 

Oh hell yeah... if you have the same, or close to the same flow rate of a carb that came on the 454, then all you'll need to do is just rejet the carburetor.

You can get jets for EVERYTHING from NAPA.

 

Should bolt on and run resonably well, if a bit lean. The thing about carbs that the FI guys forget is that they are "high tech" in an old fashioned sort of way........ They are about 90% self-adjusting by their nature. They really don't have any idea what size motor they are sitting on- they only know how much air is flowing through them and to match that with the correct amount of fuel.

That being said, if the calibration of the carb was originally for a 305 you'll be on the lean side for the big block. If you shoot me an email with the jets/rods you have in it now I can make some suggestions to get you "in the ballpark" for performance use with the 454. Give me both primary and secondary rods and primary jet size.

 

ohh, that might be tough seeing as how it is sitting atop the 350 till it passes emissions. if it fails then the 502 will follow (next month). if it passes the swap can wait till next summer.

if you are still around then I will definately look you up for suggestions once I get the jet sizes ect it has now.

 

That's cool. Unless I get hit by a bus, I'll be around. Knock on wood.