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Best carb for my 454?

hmatiak

hmatiak

1/2 ton status
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Nov 1, 2004
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Savannah, GA
Looking to help my BBC breath a bit better. What have ya'll found to be the best mix of performance, reliability, and efficient? Thanks
 
I would probably go with the q-jet since you can get parts fairly easily, and with some tuning would probably be the most efficient carb you could run...My vote's for Old Faithful:D
 
I'd stick with a Q-jet for reliability reasons.

If you don't know what size you need, use this calculation:

Engine size x max RPM / 3456 = CFM

If that didn't make sense, multiply your engine size with the maximum RPM's it will see and divide by 3456 to get your carb CFM size.
 
I plan to pair it up with a Summit aluminum intake. Any decent gain to justify the money? This is a low mile BBC that i want to keep as good as it is. Havent done enough with big blocks to be sure if its worth it, just the lil 350 based stuff.
 
thatK30guy said:
I'd stick with a Q-jet for reliability reasons.

If you don't know what size you need, use this calculation:

Engine size x max RPM / 3456 = CFM

If that didn't make sense, multiply your engine size with the maximum RPM's it will see and divide by 3456 to get your carb CFM size.
Click to expand...

Ive seen that formula before, but to me it would make more since to calculate it at the rpm you will be cruising at and then maybe add a little for those times you will be puttin it to the floor.
 
Q-Jet - Reliable, good, efficient if you stay out of it, and parts are easy to come by.
 
I have a q-jet on my healthy 454 and it works as good as a carb can
 
It's hard to beat a Q-jet for all around performance. I've messed with just about everything and NOTHING beats a properly set up Q-jet on a motor under 450 horse. They do good off road (relatively speaking of course),flow up to 750 cfm, have good throttle response, good emissions, good fuel milage (again relatively speaking) and once tuned rarely need to touched again.

If you're building a bigger motor then round yourself up a 800 cfm Q-jet off of an early 70s Buick or Olds 455. They do good up to 500ish horse.
 
hmatiak said:
What CFM?
Click to expand...

Cant remember, I think it is a edelbrock 1903 if i remember right. Came off a friends 350 and he thought it was messed up so gave him a rochester then stuck that on mine and it worked pretty well.
 
hmatiak said:
Ive seen that formula before, but to me it would make more since to calculate it at the rpm you will be cruising at and then maybe add a little for those times you will be puttin it to the floor.
Click to expand...

Actually, you'd need to dyno the engine to see what CFM makes the best numbers.

Proven time and again, calculated theoretical CFM requirements aren't the end all. Otherwise, not sure how you'd explain GM installing 750 or 800 CFM's on just about every engine they made.

A 305 with an 800CFM carb is "overcarbed" with the common formula up until 9000RPM, and I doubt the Chev 305 used in a truck was expected to turn that much. I also doubt GM had no idea what they were doing when they put "large" carbs on "small" motors.

I'd suspect the formula is a hold over from early engines, and even halfway modern engine designs have rendered it quite often wrong.

You will be hard pressed to overcarb an engine with a Q-jet.
 
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