carb choosing for a 454

[bbc71]

i have a '71 k20 with a 454 that has a mild cam, headers, 10.5:1 compression and a edelbrock performer 2.0 spreadbore intake. I'll be driving this around town but not often so im not worried too much about mileage.

The carbs i have to choose from are an edelbrock performer 750cfm, edelbrock 800, and a rochester quadrajet 800. looking for best performance don't care about fuel economy. any suggestions?

[BMERDOC]

I plugged the info into a carb calculator using .87 V/E and 6000 rev limit. It spit out 689 so I'd use the 750. If you wanna run it on the dyno take the Edelbrock 800 with you. I did plug in 5500 as the rev limit too and it spit out 628 cfm.
The smaller the carb the less tuning you need. The bigger carbs mean less restriction (like a big bore throttle body). The smalle ones will have be snappier outta the box. Blah, blah, Blah. I could go on forever. Simple answer: Use the smaller one.

[VWBeamer]

The quadrajet is the best carb and flows the most. It will work best is you are willing to set it up correctly.

The problem is the 750 will be easier to tune and easier to get parts for. It's more than likely the best choice if you just want to bolt a carb on.

[landsurvey1]

I run a 650 Edelbrock on my 400hp, 454bb and it works great.

[prostreetC-10]

A K20 is a heavy pig and I'm sure you are no where near 6,000. Also, finding a carb to feed a max RPM when we go through the traps is one thing but how often do you hold it to redline???

Are you sure you are at 10.5:1 comp and what is a "mild" cam? It takes a lot of piston to get 10.5 with a 454's large open chambered heads. The 750 quad would probably be idea if you have or can get a good one. You'd probably be surprised how good the Edelbrock 600 would be on that motor, with that heavy truck. The Eddy 750 would work but probably not needed and certainly no on the 800 AVS.

How do you drive this thing? I had a 68 GMC 3/4 ton with a 460 BBC and a Holley 650 DP. I drove it like a 68 Camaro and it ripped with that little 650 (for a 5,500 lbs truck).

[BMERDOC]

Just givin an answer with the options he had! ; )

[prostreetC-10]

Originally Posted by BMERDOC

Just givin an answer with the options he had! ; )

Oh hey....no worries. I'm sorry if it came out that I was challenging your post. Sorry about that. You are dead-on with pick a step down in cfm and enjoy a snappy throttle, a little mileage and all the carb you really need.

[BMERDOC]

No problems, no worries...I know he's never gonna worry about 5500 to 6000rpm...right BBC71? Those were his options. I'd like to see a smaller carb on a mildly warmed over Rat but if those are his options then grab the small one. He'll enjoy a strong vacuum signal and a snappier throttle. Anyone in the know has seen a lot of over carb'ed motors with soot caked in the tail pipes.

[prostreetC-10]

About a month ago I built an 850 annular for a local guy. He was running a 406 and only hitting 8.0 in the 1/8th. His current carb was a Holley 750 4010 series. He bought the 850 locally and had me go through it. I knew it was too much carb for his application. He still wanted to try it. I told him he needed a 4150 carb in the same cfm. Needless to say his time went up instead of down. His engine builder said he needed a 1050. I about crapped. Do you know what kind of prep'd 406 you need to justify a 1050?

[BMERDOC]

You can lead a horse to water....1/8 mile? One answer..more gear!!HAHAHAHA!!!

[prostreetC-10]

I told him more cowbell. Actually he's running 4.56s which it's too bad for the 1/8th.

[bbc71]

i don't know the exact cam specs but its off idle starting at about 1200. the heads are hi-perf 427 100cc close chamber heads that makes all that compression.

but that quadrajet should give me the throttle response with the smaller secondaries. so it's basically come down to the quadrajet 800 or the edelbrock 750. the edelbrock is on it right now and runs really well, about a 450hp one. have the rev limiter on the msd box at 5000 for now till i get use to it and ready for more. ha