Hey Guys,

I'm 19 years old, and I've been building my 71 lemans with my dad since I was 14. We've built a 455 and I've been running it for a year now, but I need to get a new carb. I've built quite a few q-jets that were never satisfying, and unfortunately I don't have the time to wait for a rebuild by Cliff's q-jets.

What kind of aftermarket carb will be great for street/strip? I would think something bigger than an 800cfm with vacuum secondaries? In the summer, I drive the car at least 20 miles everyday, so it has to be streetable, but I also do many type of racing with it.

Heres my specs:

74 455 block .040 over

forged pistons- stock rods/crank

Home ported and gasket matched #96 casting heads with 2.11 and 1.7 inch valves

performer rpm intake

MSD ignition


Any ideas would be greatly appreciated, thanks in advance!  

While I'm partial to the Q-jet myself, I can understand your wanting something that doesn't need work to start with. My suggestion would be an Edelbrock Performer 750 cfm, it should provide all you need and is easily tuneable with the kit from Edelbrock. I try to stay away from Holleys, especially used stuff.  

I can't remember if the oldsmobile and/or the buick engines from the 1970's had 850 cfm factory carburators. I do know 850 quadrajets were made in 1970. My 1970 pont. Grd Prix SJ had a factory 750 cfm on the original 455, I bent the linkage  a bit to open the secondaries earlier, and I bent the tab that prevented the secondaries from opening  during the initial warm up, this ensured my secondaries always opened up all the way and ensured it would open up when I floored it. I found that sometimes before I did this I would only feel passing gear when I floored it. Once I did this little modification,passing gear and Full opening of the carburator were acheived. Just make sure when the engine is not warmed up, don't floor it, it will probably stall. I've tried aftermarket carbs in the past, but the original 70 GP carb 750 cfm worked the best. If you find a 850 quadrajet new  make sure the linkage set up is the same as the one you are using now.  

I would also recommend a mechanical fuel pump mechanical or electric with at least around 8-9 PSI,(lbs per sqare inch). Electric fuel pumps, I've noticed work bettar for start ups etc..I,m not sure if they were in 1971 fuel pumps 8-9 psi. In 1970 The Pont Grd Px 455 had a 8-9 psi fuel pump. Ussually you mount the electric fuel pump near gas tank, you can take out your manual one, and purchase a gasket and cover plate to replace the removed mechanical one.  

Also I can't remember if they had HEI disributors in 1971, get one if you don't have one, more spark power, and you don't need to play around with the contacts in the non HEI distributers.  

HEI wasn't available until 75 on all GM cars, usually the advance curve needs work in the HEI as they were optimized for emissions. Don't forget to run a direct ignition feed wire to the HEI because the wire that feeds a points coil doesn't have enough voltage.
As for fuel pumps, most electrics are noisy and require the use of a regulator to keep the pressure down so the fuel pressure doesn't push the needle off the seat. They also need a sump in the bottom of the tank so they get gravity fed because they aren't designed to suck fuel up the draw tube. Probably the best way is to use a new stock or aftermarket mechanical pump  

Thanks for all the replys,

I was actually able to find a 1970's buick carb that is the 800 or so cfm type you had mentioned. My dad rebuilt it, but I think I may have messed it up while tuning it on the car, because it falls all over it's face when the secondaries open. Its using the stock jetting for that carb number according to a book I have, so I'm guessing it is the secondary air valves or something then.

I had a points distributer which worked well, but had just ok power. I then added a petronix kit which helped in driveability, and still went pretty good. I got an HEI from a neighbor, but it was very weak on the top end, which i assumed was the fact that it was an "emmsioned" distributor. So as soon as I get a little more comfortable with my finances, i'm going to buy an MSD distributor and MSD box just because i'm tired of messing with things...

So is an 750 cfm edelbrock enough for a somewhat non stock 455?  

Also, I have an edelbrock hi-po mechanical pump I got cheap and un-used at a swap meet. I think this should be ok for my setup though?  

I have a Pontiac 455 and i use a 750 Edelbrock and i couldn't be happier with it!! I use to have a Holley 750 double pumper and it constantly needed to be adjusted, due to weather temp. etc... it leaked all the time. I didn't realize how much i disliked the holley until i got an Edelbrock! and i couldn't believe the throttle response and reliability of the Edelbrock, my motor performance increased for the better!!    

i run a barry grant demon 750 on a roller cammed 455 ho with fantastick results msd ignition 3inch exhaust ho manifolds no leaks easy to tune no hesitation at all