its a 454 bored .030 over, 10 to 1 comopresssion, 230/236 dur .552/.555 lift cam, large oval port heads and a single plane manifold. how big of a carb should i put on it?

 

If you want all out power I'd say 850 CFM, if you want economy, 750 should be plenty. I'm running a 750 on my BB, gets me about 16 MPG on the highway without an overdrive gear (or lockup )... in either case if you're not reving over 6000 RPM it probably won't make much difference in power.

 

yea im afrid to go with the 850 with the single plane manifold, and with that cam im lookin at peak at right bout 6 k

 

Well if you look at it this way, there's plenty of people running around with 350's and 750CFM carbs running pretty well which is complete overkill. Worst case you might waste a little fuel.

That said, 750 CFM is plenty for a 460 CI engine @ 6000 RPM... I had a 900 CFM TBI setup which failed on me one day so I switched to a 750 CFM carb and there was no difference on readout of the the butt-o-meter... so if there is a difference in power output, the only time you'll see it is on the dragstrip or on a dyno.

 

Are you gonna do any searious racing???

I know several guy with built BB who have all one at a time switch to the
Holley 4150 HP 1000cfm Carburator as it gives you an extra edge racing for tenths againt similar cars. But none of them care about mileage and so forth, $5 gallon race gas gettin 7MPG

 

no, its nto a serious racer, if it was id have some retangle port heads and a huge solid roller, its a street car

 

Id just get a 750 Qjet then and save pennies for when ya wanna searious race.

 

or not, ive said i dont want a serious all out race car, this is going to be my fun street car, my goal was 500 hp and thats about where im going to be, im not going to dump all of my 5k investment and try to build somehitng totally different.

 

Sounds like an XE274 cam, right?

What intake are you going to use? If the powerband is somewhere around 2500-7500, you should use a torque converter that stalls around 2500. But, that cam doesn't really need a single plane, as an Edelbrock RPM would do just fine. If you stick with the single plane, an 800 CFM double pumper would work very well. If you go with a dual plane (RPM or Stealth, for instance), then go for the 850.

Any particular reason for the single plane? You seem set on that. As you said yourself, this isn't an all-out race car but a street car. The cam fits that scenerio. However, a dual plane would fit the cam and usage much better than any single plane I know.

 

yup thats the cam, im not really "set" on the single plane manifold but i firgued that the bb would have enough torque and the price diff of the intakes y not get the extra power? and im goign to be running a 3000k+ stall most likely

 

A BBC oval port Stealth is about $200.

Mismatching parts doesn't produce more power. The intake will hold back the powerband when the cam gets into its, and the cam will limit the intake when it tops out. All you end up doing is narrowing the powerband.

The stall will keep you out of trouble for the most part. But, the single plane will still make it doggy in the low RPMs. Most single plane powerbands start at 3500.

I'm running an XE282 in my baby Rat 396 with an RPM Air Gap intake. The converter stalls at 3500. I shift at 6200. You can see here https://www.thirdgen.org/forums/carb...tor-396-a.html the grief I took for considering going single plane. I'll be in a lot higher RPM power range than you (more cam, fewer inches).

But, I can say when I changed from an Action+ manifold to the RPM when I had a milder cam (270 advertised duration, .510" lift, single pattern), it did pick up on the top end without hurting the bottom end (because of the high stall speed).

 

well i have just been using desktop dyno as a feeler on what intake to use, and when i switched from a dual to a single plane manifold i picked up a singnifacant amount of power, i did loose a lil low range but not too much, i was hoping that the single plane would extent the range of the motor by 500 rpm or so, which would be nice even tho it would cut my low end( im guessing not to much of a problem with the 3000k stall?) would this be a pretty accurate thought?

 

Which oval port heads

 

781, 2.25/1.88 valves

 

I have an 850DP on the 454 in my Chevelle. It works perfectly for me.

 

i run a 750 on my 385.. i'd say 850 for your BBC..

 

Desk top dyno does not accurately model the performance of a Performer RPM dual plane. It understates its power. On your motor a performer rpm intake will only make a few hp less (if any at all) than a single plane and a ton more torque. The motor will feel a lot more torquer at part throttle as well. (nicer to drive) You'll be much happier overall with the dual plane on your motor. If your motor was more radical, say wth a 250-260deg cam then a single plane manifold would be nice.

I would not use less than a 750cfm carb. A 850 is not too big at all especially with a dual plane manifold.

The rpm range and max rpm point if more established by the cylinder head flow and camshaft duration than the intake manifold. the basic rpm range will be the same.
A single plane will just favour the higher end of the band, makeing a few more ponies up top at the expense of quite a bit of torque.

Haveing "been there done that" with a simular street oriented 454 I would go with the RPM air gap and a 850.
750 minimum. You can tame down the primary side of a 850 for better mileage on the street. (smaller primary main jet- larger PVCR size.)
It will not fit under the stock hood. The only BB intakes that have half a chance to fit under the stock hood are the stock cast Qjet flatty intake and the Edelbrock BBC Torker II 2-O.
The Edelbrock torker II sucks thou. Even the lowly Performer makes more power. And way more torque.

 

thanks alot for that response, i knew that the torker-2 was the olny option to get ti to fit under the stock hood soo i knew enough to ditch that idea, it sounds liek ill be usibg the performer rpm, does it help much to get the air-gap version?

 

If you can afford it, go for it. Its worth about 5 hp

Professional Products BBC "Crosswind" is a nice alternative. http://www.professional-products.com...uctBBchevy.php