Quadrajet Problem Solving > Dialing in your rebuilt Quadrajet carburetor

SP2P Intake

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77cruiser:
I put a RPM on a 305 that had a mild cam & headers, it felt better than with a Performer. It came with a 2 barrel, so I can't compare to that.

old cars:
I have no reason to doubt your pontiac tests. It would seem they were better designed (factory)than the chevys.

SBC after market intakes come in many designs and you need to match what you choose to your  build /use.
Of the basic 2 plane intakes I was referring to the the port shapes / corners play a big role in the improvements over the factory intake.

Cliff Ruggles:
I build and dyno SBC engines as well, or did until retiring from all that a few years ago.  The stock SBC intake is excellent.  Thru at least 1hp/CID it's a complete waste of time/funds to go aftermarket.  You may see a little more upper mid-range and top end power but almost always with a loss of low end and average power in the useable RPM range.

I'd like to have a nickel for every SBC engine powering a 4 x 4 Chevy truck that's been brought to the shop still sporting it's dished pistons, 882 heads topped with an Edelbrock Performer or even the RPM, and they owner is wondering why it's such a gutless "turd".  I refuse to get involved with those projects as there is no where to go.

I do a LOT of factory appearing work.  Even those flat Big Block Chevy intakes EVERYONE tossed aside for a aftermarket high rise intake are a LOT better than you'd think.

Recently I was helping an engine builder with a Factory Appearing Street Tire big block application, 1970 Chevelle 454 stroked to 496.  All correct factory parts used, my contribution to the project was the carburetor.  The engine builder also owned a dyno, and told me right from the beginning that the "Quadrajunk" and this POS flat iron intake would NOT feed his engine.  Dyno day came and it topped out at 424hp (he was expecting around 560-580hp.

Of course all the bad mouthing came, and the "I told you so stuff".  I went over a few things and he said it was DONE at 4500rpm's.  I asked him about the distributor and he said he built and curved it himself and "upgraded" to a Pertronix.  I asked him to remove it and go back to points/condenser.  He reluctantly did so, then called me back an hour later.........it made 567hp an nearly 600 ft lbs torque!

Not the first time I've seen one of those Pertronix act like a rev-limiter and I will not use them here........

Cliff Ruggles:
"I have no reason to doubt your pontiac tests. It would seem they were better designed (factory)than the chevys."

Keep in mind that the Pontiac iron intake is still considerably smaller than the RPM, over 1" shorter, etc and it made MORE power on a 440cid engine making right at 500hp.  There is a lesson to be learned in there someplace.  I swapped out the RPM on my 455 (makes over 550/600tq) for a ported factory HO intake and picked up some short times and quicker thru the 1/8th mile but not quite as much MPH.  So added top end charge at the expense of low end and average power does NOT automatically improve vehicle performance.......as we are often led to believe........FWIW....

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