Quadrajet Problem Solving > Quadrajet Parts and Numbers

Quadrajet Selection

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Cliff Ruggles:
Here's some cold hard facts, from dyno sessions we've made with engines prepared here, and track runs that followed.

The old 455 that powered my car produced 494hp and 514hp on the dyno with a recalibrated 1977 Pontiac q-jet on two seperate occassions, one of which was for a magazine article that made it into High Performance Pontiac and Popular Hot Roddings "Engine Masters" addition.  Several aftermarket carburetors (850 cfm DP carbs) were bolted on behind the q-jet on each occassion, and cranked out LESS power, apprx 2hp and 3-4 ft lbs torque. (back to back pulls)

Keep in mind here, that the q-jet was box stock (no sanding, grinding, knocking out casting flash, or porting in any way), only recalibrated exactly for the application.

We followed up the dyno testing by installing the engine back in the car and making track runs with it.  It ran EXACTLY .02 seconds and .30mph FASTER with the q-jet than the "big" 850 DP carburetor.

We've done the "back to back" swap with other aftermarket "high performance" carburetors, and in each and every case, they made less power and ran slower a the track than our plain old 1977 Pontiac Q-jet.

This testing included the Edelbrock 750 cfm "Performer" series carburetors, and the new "Thunder" series 800cfm units.

The most interesting part of some of this testing, was that it was witnessed, and actually asked for by representatives from magazines so they could write aritcles from the information.  Since we outran the aftermarket stuff, you will not see any of the test results in print, wonder why?......Cliff

omaha:
I agree with ya Cliff. It's hard to convince someone that a carb that you paid $20 for at the swap meet could actually outdo the carb that a person paid $300-$500 or more for. Sure you gotta add the cost for rebuilding, but even then it still is an incredible deal. All you have to add is the knowledge. That is what makes all the difference!   [btw; Cliff's book has the "knowledge"].

Cliff Ruggles:
I'm actually surprised that some of these aftermarket companies haven't put a contract out on me.  I've caused the demise of quite a few "high performance" carburetors over the years!

The other item that needs mentioned here are the intake manifolds.  Many of the factory intakes, even EGR versions, are excellent.  Aside from the weight, no negatives from using them, even for racing.

Right on the dyno, my slightly modded 1970 Pontiac cast iron intake, made 7 more HP than an Edelbrock RPM.  The Performer intake wouldn't even feed the 497hp engine we were testing.

At the track, I've tested the Torker, Street Dominator, Performer, and the Tomahawk intakes.  My iron intake ran .02 seconds faster than all of them.  The next best intake was the Tomahawk, with a 1" spacer.  It ran 2mph faster, but still slower in ET, showing how much low and mid-range power is lost when switching to a single plane intake.  At that time, my engine (455) was making right at 514hp/587tq, and the car was running mid-11's.  Imagine how much power one gives up on a smaller engine making less power?.....Cliff

omaha:
I never knew that [about the fact. intakes]. I'll keep the fact. iron on my 350 pontiac then!  ;D

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