Has anyone noticed a difference going from a quad to an Edelbrock?

[fawkes]

I have an 86 C20 with a 454 and SM465. Originally it had a quadrajet on it and ran good but had a hard time getting started (choke issue). The carb developed a leak so I swapped on a 750 Edelbrock, and the appropriate adapter and throttle cable bracket. It runs great, idles alot smoother than previously, and runs just fine down the road. But I've noticed that it just doesn't have the same amount of acceleration that it did with the quad. It used to be able to spin the tires in second and in first the acceleration would really push you back in the seat, but now it just seems lackluster. I know square bores obviously have alot smaller secondaries, but is the difference really this noticeable? Could it be vacuum secondaries of the quad vs the Edelbrocks manual secondaries making the big difference? Like I said it runs great, it's just doesn't have the same wow factor it used to have.

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[rich weyand]

Did you tune the Edelbrock, or just bolt it on?

You need to tune that carb to the engine.  An A/FR meter is the simplest way.

[fawkes]

Did you tune the Edelbrock, or just bolt it on?

You need to tune that carb to the engine.  An A/FR meter is the simplest way.

I messed with the accelerator pump, and of course idle mixture screws and all that jazz but I didn't swap springs or jets or anything like that. What would you reccomend?

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[rich weyand]

I have all the numbers on a 350, but no experience with setting up an Eddy on a 454.

Best is to get a wideband A/FR meter.  It's about $300, but you will nail the mixture.

[Engineer]

I'm not trying to be a smart allec, but, the Quadrajet could have been rebuilt for about the same price as the adapter that you had to buy to make the Edelbrock carburetor work.

I have very little experience with the Edelbrock carburetor. My son tried to run one on his '85 K30's 350. He never was able to get his to run right. I rebuilt his Quadrajet and he was happy as a clam. My '77 came with a pre-emissions Quadrajet on a 400sb. I moved on to a worn out 350 and finally a 396. It ran great on all 3 engines. When I built my 454 I went with a Holley just because the Quadrajet was going to be too small. Even though I haven't used it in 20 years I still have that Quadrajet.

I know this isn't necessarily the answer to your post that you are looking for, but it is my experience. I know others who have found the Edelbrock to be frustrating as well.

Good luck. Maybe you can get yours to work.

[75gmck25]

Adjusting the accelerator pump on an Edelbrock is one of the last tuning steps, so it usually won't make much difference on a stock carburetor.

For an Edelbrock the general tuning process is:
- check the float setting, and verify that you have no more than 5 psi fuel pump pressure
- set the idle mixture (just gets it running smooth)
- swap jets and rods to get the AFR you want for cruise and power modes
- use a kit to swap the step up springs and get a smooth transition from cruise to power (this should get rid of any part throttle bog)
- then adjust accelerator pump, if needed for a little more pump shot
- verify that the choke is working correctly

If you don't have new jets and rods, you can still usually fix a lean bog transition with higher (number) step-up springs. The higher number spring means it will transition to power mode sooner, which means you get the richer power mixture sooner.  The accelerator pump adjustment by itself is very unlikely to fix a lean bog.

I tried tuning an Edelbrock 1406.  However, I was not happy with the results measured with my wideband AFR, so I rebuilt a mid-eighties truck  Quadrajet with a kit from Cliff's Performance.  The Quadrajet consistently shows a much better AFR on my meter, and starts and runs very smoothly.  My Quadrajet is from an '86 1 ton C30, so it is one of the last carbs with no electric or electronic controls.

Bruce

[fawkes]

Thanks for the help guys. I would've originally kept the quad but it was missing a few parts and I picked up the Edelbrock for a song. I ran the Edelbrock for a month or so and I wasnt really pleased with it so I found another quad to use for parts and rebuild my original quadrajet. By the end of the week I should be back in business, thanks again guys

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