I am rebuilding a Holley 750 double pumper for my car and could use some advice on how to set it up. The car will be a combination street/strip car. I have a book by Dave Emanuel that lists the stock jetting but don't know if that is what I should use. It doesn't say anything about what accelerator pump cams to use or what position to install them.

Any advice on jets, power valve, pump cam and position, or anything else would be appreciate.

Here is some info one my drivetrain:

TKO600
3:73 gears
406 cu in small block
AFR195 heads
10.2 compression
Comp Cams XR288HR cam 236/242 @ .050
Performer RPM Airgap manifold
1 3/4" headers

If any additional info is needed let me know any I will get it.

Thanks for any advice.

I would get a baseline with 72 jets and a 6.5 PV for starters.

Get your floats set first, then after start up make your adjustments. Check for black smoke out of the exhaust, check the plugs, that will get you going in the right direction. Adjust from there.

Yep, use the set-up as delivered from the box.
Use a vacuum gauge for tuning and start the journey.
Larger than stock camshafts usually need more initial advanced timing.

I am rebuilding a Holley 750 double pumper

It doesn't say anything about what accelerator pump cams to use or what position to install them.

Any advice on jets, power valve, pump cam and position, or anything else would be appreciate.



Holley has made the 4779 for over 40 years. After the 4779, there should be a dash (-2, -3, -5..etc). The early 750s were 2 corner idles until about -5 I believe. Then they were all 4 corners. Some came with the rear PV plugged in the casting and some had the provision. All came with a 28 front shooter though many find benefit in stepping up to a 31. Whether a 600 DP or a 1,000 dp, I run the pink pump cam in the #1 position on all my double pumpers.

What can be tricky about rebuilding a carb and more over, rebuilding an old carb, is is it correct and should it be rebuilt. Gotta make sure a PO hasn't mis-matched parts/blocks/shooters....all that good stuff. A 750 seems just about right on for your combo. As others have said, best thing to do is start box stock and go from there. Holley gets them pretty close from the factory, usually a little on the rich side. Whatever you do, make sure your timing is correct before you go and try to fine tune a carb to your motor.

Let us know exactly what kind of 750 it is.

Dubs,

Thanks for the reply. The list number of the carb is 4779-3 and the date code is 3438. It is not a 4 corner carb and there is no provision for a power valve on the secondary side.

I know I am taking a risk rebuilding a used carb but I like to try to do things myself when I can. I learn a lot by trying new things. I would save myself a lot of grief if I would have someone who knows these carbs rebuild it for me but I never seem to learn.

I talked to Holley and got the stock sizes for all the air bleeds so I can make sure they were not altered. I don't know how to tell if the metering blocks are correct. I looked at them carefully and didn't see any part numbers on them. I will check the shooters and see if they are the correct size. I bought the Holley Trick Kit but haven't opened it yet. I think it might come with shooter but I don't know for sure.

Thanks for the tip on the pink pump cam. I will give it a try. Do you use the .028 shooter on the primary and .031 on the secondary? The book I have says these are the standard sizes for this list number.

Thanks again for all help.

Good advice by dubs he rebuilds alot of carbs. As for your main jets run the stock ones and tune carb at track by experimenting with which jets give you the highest mph through the traps. Increase till mph drops off then go back to highest. Thats the most fun way to tune a carb:thumbsup:

MW,

Like it has been said, "Get your timing set right first", Then start tuning your carb by setting the idle first, then the idle mixture screws (to read the highest vacuum at idle). Then work on the accelerator pump circuit and then jetting.

Most important tip I can give you is "Make ONE change at a time and evaluate that before making another"! If you make more than one you cannot get a good read on what it did for you and what it didn't do.

It is not hard as long as you go slow and I like to right notes on what I did and the results.