SprintCarDriver

With the engine combo I am running (350, KB 11.5 pistons and 6.250 rods) I had to index the plugs(older style heads). I have them indexed and on half of them I am still getting a little closer on the gap. I hope to be getting Alum. Heads in the future but need to correct this in the mean time. Any suggestions?

The carb (holley 750) is tuned close but I am getting a blubbering after cruising at a certian RPM for a while. If you jump on it, it is very short but noticeable. If you ease into it, like speeding up to pass a car, it is very noticeable and a lot longer. I thought that it might be trying to clear out the excess fuel, but the plugs look ok. I am still trying to learn how to tune this holley.

Thanks.

GWHITE75

You did not say much about the 750, condition, type etc., but let me throw out some quick things to check:

1. Vent tubes are not being covered by air cleaner cover.
2. Accelerator pump is adjusted properly.
3. Fuel levels are set properly.
4. Power valve is correct for you combination.
5. Fuel pressure is adequate.
6. No vacuum leaks.
7. Timing advance curve is set up for your combination.

These are simple and basic, but need to be checked anytime you change a carb or modify the motor.

SprintCarDriver

I have got to remember that not everyone knows what I have... :rolleyes:
The Carb is new. Started with the settings recomended by Holly sheet. Since then I have readjusted the floats (little too high) and mixture screws. The best I can do @1200rpm is 10lbs on vacumn. I did go to smaller jets as at the time was running too rich. The car still seems to be a tad rich at idle.

SprintCarDriver

ttt

GWHITE75

I just found this thread again, as I have not been looking at my past activity. Did you find the problem with you carb? You mentioned it was new, but is it a double pumper or a vacuum secondary? They have different circuits and flow characteristics. Was your motor running good before with another carb? If you can only idle at 1200 rpm's, your cam profile must include a good amount of overlap/lift. I have a few more suggestions, if you are still with the problem, but I am by no means an expert on these carbs, although I have tuned mine for years. An excellent person to contact is Lars. If this problem did not exist until you put this carb on, I think a little more work on the accelerator and power valve circuits can fix it. Also, because it was new, doesn't mean you can pull it out and put it on, I have had to clean out my new carbs before, due to blockages in some of the passages from handling or shipping, not that this is your problem, but "out of the box" doesn't always mean clean.

SprintCarDriver

The carb was running rich on the old engine. Too much fuel for the motor. I am in a holding pattern unitll I get the exhaust system fixed. I am hoping to put ann O2 sensor and check it that way. My #1 concern right now are the closing of the plugs after being indexed.

GWHITE75

Good luck with that. Did you know the shop that put the motor together? Were they new parts or at least parts you had before? I have seen where one head was angle cut and the other was not. Obviously the cylinder pressures were different on each side and this put his plugs closer to the piston on the angled side. Have you tried colder plugs or plugs with the shorter ceramic tips?