Vortec spark plugs
- Thread starter Mearl
- Start date
You need to make sure it squirts as soon as you move the throttle.......no dead spot.
If that is working as should a power valve change my be needed As Brad said.
If that is working as should a power valve change my be needed As Brad said.
Another thing to check......are you using the vacuum advance?
How do you have it hooked up ported or manifold vacuum?
Try one way or the other.
How do you have it hooked up ported or manifold vacuum?
Try one way or the other.
I'm certainly no carb tuning expert and maybe way off here, but maybe too much carb for the engine / gear combination??? What converter is in the car?
wristpin
Well Known Member
I read youre running a stock distributor so I'll assume that means stock advance weights and springs. That will cause a bog also. With that compression i would think you should be looking at 8°-12° initial and 26°-28° total advance. Fuel pressure 7psi max and fuel level right at the very bottom of the inspection plug. Have about .010 gap between accelerator pump arm and adjusting bolt so the carb isnt squirting fuel when it shouldnt be. Holley has several different accelerator pump cam profiles available so you may want to experiment with those also. The kits come with about 8-10 cams so you can tune BOTH front and rear squirters. Rarely do front and rear take same profile cams. Good luck.
Brad I will agree with all but the .010 gap in the accelerator linkage.....spec is .015 clearance at wide open between lever and bottoming the leaver in the pump housing.
Most Holleys need squirt as soon as the throttle plates move so it will cover the transition to the fuel coming out of the boosters.
Most Holleys need squirt as soon as the throttle plates move so it will cover the transition to the fuel coming out of the boosters.
wristpin
Well Known Member
You are right on that James, thanks for catching my mistale. It's been a very long time since i read what Holley says to set gap at. I set it with 6-7psi fuel pressure (engine running) and then eyeball the gap. I've found over the years that most Holleys have been set with that gap tight...some so tight there is almost no stroke...so the carb cannot be set properly until that gap is set properly.
I find the factory Holleys being the best for street driving with better driving manors that the off the shelf ones.
On all the Vortec headed engines that I've done[helping build #7 now] the total timing was 32-34 degrees for the best results.I suspect the power valve as well ,but a good starting point for jetting when using ethonal laced fuel would be 74-76 primary.Check what jet is in there while it's apart for the power valve.I'd suggest a #6 valve .That engines compression is likely just above 10-1,and that little Magnum cam should have decent vacuum at an idle.I've always had better luck with 750 cfm carbs.than I've ever had with 650's,I don't know exactly why.
I've had a little time to mess with the Nova today and I still don't know what's wrong but here is what else I have found. I checked the vacuum and have 16.5 inches at idle in park. The power valve is a #65, float level is right at the bottom of the hole. I messed with the dwell and it or the timing either one don't make any difference. It does this in park or in gear and if I step on it quick and hold it, it dies. If I ease down on it, it will eventually go. I'm ready to put in the new gears but I don't want to do that until the engine is right.
What is the list # on the carb?
I would stand by the engine and wack that throttle open...and if I seen flames coming up out of the carb I would put my hand over it and see if it helped....if so I would throw some jet at it....now that being said with a BP and the wrong gear and converter you my not be able to just mash it to the floor and not expect it to just take it.
I would stand by the engine and wack that throttle open...and if I seen flames coming up out of the carb I would put my hand over it and see if it helped....if so I would throw some jet at it....now that being said with a BP and the wrong gear and converter you my not be able to just mash it to the floor and not expect it to just take it.
When you get the timing and jet right,you'll be able to hammer it from a dead idle in drive,even with a stock convertor,and have instant response.If it doesn't .you've not got the carb right.You may need to change to a 750 dp carb to achieve this,but I've done it on Eddies,Q-jets,and Holley 750 double pumpers,so it can be done.It just takes some tinkering.Set the timing at 34 total by 2500-3,000 rpm,hook up the vacuum advance,then put the primary jetting at 72-74,the secondary may need to go up to 80-82 as long as that carb doesn't have a secondary power valve.