86 F150 302 t18 4spd DSII swap. Holly 4160 600 CFM 4bbl. I think it has to do with the carb tuning but I'm not sure. It will pull fine and strong in 2nd and 3rd no pinging whatsoever, but try to speed up in 4th gear and sounds like marbles in a can. Timing with the advance unplugged is at 4btdc, and I don't want to go much lower. The timing does advance like it should with the vacuum hose attached. I am running 89 octane fuel. I don't know much about carb tuning. What can I do?

 

Sounds like you don't have the EGR installed, either. Did you have your distributor's advance mechanism re-curved?

 

No I did not. The intake manifold is one from Jegs with no provision for egr. Do you believe the distributor advance was set up for egr. Is a $60 orielleys reman I asked for one from an 82 model.

 

It could be timing. If I leave the vacuum advance disconnected and set the timing to 8* or 9* and drive the truck it won't ping in any gear, it is just down a little on power.

 

I think I just answered my own question. I love doing that. I don't think this dizzy is adjustable. So should I get the mechanical adjustment kit springs and weights and stuff? I read a thread in the engine forum about adjusting the mechanical advance. Or do I need a different distributor?

 

With no vacuum advance and base mechanical set to 13* the truck runs great and pulls in any gear with no pinging, however it does not want to start while it is warm. I have the 12v start bypass hooked up and that helps but it still drags. So I guess I need less vacuum advance correct?

 

On your DSII swap, did you hook the white wire from the module to the "s" terminal of the solenoid(the red/blue wire)? That should help your dragging when hot problem.

Your pinging problem is the vacuum advance unit, it advances too much. Go to summit or jegs and see if you can buy one that will fit that is adjustable. Then you can tune the ping out, and still leave the timing up around 13.

 

Not sure if it makes any sense to re-invent the distributor curve unless you've got fancy heads, and exhaust, and intake, and carb, to match. A better bet might be to study the vacuum advance and make sure it's hooked up correctly. In certain applications the vacuum to the advance goes away under lugging acceleration, thus retarding timing to eliminate ping. Then, once the RPMs are high enough, the mechanical advance comes in.

I also second what ctubutis said about a properly functioning EGR helping with ping. I don't know about yours but my EGR is mounted on a spacer that goes between the carb and intake.

Speaking of carbs, there isn't much you can do to tune a 4160 from the outside except idle speed, IDLE mixture, choke, and perhaps change the spring that controls when the secondaries open. Internally you can play with the jet sizes and change the power valve to something that opens at some other point, but what good is it to exceed the ideal air / fuel mixture? It won't run any better if it's too rich and you'll only waste gas.

A quick search turned up these specs for a stock 302:

190 HP at 3800rpm and 285 lb ft of torque at 2400rpm.

If these specs are correct, tune accordingly.

 

It sounds like 13* base advance may be too much, especially if your going to run vacuum advance on top of it. But Franklin makes an excellent point about the DSII retarding the ignition timing while cranking (provided it's hooked up correctly).

The idea of an adjustable vacuum advance unit is also intriguing.

 

Upon investigating the timing issue I realized the carburetor is functioning correctly. I believe the problem is strictly timing with the vacuum advance. My setup is not what the distributor I have is setup for. I will have to adjust to fit my application. I am going to look at my ignition module wiring now.

 

Here's the adjustable advance from Summit. It's not cheap, but oh well.

http://www.summitracing.com/parts/cr...view/make/ford

 

I do not have a factory ignition module I have an aftermarket one. I read somewhere that some of the aftermarket ones didn't have the start retard function. But yes the white wire plugs into the red/blue wire that runs to the solenoid.

 

$50 a'int too bad.

 

Franklin, thank you! the PDF instructions for the adjustable vacuum advance is a wealth of information!

http://static.summitracing.com/globa...s/crn-271e.pdf

 

I figured that I would set the base timing back to 10 and adjust the vacuum as necessary.