Need help, still having engine problems..

[galen1970b]

ok, heres my problem, when i start up my 302, it will idle fine, then after about 10 minutes or so itll start to hicupp, through the carb. i can get this to stop by retarding the timing....but when i get on the throttle, it hicups right at first then revs up fine. and when i retard the timing so that it stops hicupping at idle it doesnt want to start...ive rebuilt my heads(had a shop clean put in hardened valve seats ect), changed to a electronic ignition(duraspark I), put a holley 4160 (600 cfm)on it...and still cant get rid of this problem. The vacum advance on the distributor is good and is hooked up to the ported side of the carb) ive checked and rechecked the wiring and firing order(15426378?..is that right..?)compression check and everytying (it was good by the way) this problem is driving me mad!!!, any help would be apreciated...Thanks

 

[mtkawboy]

Module or pickup unit in the distributer could be going bad. Seroiusly when it starts to run bad wire tie a bag of ice on the module and see if it runs better. I know that sounds crazy but thats how we used to pick them up off the interstate when they quit running at the ford dealer I worked at in the late 70's. They usually start out stalling when you turn right {dont ask why, I dont know} as the first sign of going bad. An awful lot of people would come in and want a carb overhaul because their neighbor told them thats what the problem was. We would ask them what it was doing first because if you did the carb they would come back saying it still does the same thing which they neglected to tell you to start with. Thats just my guess for what ever its worth anyway

 

[WheelHorse]

13726548 is the HO or 351 firing order.

ID recheck where you have your distributer dropped in at.

Bring it to TDC and check to make sure it is pointing at # 1 on the distributer.

Once you establish a base time.. check the advance.

Now, if it runs just fine where it is now; then where is the timing at in ten minutes?

popping through the carb can be a lean condition, but not after ten minutes, unless your drawing a vacuum in your gas tank. Not as likely to happen on an old vehicle as it is on a newer vehicle.



If this did this before your heads and it still does the popping after, I would hopefully eliminate the possibility that the vavle lash or lifter preload is set correctly, especially if you had the stud mounted rocker.

Check timing first.. with distributer check.
Check timing after ten minutes.. see if same

Proper valve adjustment?

Make sure valves aren't hanging up.. no one poured pepsi in your gas tank did they?

 

[galen1970b]

basically all this happened before i changed a single part, and it still hasnt changed after the gobs of cash Ive thrown at it......whitch means it wasnt a part....it was me not knowing what the hell i was doing....anyhow, Ive changed the distributer out, since the old ones vaccum advance dumped out. Today after ajust the electronic choke, i was able to get the truck on the road...allthough it would backfire and be generally unpleasant i could get the truck moving with little hassle( aprt from the intermittant backfiring) dont know if its from the carb though.. but anyhow im thinking it was a timing problem for the start. But I really appreciate all your guys input and it has helped alot, Thanks-G

 

[broncnaz]

I think your right about the timing problem. Whats your timing set at ? You may want to check your balancer it could have slipped and is showing the wrong timing. or the timing chain has jumped a tooth and is causing the timing to be off. You may want to set the timing by ear/feel loosen the dist and start the engine rev to about 3000 rpm and turn the dist until you find the smoothest running setting then tighten down and take it for a drive this usually works out to be about 12 degrees BTDC on my engine.
As for the back firing if its from the carb its usually just a poof that comes from under the hood and may cause the engine to jerk if its from the exhaust usually its just a loud bang and causes no stumble.

 

[galen1970b]

im definatly going to do that tommorow, my problem with the timing thing...is the the enging came out of a car so the timing marks are on the other side of the engine...which is covered by the water pump and radiator hose......and i really dont want to go out and buy a new H-Balancer...since pretty much the entire topend is new now.....(from heads to plugs) so ill get a Tach guage insteag and do that, but i do have a question.....Do i need to disconnect the vaccum advance and plug it to do this..?

 

[broncnaz]

I usually dont unplug the advance when I do it this way. May have to try that one of these days. But with no load on the engine I'm pretty sure the vacuum advance doesnt come into play anyways during this process at least not at a sready RPM.
You dont have to buy a new balancer you could intall a bronco pointer and remark the balancer they sell tape with markings that can be put on the balancer but I would rather etch the markings as its more permanent.

 

[ken75ranger]

You could mark on the balancer TDC where you can see it. Get an adjustable timing light and you can set it to 12 deg. You can get an adjustable timing light at Harbor freight for less than 50 bucks. Worked fine for me.