Are the rocker arms adjusted right? Sometimes if the lash is not set right, solid or hydraulic, the engine will shake and stuff like there is a timing problem. Had a buddy call me with a similar problem on his first rebuild job a few years ago and I checked it out for him, started with the timing and the obvious firin order and such and finally narrowed it down to a compression problem. He somehow misread his instructions on adjusting lash and had the valves all jacked up, some probably never closing fully and some were probably barely opening, had him snatch off the valve covers and ran through them real fast setting the proper lash and it ran like a top.
157 tooth 50oz is NOT a factory option. You need to buy a special flywheel to get that combination. You cannot go to AutoZone and ask for one. It will need to be a specialty part, such as Summit, Jegs, or e-bay. But if you are pulling wires and the engine is not affected, I think you have your distributor dropped in wrong, or wrong timing. I have done this several times before, with varying odd results. One time, it ran just fine at idle. Didn't want to accelerate like it should, but it would idle fine for a while, then every 30-45 seconds, it would just POP out the exhaust. It idled too good to be "out of time" so I refused to think that was the problem. But in the end, that was it. Smelled gassy, like it was running rich, and every 30 seconds...POP! but otherwise, smooth. Another time, it would not run smooth at all. It would idle, but only at high rpms, like 1000-1200 and then with a very heavy lope. I guess the Ford firing pattern is set up so that if you are off quite a bit, it will still run, but not right. Until you get it right, you are out of luck. Like I said earlier, this guy bought a rebuilt 88 5.0, dropped it in his truck, and tried to run it. It "ran", but not well, and spit and sputter like crazy. He gave up. When I got the engine, I pulled the heads and 2 of the 8 cylinders were still SILVER!!! Never fired on, and yet the engine ran a least a bit for him. I still say it is timing. Re-do the distributor, or try a stock dizzy to see if it will run, and cancel out the HEI factor as the possible culprit.
The flexplate I got was a cat brand 50oz 157 tooth. And I know my cam timing/degree is ok. This weekend I am gonna swap out the HEI with a points distributor that I know works, and if I still have the problem then I am gonna look into the rocker arms. I thought I had the valves adjusted right but this was actually the first set of adjustable rockers with polylocks I have installed, before these I had only dealt with shims and such. I had a set of proform full roller rockers that I got a long time ago and decided at the last minute to put them on. If its the rockers then I will need a good set of pedestal mount rocker arms because those are the only ones I feel confident installing.
I might take you up on that offer, Im gonna try the distributor swap to eliminate one possibility, if that dont pan out then its on to the rockers, if neither work then im gonna push the car into the Ohio river and let the fish have it.
I'd like to point out that the distributor will either work or not work. There should be no running rough due to a faulty distributor, unless you have a very used, worn out, and rusty unit. I would like to know how you broke in the cam as well. Did you prime the lifters before installing? Did you prime the oil pump? I am starting to think you wiped the cam or have your lifters set way tight.
The car pretty much fired on the first try, I immediately brought the rpm up to 2500-3000 and alternated speeds staying above 2000. The breakin went fine, no smoke or leaks, no loud noises and temperature was fine. Nothing really seemed wrong until after the breakin where we could see it at idle. The rpms wouldnt fall below 1000 and the timing seemed off. I backed the car out of the drive way and headed down the street. I immediatley knew something was wrong. The car shakes like crazy when accelerating, especially above 2800 rpms. I was too scared to drive it fearing I might ruin the internals so I parked it and it has been there ever since, which was early October. To hear the engine run it does not sound bad at all, it just sounds like the idle is too high. I tryed to check the timing but its all over the place and couldnt get a number off the balancer. The vibrations are so bad that I first thought the balancing was wrong, but after some closer examinations and some help from the neighborhood hot rodders I know that not all of the cylinders are firing. If not all of the cylinders are firing could this make the car idle high like its doing now?
My father said the same thing about the distributor "either they work or they dont" but then again neither me or my father have ever used an HEI. As far as priming, I primed the engine with a primer before starting and also before adjusting the valves. When the valves are closed I can jiggle the rocker a little, so I didnt think I had them overtight. When running all rockers move like they should so I believe all my lobes are intact. I guess what I need is to have someone do the valve adjustments for me, someone who has done it before.
have you pulled the plugs? pull them and look at them. some times they can tell you some thing. also if your running headers you should be able to tell which cyl's are or not firing on a cold engine. just grab ahold of each tube!
Everything we throw out, you got the right answers. When it comes to electronic ignition, it is pretty much either off or on. Points is where you can have "half-arse" operation. Could your harmonic balancer have spun the ring? That would explain both vibration and not being able to get the timing to settle.
i had purchaced a "cat" balancer when i rebuilt my 5.0 motor. when the machine shop went to balance it they said that it was a 28 oz balacer. so it exhanged it with another "cat" balancer and the machine shop again said that its 28 oz. the part numbers were for the 50 oz but they came with a 28 oz weight on them. i went with a different brand in the end. i never ran the motor with the wrong balancer. i cant see it causing a idle problem. i would suspect the vibration to be a higher rpm problem if it was out of balance. are you puting the plug wires on in the correct rotation. ive seen that happen. they should be put on in a counter clockwise postion. have you checked for vac leaks?
I have an HEI in my car. It works good. Do you have a solid lift cam, or hydraulic? If it's hydraulic, you need to have the cylinder on TDC, tighten to zero lash plus 1/2 turn. The vibration could be fouled plugs due to improperly adjusted valves. The high idle is probably a vacuum leak, but if you have an electric choke, could just be stuck on the high idle circuit. If it's a Holley it's an adjustment screw below the choke horn. The '86 has a 50 oz imbalance, where the earlier engines had a 28 oz imbalance. If you have the wrong flywheel or damper it will vibrate too. Also, if the ignition timing is too high, you'll have a high idle. Good luck with it.
Since you didn't assemble the engine - Have you looked at the cam timing? Maybe that is why the previous owner gave up. If the cam is out of time there is no amount of messing that will make it run right.
