Need help with some cylinders not firing
 

Let me first explain what all I have done to help better diagnose the problem: The car sat for about 2 years because I was getting no spark (due to the MSD ignition box) and I had a leaky rack and pinion and some tranny trouble, but before the msd box went bad it ran fine. So I pulled the engine ( a 460) this winter, took off the heads, manifold, timing chain cover and oil pan so I could repaint them. I replaced the gaskets to those parts and put it back together and dropped it back in the car. I went with a new "Summit" brand ignition box and also bought a new Crane Cams distibutor to replace the MSD one and a new coil. My trouble now is, cylinders 5,6 and 7 are not firing. The header tube to #5 is warm to the touch, 6 and 7 are cold and 8 is hot. So far, I have messed around with the timing (which doesn't change anything with those cylinders) replaced the coil (again), swapped plug wires and plugs with good cylinders, rotated all wires around the cap a couple of times and re-adjusted timing. I have good spark to all plugs. I did a compression test of all cylinders (all were good), then tonight I just did a leak down test just to be sure it wasn't anything going on with the valves or anything. And yes, I have checked to make sure the wires are in the right order, multiple times.
I am fairly certain that when I rotated the plug wires around the cap to different posts, that should eliminate problems with the ignition system, right? I am not 100% sure on an HEI system though, so correct me if I'm wrong. Since it is carbureted and one of those cylinders (#8) on that head is firing they should all be getting fuel, right?
I don't know what else to do and am totally stumped, so any ideas are welcome. Thanks. (sorry about the novel)

You say that all plugs are firing, but Then you say that #5,6,7 cylinders are not getting any spark from the distributor? If you pull the wires from those cylinders while the engine is running, can you touch them to the block and get a spark?

If the wires and plugs are good, it has to be a faulty rotor or cap. Try swapping out the distributor with the one you replaced.

Got to be spark related. Work back from the plug to the dizzy.

Sorry for the confusion in my wording. All spark plugs are getting good spark but the cylinders remain dead. Unfortunately, I sold the old distributor to put the money towards the new one. I did swap out the cap and rotor already but, there was no change.

Do you have fuel coming out both side of the carb when you hit the throttle. You don't need to have the car running. If not carb problem with letting fuel sit in bowls and pluged up jets. If you do have spray from both sides, is this a hydro lifter motor? I would pull both valve covers and make sure you have good valve lift cycles. Complete open and close. If leak down is good and compression is ok, spark is strong, I would start with the carb. You do have new gas going into the motor?? Go back to basic and get new gas in seperate 1 gallon can, drain all fuel from lines and carb and start there. If this has no change, on to igition and test for good grounds and battery voltage to coil and ignition box. Rick L.

You have done just about everything, compression is good, leakdown test is good, spark to all cylinders, swapped spark plugs around etc.

I'd say if you had the intake manifold off, you have a gasket alignment issue on that bank.
The engine then inhales from the crankcase at low throttle angles instead of the intake manifold.

What inlet manifold do you have and what is the firing order please?

Did you touch the plugs at all. I mean clean them before this happened?
JD

This was a common problem after people worked on their engines back in the fifties---------You probably have the # 7 wire on #5plug, #5 wire on #6 plug and #6 wire on #7 plug---this problem arose because Ford separated the #7&8 wires by putting them in the 7,5,6,8 order over the valve cover---------

Thanks everyone for the replies. I did change out the gas already, have again checked my firing order (1-5-4-2-6-3-7-8) and checked the ground and voltage. I did re-gap the plugs to 45 according to what crane cams recommended for their dizzy, but other than that did not do anything else to the plugs. Today I shot a little starting fluid in the carb but it didn't change anything with those cylinders. Going now to see if I can find a different distributor to borrow. Gary, I have an aluminum 429 scj dual plane manifold. If a different dizzy doesn't help I will take the manifold off and re-do the gaskets. I'm pretty sure they are right but that is a good thought and will try it. Rick, I do have good shots of fuel coming out of both sides of the carb. The engine has mechanical lifters.

Mechanical lifters?

Have you checked valve clearances hot?

If you have both fuel and spark to the cylinders in question, and you are positive that they are wired correctly, but still no ignition, then the intake valves are not opening and letting any fuel/air mixture into the cylinder. Seems like a longshot, but that's all that's left.

I would still bet the firing order on these cylinders is messed up.

You would also get the same condition with no exhaust valve operation.

My bet is on the intake manifold gasket.

Or "riding" valves. Recheck valve clearances.

So you don't want to address the wires are lined up wrong on the 3 cylinders????????????
Cylinders 7 and 8 fired 90degrees apart and there was a problem of crossfiring from inductance between the two parallel wires so ford separated 7 and 8 by putting 5 and 6 bewteem them in the wire loom over the valve cover---then when some body did a tune up they put the wires straight onto the plugs from the valve cover wire separater---and that would put 7 on 5, 5 on 6 and 6 on 7 which caused the results that you are having----

Well, I got it figured out. Turns out it was the harmonic balancer (I know you might be thinking..."huh?"). Apparently on some of the aftermarket ones, I was reading about how the outer band (where the timing marks are) can actually slip if it is worn and/or faulty. After reading about that I actually checked to see if TDC was actually TDC on the balancer. I couldn't even see the timing marks when it was at actual top dead center, so it was way retarded. I remarked tdc and re-set the distributor and got all cylinders to fire. After running it for about a minute, I checked my new tdc mark to actual tdc and it had already moved again.
That was a really frustrating, costly and time consuming, stupid ordeal but, I'm happy the problem is solved. Thanks to everyone for your input!

Dave,

Can I ask how you performed your leakdown test and didn't find your balancer problem?

Still wondering how the engine had such vastly different EGTs and only 3 cylinders misfiring.

Hopefully you're sorted now.

Gary, I'm wondering the same myself, now that you mentioned it, as I used the #1 cylinder as a base for the test. My only guess is that it was coincidentally close to tdc with the timing marks and both valves were closed at the time I did the leak down test on #1. I just found tdc manually (aka a drinking straw with hash marks) for cylinders 5,6 and 7 to do the leak down test for those and didn't check anything else with the timing while doing that. I realize it all sounds kind of silly and might seem stupid that I over looked it, and I can't explain why everything worked or didn't work the way it did, but you just don't expect your timing marks to be moving around. I think my car was just mad at me for letting it sit for 2 years.

Dave,

You have done everything correctly.

I too, would be have been flabergasted to find the balancer ring had shifted after all your time and effort.

I feel your pain.

Now, a new better quality balancer, and make that 8 sound as it should. :)

It is amazing how stuff like this can at times overwhelm us especailly where we do not twist wrenches for a living.I have always been very fortunate at troubleshooting simply because always do the basics first but a slipped dampner ring.That throws a wrench in the works. Hope my car is not pissed at me for sitting so mauch this last few years.
Good to hear you solved your problem