I have a 72 with a 350in it. I rebuilt it last year and have gone 8000 miles with no problems until now. Rebuild consisted of: valve job with new valve springs, comp cam 262 with new lifters, timing chain and gears. Honed with new rings, all new bearings, edelbrock with 1850 holley, headers, rebuilt dist. with petronix II conversion with coil.
I drove it to Houston to a show (300 miles one way) and back with no problems. I parked it when I got home and didn't fool with it for two days. When I went to start it, it won't start. Turns over good but no start. Two days later I try it and it starts,but with a miss. Checking , I find that no. 7 cyl is not firing. I replace the plug, no change, Replace plug wire, no change. Check dist.,change cap and rotor, no change.
Replace the dist. with a points dist.(new points and cond.) new coil, No change. Replace all plug wires, no change. Check compression, good comp on all cyl.'s Pull intake and look at valve train,looks good, no broken springs, valves going up and down. It seems that 7 and 2 are not firing or very weak. The miss is total when cold, but seems to improve as the engine warms, but even warm, I can pull no.7 wire and get no change in idle. There's a good spark going from wire to cap.
The engine starts easily and runs, but just with the miss. I checked the pre-load on the lifters, and reset them(they were loose), no change.
At this point I would welcome any suggestions. Tom

Sounds as if you may have a dead hole. Run a compression test. You may have a broken compression ring.

Reid '72 T-top

As stated in my post, I checked compression and it is good on all cylinders.

As stated in my post, I checked compression and it is good on all cylinders.

Try a leak down test

Reid '72 T-top

You also may have a valve sticking in the guide. I have seen that before. Not with 8,000 miles tho...did you replace or gnurl the guides?
Reid '72 T-top

7 and 2 are next to each other in the firing order. They may be crossfiring inside the dist cap. I know it's a new cap, but check it out. You may also want to add a bit of fuel to the carb air intake. Propane or carb cleaner works well. If the engine picks up, it 's a fuel problem. A lean condition will be worse cold, and still be bad warm. You may have an intake leak. Or perhaps if you have an EGR valve, it could be leaking.

|UPDATED|4/18/2004 6:27:30 PM (AZT)|/UPDATED|

I haven't been able to detect a valve sticking, and I've gone over them closely. Both seem to be opening and closing.
I too have noted the relationship of two and seven, but I have tried three dist. caps and two distribtors and no change in the miss. This would seem to rule the cap out unless I picked three bad ones in a row. I'm at a loss right now. I will pull the head as soon as I have exhausted everything else.
The only good part about this is how happy I will be when I find the problem.
Thanks for the input. If you guys think of anything else, let me know.
Tom

This may sound stupid, but have you checked the intake manifold for an obstruction? Or a crack? Maybe try mounting a new manifold and see what happens. I just put a new manifold on mine and it got rid of a vacuum leak that I couldn't nail down even after replacing gaskets. It's worth a shot...

Here's two cents-worth of information. My '72 had similar symptoms. While tinkering under the hood, I just happen to check the nuts holding the carb to the manifold. LOOOOSE!!! This may not be the reason for your missing but it sure helped mine, and it's so simple to check. Good luck.

JR - Miramar,FL