57 F250

I don't know if I have a major problem or am I missing something. My engine runs smooth burns a little oil but runs good.
I could take off some of the spark plug wires while engine is running and nothing happens, engine runs no skips no knocking, Yes I'm getting a good spark. I take some of the other plugs wires off and there is a big difference in the engine. I have replaced all spark plug wires, distibutor cap, rotor, Pertronix ignition. Could I have a couple dead cylinders and not know it. I have checked and rechecked the spark plug wires and everything seems to be right, timing is correct, gap on plugs is .40. Any ideas would be helpful,

tbird100636

Does it seem to have a rough idle otherwise??? Little or no difference when disconnecting a plug wire indicates a weak cylinder. Adjacent cylinders usually indicates a head gasket issue. A compression test and cylinder leakdown test is in order.

__________________
Master ASE Certified L1 Chrysler Technician- still a Ford fan at heart.
1964 Thunderbird Hardtop- Chantily Beige- 390 FE 4V V8-Uncle's Car
1966 Thunderbird Convertible- Red- 390 FE 4V V8- Uncle's other car- waiting for paint and body work!!!
1967 Mustang Convertible- Blue- 289 V8- helping a friend re-assemble this classic

chipset

First off the plug gap is .032 not .040. the manual says .035 but those engines idle
better at .032 and if you can pull off a few wires and not notice a difference your engine is NOT running smooth. do a compression test. If it is running , as you say smooth there is probable a few piston tops missing or badly burned valves causing no compression to make it seem to run smooth. It's the compression on a non firing cylinder that makes an engine
shake and not run smooth.

57 F250

Thanks for the advise, I did do a compression test 160 on all cyliders. I gapped the plugs at .40 to see if I could get better gas mileage\ performance I usaully gap the at .35. Maybe my engine doesn't run as smooth as I said. I do burn oil after the engine warms up which I don't understand when my compression test was good. Could a bad intake gasket cause the same problem? I think my next step is to pull the heads and probally do the rings while I have this far apart. Any other ideas would be helpful.

NoLeaks2001

I remember doing this with my '64 Galaxie. Hook up a tach and remove wire #1 and note the RPM drop.Then replace it and go to #2 etc. The cylinders that caused the least drop when disconnected were the ones to correct.
In your case if you have verified a good crisp blue spark on each plug,and good compression, then you need to measure how much each valve opens by hooking up a micrometer with a magnetic base or I just used a steel ruler with .01" markings.
Incidentally, I always check for a dropped cylinder by cupping my hand over the exhaust and if it purrs smoothly they are all good but if there is a puff puff in there then one or more are not firing.-Brian-

__________________
2001 Grand Marquis LS, 30K miles mint. Finally a vehicle with NO LEAKS !

chipset

160 is a little low for that engine and to get 160 across all cylinders is almost impossible.
That engine has a " flat manifold " and is prone to sucking oil into the cylinders when the gaskets leak or the web is cracked on the torque bolt holes for the manifold. If you pull that engine apart and only replace the rings without rebuilding the entire engine you are asking for problems. Your crank will be the next to go. Remember an automotive engine is the closest thing you will ever get to a " PERFECT MACHINE " . When one piece is worn out EVERYTHING is worn out at the same time.

57 F250

I plan to remove intake manifold and heads in the very near furture. I agree that there is something going on with the head gasket and or intake manifold gasket or intake manifold itself. Years ago I did put on an a edlebrok manifold, truck always ran good until I let it sit. The bolts holding on the exhaust are all deterioated and need replacing who knows what ever else I"ll find. The advise on rings and the crank are well taken, Im no mechanic but I enjoy wrenching my truck, its theropy. Thanks