Cold cylinder

[Ron R.]

I just noticed that my #6 cylinder is running colder than the other cylinders with a temp gun, # 6 temp is about 200 degrees while the other cylinders are about 350-400 degrees. My next step is to replace plug and change plug wire. I already checked clearance on rockers, which looked good on solid lifter cam. Motor has about 600 miles on 301 engine with LT 1 heads.
Any more suggestions is appreciated.
Ron

[Domenic T.]

Re: Cold cylinder

Ron,
Check the plug for color and see if it is fowling or if your engine runs a bit rough. If the plug is not the same color as another, a simple way is to switch the plug in #6 with another and see if the problem moves. Same with the wire.

Dom

[Duke W.]

Re: Cold cylinder

Sounds like a dead cylinder. Hook a timing light up to it and see if it flashes. Check wire contintuity. If okay replace the plug. If it's still dead time for a compression and/or leak down test. Duke

[Ron R.]

Re: Cold cylinder

Did the timing light test, it does flash, will next replace wire and plug. It's just tough to get to with headers. Would a burnt valve cause the cylinder to be cold? Not running that rough, but it has fairly radical cam. Ned to get this early tanker on the road again after many years.

[Duke W.]

Re: Cold cylinder

A valve or ring problem will show up on a compression or leakdown test. If you bring the engine up to at least 2500 revs, it should smooth out, and a dead cylinder should definitely be felt as a miss. Do this with the #6 plug wire connected and disconnected to see if there is any change you can feel.

Duke

[Ron R.]

Re: Cold cylinder

Just did a compression test on the dead cylinder(#6) and the adjacent cyclinder (#4), both were between 160 and 170 after about 4 revolutions.
leaving compression gauge on #6 to see if it holds for a few minutes. I will next change plug, wire and cap.

[Mark E.]

Re: Cold cylinder

Checking for mechanical problems first seems out of step. After many years of not running, make sure the ignition and fuel systems are first rate. This includes replacing plugs, wires, cap, rotor, points, condenser. They're old, and do you really know how many miles are on them?