Exhaust port color difference.

skyhighZJ

skyhighZJ

Gov retirement < needs to live
Joined
May 31, 2012
Location
Aberdeen, NC.
Dad did the first fire up on his ‘55 Ford 272 Y-Block. everything started great, was able to fine tune the dizzy and get it up to high idle to do a cam break in. He wanted to double check the head bolts afterwards and this requires the exhaust manifolds to be removed. The #3 cyl is a good bit lighter than the rest. Any ideas?

Motor is basically stock for internals (.030 over) it has a T-Bird 312 4 barrel intake with a Holley 390 cfm 4bbl. All exhaust ports were the same temp during break in per the laser temp gun.

TIA
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skyhighZJ said:
Dad did the first fire up on his ‘55 Ford 272 Y-Block. everything started great, was able to fine tune the dizzy and get it up to high idle to do a cam break in. He wanted to double check the head bolts afterwards and this requires the exhaust manifolds to be removed. The #3 cyl is a good bit lighter than the rest. Any ideas?

Motor is basically stock for internals (.030 over) it has a T-Bird 312 4 barrel intake with a Holley 390 cfm 4bbl. All exhaust ports were the same temp during break in per the laser temp gun.

TIAView attachment 385684
Click to expand...
Looks like that cylinder hasn’t been firing.

Bunch of things it could be.

Start with compression test of that cylinder.
 
Before I’d get to excited I’d pull the plugs and see how they read, it was running High idle and not under load so actual fuel mixture wasn’t consistent. Remember, ’50s-60s air flow technology wasn’t the greatest, so getting a super even mix over a short time probably isn’t likely.
toss a new set of plugs in it and go for a drive, the cam may be broke in but the rings havent fully seated, and likely the valves are still working in as well. Drive it, if it’s gonna break it’ll do it on the drive. It may out last you….
 
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