Posted by John W S son of John S [172.70.175.42] on Monday, January 23, 2023 at 09:13:53 :
In Reply to: FFPW Engine Health Diagnosis posted by Daniel Saucy [162.158.186.37] on Friday, January 20, 2023 at 19:41:39 :
Just confirming, this is a 251, correct? It is also a "hump" head and block for those who care about this sort of thing...
It appears there might have been a compression leak between the gasket and block between 5 and 6. The water port between 3 and 4 is also questionable, however, I do not see one cylinder that has been "steam cleaned" from burning coolant. Looking at the block I see the same questionable area on 3 and 4 but I cannot be certain from the picture. Was the engine burning coolant or were you just finding it in the oil? How long did this occur before you pulled the head?
Plugs from cylinders 1,2,3, and 6 look like a carbureted flat head that is running okay to me. Plugs from 4 and 5 are fuel rich but not horrible for a flathead. The exhaust valves confirm fuel rich in two cylinders (4&5) which could be from lower compression, a valve leak, or weak ignition in these cylinders. Cylinder 3 is likely your strongest looking at the valves and plug. If the plugs were burning lots of oil they would have oily carbon barnacles all over like my picture.
A flathead is really inefficient just based on its design so some carbon is going to be inevitable. Typically you will see cylinders 3 and 4 be fuel rich, caused by the short intake runner, and the others be leaner. A hotter heat range plug may stay cleaner in those cylinders, but that is a conversation for a different post.
If this were my engine I would be inspecting the block and head for flatness and the cylinder bores as deep as I can see. I'd also look at the valves, nothing to do with water, just something to check while the head is off. If you think there is a crack somewhere Id be carefully checking things over before reassembly.
