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I did a cold compression test today on an engine with no history (It is a 1986 300 inline 6 purchased in non-running condition). The Coles notes are as follows: I dragged home this heap of junk 1980 F150 Flareside 4x4 mostly in pieces. It had a 300 in it that I have identified as a 1986. It has been sitting for years, not running. I don't know how long, but at least 5 years.
Six months ago I sprayed some Kroil in the cylinders and rolled it over by hand a few times. I did that again maybe 3 months ago.
Today I gave the "new" junkyard PMGR starter a workout and whirled her over at cranking speed for a cold compression test. Here are the results:
So, what are you thoughts on cylinder number 2 @ 168 PSI? I later tested it again and got the exact same number. I also cranked it over with no spark plug in case there was any oil in there to spit out. I've read that compression numbers for a 300 should be between 100-150 lbs, so the cold numbers look OK, but cylinder #2 is weird. Carboned up I suppose?
Tested for spark (good) and gave her a spray of starting fluid and it flashed up instantly. Only ran it for a couple seconds. I won't try it with actual gasoline until next weekend.
So far, it looks promising lol. I'm thinking that once I can run it and warm it up a bit it would loosen up and maybe given me some different readings/?
That is a little strange I would think that would be a lot of carbon to up it that much.
I would hook up a gas can on the fender and let it run for a little bit but not long as it looks like you don't have the cooling system together yet but a min or 2 should not hurt it.
Then do another compression check to see what it shows.
Did you have open exh or through a muffler & pipe?
If open wonder if a mouse & nest came out and maybe that is why the high number on #2
Dave ----
Number two intake lifter is still partially collapsed from sitting. The valve is opening late and closing early. As soon as the lifter pumps up, I bet you'll be good.
I would think that would be a lot of carbon to up it that much.
