Just about ready to pull the engine, drivetrain, and suspension in preparation for doing the under body and engine bay restoration. But before doing this it occurred to me that I should do a compression check. It would be a good idea to know ahead of time whether the engine is tired, and it's easier to do this check with the engine in place. I knew that the oil pressure was very good, 70lbs, from the previous brief minutes I had run it.
Well, I just completed the compression check and was surprised by the results: 175, 175, 172, 173. This was totally unexpected, since the engine would have had low compression pistons originally. Further, this was a cold test and the engine hasn't been run in 9 months, so the cylinders should be a little dry. It tells me that the engine has recently been gone through and someone changed out the pistons for higher compression ones. A peek though the spark plug holes confirms that the pistons don't have any significant dish to them, and there's not much carbon buildup. I'll do some disassembly and fit new gaskets and paint, but it looks like I may not have to do any major engine work!
I was curious about the components on my engine after discovering the high compression readings. The engine number on the block was correct for the year, but what about the head? So I removed the valve cover, and the first thing to grab my attention was these oddball valve spring shields. Looks like something off a vintage Chevy. I've never heard of them being used on a B engine. Pretty sure I'll be getting rid of them.
So anyway, the casting number on the head is the 12H2923, which is the big valve 38cc chamber head, and also correct for the year. With this head and the high compression pistons the compression ratio should be a bit above 9:1. The head has clearly been reworked as there are bronze valve guides in it. So probably also skimmed, which would also give a bump to the compression.
No comments:
Post a Comment