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Posted by David Sherman [24.32.202.83] on Wednesday, May 26, 2010 at 01:07:31 :
I've mentioned before the old slant 6 powered minibus trolley we use for the mine tour. I got the head off today and into the shop to deal with no compression on #4. The #4 exhaust valve wasn't burned, but it was extremely sloppy in its guide and clearly wasn't seating, plus the oil on the head around it was coked up and the valve stem seal was crumbled.
Getting this fixed should make it run smoother, but I still suspect it has the wrong carburetor. I got a rebuild kit for the one-barrel Holley that the book said was commonly used with that engine, and it's clearly not for the same carb that's on it. The accelerator pump squirts, but it still hesitates badly on acceleration. On the other hand, all the exhaust valves look (according to the machinist) like they've been running hot due to a lean condition. It backfires through the carb a lot, and the intake manifold is well coated with carbon and gunk inside. The old guy who used to work on it 10 years ago, and is an excellent mechanic looked at it and said that the carb that's on it now isn't the one he remembers. The engine was overhauled in 2002, and I suspect they changed out the carb for unknown reasons to one that fit but wasn't really right for the engine. The carb they put on is missing its stamped aluminum tag so we don't really know just what it is/was.
At this point, I'm willing to buy a new carb so long as I know it's one that was used successfully on slant 6's back in their day. The choice appears to be one-barrel Holleys and 2-barrel Carters. I would rather have the 2-barrel, but we'd need to change the intake manifold then, so I'll stick with a Holley if someone can tell me what's the right one to get that is tuned right for that motor. Better yet, if anyone has a good take-off to sell, we'll buy it. If it needs a kit put in it, that would be okay so long as it still has the stamped tag so I can get the right kit.
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