Posted by David Sherman on Friday, June 20, 2003 at 4:21AM :
In Reply to: Clatter in engine under, is this right?! posted by Chris Becker on Thursday, June 19, 2003 at 11:43PM :
The timing is probably off, as others suggested. Cheap gas is unlikely to do it since these engines were built when regular gas was 60-something octane and 87 octane was "fighting grade aviation fuel". Crud (carbon and scale) built up in the cylinders can raise the compression to the point where an engine will knock even on good gas. I've seen it happen. Is there a lot of crud on the plugs? Has it been running rich? The easy way to clean the carbon out is pour about a quart of water slowly down the carburetor while keeping the throttle far enough open to keep it from stalling. The harder way is pull the head and scrape it off.
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