Reproduction Parts for 1916-1964 Chevrolet Passenger Cars & 1918-1987 Chevrolet & GMC Trucks



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#135932 01/31/09 04:38 PM
Joined: Aug 2007
Posts: 241
Backyard Mechanic
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Backyard Mechanic
Joined: Aug 2007
Posts: 241
I had an exhaust value (#1 cylinder) that had too much lash and knocked. It must have been opening late enough that there was significant pressure already built up in the cylinder when it opened.

But, looking at the specs in the manual, there's plenty of room to allow knocking, since the lash can be between 0.013 and 0.020 inches (for heavy duty). People must have just put up with a lot of tappet clatter and some knocking.

Adjusting back to 0.014" lash took most of the hard knock out of it, anyway.

Harrell Sellers
Brookings, SD


"It ain't what a man don't know that bothers me, it's what he knows that just aint so", Will Rogers
Filling Station - Chevrolet & GMC Reproduction Parts


Filling Station


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ChatMaster - 25,000
Joined: Jan 2002
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The correct seting may be impossible to make due to the valve stem tip wearing into the rocker arm. The rocker arm could be replaced with a new one or resurfaced. There was a set-up for resurfacing rocker amrs years ago. Ground the correct angle which is important for keeping even pressure on the stem.
I may have a new one - will check. #1 ex. would be an easy one to slip in place.


Gene Schneider
Joined: Aug 2007
Posts: 241
Backyard Mechanic
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Backyard Mechanic
Joined: Aug 2007
Posts: 241
Many thanks, Chev Nut. Next time I open the valve cover, I'll inspect the rocker arm surfaces. I did look at them before and didn't feel that there was excessive wear, but I wasn't really focusing on that.

THanks,

Harrell


"It ain't what a man don't know that bothers me, it's what he knows that just aint so", Will Rogers

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