Lrdurbin

New to the forum. My new to me 67 has a 69 xh engine with 48 heads. I pulled the heads due to a blowback problem-unfortunately I don't see an obvious problem. When putting things back together and adjusting the valves I find that about half of the adjusting nuts bottom out before the tight plus 1/2 turn is complete. The car has been driven hard in it's history including a lot of drag racing. I put a new oem cam in the car. Could the valve stems have excessive wear? What about the rockers or pushrods. They appear stock.
Your wise counsel is appreciated.

joesweeting

I had a similar issue, but just on one valve rocker bottoming out when adjusting. I had some worn parts. I don't recall what was worn/damaged since I planned on purchasing new heads. Out of curiosity, I switched some parts to change wear points and it seem to temporarly fix the problem, but I never used the heads.

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BearGFR

If you've got stock heads, stock rockers, stock bottlneck studs, stock cam... the adjustment procedure is simple --- torque all the rocker nuts down to 20 lb.ft. They're -supposed- to bottom out.

All that changes when you start getting into aftermarket valve trains that require a fully adjustable system.

Bear

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BearGFR
Garland, TEXAS

Lrdurbin

Thanks. I learned something

geeteeohguy

Also, use new nuts. I've had problems with re-used nuts backing off after use. Engine oil blowby is caused by worn piston rings, not valves. Worn valve guides/seals will cause oil smoke out of the tailpipe on deceleration, as in coasting down a long grade. If you have oil smoke coming from the breather cap, it's worn rings.