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I just replaced a chipped cam follower on my '48 356 cu. in. engine. I did the timing check as described in the shop manual and find that the #8 exhaust valve hydraulic plunger breaks loose at TDC instead of 10 deg after TDC. The crank and cam timing marks are spot-on and the chain is new. I will retard the cam sprocket one tooth and try that. Does anyone have any experience with this issue?

Isn't the spec for the number 1 exhaust valve?

JT120, correct, but No. 8 is 360 deg from No. 1. in firing order, so the two should be the same.

elwoodp44, what is No. 1 exhaust valve doing?

(o{}o)

JW, you're right, and I thought 1 & 8 should be the same after posting that.

If damper marks are being used as reference to TDC they could be incorrect.

JT120, I agree, most likely the outer part of the damper has moved and now the timing marks are in an incorrect location.

(o{}o)

One more thing, or the pointer not in proper location.

My shop manual says that the #8 exh valve timing is to be used for checking the timing on the hydraulic lifter engines. I looked in another manual to see what the inlet valve timing is supposed to be and noted that it is supposed to open slightly before TDC...I checked my #8 cyl inlet valve and it is starting to open late. (If you had a solid lifter engine with large tappet clearances it seems like this would be the result.)

Now...could the hydraulic lifters not being full of oil have any effect on this? I bled-down all the lifters before re-installing the camshaft. Later in the day I'll pre-oil the engine and fill the crankcase with oil. Then I'll rotate the engine several revolutions to see if I can pump the lifters full of oil. Then I'll recheck the valve timing.

M.

Having just changed one of those dampers yesterday, I can tell you that the timing marks will not move as they are keyed to the crankshaft through the housing. The center part can break free and move, but not the timing marks. If you still have the head off, it is easy enough to see if TDC is TDC.

As Ross says, the timing marks on the damper can not be out of position. But the pointer can be installed under the wrong set of timing chain cover bolts, seen that quite a few times. But that would make a error of several inches at the damper circumference so not the issue in your case.

Pre-oiled the engine and rotated the crankshaft many times. The #8 exh valve now does what it is supposed to do...the lifter for the #8 exh valve 'breaks loose' at 10 deg after TCD.

Using a dial indicator I verified that the TDC indication point on the damper is exactly TDC for the piston. BTW...if you mis-installed the sheet metal indicator on this engine you'd know it immediately.

I'll put the head on this afternoon but that's as far as I will go before next Monday. I've got a BMW motorcycle rally to attend tomorrow at Sipapu Resort near Taos, NM. This afternoon I must prep the motorcycle. Next Monday I'll return to the Packard and should have it running Wednesday or Thursday.

Mike

Mike - Pleased to read you got the problem solved. My comments on the pointer were if it got bent slightly. Your BMW rally should be a great ride.

(o{}o)