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1940 Buick Straight-8 mechanical valve lash adjustment

Guest bshelden

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Guest bshelden

How do I adjust mechanical lifters? Can't find anything in the Buick shop manual. I've followed a few articles but haven't had any luck. My car is now not running so I must do the initial adjustment with the engine cold.

Thank you..:confused:

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  • 2 weeks later...

I'm doing the same thing with my 41 248 motor - newly rebuilt.

When the motor is running, the valves are to be set at .015. I'm going to start by setting mine cold at .018.

Turn the motor over until #1 intake valve closes. As it does, look for the timing mark on the flywheel through the flywheel cover on the lower passenger side of the motor. With the timing mark at TDC, you should be at TDC with both valves fully closed on the #1 piston. Do the set of valves noted below first. Then do the same thing with the # 8 cylinder as noted below.

No 1 cylinder is in the firing position adjust the following valves,

cyl#1 intake,exhaust,

cyl#2 exhaust

cyl#4 intake exhaust

cyl #6 intake, exhaust

cyl#7 intake

rotate the engine to No 8 cylinder firing position and adjust the following valves.

cyl#2 intake

cyl#3 intake exhaust

cyl#5 intake exhaust

cyl#7 exhaust

cyl#8 intake exhaust

Before you try to start, it helps to use a 1/2 drill with the proper tool to turn the oil pump over to oil prime the engine. This is done through the distributor hole in the block. That way you know everything has a film of oil present before the actual start.

When you put the distributor back in, put your motor back on TDC for # 1 cylinder and make sure the distributor rotor is also ready to fire #1. Recheck that the spark plug wires are in the order below.

Firing order 1-6-2-5-8-3-7-4

Once you have it running decently, you can reset the lash to .015, where it is supposed to be.

Good luck - let us know how it goes.....


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Guest bshelden


Thank you for replying. I followed your instructions and now have a running

motor. Sounds great!

Hope your project is going well.


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  • 10 years later...

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