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1967 Pontiac 400 engine problems.


rbk
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My friend has a 1967 Pontiac with a 400 engine.

Trying to start it the engine cranks over very fast and has no compression.

It seems that the valves are not working and because this engine has hydraulic lifters

he suspects that the oil pump is not working and the valves stay open.

I know nothing about GM engines and before we take the pan off and and  change the oil pump

I wanted to get the input from you experts on how to do this and is that the problem?

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Don't worry about the oil pump. The valves will work without it, badly and loudly, but they will work. 13CADDY's timing chain is a good guess.

 

If nobody has been moving the distributor around you should be able to turn the crank to TDC and see if the distributor rotor points to #1 (or exactly away from #1). If it points anywhere else, the timing chain probably jumped.

 

If, on the other hand, the rotor is pointing where it should, then proceed to a compression test.

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x2 on a jumped timing chain.  Set #1 piston at TDC, remove the distributor cap and check the orientation of the rotor. It should be pointed at the #1 terminal on the distributor cap -- if it's not, then pull the driver's side valve cover and ensure that both valves are closed.  If not, the cam is no longer synchronized with the crankshaft and a new timing chain and cam gear is needed.

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  • 1 month later...

This doesn’t make much sense, if the valves aren’t working the engine would still have compression on some cylinders, some pairs may have one open but some would be closed, you’d have to pull the valve covers and turn the engine over and see that none are moving then pull the intake and see the cam is/isn’t moving, sounds like the piston rings are gone, 

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