Engine rapping noise 59A
 

I have a 35 Pickup with a rebuild 1937 59A engine. Has approx 1K miles on it since rebuilt. The noise is more of a rapping or tapping sound and it's seems to be located in the lower right front of the engine. I have had several mechanic's say it's not a bearing noise. Maybe a wrist pin or piston slap ?.
Good oil pressure and truck starts and runs well.
Have taken the fan belt off to eliminate the water pumps and have tried finding anything listening with a screwdriver on engine .
The noise started out real faint but now has progressed to fairly loud at half throttle under light load.

If you have any thoughts or experience, I'd be grateful. I'm hoping to get a better idea before I pull the engine and start hunting. Thanks.

Re: Engine rapping noise 59A
 

The only thing i can suggest is to remove the sparkplug wire and see if it changes . If its anything listed your still going to tear it down to find out . Starting with cyl heads . Id pull the plugs and look at each electrode to see if any porcelain is broke frome something in the cylinder hitting.

Re: Engine rapping noise 59A
 

"Tapping" could be a loose valve from cam lobe wear. Maybe one cam lobe did not get properly coated, or the engine sat too long between assembly and test run. That said, a loose valve should be easy to locate with the long screwdriver to the ear.

Re: Engine rapping noise 59A
 

Do you know if the engine has the original style two piece valve guides? I read that if one of them is misaligned it can cause a tapping noise.

Re: Engine rapping noise 59A
 

I would remove the manifold, and check for valve trouble.
If its not i guess you have to remove the head.

With this said my son had a SBC that started to knock (ping) So we retarded the ignition.
And i went away, but come back he drove it 500 miles with ping(knock) retarding the ignition a couple of times. It was no 1 rod bearing that had given up.
So weird things happen.

But start with the basic checks first.
Remove ignition wire to a cylinder at time to see if the sound changes.

Re: Engine rapping noise 59A
 

By removing the intake manifold and checking the valves should you be able to eliminate most if not all valve problems ?