Stumped - Strange Noise

[Bushman66]

Got the Chevrolet 350 Crate Motor up and running, but me and all of my buddies are stumped. There is a grinding/growling noise coming from what seems like the top end of the engine. The alternator is new, as is the water pump. When we took a folded blanket and covered the distributor, the sound was gone.

So...ordered a new (remanufactured) distributor, a new AC Delco cap and new rotor. Reused the new premium Accel points set out of the old distributor. One thing I noticed when I removed from the old distributor was that the fixed post of the Accel points set was bent, and I definitely didn't drop them. Took a pair os smooth jaw pliers and bent them back to parallel.

Installed the new distributor, timed it up and...I STILL HAVE THE GROWLING NOISE. Oil Pressure is good, throttle response is good, and the engine sounds healthy.

I'm totally stumped at this point. Ordered a mechanics stethoscope to see if that would help.

Brand new Edelbrock AVS2 carb. Edelbrock Performer manifold. Tall stamped steel chrome valve covers took one off, no obvious valve train noise or interference with the valve covers.

[Bushman66]

Well, I am a dumbass. Used the blanket trick again, and before I ever covered up the distributor, the noise stopped. Pulled out the Edelbrock manual...forgot to plug the brake booster port at the back of the carb. DOH!!!

A pipe plug and some thread sealant and the truck is running like a top!

[The Rocknrod]

Well the good thing is you found it and probably have even better vacuum.

[Bushman66]

Originally Posted by The Rocknrod

Well the good thing is you found it and probably have even better vacuum.

These are the best brain farts to have. Didnt cost anything, no engine damage, and your buddies get to laugh at you. 😂😂