'66 BB ENGINE RAPPING NOISE/ENGINE TEARDOWN

[John R.]

Re: '66 BB ENGINE RAPPING NOISE/ENGINE TEARDOWN

Rob,

If it sounds like a ball peen hammer against a piece of metal, I think you have found your problem. From your description several weeks ago it sounded like the cam. I'd still check everything else out while you have the engine out.

[Rob A.]

Re: '66 BB ENGINE RAPPING NOISE/ENGINE TEARDOWN

John,

What roller type setup did you put in your engine. I'm not looking for any substantial increase in performance, but I'm considering installing it to avoid the chance of future problems. I'd like to in stall a roller type that requires as little modification to the heads as possible. I've checked the rod and main bearings and they look fine with no real wear or scrapes.

Thanks, Rob

[Rob A.]

Re: cam/lifter problems with BBC

Clem, I've checked a couple of the rod and main bearings and they show no noticeable wear. The rear main shows slight wear but nothing that a fingernail catches on.

I checked all the lifter bores and they are smooth and allow the lifters to slide up and down and rotate easily. Is there a way to check oil flow to the exact cam lobe that is ruined, or is it just lubricated from the oil splashing up onto it.

[Clem Z.]

Re: cam/lifter problems with BBC

the interface between the lifter and cam lobe is mostly splash off of the crank. when i used solid lifter race cams i would grind a .003 deep flat on the side of the lifter from the groove in the middle of the lifter body down to 1/8" from the bottom to allow more oil from the lifter bore to get to the interface. comp cams sell a grooving tool to do the lifter bores to let extra oil to the interface. the tool part # for both BB and SB chevys is 5003 and the cost is about $190

[Roger Legge]

Re: '66 BB ENGINE RAPPING NOISE/ENGINE TEARDOWN

I'd like to throw out a thought. As the cam lobe and lifter wear, would it not be possible for metal 'junk' to fall onto the skirts of the pistons when they are at the bottom of their bores? Is the engine going to be completely taken apart and inspected?

Roger
#36316

[Rob A.]

Re: cam/lifter problems with BBC

Clem,

A fellow at my local engine shop said that putting assembly lube or other breark-in compounds on the bottom of the lifters can cause them not to rotate, and quickly wear away. Any truth to this?

[Joe R.]

LOL Rob LOL *NM*

[Mike McKown]

You have my curiosity up,

What did this June Bug recommend you do as an alternative?

[Joe L.]

Re: cam/lifter problems with BBC

Rob-----

That's an absolutely absurd statement.

[Rob A.]

Re: You have my curiosity up,

Mike,

Actually I didn't ask. When I told him one of the cam lobes was ground away and the lifter worn, he suggested it was the cam assembly lube that prevented it from rotating. Maybe he meant if the entire lifter body was coated, as opposed to just the bottom it might not rotate.

[Clem Z.]

Re: cam/lifter problems with BBC

no truth at all and i prefer pure molydisulfide as my breakin compound. also remember that it will plug the oil filter so as soon as you are done breaking in the cam change the oil filter.

[Don Barnes]

Thats complete B.S.!!!!!

I've seen it both ways from people and friends but let me tell you if you are using a good assembly lube it ain't gonna happen whats he use wheel bearng grease? Talk to any cam builder Crane,Comp,Isky,they all say use it to extend the life of ypour cam.Your problem was caused by either not a proper break in or a rocker arm too tight putting excessive pressure on the lifter plain and simple just follow the instruction that Clem and the manufacturer of the cam and you won't have a problem

[Rob A.]

Re: '66 BB ENGINE RAPPING NOISE/ENGINE TEARDOWN

I inspected the main and rod bearings and found no more than normal wear. I also inspected what I could of the pistons and all looked well. It appears that the screen in the oil filter did a good job. I'll be installing a new cam and lifters and putting it back in the car next week. Crane will be replacing them under warranty.

[Dick W.]

Re: '66 BB ENGINE RAPPING NOISE/ENGINE TEARDOWN

I would follow Clem's advise on preping the lifters. I picked up this trick in the '60's when fooling around with the hemi. Some of the cams/lifters (all Racer Brown which were very aggressive) were prone to failure. I have seen the big blocks fail due to what I think was excessive idling. When we built engines in the '60's we would fire it up, get oil pressure, and not let it fall under 2500 rpms for 30 minutes. Adequate oiling for the cam.

[John R.]

Re: '66 BB ENGINE RAPPING NOISE/ENGINE TEARDOWN

Dick, I was told that it was probably excessive idling that caused the cam in my 67 big block to fail. 2,000 miles after rebuilding the engine I experienced an extreme rappinmg noise which resulted from one cam lobe being worn away together with about 3/8 of an inch of the lifter. I still can't believe that this happened and never heard about it in the 60's. The guys at the machine shop think I am being too hard on myself for trying to find fault in my rebuilding efforts. How common was this problem? I didn't want to run the risk of it happening again and have installed a roller cam.