Reply to "Engine Rebuild"

Steve,

there is no "breaking-in" a roller cam like there is for a flat tappet cam. The main reason I make this recommendation is because of the ZDDP issue; with a roller cam it is a non-issue. However the roller cam is also superior technology, capable of running more agressive lobe profiles & lift while maintaining drivability and reliability, than possible with a comparable flat tappet cam.

I believe your camshaft problems could have been alleviated if somebody had gotten to you with the advice to use an oil containing ZDDP. There is also an issue these days with the quality of the lifters, as many are sourced from China. Many independent cam grinders source their own lifters, so they can provide their customers with domestic manufactured lifters.

There are 2 choices in the retro-fit roller cam market:

1) Crane cams uses a steel billet camshaft and special tie-bar style roller lifters.

2) Competition Cams uses an iron camshaft and Ford OEM style lifters. This is the less expensive of the two choices, but requires drilling the block in the lifter valley to install the Ford holder that keeps the dog-bones in place.

I recommend the Crane Cams camshaft & lifters if there's budget for it. The Crane lifters are a far superior lifter. Comp Cams has also began marketing such a tie bar style lifter just recently, but I haven't read anywhere that they have compatible cams on the market for their new lifters. Comp Cams tie bar lifters are more expensive than Crane's. There have been issues with the CompCams retro-fit system using the Ford OEM style lifter. The lifter in some engine blocks rides too high in the lifter bore, even though their camshafts are ground with a reduced base circle dimension. This exposes the oil slot on the side of the lifter when the lobe pushes the lifter upwards. Its simple to see if you ran the motor this way oil pressure would be lost by such a condition.

With either choice, some of the considerations involved include:

1) a replacement distributor drive gear made of a material compatible with the camshaft material

2) springs compatible with the camshaft profile & lift

3) do not attempt to use OEM valves, retainers or keepers

4) use roller rocker arms, they do not need to be adjustable, bolt down roller rockers are OK

5) use new push rods of the proper length, it is always best to custom fit & custom order push rods. The push rods need to be heavy wall 5/16", or 3/8" diameter, as the more agressive lobe profiles and stiffer springs will create flexing of a standard 5/16" push rod.

6) Piston intake valve reliefs cut deep enough for the cam profile & lift

The best advice I can give, is to go to a Cleveland "wise" engine builder and let him assemble a kit for you, spec out a cam to meet your requirements, have the cam custom ground, etc. I would like to recommend Mark McKeown of MME Racing in Maryland. You'll find his prices will run $50 to $100 more than if you try to roll your own. This is a bargain if you consider the experience you are buying, the confidence you'll have knowing your kit was put together by an expert, and the fact you'll have a camshaft that is better suited to your application than an off the shelf cam can ever be (especially considering you are running Weber carbs).

There are several old topics in this (engine technical advice) forum with posts by Dan Jones and myself discussing the particular details of roller cam installation in much more detail. This will at least get you thinking, and help you start your way towards the goal.

Your friend on the DTBB