Roller cam retrofit to 67 small block?

[Joe R.]

I am about to put a new cam in my 67 small block. After considerable research, I have picked out a mild Crane hydraulic flat tappet cam that has the timing characteristics I want.

For a much higher cost, I can get essentially the same timing in a roller cam that Crane sells. The only reason I would consider a roller cam is concern about anecdotal reports of an increased liklihood of wiped cam lobes with flat tappet cams. I have a few questions I'm trying to answer to help me decide how to proceed:

1) I've read that a likely cause of the wiped lobes is the reduction of zinc additives in modern oils. Right now I use the Shell Rotella diesel oil to combat this problem, but I've heard that even diesel oils will eventually lose some or all of their zinc. Is there a chance that suitable oils will not be available in 10-20 years?

2) Is the Crane hydraulic roller cam a bolt-in fit for the 67 small block?

3) How hard is it to fit the so-called "cam button" that keeps a roller cam from walking? I have not been able to find a description of the fitting process.

4) Does the 67 timing cover need to be reinforced where the cam button contacts it?

I'm tempted to just put in a flat tappet cam and avoid all the uncertainty associated with a roller cam retrofit, but I'd like whatever cam I install to have good long term reliability.

[Joe L.]

Re: Roller cam retrofit to 67 small block?

Joe-----

I like hydraulic roller cams. I don't think that I'd build an engine anymore without one. As far as your questions go:

1) A lot of the current problem with break-in failure of cams might stem from the reduction of zinc high pressure additives in modern oil. The Rotella should work fine for now, though. As far as what the future holds, who knows? However, you could always add a little GM EOS with each oil change to gain the advantage of the zinc additives;

2)The Crane RETROFIT hydraulic roller camshaft and lifter kits are a direct bolt-in for pre-1986 small blocks;

3) It's not too hard to fit the cam button. It's somewhat of a trial-and-error process, but not very difficult. Use a dial indicator to measure the end play;

4) It's best to add a reinforcement to the timing cover. I braze them in. See attached photo. This one is a bit sloppy of a brazing job, but it gets the job done and no one will ever see it.

[Joe R.]

Re: Roller cam retrofit to 67 small block?

Hi Joe:

Thank you for the explanation and the very helpful photo of a reinforcement for the timing cover. I think I may chicken out and just put in a tappet cam for now, but I remain interested in the roller cam option and can't quite let go of it yet. I have a few more questions if you don't mind answering them:

1) Is the metal piece that you brazed in a pre-made component that I can buy somewhere?

2) In catalogs I have seen needle bearing cam buttons and what appear to be Teflon cam buttons. For the Teflon ones, do you just shave one end on a piece of sandpaper to get it to fit? How do you fit the needle bearing buttons?

3) Other than the pushrods being shorter, does the roller cam use the conventional 1967-style pushrod and stamped rocker? I thought that the offset center of the original tappet cam lobes caused the lifter and pushrod to "spin" to help even out the wear pattern. The roller lifters with locking bars won't spin of course, so I'm curious about the effect on the pushrods and rockers.

Sorry for asking all these questions, but after searching for published information on retrofit roller cams I was not able to come up with much.

[Joe L.]

Re: Roller cam retrofit to 67 small block?

Joe-----

1) I fabricated the reinforcement from a piece of steel stock. Not very difficult to do;

2) There are several types of cam buttons. The Teflon, aluminum, and brass are "monolithic". They are adjusted by sanding down the end or shimming (you have to make your own shims). The needle bearing type is adjusted by filing down the inner end or shimming, pretty much the same as the other types;

3) rocker arms are exactly the same as stock. Pushrods, except for length, are the same as stock. However, either "1 piece" or welded-ball can be used. Welded ball was used on many later small blocks, including those originally fitted with roller cams.

[Joe R.]

Thanks Joe! *NM*

[David B.]

Re: Roller cam retrofit to 67 small block?

Joe,

Great info! Thanks.

Would you please share your thoughts on roller rockers as well (full roller, not roller tipped)? Is it worth doing in a SBC rebuild for the street in your opinion?

Thanks
David B.

[Joe L.]

Re: Roller cam retrofit to 67 small block?

David-----

Fully rollerized rockers aren't going to provide any significant gain in horsepower. However, I like them for their friction-reduction capability, anyway.

GM first validated the roller rocker design for a PRODUCTION application with the 1996 LT-4. Before that time, I was a little hesitant to use them. PRODUCTION validation changed my mind, and I've never looked back.

The Gen III and Gen IV small blocks use an investment cast (and, less expensive) version of the "roller" rocker. However, this further validates the basic design to PRODUCTION engines.

[Gary B.]

Joe, does no one sell such a reinforcement...

to attach to the inside of the timing chain cover to counter the cam thrust? Too low a volume item to make a profit?

Gary

[Joe L.]

Re: Joe, does no one sell such a reinforcement...

Gary------

No one that I know of sells a reinforcement like this. However, you can purchase timing covers with the reinforcement already installed. Unfortunately, they are the later style timing covers with the "dish" center configuration rather than the early style, "spoke" configuration.

Actually, even for the early style covers it's not really necessary to fabricate the "3 spoke" type of reinforcement that I have shown in the photo. If you're more careful about brazing or tack-welding, a simple, round reinforcement will do. I just didn't have a photo handy of any of those that I've done.