BruCru

Experts,
I'm building two pre-'87 350 SBCs for my boat. One of the engines is reverse-rotation. I would really like to retrofit the engines for hydraulic roller cams. The trouble I'm having is that none of the major cam grinders offer a retrofit hyd roller cam for a reverse-rotation engine.

However, Crane has suggested that I use a cam ground for an '87-later block along with a fabricated spacer between the cam gear and the block, and a cam button to hold the cam inplace. The spacer would take up the space in the cam/gear assembly normally occupied by the limiter plate used on the later engines.

This all sounds reasonable to me, but I would like to hear from others that may have done this. Has anyone ever done this? Can anyone foresee problems with this setup?

Thanks in advance.

BAD-HABIT

Comp Cams can custom grind any cam at a very reasonable price...

BH

Dennis Moore

Of course you realize that you will have to use a gear drive for the reverse rotation engine (not chain and sprockets). Look into the type of gear drive that you will be using and base your modifications on the design of the camshaft gear. You may end up with a simple modification depending on the gear design. It may be hard to find a gear drive for the new camshafts (smaller diameter bolt pattern on the camshaft). Good Luck!
Sincerely
Dennis Moore

BruCru

Thanks for the responses.

Bad Habit,
I actually spoke to Comp Cams about this. The guy told me that they don't have a blank for a reverse-rotation retrofit hyd roller cam. He didn't seem to want to talk about the subject either.

Crane was much more helpful. Maybe I'll call them again and try to get someone else.

Dennis,
The guy at Crane mentioned a gear drive as well. I have not pulled the engines out of the boat yet, but the gear cover looks normal to me. Can you still have gear drive behind a stock cover? Why do you need gear drive for reverse-rotation? By the way, your book has been very helpful.

Dennis Moore

A reverse rotation engine still turns the camshaft the same rotation as a standard rotation engine (or the oil pump and distributor would run backwards).

A two gear drive will rotate the camshaft the opposite way of crankshaft rotation while a timing chain turns it the same way. For a good example of gear driven camshafts, study any of the traditional Chevy four or six cylinder engines. They all have a nice gear drive setup.

The differences between camshafts is lobe placement on the shaft for the different firing order.

Don't forget the correct rear main seal for a counter rotating engine or it will leak oil like crazy!

I wouldn't build a reverse rotation engine if I were you. It is too easy to change the prop rotation in the drives or transmissions these days.

Sincerely
Dennis Moore

BruCru

Dennis,
Helpful info. At least I won't have to locate a reverse rotation high volume oil pump.

I really don't want to build a reverse rotation motor either. It has become a real pain. But from a cost point of view I'm thinking it is cheapest.

The engines are bolted to BW Velvet drives 1.91:1. I'm told the reverse clutch packs have fewer plates/discs than the forward packs. So I can't just run the transmission backwards.

Do you know of a way to retro fit these Velvet drives to run backwards?

Thanks.