NOBODY

There are different ways to get from point A to B. Swapping the cam for a reverse rotation one is the easiest way to go.
You will have to remove the cam in your new shortblock and have a reverse rotation one ground for the original 415 HP motor. If the one in your shortblock is right you will have to send the cam to the cam place or tell the cam place the specs so they can grind it on the reverse rotation cam core.
Then you will have to buy a reverse rotation gear for your dist. The cam specs have to be the same so you don't have to have the computer reprogrammed.

jerosejr

Thanks for the info but if you go to 1800runsnew, they sell a 502 already setup for c/r. I assume this includes cam,etc..
Would you agree?

NOBODY

Like I said different ways to get from A to B, I would call them and see if the shortblock already has a reverse rotation cam in it and if it has the same specs as the 415 HP merc. That's the only way to know for sure.
If it does all you will need is a cam gear.

Ive done this reverse rotation in a lot of pullen trucks and the reverse cam is the easiest way.

jerosejr

THank you
This has been a tremendous help
Jim Rose

NOBODY

------------------Your welcome-------------------------------------

mcollinstn

Merc CR motors USUALLY use an odd gear drive for the cam. Uses same cam, same distrib gears, same everything.

Only the gear drive for the cam is different, and the water pump, and the starter motor, and the timing marks, and the fan for the alternator. Don't run a power steering pump on the CR motor.

He may already have a usable gear drive in his CR 340.

NOBODY

The engine would still have to have it's own cam because the valve events would be wrong if it spun backward. Even if your gear drive only had 2 gears.
It makes more since if can turn the motor backward with the heads off and imagine how the motor will fire, then you see the piston is in the wring spot when the cam is in the right spot.
I've seen many different ways to do cr but the way I mentioned is the easiest.

mcollinstn

Yeah, of course. You're right. Different cam needed, unless it is on a 4 banger. And Merc did use a 2-gear setup just as you mentioned. Those parrts are hell to find these days, if you need replacements...

Reversing the cam, though, DOES keep distributor thrust going in the correct direction and doesn't require a different distributor gear. Another plus is that twisting the distrib to set the timing is in a normal direction.

Young Performance

jerosejr,
If Runsnew sells a c/r motor, then just drop it in. The computer does batch fire 4 injectors at a time. It has 2 drivers in it. The computer will not have to be reprogrammed. Just so you know, that computer can be reprog.Talk to JK at Runsnew, he is pretty knowledgable.

NOBODY

No offense--
Not trying to school you you've always had very knowledgeable posts. I've always been impressed.