I have a 94 scarab with twin 350 chevy mercs. I am just wondering if they are flat tappit or roller?

We just rebuilt the top end on a 94 suburban which had the standard 350 truck motor. It had a flat tappet cam in it, but it had all the machining done so we were able to bolt in a roller cam without modification.

So, if the standard black mercruiser motors are just production truck motors, I would guess you have a tappet cam. But it would be an easy upgrade to the roller cam.

What HP are the motors listed as? When did mercruiser go to roller cams? Was it when they hit the 290/300 HP numbers on the 350's? Vortec heads came out in 96.

The other way is to pull the valve cover, time out the duration and lift and see what cam it matches up to.

Brian

Could be either. Merc had them both ways at that time.

I agree that it could be either.

knowing merc, motors are probably a year or two older than model year of boat.

if you can pull out a pushrod if it is just under 8.0 in ( 7.800) it is a flat tappet if it is alot shorter it is a hyd roller.