Were all 502 engines roller cams?? I have a buddy with an older carbed 502 and he asked . I really don't know. He was wanting to do some upgrades and I didn't want to give him bad advice....

It's a 1991 model.

No, not all 502 were roller motors. I had to do a retro roller cam in my 95 502.

1991 502 Carb, would be a flat tappet camshaft.

Kenny,

What are the last two letters of the engine code?
It will be stamped at the base of the china wall above the timing cover.

Bob

He was talking about a cam and intake swap, I told him to call my buddy Bob!

1991 would be Gen V and flat tappet cam. If its a Merc(390hp) engine, it used the same flat tappet cam as a 454mag

If that is the case then off the top of my head it is 224* & .510 intake and exhaust. Somethimes my memory is not what I think it is though.

Mag BBC 454/502 Flat Tappet

.004” 296*, 296*
.006” 286*, 286*
.050” 224*, 224*
.200” 130*, 130*
Valve lift with 1.7 .510”, .510”
LSA 115.5
Merc Part#431-9830 / GM#14096209
ICL 114 ATDC
ECL 117 BTDC

Yup. Reworked a '96 502MPI. Had a Gen V block and flat tappet cam.

Also, reworked a '97 502MPI and it had Gen VI and roller cam.

Merc lists the GEN VI (ie:roller) starting in '96. But, maybe the '96 I had was off a little since a Canadian boat. I dunno. But it was a Gen V with flat tappets.

The GEN V HP500's had retrofit roller...obviously the Gen VI"s had rollers too.