Scott Hamel

i have a 68/69 olds 455 i am looking to upgrade my cast iron 4bbl to a air gap style Alum intake.. and want to slide in a 287 ***** THUMPR cam. its got around .500 lift on the (IN) and .487 on the (EX) would new stock rockers work with this? (because i plan on replacing them anyway) i seen a thread that says there good up to .500 lift? i just want some thoughts on the build. has anyone done/tried this?

thanks Scott

My442

Have you had any block or head milling?

If so, I would opt to go with an adjustable valve train.

I would also suggest that you change out the springs to match the cam.

ah64pilot

I wouldn't advise it...BUT I'm not going to say that back in the day I didn't use stock rockers on a .512 lift cam. It will work, it's just not the most reliable way to do it.

There are adjustable systems (comp cams magnum rockers) that don't cost a fortune and work with stock heads. Have you considered those?

Scott Hamel

I dont think it's been milled i believe its all stock. and i was going to buy the kit that had the cam, lifters, springs and timing chain. i don't mind spending a little more for adjustable roller rockers. this is my first olds build.. i was always a Chevy guy. so i'm still learning the in's and outs of hot rodding a BB olds 455.

now my second Question would be is there any machine work that needs to be done to the heads to install the adjustable rockers? i i plan on replacing the converter with a 2500 stall.. as suggested by comp and a rear gear change. its already running headers and i just put a full 2 1/2 exhaust with flowmaster super 10s.. Sounds pretty sick

Run to Rund

The rockers should be fine, with valve spring open pressures up to 400 lb or so. NHRA Stockers run 550 lb and that is a little hard on them. I doubt you will have to grind the slots longer for only .500 lift, but check them. a carbide bur in a die grinder will lengthen the slots easily. I have run stock rockers with over .6 lift after lengthening the slots a bit, and upwards of 400 lb open.

Scott Hamel

what do you mean by Grinding the slots? where the spring sit in the head? so theres no coil bind?

Run to Rund

The slot in the rocker, where the stand goes through it.
Coil bind is a different issue and is checked separately.