gen vi bbc cam lifter timing chain question
 

so, I can give you guys the back story if you'd like. But I'll spare it.

My question is:

if one wanted to, can retrofit roller rockers (you know, the kind used in mark iv gen v blocks) be used on gen vi blocks? I know they say the lifter bosses are taller, does that matter?

On this Gen VI - can I us a mark IV/gen V retrofit roller cam NOT using the gen VI nose plate and use the double roller timing chain with the torrington bearing used in a Mark IV/gen V with the thrust button and the gen V timing cover. - My research says that shouldn't be an issue.

Thanks.

I believe a rocker arm is a rocker arm, but the issue with Gen V and Gen VI heads are stock rocker arms are bolted down (dumb idea IMO) so if you have that style you will need the conversion studs if you want adjustable rocker arms.

Yes you could put a Mark IV cam with retro lifters but you would need a Gen 6 timing chain and a thrust bushing. The retro lifters are used all the time in Gen 6 engines with large cams. The question is why would you want to do this?

You can't use a Gen VI timing set on a Mk IV/Gen V cam. The bolt circles are different. The Gen VI cam has a step nose so the bolt circle on the timing set is smaller.

You can use a flat nose cam and retro lifters in a Gen VI block, but you will need an aftermarket timing cover to clear the MkIV timing set that you will need to run.
Eddie

good call on knowing I meant LIFTERS not rockers...Whoops!

will the standard height ones work? or are the +.300" ones needed? I did some more searching and I was surprised to see its come up before, but I'm getting differing responses.

You are receiving differing responses since there is not a definitive answer to your question. Absent the necessary data it’s just a guess. In order to correctly determine if a .300” long lifter is required you will need to;

• Measure and calculate the base circle of the camshaft, along with a number of dimensions, and mathematically determine if your lifters are long enough. Not likely.

• Mock up the valvetrain, drop in the lifters, and measure the lifter drop into the link bar, with a proper margin of security.

• Install the + .300” (either horizontal or vertical tie bar (retrofit)) lifters knowing you will have the necessary clearance with this, and any future cam changes.

Bob