comp cams roller rockers

[teslapwr]

I'm inquiring about useing Comp cams roller rockers on my 3.1 gen 2 engine. I saw them on 60 degree store. I was told they can be used in place of stock rockers but pushrod guide plates will interfere but With a little grinding this will be sufficient?

If useing a aftermarket cam with higher lift, in theory base circle becomes smaller, so this must be compensated by useing longer pushrods. Would I just take the difference from stock vs aftermaket basecircle and add it to the length of pushrod. valve cover clearance?

Do I have to add the preload .030-.040 to length to pushrod length also?

Is there anything else that I'm overlooking, Are the stock rocker arm studs adequate with the comp cams rockers? I beleve their a 10 by1.0mm

Is there a tool that they sell adjustable pushrod, to give you a measurement so you can use it as a reference for a custom pushrod? Currently I'm useing the stock pushrods, not sure if I need them for the new cam, just tring to be prepared.

In theory just want to keep the same rocker arm geometry, I'm a vw mechanic, never really got into the performance aspect, so I'm looking for someone who has more knowledge in this area than myself.

Any imput on a blower cam 3.1 with m62 blower currently crane cam 2030 423 in 423ex @1.5 stock rockers264 in 274 ex. 109 lobe seperation. also useing reccomended valve springs etc. Like the cam but would like more midrange and top end if possible.

Don't want to be too agressive with cam meaning too much overlap or duration, don't want to blow it all back the exhaust. had a few thoughts duration 268 in 276 ex . lift 450 in @1.5 . 471ex @1.5 lobe seperation 112
centerline in 108 ex 116 figured a little more lift and duration on exhaust side due to stock exhaust manifold, but didn't want to go too high. A penny for your thoughts, thanks for your time and knowledge

[Lilchief]

comp cam part #7901-1 (7.5"-8.7") or #7902-1 (8.5"-9.8"). This tool is for measuring proper push rod length.

[torq455]

preload is ZERO lash. iirc you won't have to mod the guides if you use the correct length pushrods,

[SappySE107]

Our pushrods aren't that long. Gen 2 will want one that measures 5.8-6.8". Preload is .030 on the lifter.

[sharkey]

never heard of anyone having to go with custom leangth pushrods just for a cam swap. just because the cam has more lift does not nessessaraly mean the base circle is smaller. i know of plenty of guys that swapped in an aftermarket cam in 660's without issues.

get the cam and drop it in and see. an easy way to get an adjustable pushrod is to cut an old one in half and thread it. leave enough room for 2 nuts (to lock it down). as for preload, comp cams says zero lash and 1/2 turn. thats what i have always done on my motor and never had valvetrain noise.

[torq455]

yeah, but they may not have the ideal valvetrain geometry either, but it still works. better to measure and be safe.

for forced induction you'll want a lobe separation angle of at least 112 degrees. for more boost say 10+ lbs, you'd be better off with an LSA of 114 or more. 212/202, .432/.417, 114 LSA with 6-8 lbs will do you very well. that cam got one of us with a completely stock 3.1, polished heads, gasket matching, all this: 230HP @5400, 260 lbs @ 3100 - 4500. at the wheels with a 5 speed and only 7 lbs of boost!