buzzman1

looking to run a .470 lift cam with 081 heads that were just freshened up and rebuilt to stock specs. I think from what Ive read this should be fine without changing the springs or studs but can only find info on 187's not 081....any help is greatly appreciated. Thanks Buzzman1

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Sonix

Should be able to, but check to be sure.
Depends on the valve seals you've used eh? (and don't tell me what valve seals you used and expect me to know how close it is eh?)

Assemble the heads. Use a caliper to measure the height from top of retainer to the bottom of the spring (or any other good repeatable measuring surface). Then use a valve spring compressor of your choice, and compress the spring until something hits. Retainer to seal, retainer to guide, spring solid height, etc, and remeasure that height. That's your max lift. Subtract .050" for a safety margin, and that's your TRUE max lift that you should use.

buzzman1

thanks Sonix ...appreciate the info

Buzzman

five7kid

You didn't mention duration, but with .470" lift, it's a fair assumption that you're going to be reving higher than stock. If that's the case, you should assume you'll need new valve springs. If you get new retainers as well, you can eliminate those heavy exhaust rotators which lead to valve float.

Kevin91Z

New springs are recommended any time you change the cam. Are you going to trust stock 20 year old springs to handle your higher lift cam? I wouldnt.

Manley 22410-16 springs and 23652-16 retainers will handle that just fine. Screw in studs are recommended over .500" lift but remember, your stock ones are 20 years old too. Are you going to trust them? Manley 42106-16 studs will work.

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