Mrbowtie26

iTrader: (3)

I am doing a 402 motor with afr heads milled to 66cc. I installed new lifters that I had soaking in oil for a month. When I tried the stock pushrods I marked the valve tip with marker etc. After spinning the motor I found the mark on tip of valve about 1/16 inch out towards exhaust. I don't have a length checker so I'm not sure what size to try. Also if the lifters are considered "pumped up" will there be any movement as I can push the pushrod down about 1/8 inch. Not sure if I should run motor with stock pushrods till they are pumped up or if it was good enough to soak them in oil. I would think if they weren't pumped the mark on valve tip would be in towards intake side ? Any suggestions would be appreciated.
Thanks
Ron H.

Mrbowtie26

iTrader: (3)

any idea's ?
ttt....

Mrbowtie26

iTrader: (3)

Is this the wrong forum for this question ?
ttt.....

SHINER

iTrader: (18)

go with a solid lifter setup with 7.4 stock pushrods

Mrbowtie26

iTrader: (3)

Heads are already on and I want to stick with hydraulic lifters. I'm just wondering what to do at this point. How do other people check Valve train geometry in this situation ? with a solid lifter ? the pain is you cant remove the lifters with the heads on which mine already are on . Any comments on what size I may need or what to do at this point ?
Thanks
Ron H.

SHINER

iTrader: (18)

i would go with 7.6 length then and see if that takes care of it.

69firebird

iTrader: (14)

while we're on the subject, does anyone know what size pushrod will be needed with the L92 heads?
Thanks
ed

SHINER

iTrader: (18)

no idea. Google it L92 Pushrods.

Mrbowtie26

iTrader: (3)

Wouldn't a longer pushrod move the contact point farther out towards the exhaust ports ? Mine is already about 1/16 " out and needs to come in . I thought I would need a shorter pushrod ?
Thanks
Ron H.

SHINER

iTrader: (18)

well i forgot about u mentioning that, i guess so i dont know any other alternatives, different ratio rockers?maybe

Michael55123

iTrader: (3)

Pushrod length checker, anyone?

Mrbowtie26

iTrader: (3)

Any comments about if it's ok to check valvetrain geometry if the hyd. lifters are new but soaked in oil and can be compressed about 1/8 of an inch ? or is that normal even if the lifter is pumped up ? or can it not be checked correctly unless there is no play/compression of the lifter.
Thanks
Ron H.

NoMoreFWD

iTrader: (1)

If your rockers are non-adjustable, your not going to be able to change the valve contact. Pushrod length will change your lifter preload only.

MSURacing

iTrader: (1)

You really need to get a pushrod checker. Then, figure out what lenght it takes to just touch the rocker, go .070 to .100 longer and call it good. The factory sets preload on the lifters around .120, I think this is a little excessive. The lifter will bottom out at around .160.

Mrbowtie26

iTrader: (3)

Damn, so if my valvetrain geomety is off as far as the contact line is out too far I cannot use stock rockers if I want to center the contact point and I can only do that with adjustable rockers ? If thats the case I'm not sure what to do. I wonder if it will be ok to leave the contact point of the rockers about 1/16" off of center of valve tip.
Now if I do put in shorter pushrods to lessen the lifter pre-load will that in turn not open the valve as much and move the contact point ?

Thanks for the help.
Ron H.

dragon93308

iTrader: (1)

Your getting some HORRIBLE advise here. There are about 5 posts above that are completely wrong. Call one of the LS1 sponser shops and get some tech help over the phone.

NoMoreFWD

iTrader: (1)

I have just set up a couple motors in the last couple weeks that use stud mounted rockers. Raising or lowering the rocker arm pivot point is the only way to change the valve tip contact.
According to an article in the Aug. issue of Circle Track by Keith Dorton, rockers without roller tips can cover some error. This would be in your favor.
A couple questions.
Did you turn the motor over a couple times and are you getting a clean line on top of the valve? Maybe post a pic?
Are there any shims under the rocker pedestals? I assume there isn't, but moving the rockers down will solve your problems.
How much lift does the cam have?
As far as the lifter preload, I agree with MSURacing's post. I would lean toward .070" of preload. The dyno comparisons that I have seen make more power with less preload.

stang90gt50

iTrader: (6)

Agreed...when you have guys recommending different ratio rockers and 7.6" pushrods to fix the problem, your recieving advise from the wrong people (no offense to you guys trying to help, but you should leave it to people with knowledgeable background and not what youve read on the internet)

Get a pushrod length checker, do it right. Most likely a 7.400" pushrod is going to work perfect, if the heads are milled alot sometimes a 7.35" will be right. Only way to know is check with pushrod length checker.

NoMoreFWD

iTrader: (1)

I agree with getting a pushrod checker, a very good $20 investment. I think Mrbowtie26 is knowledgeable enough to sort out the bs. As far as what I have stated here, I can give you the references that I am using, such as W2W and Keith Dorton. I am very conservative with the info I share.

MSURacing

iTrader: (1)

According to old GM thinking, you need to have the valve open 33% by the time the fulcrum to contact tip line is perpendicular to the valvestem. If you follow that, you will be at the best possible scrub radius.