1990 alum head stud size?

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Mar 4, 2015 | 09:06 PM

samples45

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From: Norman OK

1990 alum head stud size?

I have a 1990 alum head l98 motor.. when it comes to buying full roller rockers what are the stock stud size? should i be looking at 7/16 or 3/8?

thanks!

Mar 4, 2015 | 09:42 PM

WW7

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From: WV

Quote:

Originally Posted by samples45

i have a 1990 alum head l98 motor.. When it comes to buying full roller rockers what are the stock stud size? Should i be looking at 7/16 or 3/8?

Thanks!

3/8" is stock....The stock rockers are self aligning rockers.."Be forwarned", roller rockers are usually much louder then stock rockers and alot of guys don't like the added noise they make.....WW

Last edited by WW7; Mar 5, 2015 at 08:00 AM.

Mar 5, 2015 | 09:10 PM

samples45

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From: Norman OK

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Originally Posted by WW7

3/8" is stock....The stock rockers are self aligning rockers.."Be forwarned", roller rockers are usually much louder then stock rockers and alot of guys don't like the added noise they make.....WW

Thank you sir.. so i would need guide plates if i do this? And do you know what the 1.6 roller rockers would make the lift on the stock cam??

Mar 6, 2015 | 05:24 AM

WW7

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From: WV

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Originally Posted by samples45

Thank you sir.. so i would need guide plates if i do this? And do you know what the 1.6 roller rockers would make the lift on the stock cam??

If you use self aligning rockers, you can just put them on and your good to go...If you use non self aligning rockers, you need hardened guideplates and hardened push rods..I'm not sure on the valve lift, I don,t know the specs on the 90 cam.......WW

Last edited by WW7; Mar 6, 2015 at 05:30 AM.

Mar 6, 2015 | 05:49 AM

Churchkey

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From: Cherokee National Forest TN

CAM 90-91 L98 10111773 In/Exh Dur@.050" 202'/207' Lift (w/1.5) .413"/.428" LobSep 114.5'

W/ 1.6 rr I.440, E.456

Last edited by Churchkey; Mar 6, 2015 at 05:58 AM.

Mar 6, 2015 | 05:35 PM

samples45

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From: Norman OK

Thanks! Do you know the dia of the pushrods and the length I need to get??

Mar 6, 2015 | 09:22 PM

Churchkey

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From: Cherokee National Forest TN

Stock l98 pushrods = 5/16 dia, 7.200 length.

7.200 is the correct length for the aluminum head TPI. Early iron head engines used 7.800.

Mar 6, 2015 | 10:58 PM

WW7

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From: WV

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Originally Posted by Churchkey

Stock l98 pushrods = 5/16 dia, 7.200 length.

7.200 is the correct length for the aluminum head TPI. Early iron head engines used 7.800.

But as soon as he puts different rockers on the engine, the push rod length may very likely change. The OP will have to install test springs on his head , then use an adjustable pushrod to figure out which length pushrods are needed to get the roller hitting in the center of the valve tip..If the OP doesn't have the knowledge to do this procedure, then he will have to get a shop to handle the job....WW