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383 crate sbc with PN 10089648 rockers. I am considering switching to aftermarket roller rocker arms before firing the engine. Am getting somewhat confused about the method of aligning the rockers/pushrods on this engine. (I have not pulled a valve cover)... Do I need "regular rockers" - that guide plates would keep under control or is there an updated method of dealing with this issue that use the valve itself to keep things in alignment. I would prefer ordering the correct set of arms the first time. TIA, Best, Dennis
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Re: Joe L. et al... Rockers on crate engine...
Dennis-----
Yup! It's always best to get it right BEFORE ordering the parts. Here's the deal:
The GM #10089648 are GUIDED rocker arms. GM has not sold in SERVICE or used in PRODUCTION a non-guided, standard rocker arm for Gen I or II small blocks in over 10 years. These are, indeed, the rocker arms supplied with your crate 383.
I don't think that the GM #12464298 cylinder heads used on your crate 383 utilize any sort of guide plate, at all. However, if you find any there, they simply serve as spacers and an "assembly aid". They are NOT true guideplates. They are a non-hardened plate with slots of sufficient size to remain out-of-contact with the pushrod under all operational conditions.
So, if you choose to replace the standard rockers with the roller variety, you need to replace them with GUIDED roller rockers. GM #12370838 is a set of Crane-manufactured, aluminum roller rocker arms which are of the self-guided design. These rockers will retrofit perfectly to your engine. Most of the rocker arm manufacturers offer roller rocker arms of various designs and materials which are of the self-guided design. So, if you want to use something other than the Crane aluminum arms, you have many other choices.In Appreciation of John Hinckley -
Joe - Once again, you be da go to guy. Thanks, DC *NM*
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Re: Joe - Once again, you be da go to guy. Thanks,
Dennis-----
Also, keep one other thing in mind: if you upgrade to roller rocker arms it may be necessary to change the rocker studs as well. Very often, the studs supplied with a stamped steel rocker engine will be a little too short for use with the "poly-lock" type nuts used with all roller rocker arms. Not always, but often.
If so, it's no problem, at all, to change the studs and it's not too expensive, either. I recommend using ARP studs.In Appreciation of John HinckleyComment
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Joe, Thanks for the "heads up"... DC *NM*
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Re: Joe, Thanks for the "heads up"... DC
if you plan to BEAT this engine i would replace the 3/8" studs,if thats what it has,with 7/16" ones because the pivot point of aluminun rockers is up higher than the ball pivot of the stamped steel ones and this put extra strain on the 3/8" studs. i believe the LT-4 engines used these rocker BUT had 7/16" studs. also they may not fit under the stock valve coversComment
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Re: Joe, Thanks for the "heads up"... DC
clem-----
LT4 used studs with 3/8" shanks, but 7/16"-14 thread size into the head.In Appreciation of John HinckleyComment
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sounds like Willy is gett'n some rumpdy rump *NM*
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Thanks Clem & Joe... I've been working on '62's
...way too long. Don't know much about this modern stuff. Appreciate the help. DennisComment
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tc, Willy is happy w/350/350. Now we be banging
on a 57 Nomad going with a 383/400... Am I getting too old for this? Best, dcComment
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Nice pick....never too old, go forth and multiply! *NM*
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Re: tc, Willy is happy w/350/350. Now we be bangin
willy be powered by a 350 but its one of them durn mercury marine 350's puttin out about 450, er 250 hp. how many car lengths ya gonna spot poor willy, Dip? mikieComment
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Re: tc, Willy is happy w/350/350. Now we be bangin
PS: i just realized dipstick is referring to his 41 Willy pickup with its 350/350. think TC was refering to the one being hatched here in western md. mikieComment
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Re: Nice pick....never too old, go forth and multi
TC: ask the dip who put him on to the purchasing of his 57 Nomadd and his 41 Willys pickup. just love spending the dipstick's frogskins. mikieComment
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question Joe,
why does the GM performance parts book say "these rockers are similar to the ones used on the LT4 engine except the trunnions are machined for 3/8" studs"?Comment
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