Fox T-Bird/Cougar Forums

Technical => Engine Tech => Topic started by: Nate on May 24, 2005, 07:51:38 AM

Title: gm rocker arms
Post by: Nate on May 24, 2005, 07:51:38 AM
i know gm rocker arms (working on a 307?) need to be adjusted. anybody got some good directions on how.  you dont just torqu em down rite?  a friend of mine asked me to fix his car that his uncle f'd up alot... he paied him over 3grand  to do an engine swap...

.....took a 307 from some 85 pontiac i think, and put it into his 86 cutlass that also had a 307 apairently (i thought it was an 305)  but his uncle said he was going to rebuild the engine to. took him over 3 months, and the engine looks like ass, its compleatly NOT rebuilt, the carb isnt even rebuilt... the dirt isnt even brushed off the engine. and when i looked under the hood, parts are missing and or bairly attached...

so im gonna fix it up for him. only thing wrong with it that im not 100% sure on  is adjusting them rocker arms.
Title: Re: gm rocker arms
Post by: MasterBlaster on May 24, 2005, 08:03:05 AM
Quote
took a 307 from some 85 pontiac i think
you dont just torqu em down rite?


If it's really a Pontiac, I believe you do.

http://www.boxwrench.net/specs/pont_265-455.htm (http://www.boxwrench.net/specs/pont_265-455.htm)

Unless it's been converted to Chev-style rockers.
Title: Re: gm rocker arms
Post by: TurboCoupe50 on May 24, 2005, 08:44:14 AM
I believe the '80s 307 was actually a Olds engine.. Chevy mfg a 307 from '68-'73, then dropped it for the 305.....

Anyway I'm 99% sure those later Pontiac and Olds engines do not have adj valves...

EDIT  Per 1982 Motors Manual... The 307 is a Olds engine and valves are not adjustable(only GM engines it lists as adj, are the Chevys)... I have a '84 Chiltons out in the garage, I'll see what it says as well....
Title: Re: gm rocker arms
Post by: Thunder Chicken on May 24, 2005, 09:04:52 AM
According to Mitchell OnDemand they're not adjustable. Torque 'em to 28 ft-lb
Title: Re: gm rocker arms
Post by: Nate on May 24, 2005, 11:30:12 PM
ok cool thanks. i rember watching the guys adjust their rocker arms on their camaros at my dealership and i thought i heard something about it being a gm thing. but apairently its only chevy, cool.

looks like i'll be replaceing his radiator, rebuilding his carb, and fixing misc. things that were forgotten on friday.
Title: Re: gm rocker arms
Post by: Thunder Chicken on May 25, 2005, 08:25:33 AM
On the two small-block Chevy engines I've owned I adjusted the rockers with the engine running. I just started it without the valve covers on, let it warm up, and cranked the rocker stud nuts down 'til the tapping stopped, then back just a hair. It wasn't scientific but it was quick and was also a cool way to see the valvetrain in action :hick:
Title: Re: gm rocker arms
Post by: Tbird232ci on May 25, 2005, 09:21:39 AM
and cover your fenders in oil
Title: Re: gm rocker arms
Post by: Thunder Chicken on May 25, 2005, 11:59:22 AM
Nope, not a drop spilled. The oil that comes out of SBC pushrods at idle is just a trickle. Rev the engine up and you'll see some action, but at idle the oil just dribbles through the pushrod hole, runs down the rocker arm, and then down over the valve and spring onto the head and back into the oil pan. Not even enough oil flowed to overflow the lower edge of the head, where the valve cover gaskets seated.

Funny story though - do NOT try this with a Chevette. In trade school my teacher had a Chevette with a noisy cam. He decided to show the class what was causing the cam to be noisey (worn lobe) so he took a valve cover off and had somebody start the engine. Immediately upon starting, the teacher, whos face was just inches from that cylinder head, was covered in black oil. He jumped back and a stream of oil shot up and hit the shop ceiling and sprayed all over several other cars in the shop before the engine was shut down (this all happened in a matter of seconds). Needless to say laughter filled the entire shop, and we all learned how NOT to inspect a Chevette camshaft :D
Title: Re: gm rocker arms
Post by: Tbird232ci on May 25, 2005, 12:49:57 PM
my buddy was adjusting the rockers in his 88 firebird, with a 350, and it idle, it looked like a little fountain from each pushrod, it was really neat looking, but he got his engine compartment nasty oily
Title: Re: gm rocker arms
Post by: Thunder Chicken on May 25, 2005, 01:03:40 PM
Ahh, see, given the shape of the two SBC's I had (one was a 1970 LT1 in a beat up '78 T/A, the other was a 305 in an '83 Chev 1/2 ton) they probably had about 3 PSI of oil pressure anyway...
Title: Re: gm rocker arms
Post by: V8Demon on May 25, 2005, 01:20:21 PM
Quote
my buddy was adjusting the rockers in his 88 firebird, with a 350, and it idle, it looked like a little fountain from each pushrod, it was really neat looking, but he got his engine compartment nasty oily

I remember pulling my covers on my Oldsmobile (with an Olds 350) years ago while it was running to check the cam.  The covers were pulled while I ran it to investigate.  It had one flattened out lobe.  The others were in fairly good shape and the oil didn't go all over.  It mad a little bit of a mess, but not waterfall type spewing.
Title: gm rocker arms
Post by: jimfulco on November 25, 2005, 05:20:49 AM
Some of them (Chevys) will squirt oil all over the opposite fender and everything in between.  Then the headers catch on fire & you have to blow it out before the panicky owner pours water on it.
Title: gm rocker arms
Post by: SirChirpAlot on November 28, 2005, 05:26:55 PM
Easy way is to tighten then down till there is no slop in push rods but u can still turn them with your fingers,  No ajustment in Hyd lifters the oil takes up the slop when running.

Solids u have to set up and run the vaulves all the time.
Same for soild rollers too.
HYD rollers u set it and forget it.