Rocker arm issues.
#3037838
04/28/22 12:16 AM
04/28/22 12:16 AM
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Joined: Sep 2017
Posts: 342 Red Deer, Alberta
Greenwood
OP
enthusiast
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OP
enthusiast
Joined: Sep 2017
Posts: 342
Red Deer, Alberta
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So, as part of my refresh, I decided to replace my ancient Crane Golds. After some consideration, including the premise that they're made in the USA, I purchased a set of PRW rockers. In the end, this also necessitated a switch to new beehive springs. Now the engines all assembled and ready to bolt up to the trans and drop in. Just for the heck of it I put the dial indicator on the head tonight and measured up my actual valve lift. I'm at .513" net valve lift on a .575" roller, at .020" lash. With 1.6 rockers. Wonderful.
Last edited by Greenwood; 04/28/22 12:17 AM.
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Re: Rocker arm issues.
[Re: lewtot184]
#3037910
04/28/22 10:13 AM
04/28/22 10:13 AM
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Joined: Jan 2003
Posts: 14,499 So. Burlington, Vt.
fast68plymouth
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So. Burlington, Vt.
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I just recently had a builder verify the net lift at the valve was going to be under .700” for this particular build. He checked two rockers, the theoretical lift would have been .690. One was like .650, the other .665. The lobe lifts were .460” for both. PRW steel 1.5 rockers. This was on a BB. If you’re working with a SB and the stock 59* lifter bank angle, that alone will cost you about .05 worth of effective ratio.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Rocker arm issues.
[Re: Greenwood]
#3037920
04/28/22 10:53 AM
04/28/22 10:53 AM
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Joined: Jan 2003
Posts: 14,499 So. Burlington, Vt.
fast68plymouth
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The Cranes I have checked were always higher than the advertised ratio.
Also, if you’re using a shaft relocation kit for geometry improvement, I’ve seen instances where they have resulted in a lower effective rocker ratio.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Rocker arm issues.
[Re: B1MAXX]
#3037941
04/28/22 12:12 PM
04/28/22 12:12 PM
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Joined: Jan 2003
Posts: 14,499 So. Burlington, Vt.
fast68plymouth
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So. Burlington, Vt.
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I’m saying that when the lift was checked with and without the relocation kit, there have been instances where the addition of the kit lowered the effective ratio. So, if the OP has one of those kits installed, he could remove it and see if, in his particular situation, it has any impact on the ratio.
The highest departure from the “advertised” ratio I recall seeing was 1.67 from a set of HS 1.6’s on some Indy SR’s using checking springs. With the full spring force(700lbs) at .700” lift, the effective ratio was still 1.63.
Edit- re-read the OP. I didn’t see where it said if the lifters were solid or hyd. You can’t get a good read on the true running lift using a hyd lifter for mock ups(it compresses)......... if that’s what you’re doing.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Rocker arm issues.
[Re: Stanton]
#3038178
04/29/22 10:19 AM
04/29/22 10:19 AM
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Joined: Jan 2003
Posts: 14,499 So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
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So. Burlington, Vt.
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Here's the thing with Mopar rockers, the length from the fulcrum to the contact point on the valve should be fairly close on any rocker It should be....... but in reality, there are definitely length differences on the valve side between the different brands. Stealing a pic from Andy’s book:
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Rocker arm issues.
[Re: Greenwood]
#3038181
04/29/22 10:26 AM
04/29/22 10:26 AM
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Joined: Jan 2003
Posts: 14,499 So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
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So. Burlington, Vt.
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Solid roller, and no shaft relocation. Sounds like you just have to decide how badly you want that ratio to be closer to “correct”.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Rocker arm issues.
[Re: AndyF]
#3038211
04/29/22 12:18 PM
04/29/22 12:18 PM
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Joined: Jan 2003
Posts: 75,020 U.S.S.A.
JohnRR
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U.S.S.A.
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Yeah there were all these arguments on the forums years ago so I went and bought one rocker from each mfg and put them all on a shaft. Once I did that I said "okay, now I get it"!
The Mopar rocker arms are all over the map. You don't know what works until you try it. Eventually I created a little cheat sheet that told me which rocker arms worked with which cylinder heads. If a person just randomly selects a rocker arm package then good luck and may the force be with you. Not everything works on everything. Have you shared this cheatsheet ?
running up my post count some more .
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Re: Rocker arm issues.
[Re: JohnRR]
#3038239
04/29/22 01:30 PM
04/29/22 01:30 PM
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Joined: Jan 2003
Posts: 14,499 So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 14,499
So. Burlington, Vt.
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I’ve used the Crane golds on stock heads, stage 6’s, Indy SR’s, Indy EZ’s, B1/BS, and RPM’s........no problems with the fit that were serious enough for them not to be used.
Plus...... they were pretty affordable too.
My go to replacement for them are the Mancini rockers, but I haven’t had the opportunity to test fit them on all of those applications.
The solid spacers between the rockers that the Mancini rockers use aren’t as universally install friendly as the springs that came with the Cranes.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Rocker arm issues.
[Re: Greenwood]
#3038265
04/29/22 03:38 PM
04/29/22 03:38 PM
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Joined: Nov 2003
Posts: 1,363 Out of the State of Confusion
blue_stocker
pro stock
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pro stock
Joined: Nov 2003
Posts: 1,363
Out of the State of Confusion
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I really hate to sound obtuse but I fail to see how a 'geometry correcction kit' can have a ratio effect (change) on a set of rockerarms. Regardless of the rocker ratio itself, all a 'correction kit' does is move the position of the rocker arm contact to achieve proper scrub angle...does it not? So, how then does THIS change the actual ratio or effective valve lift/ratio?
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