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Rocker arms
https://slantsix.org/forum/viewtopic.php?t=56165		 Page 1 of 1
Author:  SlantSteve [ Tue Sep 09, 2014 11:30 pm ]
Post subject:  Rocker arms
Hi all,just curious...are the intake and exhaust rockers the same?? I've got 2 complete sets of loose rockers laying around here in a box and a quick look would indicate they are all the same but wanted to be certain...something seems to be in my mind the exhausts had slightly different oiling? But I could be thinking of something else...I'm Just trying to put the best set together with similar ratios etc. thanks!
Author:  Pierre [ Wed Sep 10, 2014 12:14 am ]
Post subject: 
They are the same. You may be thinking hydraulic vs solid lifter rockers. Or maybe about the spacers, those aren't all the same.
Author:  Sam Powell [ Wed Sep 10, 2014 5:26 am ]
Post subject: 
I blueprinted a set one time, and they actually vary from 1.44:1 to 1.55:1. I put the higher ratio ones on the intake. But they are supposed to be all the same. You will be doing factory quality work if you just put them on.

Sam
Author:  DadTruck [ Wed Sep 10, 2014 7:40 am ]
Post subject: 
Quote:
I blueprinted a set one time
been thinking of doing that,,,

something like

* afix a rocker shaft in a stand so it is stable
* have two dial indicators fixed on a plate so one registers into the push rod pocket and one onto the valve stem contact patch
* zero both indicators,
* move the push rod side up .100
* record the .100 + reading on the valve stem side
* do the math

or is there a simpler method?
Author:  Sam Powell [ Wed Sep 10, 2014 8:34 am ]
Post subject: 
I did what you said, but mounted rocker shaft solidly and slid rockets on and off checking each one. Cheap fun.
Author:  Pierre [ Wed Sep 10, 2014 9:57 am ]
Post subject: 
The differences aren't surprising since they are stamped.

These measuring gadgets sound nifty. Aren't springs required to prevent the arm from flopping around?
Author:  Joshie225 [ Wed Sep 10, 2014 10:17 am ]
Post subject: 
Dial indicators are spring loaded.
Author:  SlantSteve [ Wed Sep 10, 2014 2:12 pm ]
Post subject: 
Thanks guys, much appreciated. Yep, I'm going to pick the best ones that not only give the same ratios but also the best geometry.... Something tells me it's going to be a compromise, but at least it will be as close as practically possible
Author:  Pierre [ Wed Sep 10, 2014 2:26 pm ]
Post subject: 
Yep they are but those springs are so weak you could sneeze and they move, would be finicky to set them up at least the way I'm picturing. If you do this again I'd dig a pic of the setup.

Also - doesn't the ratio change dynamically as the rocker goes through it's motion? The rod end pivots on the screw, but the valve stem point of contact gets pushed out towards the tip of the rocker as it opens the valve. If this distance changes an integral may be needed to figure out ratio instead of simple math.
Author:  SlantSteve [ Wed Sep 10, 2014 2:53 pm ]
Post subject: 
Yeah,very true...or just blue the tip of the valve to check contact area and put a dial indicator on the retainer to check lift....gives you exactly what the engine is going to see. Remember the head will be another variable,i doubt all the guides were machined perfectly parallel to the rocker shaft,or even to each other for that fact...it's 60's Detroit tolerances at its best! I think doing it this way rules out all variables...I hope! And yes,the valve springs are pretty low pressure,but I still think doing this May still help reduce guide wear, plenty would never bother checking rockers etc...but hey,why not put in a little extra effort to do it. Thanks for your help everyone,always appreciated! I'll tell you what I find when I do it.....hopefully over the next few days,work and life permitting.
Author:  SlantSteve [ Sun Sep 14, 2014 2:59 am ]
Post subject: 
Well,I went thru all the rockers I had today,basically 2 complete sets.i just set a dial indicator up on the spring retainer of each valve and measured actual lift. To my surprise they weren't as bad as I thought,there were a couple of shockers...there was like .020" difference between the worst and best. So I mixed and matched and put the better ratios on the intake. I ended up pretty close,within .005" variance between intakes and pretty similar on the exhausts. Bit of a fiddly job but can't hurt...got some free extra lift so that can't hurt! :D
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