Author Topic: EC Roller Rocker Installation: 33 vs. 31  (Read 2773 times)

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Offline Jeff McKelroy

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EC Roller Rocker Installation: 33 vs. 31
« on: June 20, 2014, 07:38:12 PM »
Building an engine for someone, and I am attempting to install EC's fantabulous roller rockers on a 33 head, and I noticed that there is a .200" difference in height between the 33 head and the 31 heads' rocker stud bosses, leaving a large gap between the bottom of the roller rocker mount to the stud boss on the 33 head. The 31 head accepts the mount perfectly, with the bottom of the mount reaching the floor and touching the stud bosses. You can mic the floor of the valve area between the two heads and that is where the difference is. Total head height, etc are all the same otherwise. 

So has anyone else run into this problem? I didn't call in to see if there are part number differences between the old OHV and the newer AVS, but EC only shows one number.  The mount I received looks nothing like the one in the picture on EC's site, and indeed looks much sturdier with its extra reinforcements. Naturally, I received the parts on a Friday so I can't call in for tech information.

So, can I safely remove .200 from the bottom of this rocker mount? This certainly would be the easiest thing to do...



Offline redline

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Re: EC Roller Rocker Installation: 33 vs. 31
« Reply #1 on: June 20, 2014, 08:41:50 PM »
Could you take the .200" off the bosses on the head? That way the rockers could still be used on a 28/31ci Head if the future ever required it?

Wait, I re-read your post, you said you have a gap on the 33 head? That would mean the bosses are shorter on the 33, no? If that's the case, couldnt you machine a spacer?

Either way, I would try to modify the head and not the rockers. Like i said, then they could be used on a different head if required.
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Offline George Herrin

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Re: EC Roller Rocker Installation: 33 vs. 31
« Reply #2 on: June 22, 2014, 01:09:41 AM »
Cut bosses down not the rockers or mounts
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Offline Jeff McKelroy

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Re: EC Roller Rocker Installation: 33 vs. 31
« Reply #3 on: June 22, 2014, 08:34:46 AM »
The only way I can modify the head then, since the stud bosses are shorter on the 33 head, is to make spacers between the rocker mount and the stud bosses of the head, intall .200" longer valves and .200" longer pushrods??? 

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Re: EC Roller Rocker Installation: 33 vs. 31
« Reply #4 on: June 22, 2014, 03:24:02 PM »
Send some p[ictures to sales@eccarburetors.com and call and speak with Carroll.
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Offline Jim Knutson

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Re: EC Roller Rocker Installation: 33 vs. 31
« Reply #5 on: June 22, 2014, 05:24:54 PM »
Jeff, if the pushrods are the same length between the 31 and 33 you have, then shimming the mount  up the .200 on the 33 head would be the same as using them without a shim, on the 31 head...right? If the head design has been changed, and not pushrod lengths, then you should be fine by shimming.
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Offline Cromwell C4

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Re: EC Roller Rocker Installation: 33 vs. 31
« Reply #6 on: June 22, 2014, 07:38:00 PM »
Why not just use a 31ci head or one with the normal length stud bosses? That would be much easier. I built a 33ci head for a customer before and didn't have this issue.
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Offline Jeff McKelroy

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Re: EC Roller Rocker Installation: 33 vs. 31
« Reply #7 on: June 23, 2014, 11:10:07 PM »
Send some p[ictures to sales@eccarburetors.com and call and speak with Carroll.


Will do.  ;D
Why not just use a 31ci head or one with the normal length stud bosses? That would be much easier. I built a 33ci head for a customer before and didn't have this issue.

I suspect you didn't have this issue because they have since changed the girdle.  It now has a cross-brace with two additional fastener holes for added strength, and I find it rather superior to the older version.  Also the rocker-to-valve contact has been improved.

I also find the 33 head to be superior to all other OHV heads, with the exception of the exhaust port on the old 28 head.  There is no taper in the intake runner.  The bowl has a better radius.  There is material added around the intake manifold flange area on the outside, as well as extra material across the bottom side of the intake runner for added bracing.  Needless to say this and other features have caused the floor of the rocker area to be raised considerably, but without changing the length of the factory pushrods, which is why I might be over-complicating things, yet again.

I think milling the bottom of the cross bracing of the stud girdle .200" will no only save me the trouble of making spacers, and making other valvetrain changes, but will, and I hope, not affect the strength of the girdle.  It's nearly .500" thick.

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Re: EC Roller Rocker Installation: 33 vs. 31
« Reply #8 on: June 24, 2014, 11:05:14 AM »
This is real good to know. We don't always see what the new stuff brings. It is also good to know they fixed a headache. Now if they would do something with that AVS stuff we would be good!
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Offline Jeff McKelroy

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Re: EC Roller Rocker Installation: 33 vs. 31
« Reply #9 on: June 25, 2014, 09:16:08 PM »
This is real good to know. We don't always see what the new stuff brings. It is also good to know they fixed a headache. Now if they would do something with that AVS stuff we would be good!

Oh but they have.  A few dimly lit garages around the country have been figuring this lightweight motor out...

Offline DoNoHo

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Re: EC Roller Rocker Installation: 33 vs. 31
« Reply #10 on: July 24, 2014, 01:59:10 PM »
What's the solution to the problem? 
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Offline leadslead

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Re: EC Roller Rocker Installation: 33 vs. 31
« Reply #11 on: July 24, 2014, 05:50:35 PM »
Kohler .. Tecumsha ... Honda
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Re: EC Roller Rocker Installation: 33 vs. 31
« Reply #12 on: July 24, 2014, 09:36:35 PM »
Kohler .. Tecumsha ... Honda
LOL "Like"!
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