rocker box clearancing

[scoopfraser]

I recently pulled apart my rocker boxes to have a look at things and noticed something.  The top rocker cover on the rear cylinder had some clearancing done to it whereas the front cover wasn't touched at all.  The engine build is a 95" UG build with Wood TW6-HG cams, 155 lb. Crane springs with stock rocker arms and supports.  I would assume that if there was a need for clearancing on the rear cylinder that the front would require something similar.  Anyone have any thoughts on this?  Does the 0.590" lift on these cams require clearancing in the rocker box webbing?

Thanks for any input,
Sean
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[Mike52]

Every time I've used Crane springs, I've had to clearance both rocker boxes. Remember, it's the spring retainer area that needs the clearance more so than the spring. I use a 1" round stone in a die grinder, give it a good squirt with WD-40 before grinding and the aluminum won't build-up on the stone.

Mike

[GoFast.....]

I recently pulled apart my rocker boxes to have a look at things and noticed something.  The top rocker cover on the rear cylinder had some clearancing done to it whereas the front cover wasn't touched at all.  The engine build is a 95" UG build with Wood TW6-HG cams, 155 lb. Crane springs with stock rocker arms and supports.  I would assume that if there was a need for clearancing on the rear cylinder that the front would require something similar.  Anyone have any thoughts on this?  Does the 0.590" lift on these cams require clearancing in the rocker box webbing?

Thanks for any input,
Sean
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If you have run them like they are you should see some wear on the rocker boxes if they are hitting

[POORBOY]

Wonder if one of the valves were sunk a little deeper for some reason.

[Mike52]

I recently pulled apart my rocker boxes to have a look at things and noticed something.  The top rocker cover on the rear cylinder had some clearancing done to it whereas the front cover wasn't touched at all.  The engine build is a 95" UG build with Wood TW6-HG cams, 155 lb. Crane springs with stock rocker arms and supports.  I would assume that if there was a need for clearancing on the rear cylinder that the front would require something similar.  Anyone have any thoughts on this?  Does the 0.590" lift on these cams require clearancing in the rocker box webbing?

Thanks for any input,
Sean
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After rereading the original post I feel like a dumbass, it's true, sometimes you can't see the forest for the trees.

Ron's post makes perfect sense now.

Mike

[scoopfraser]

Thanks for the replies!  I've attached some pics that are hopefully clear enough.  In pic 346 there is an odd circular (tooling?) mark that I can't explain.  I'm interested to hear anyone else's thoughts.  Pic 352 has a smooth (rub?) mark that doesn't look like it was made with a die grinder.  It's the one below the casting stamp that runs horizontally.  I should mention that the reason I opened up the rocker boxes is that I'm chasing a rattle that only occurs at certain rpms and when the engine is cold.  It disappears once the engine has warmed up.  I've also put in all new lifters.

http://i396.photobucket.com/albums/pp43/scoopfraser/CIMG0352.jpg
http://i396.photobucket.com/albums/pp43/scoopfraser/CIMG0346.jpg

Thanks!
Sean
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[scoopfraser]

I've outlined the rub mark in this pic...

http://i396.photobucket.com/albums/pp43/scoopfraser/CIMG0352a.jpg

Sean
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[Mike52]

Those are really unusual marks. When you lay the cover back on the rocker box, what is directly underneath the marks?  The same would apply to the round mark you showed.

Mike

[POORBOY]

Put your cover on with a couple bolts, pull spark plugs, turn engine over with starter and your hand laying on the cover and see if you feel them hitting or better yet clay up the cover and check clearance then you will know what is going on.

[GoFast.....]

Thanks for the replies!  I've attached some pics that are hopefully clear enough.  In pic 346 there is an odd circular (tooling?) mark that I can't explain.  I'm interested to hear anyone else's thoughts.  Pic 352 has a smooth (rub?) mark that doesn't look like it was made with a die grinder.  It's the one below the casting stamp that runs horizontally.  I should mention that the reason I opened up the rocker boxes is that I'm chasing a rattle that only occurs at certain rpms and when the engine is cold.  It disappears once the engine has warmed up.  I've also put in all new lifters.

http://i396.photobucket.com/albums/pp43/scoopfraser/CIMG0352.jpg
http://i396.photobucket.com/albums/pp43/scoopfraser/CIMG0346.jpg

Thanks! it looks like the valve have sunk in and the springs are hitting top, What kind of heads are on this
S
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[Admiral Akbar]

As fas as I can see, it looks like someone might have screwed up something on the assembly and repair it.. You don't need clearancing of the top cover with stock rocker arms. You will need clearancing of the lower box for springs though... Max

[scoopfraser]

Thanks for all of the replies guys!  The rub mark would be over the intake valve side on the rear cylinder.  As for that round mark, I can't imagine a running engine could produce something like that.  The underside of the cover actually looks like an apprentice got to practice with a die grinder.  I think I mentioned before that the cover on the front looked mint-no grind marks or anything whatsoever to suggest rubbing.  I may be just reading a lot more into this than there really is.  I think it might be worth claying it up just for curiousity's sake. 

Thanks again!
Sean
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