I have some questions about rocker geometry that may have been addressed somewhere individually but not as a "concept".

I have decked my block, changed my cam, and installed longer SBC valves. I just purchased a new Erson cam and wonder about geometry.

The old setup with Comp 264s was on the very edge of running out of rocker adjustment and I had installed jam nuts to keep the adjusters from backing out. I dont like more weight in the valve train. I would like to have the adjusters more in the middle of the range.

I have had to dimple my valve cover baffle for clearance because the top of the adjusters can hit the baffle.

I have had to grind a little on some rockers so they dont hit my valve retainers at certain lifts.

I can solve the adjuster problem by shortening my valves or pushrods.

I can solve both problems with a rocker stand solution.


My questions: Was the factory geometry ideal?

Are shorter pushrods a better fix than rocker stand shims
or new stands?

What are the implications of rockerarm
massaging/trimming?

Can I just file fit my valve tips to take up some slack like
I did on my Flathead?

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Longer valves are a bad deal as they not only create rocker adjustment problems, but reduce the rocker ratio. The longer the valve the the closer to the rocker shaft the tip becomes reducing the ratio. In theory you need to move the rocker shaft upward and away from the valve stem to get the rocker to valve geometry correct. Then get pushrods to match. Decking the block doesn't hurt the valve train geometry only the needed pushrod length because the rocker pivot point is fixed unlike anything with a moveable fulcrum.

The factory geometry is rarely ideal and usually falls short of the published 1.5:1.

In your case you need either shorter valves or a higher rocker shaft placement. Simply moving the rocker shaft up will help you clear the reainer, but leave you with a lower rocker ratio.

The implication of rocker arm trimming is strength.

The valve tips need their hardened tip because the rocker arm wipes across the valve tip. The flathead didn't have rocker arms and no wiping action.

Did I miss anything?

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Joshua

Luckily I dont need to move the rocker away from the valve...its very good where it is....if I shim a little....

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Josh, are you looking at a slant head or a V-8 head? I am working on a long valve slant head, and my rocker shaft needs to be raised up and move toward the valve. On a slant head the valve stem tilts away fron the rocker shaft. On a Mopar V-8 the valve stem tilts toward the rocker shaft. On my head it looks like (eyeball) the shaft needs to be raised about .250 and moved toward the valve about .100. I still need to get acurate measurments. Then I will have to make longer pushrods (I think).

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

so I jumped in the other tread that took this subjuct up. Ill try again, if the head deck serface is not milled say past .050 would that creat a problem with the SBC valve useage? or is the lenght or the valves to much? Where can one find the shims to heighten the rockers to the correct lenght.

Rocker ratio my be adjusted buy using 1.6:1 rockers. Also if they are roller type would that take off some of that "swipe stress".

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it's like a vw, sounds like a million miles an hour but goes really slow. (for now)

Ahh, that's what I missed! So longer valves would help the rocker ratio on a slant!

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Joshua

the length that the ajustment screw is away from rocker also affects rocker geometry by lowering the pivot point witch lower rocker ratio, when i shorten my valves at the tip with all the milling on both surfaces,with lash done there was only 2 treads showing ,1 would have been closer as to clear push rod to rocker clearance at max lift.the valve tip show no wear although the mechanist did say the ex tip was harden at the tip.

Looks like I need to go up about .250 to get to where I need to be with my setup as well. ...

Then I would have correct geometry , stock pushrods ....

Time to hand file some shims from an old shaft........?

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Be careful shimming the rocker shaft as it will split the sides off the stand.

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Official Cookie and Mater Tormentor.

Hence my hand file remark. It definitely needs to be done correctly.

A piece of thick wall tube same OD size as rocker shaft. Slice the top 1/2 off and hand file till the rocker shaft "nests" into the ID. Done correctly there should be no side loading on the stand......

Im good at making 2 items....the first is usually a mess..the 2nd pretty dialed....the rest are so/so cuz Im bored.

"LUCY!....yoo bin filing loominum with my chainsaw files again!?"

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Yeah....Im the one who destroyed this rare, vintage automobile.....

I'm thinking about machining the top off the rocker stands, and making stands to bolt on, like on the W-2 heads.

I did that to a set of 440 heads, and used the 413 bolt on stands, to allow me to use some shaft mount Chevy roller rockers. Back then, I had access to a machine shop. Now I do not.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Add shots of rocker shaft, most will not need to go to this extream but it will give you some ideas.
Got the truck back from body shop yesterday, I will add pictures of new paint.
hope link works!!!???

http://slant6racer.mysite.com/?refcd=WSUOWS080630NE03

Will. The link works, but I don't see any shots of the valve train.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Charlie, click the middle link to "My Photos" on the left hand margin. There are a couple of valve train pics in there.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

Will, that looks really great. Let us know how it works.

Sam

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