RHS head valve train geometry issue

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Rat Patrol

Rat Patrol

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1st off - I have no pics to go along wth this question - so please be pateint .

2nd - These are NOT MY HEADS . ..I'm postng this as a favour to a guy in my home town.

3rd - The facts have been verified by hard core race guys And TWO engine builders - please don't make any assumptions about ability in relation to this issue - the problem was genuine and did exist.

OK - here we go...........:D

Background

About 12 mths ago local guy down here in Melbourne Australia ordered a set of OOTB 1.92 valve RHS LA-X heads from the local wholesaler - The local Wholesaler is the Comp rep. for Australia amongst other brands.

I have no idea who supplied them in the US - I am assuming Comp did?

I know it wasn't IMM, Hughes or Indy.

He took them to an established and reputable hi performance engine builder which is how I know about the issue - I was in his shop today discussing something unrelated about piston shaving.

Issue

Put simply - when std 1.5:1 ratio roller rocker gear is fitted up - the rollers hangs on the edge of th tip, and things get worse when the valve spring is compressed....:rolleyes:

The builder tried Harland, Comp Pro Magnum and Crane Gold and the same issue came up - as the valve opened, the roller tip fell off the tip of the valve! :eek:ops:

Put simply - the shaft stands in the heads have been cast in the WRONG PLACE -

Engine builders on here will know that it doesn't matter what length valve is used..or if the shaft is shimmed - the distance between the shaft and the tip is simply too wrong to achieve sound geometry.

The roller starts on the ist 1/3 of the tip, and as the valve is pressed down, the tip jsut rolls off the end of the valve!


Action


The Comp rep called Comp who didn't want to know.

The owner called Indy and Hughes - here were the responses.

Indy said - "you have to use our rockers"

Hughes said - "you have to use our rockers"........

These are weird responses - why would Hughes or Indy create a rocker set up just for RHS heads?

If they worked for these heads, they clearly wouldn't work on any others like Eddies or OEM.

:wack:



RESULT

The owner of the heads gave up - the local Comp rep took them back but now the user is worried about ordering any further sets either direct from the US or through the rep because of this casting issue.

QUESTIONS

before i ask - please no "suggestions" on how to fix it - it was unfixable and the only option would have been to drill and tap for pedastal rockers.

Q 1 - Have any users or engine builders on this forum experienced a similar issue with rocker gear not lining up in the correct position on the LA-X castings?

Q2 - Was there a bad batch that has now been recitifed?

Or are most guys just putting their hands up and going with pedastal stands.?

Please understand - Australia is 18000 miles away and if there was a bad batch issue - we never heard about it and we need to know.

Partly so people can buy them without fear now - and partly so any "returns" can be done with the correct information supplied back to the sellers.

Any feedback gratefully received.

Thanks for your patience.

RP
 
It's not "unfixable". I won't say I've seen it a lot, but I've seen it. There's these little thingies been around about 100 years called lash caps that'll fix it right up.
 
StrokerScamp said:
It's not "unfixable". I won't say I've seen it a lot, but I've seen it. There's these little thingies been around about 100 years called lash caps that'll fix it right up.
Click to expand...

Rat Patrol clearly said that it is not a valve length issue. Just get yourself a set of EQ Magnums and motor on if you just have to have a Magnum style head. J.Rob
 
My son had the same problem. We had ordered the heads from Indy.
We put His Harland shape rockers on was running his engine and bent 2 valves.
Called Indy they said older rockers we actually to long. We purchased there rockers everything worked fine. IT was 360 Roller motor.
 
My friend had a 408 with RHS heads built recently and the builder tried all sorts of rocker gear, finally decided that the Indy rocker arms were the only ones he could achieve the proper geometry with. I think the rocker set cost him $497.
 
I had no issues with my RHS heads, but they were for the magnum engine.

I look at it this way, don't "assume" anything when buying a product, ask questions, & then ask more, if the merchant is inpatiant with you, take your money elsewhere. I'm sure the RHSs were designed this way to except a different length rocker.
 
Longer valves can cause issues on any shaft mounted head. That's why long stem valve W-2 heads required the offset stands. You need to know if the valves are OEM length or longer. Then you'll have a better idea how much it's the stand location and how much it's the valves.
 
Mal - were these LA-X or MA-X heads? The head's basic design is Magnum, but it can be machined for either setup. Just out of curiosity, and sorry if I missed it, but did you try a set of 1.6 rockers?
 
RAMM said:
Rat Patrol clearly said that it is not a valve length issue. Just get yourself a set of EQ Magnums and motor on if you just have to have a Magnum style head. J.Rob
Click to expand...

Yeah I saw all his little requirements to answer. Lash caps are not just for length discrepancies, they also very handily address diameter issues adding surface area and are a fine fix for valve train geometry issues.
 
Not just 20 minutes ago, I tried a set of PRW stainless rockers that fit great on the factory LA head, on the 360 LA-X. They are waaaaaay to long to work on the LAX head. I believe the LAX heads were designed that way on purpose.

The only thing I have used the LAX head for is flow testing and for converting to Chevy style stud mounted rocker arms. Hmmmm. I have to buy Hughes or Indy huh? Why am I not happy about that?
 
StrokerScamp said:
Yeah I saw all his little requirements to answer. Lash caps are not just for length discrepancies, they also very handily address diameter issues adding surface area and are a fine fix for valve train geometry issues.
Click to expand...

sure....but then u have side loading issues on the guide, increasing the contact area yet leaving it offset ..is not the answer.

the stems could be cut down...but he might find by the time he is done ..that the tips recede below the locks.lol

'usually' if its too far to the exh side...the stems are too long.
 
StrokerScamp said:
Yeah I saw all his little requirements to answer. Lash caps are not just for length discrepancies, they also very handily address diameter issues adding surface area and are a fine fix for valve train geometry issues.
Click to expand...

sure....but then u have side loading issues on the guide, increasing the contact area yet leaving it offset ..is not the answer.

the stems could be cut down...but he might find by the time he is done ..that the tips recede below the pop up locks that tend to be used on these heads since the spring int height is so short.lol

'usually' if its too far to the exh side...the stems are too long.
 
Right....I have since been told that the problem is that the rocker tips roll over the outside edge of the valve tip and not the inside. That's about as F&%!! up as it gets.
 
More of an FYI than anything truly helpful but my LAX heads (running Brian's standard Ferrea/beehive combination) are fitted with Comp Magnums and start with the roller only SLIGHTLY outboard of centre with the valve closed. Not quite ideal but not a concern I hope!
 
MoparAnglia said:
More of an FYI than anything truly helpful but my LAX heads (running Brian's standard Ferrea/beehive combination) are fitted with Comp Magnums and start with the roller only SLIGHTLY outboard of centre with the valve closed. Not quite ideal but not a concern I hope!
Click to expand...

yeah. not really gonna hurt anything like that.

maybe lose a lil lift, but nothing harmful
 
1wild&crazyguy said:
yeah. not really gonna hurt anything like that.

maybe lose a lil lift, but nothing harmful
Click to expand...

good to know .... my LA X had the wipe pattern just to the exhaust side of the valve stem .... I have 1.6 PRW stainless

this may sound stupid.... but could I mill the shaft groove deeper to improve this? or would that do nothing.
 
OK thanks for the replies - so it seems there IS an ssue - and the Indy rockers are the only ones that appear to address the issue.

I guess that means that Indy rockers on an OEM head would be out of spec but possibly less of an issue.....Thats crazy!

I guess I need to ask if anyone has had NO issues?

That might mean it was limited to one casting run?

Maybe Brian from IMM might know?

@ Moper - They're LA-X mate - shaft mounted rockers.

@ Stroker scamp - Sorry my description mislead you - I not an epxert on this stuff - but the Engine builder tried longer and shorter valves and the issue was the distance of the stands from the valves....

@ IQ52 - seems you've hit the same issue -

Are Hughes rockers the same as Indy?

Thanks for the feedback so far -
 
The sweep is the MAIN conscern, not how centered the sweep is (within reason). The best rockers I've found were Hughes older style rockers. Have not tried their new rockers so I cannot comment about them.
I use the PRW's almost every time now because they work, they are priced well, complete kits, and the sweep is very good for a mopar rocker.
I only use the stainless version though!!

I can tell you, I had a set of HS rockers on one of our heads to do a mock up for a customer to show him how bad HS geometry is....I saw the same thing. They will WALK OFF the tip of the valve!
 
Someone on one of the site put 6 or 7 different roller rockers on a shaft, side by side. The difference in roller tip centerline to the shaft centerline was significant. Very easy to see.

I had a set of HS rockers and mocked them up on an ede head I planned to use and they were terrible. Much like described by Mal. The recommended HS fix made the situation worse. Unfortunately we get to work with intersecting angles regarding valve and rocker shaft/pedestals mount.

IMO, a lot of this has to do with trunion diameter and where the adjuster is located. Fat trunion = move it out. Move that away from the shaft centerline and the roller tip need to move further out as well.
 
Rat Patrol said:
@ Stroker scamp - Sorry my description mislead you - I not an epxert on this stuff - but the Engine builder tried longer and shorter valves and the issue was the distance of the stands from the valves....
Click to expand...

The apology is mine. I didn't mean to be so snappy....it kinda comes natural for a smartass. lol
 
yes there is a balance between centered and sweep width, but most of the time u end up with a narrow sweep the closer you keep it to being centered on the valve stem. ime
 
Thanks all for your feedback

Its clear now that there's an issue with some rockers more than others - I'll pass on what you've all found and hopefully people will get an understanding of whats required.

I now have pics of the actual rockers and heads.

Comp rocker - RHS head

ComponRHS.jpg


Comp RHS again

ComponRHS2.jpg


Same Comp rocker on an Eddie

ComponEddier.jpg
 
Very interesting thread. Thanks for the pics...you can easily see the difference. Valvetrain geometry has always fascinated me. We run 1.3"(not a typo) of lift on our big race motor...talk about seeing some crazy angles and geometry!
Glad this guy wasnt the only one who has experienced the same problem. Its always refreshing knowing youre not alone when a problem arises. :)
 
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