Lash cap help needed

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rapom65

rapom65

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Hey guys. Prior to ordering new push rods I have to correct a geometry issue with my roller rockers riding on the outer half (exhaust side) of the valve tips. The fix is to install lash caps. Having zero experience with these I'm in need of some advice.

The combo: Edelbrock RPM heads, 1.5 Crane Gold adjustable rockers. Valve stem dia. listed for these heads is .341.

The closest cap I've found is .342. Is this the correct cap to use with a .341 stem dia?

In order to move the roller contact point approx. 1/3 of the way across the valve tip what thickness of cap should I use? I've found .090, .080 and .060 cap thicknesses in the .342 size.

Thanks for the help.
 
hi, I assume you have 10 deg locks and lash cap friendly retainers? 7 deg retainers are not made for lash caps, they come out !! your measurement was taken at mid lift of the valve?? or at rest ? that makes big difference. at mid lift, roller should be in middle of stem. just food for thought.
 
Exactly how far off-center is the roller contact point? Being a modest amount off center does not matter with a roller tip. As above, how does it look through the full motion of lift. BTW, what lift are you using?
 
nm9stheham said:
exactly how far off-center is the roller contact point? Being a modest amount off center does not matter with a roller tip. As above, how does it look through the full motion of lift. Btw, what lift are you using?
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couple of notes from my experiance. We ran lash caps on the hemi back in the day(.785 lift cam dynamics roller). They fit a little tite when we put them on, after the oil got under them they were very hard to get off. Bought a set for the 505 i`m currently playing with, and they threw my contact patch off so bad i didn`t use them, i had already purchased my 9.400 push rods beforte the lash caps. Do the las caps first , them measure for pushrod length. I do have a brand new set of compcams 9.400 push rods for sale if u happen to need them.----bob
 
I've read everything I can find on this subject until my eyes feel like they're bleeding. Opinions range from "don't worry about it the roller tip negates side loading on the valve" to "guide wear will be greatly accelerated" to "it will send shrapnel into low earth orbit!". The motor is not a radical set up in the least but it will get hammered on in various venues along with, I hope, lots of highway miles in between.

Here's what I got: Motor is a 360 with Edelbrock RPM top end: ported RPM heads, RPM Airgap, RPM Cam (488 int / 510 exh), hyd lifters, Crane Gold adj rockers & shafts. Compression should be 10.25 or a bit less. The Eddys heads were rebuilt and surfaced by Brian at IMM. The original J heads were swapped for the Eddys and the adj valve train requires new push rods (cup & ball). I did a geometry check at the same time I was determining preliminary push rod length. Both valves at all 4 corners were checked. The checking push rod was set with 2 threads showing on the adjuster, including a 1/2 turn for lifter preload, and worked well for all 8 valves. The valve tips were inked and the motor spun for 3 cycles of the valve. All 8 had the same wear pattern, ie. roughly centered 1/2 way between the valve center and the exhaust side edge. I will attach a pic if I can get a clear shot. I would like to correct the wear pattern back to the center of the valve if possible. Sounds like caps and locks may not be available for the Eddy heads and if that is the case the only other option is to mill the shaft stands which I don't want to do. Having zero experience with adjusting valve geometry I'm in need of some consensus advice on what to do with this mess.

Thanks for the offer but the preliminary overall measurement on the push rods looks like they will be in the 7.200" area.

Thanks for the input, Ron.
 
ok, my question, was . do you have 7 deg locks and retainers ?? if so, lash caps are too tall and will sit on retainer/locks. lash caps are usually for 10 deg locks and retainers made for lash caps.
 
Took some searching but found an answer: 7 degree locks. So no lash caps.
Best out of the 15 pics I took trying to show the wear pattern and location. The left valve tip is what all 8 look like. Problem? Or am I worrying over nothing?
 

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How wide is the swipe? Sometimes its not about centering the roller and its more about getting the smallest wipe you can so there is less lift loss and side loading.
 
rapom65 said:
I've read everything I can find on this subject until my eyes feel like they're bleeding. Opinions range from "don't worry about it the roller tip negates side loading on the valve" to "guide wear will be greatly accelerated" to "it will send shrapnel into low earth orbit!".
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I like the last phrase LOL! The force through a roller tip rocker is transmitted through the rocker's roller axle, and then through the roller to the tip. If the axles are reasonably snug in the rollers, and the rollers are free to rotate on the axles (no burrs, well oiled), then the force goes straight down into the valve tip and stem. It does not matter if the contact point is dead center or off center, or at what angle the rocker tip is moving at any point in the cycle; the force is transmitted perpendicular to the tip surface, and so it will be straight down through the stem if the tip is perpendicular to the stem. If anything tries to generate a side force, the roller just rolls in response; that is it whole point of the design.

If the roller binds on the axle, or if the tip surface is not perpendicular to the stem's axis, or if there is any sideways motion of the rocker (along the rocker shaft), then some side force can be generated on the stems, but this will happen regardless if the roller is centered or not in all of these situations.

FWIW..... Your scrub pattern looks very close to ours, maybe a hair further offset from centered. I thought about the roller tip action and then did not worry about it.
 
You will experience premature valve guide wear with that pattern . Crower makes lash caps that will help solve your problem , $45 from summit.
 
Lash caps seem to be a band aid. On my eddies we had to mill the shaft pockets to drop the shaft down a bit. If you need to raise the shaft they make spacers.
 
GMachineDartGT said:
Lash caps seem to be a band aid. On my eddies we had to mill the shaft pockets to drop the shaft down a bit. If you need to raise the shaft they make spacers.
Click to expand...

Agreed, not that I am against 'band aids'... but given the pic below & the red circled
pedestal ...Yikes !!! ???? are all the others ... mmmm..so 'fretted'
View attachment untitled.JPG

With most humble respects Honored Posters , bandaid indeed & no slight intended.
 
You need to contact B3 racing engines. A lash cap won't fix your issues. He has some good info on his web site. Go there BEFORE you spend any money.
 
That is just some assy lube that got smeared on there as I've had the shafts off and on about 20 times in the last coupe of days. I saw it when I took the pics but didn't wipe it off. Sharp eyes!

Thanks for everyone's input.
 
If you didn't have roller rockers the sideways pushing action would definitely be hard on the guides and valve stems but I believe that if the roller rockers are quality units that roll smoothly across the valve the amount you are off is not a problem. Some say lash caps are a band aid, here's my thought on that. If you set up race heads for proper geometry when using lash caps what do you do, you cut the valve stems shorter. The lash caps then reproduce the correct valve height. It looks to me like for some reason your valves are a little short (possibly new valve seats that set a little high??) so IMO lash caps will give you the height you need but you do need 10 degree retainers and keepers that accept lash caps, as perfacar pointed out.

I ran my old 360 that had a more aggressive cam than yours with geometry that looked nearly identical to yours for about 12,000 miles when I sold it and I took it apart to inspect it to make sure I was selling something that was in good shape and it showed nearly no wear at all. I had good quality roller rockers on it and believe that was the reason it was ok with less than perfect geometry
 
Just read the info from B3 Racing that Yellow rose recommended. Very informative. I can see that level of detailed set up and the requisite expense to squeeze efficiency out of a racing engine but it just isn't practical for a hobby car, at least for me. Manufactures have to make a lot of concessions in design to make things cheaper to produce and minimize longevity issues. None of that is good for optimal performance. I'm stuck with the parts I have already invested in. Hopefully my junk will last in it's current state and I will get results like fishy88. Thanks for everyone's input and the education. Ron.
 
rapom65 said:
Just read the info from B3 Racing that Yellow rose recommended. Very informative. I can see that level of detailed set up and the requisite expense to squeeze efficiency out of a racing engine but it just isn't practical for a hobby car, at least for me. Manufactures have to make a lot of concessions in design to make things cheaper to produce and minimize longevity issues. None of that is good for optimal performance. I'm stuck with the parts I have already invested in. Hopefully my junk will last in it's current state and I will get results like fishy88. Thanks for everyone's input and the education. Ron.
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if it were mine, I`d fix up an adjustable pushrod, and experiment w/ it to see how it will effect the pattern . may help u form an opinion on which way to go next. hughs says the small blocks are more critical than the big blocks. either way, I like mine as close to perfect as possible. rollers do help in this situation tho.
 
My roller rockers are Hughes.

First check I do is with valve on the seat, checker spring installed, and no pushrod installed. Mark valve tip with a sharpie and slide the rocker side to side, this will give you the initial roller contact point.
Second check is pushrod installed, (if using hyd lifter use a test lifter with washers installed set to the preload you are going to run) go to mid lift point and slide side to side.
Third check is at full lift point.

If the 3 marks are an acceptable wipe pattern install full valve springs and recheck pattern rolling the engine.
 

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I don't know if adjustable push rods will solve the problem because your still on a fixed pivot. Its not like a chevy where the pivot is moveable/adjustable as far as height of center in relation to valve tip. Brand of rockers may affect this, depends on at what point in the rocker they make the ratio vs oal. Length of the rocker from pushrod cup cl to shaft cl vs roller cl to shaft cl is your ratio but if they messed with it some it could cause the problem. 1.6 rockers vs 1.5 ect. There's a few variables involved, much of it in the machine work. Tolerance stack up is not always a good thing!
Me personally I would turn the engine over by hand and see how far up the valve it goes. (Swipe) if it's like that on the open side it's probable fine. Roller tip make it easier on the valve but may still have a negative affect the on longevity as far as wear goes. My roller rockers rest on the exhaust side at closed and are just past the cl of the valve on the intake side full open.
 
Mike at B3 Racing Engines builds shims to correct those issues.
 
B3 is awesome to work with, Mike knows Mopar geometry. If you plan to keep those rockers contact him and follow his directions. Plan to possibly open the push rod tunnels or get Hughes rockers as mderoy340 shows. I ended up not running my rocker offsets and went with Hughes rockers.
 
mderoy340 said:
My roller rockers are Hughes.

First check I do is with valve on the seat, checker spring installed, and no pushrod installed. Mark valve tip with a sharpie and slide the rocker side to side, this will give you the initial roller contact point.
Second check is pushrod installed, (if using hyd lifter use a test lifter with washers installed set to the preload you are going to run) go to mid lift point and slide side to side.
Third check is at full lift point.

If the 3 marks are an acceptable wipe pattern install full valve springs and recheck pattern rolling the engine.
Click to expand...

Apologies, the O/P's head(s) (from one pic) are worn out 2-3x rebuilt aluminum units.

Lets , Hypothetically, infer some horizontal center lines here.
1) Crank to Cam.
2)Equal Cam Base circle to equal pushrod length.
3)Equal Cam to rocker SHAFT .
4) Combustion chamber (valve stem to placement).
Then however, Gents, we must consider the 'Y' ANGLES !!! most important
is Rear to Front alignment ... Apologies I wax philosophic...

rapom65,
Don't over think this, save up Your $$$ .
 
rapom65 said:
Just read the info from B3 Racing that Yellow rose recommended. Very informative. I can see that level of detailed set up and the requisite expense to squeeze efficiency out of a racing engine but it just isn't practical for a hobby car, at least for me. Manufactures have to make a lot of concessions in design to make things cheaper to produce and minimize longevity issues. None of that is good for optimal performance. I'm stuck with the parts I have already invested in. Hopefully my junk will last in it's current state and I will get results like fishy88. Thanks for everyone's input and the education. Ron.
Click to expand...

Ron,
Most of the engines I do kits for, are the milder street engines. They have just as much of a problem, sometimes more so, than the racing engines do. The tech articles I wrote are not geared toward just racing engines. They are to show the importance of proper valvetrain geometry on any engine, and the additional effort needed on Mopar engines because of the fixed rocker stands. The purpose of the roller tip is not to reduce friction, and once under spring pressure load in a running engine, the roller no longer rolls, it slides. Rather than run a roller rocker with poor geometry, you would be better off to stick with a stock rocker. If it's practical enough for your hobby car to spend the money for the roller rockers, then it seems logical that it is practical to get them set up correctly.

FWIW, I saw a guy break three Crane Golds in one weekend, but according to him it was the rockers fault. It wasn't, the setup was way off.
 
dano said:
B3 is awesome to work with, Mike knows Mopar geometry. If you plan to keep those rockers contact him and follow his directions. Plan to possibly open the push rod tunnels or get Hughes rockers as mderoy340 shows. I ended up not running my rocker offsets and went with Hughes rockers.
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Thanks Dano, I appreciate the kind words, but I have to wonder. Why did you decide to change the rocker instead of using the kit to have proper geometry? Using a different roller rocker can have some effect on geometry, but it will never make it correct. I'm disappointed, because I don't do this to make a lot of money. I do it to help Mopar guys have the best valvetrain possible within their budget, and buying a different set of rockers is not budget friendly.

I'm not trying to call you out buddy:coffee2:, but I don't want people to think that buying Hughes rockers is automatically going to solve a geometry issue. They will not, and I have corrected plenty. Like mr68gts pointed out, "The pivot (fulcrum) point does not move", and that is regardless of the brand of rocker.
 
I have to wonder how many thousands of engines ran 100,000 plus miles with geometry right from the factory worse than that. Probably a lot.
 
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