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rocker bar shims.... is it possible? I need pro tech advice

Guido

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New motor with .488 hyd-flat tappet cam. Broke-in and running fine. Puled heads off for correct spring pressure replacement and decided to increase the lift with 1.6 rockers. I Bench-set the 1.6 rockers but the roller tip is a little past the center of the valve tip towards the exhaust side. Can I shim the rocker bar to achieve the correct geometry? I know it may need longer pushrods. No problem there if needed. But the geometry is still not perfect. I can live with the 1.5 set if no other solution. I don't want to change cam bearings and cam and lifters, ect. I would leave it alone if that's the only way to get a higher lift at this point. All answers greatly appreciated.
 
First, check out B3 racing website tech forum. Super info on mopar rocker geometry problems and fixes. Then call him, tell him what rockers you want to use, (the various brands are all over the map, regarding arm length, ratios, adjuster angles etc.) and ask his advice. It will keep you from breaking the rocker stands with badly designed shims, like happened to Warrenavenue. See his thread, edelbrock performer heads b block.
 
You need to know if the block and/or heads have been milled. Are the valves new or sunk into the seats ? The tolerance stack up can lead to major geometry changes. Custom push-rods are required. Get a couple of adjustable push-rods so you can measure what length they need to be. Any good engine builder will want to know the answers to these questions to give you a good answer about geometry.
 
Thank you...Block was milled 10 thousandths and new aluminum heads. There's no valve seat subduction. valve tips are straight as an arrow. Using PRW 1.5 roller rockers with some custom cut pushrods I got from 440 source after measuring with adjustable push rods and the geometry is perfect with the current 1.5 rockers. May have to cut new pushrods if the rocker bars can be shimmed and get the geometry correct for the 1.6 rockers. But new to the Chrysler rocker bar system - Any rocker bar system for that matter. My first Chrysler build with performance parts and I'm at an im-pass. Thank you for your input. I will contact 440 source and see if anything can be done other than running a bigger cam. I don't want to pull the motor back out for new cam bearings. It's ok the way it is. just hoping to kick it up a tad.
 
First, check out B3 racing website tech forum. Super info on mopar rocker geometry problems and fixes. Then call him, tell him what rockers you want to use, (the various brands are all over the map, regarding arm length, ratios, adjuster angles etc.) and ask his advice. It will keep you from breaking the rocker stands with badly designed shims, like happened to Warrenavenue. See his thread, edelbrock performer heads b block.
I just looked and it's just what I needed. thank you so much.
 
First, the location of the rocker tip relative to the valve stem, as you described, has nothing to do with geometry. Second, the tip to valve geometery will not change from rocker to rocker. Its the relation of the shaft mount to the valve tip. Cutting the heads has nothing to do with it.

Chasing after rocker geometry on a .488" lift hydraulic cam is a complete waste of time and money.
 
using roller rockers on a 488 cam is what's a waste of time and money
"Chasing after rocker geometry on a .488" lift hydraulic cam is a complete waste of time and money " BS
if you go roller rockers and you want it to last and you have your rollers running off the valve tips???

Lots of good engine builders know little about mopar rocker geometry as do many good camgrinders

most likely 1.6 on the exhaust does not help unless stock manifolds
 
First, the location of the rocker tip relative to the valve stem, as you described, has nothing to do with geometry. Second, the tip to valve geometery will not change from rocker to rocker. Its the relation of the shaft mount to the valve tip. Cutting the heads has nothing to do with it.

Chasing after rocker geometry on a .488" lift hydraulic cam is a complete waste of time and money.
I agree, unless for some reason it's really bad. In that case maybe there's something else wrong like a parts mismatch?

Guido--whatever you do, don't put those little 440 source/Mancini/Hughes shims under the shaft that are a uniform thickness. They most often make matters worse because they only move the shaft in one direction, when we need to be going up AND away from the valve. And, they can cause the pedestals to crack:eek:
Post up some pics of the tip location through the lift cycle so the experts can get a look at it, your best bet may just be to leave it alone...
 
First, the location of the rocker tip relative to the valve stem, as you described, has nothing to do with geometry. Second, the tip to valve geometery will not change from rocker to rocker. Its the relation of the shaft mount to the valve tip. Cutting the heads has nothing to do with it.

Chasing after rocker geometry on a .488" lift hydraulic cam is a complete waste of time and money.
.
 
Not sure what it's called when the roller tip hangs too far over the valve stem tip. I thought is was part of the geometry. What ever the case may be as to why the 1.6 are too long if I can say that anyway. I had a talk with a tech at 440 source this morning and he said basically the same thing u did. It's just not worth it. Just more money and more things that can go wrong. I thought changing the lift from .448 to .521 would give a noticeable boost in power. But after everything I've heard Ill just let be. It's just fine. Not a rocket ship obviously, but still very fun to drive. For me, anyway...Bet you're more of a Mach 10 with your hair on fire kinda guy. LOL The current 1.5's are perfectly centered so I will just put the bigger springs that go with this cam and leave it at that. Thanks for taking the time. Appreciate it very much.
 
I agree, unless for some reason it's really bad. In that case maybe there's something else wrong like a parts mismatch?

Guido--whatever you do, don't put those little 440 source/Mancini/Hughes shims under the shaft that are a uniform thickness. They most often make matters worse because they only move the shaft in one direction, when we need to be going up AND away from the valve. And, they can cause the pedestals to crack:eek:
Post up some pics of the tip location through the lift cycle so the experts can get a look at it, your best bet may just be to leave it alone...
 
Thank you for taking the time to write me. Appreciate it very much. I will leave it alone. My first Chrysler build and the learning curve was very steep for my little ol' brain. Lol I just wish I woulda went just a little bigger with cam. Thanks again.
 
"Chasing after rocker geometry on a .488" lift hydraulic cam is a complete waste of time and money " BS

Roller tip rockers have been around for 40 years used in God only knows how many shaft applications, and for how many millions of miles. All of a sudden, they are deemed to be unacceptable when used as purchased. I have a set of 25 year old heads here that suggest otherwise.

Slapping roller tip rockers on any stock and many aftermarket head applications will cause the geometry to be less perfect than without roller tips. However, the significance of the consequence for this lack of perfection has been exaggerated for many applications. As lift and spring pressures go up, better geometry does become more important. But even then, how much?

Folks will simply need to do objective review of information on the relative importance of perfect geometry for their situation, total cost, time and effort, and value.
 
BD I've had to fix lotsof guides and trashed engines from roller tip rockers
Either get the B3 type kit or do not use roller tip rockers
on the road racers and high lift dodges we machined the pedestals off and made blocks like the early BBM and Max Wedges
would not have done it if we did not have to
good move Guido get B3 kit or forget it
some try lash caps if not too far off but that just hides the problem
and X2 on just using shims
those with long valves or larger springs or both like for 2" Battleship springs can get themselves in real trouble
some grind the underside of the rocker and some of those break rockers
beehive springs and their smaller retainers appear to solve the rocker/ retainer problem but again that just hides the real problem of fulcrum being too low
cheers
if you do work with mike ask about 1.6 on intake only I do not see where they help on the exhaust without a blower or nitrous
 
Roller tip rockers have been around for 40 years used in God only knows how many shaft applications, and for how many millions of miles. All of a sudden, they are deemed to be unacceptable when used as purchased. I have a set of 25 year old heads here that suggest otherwise.

Slapping roller tip rockers on any stock and many aftermarket head applications will cause the geometry to be less perfect than without roller tips. However, the significance of the consequence for this lack of perfection has been exaggerated for many applications. As lift and spring pressures go up, better geometry does become more important. But even then, how much?

Folks will simply need to do objective review of information on the relative importance of perfect geometry for their situation, total cost, time and effort, and value.
 
It would be interesting to dyno a before and after. May be someone has.
 
I've decided to leave it the way it is. Thank you for taking the time to write. This whole Chrysler rocker system is a very complicated to me. Rocker off-set? I'd never in my 35 years of building motors (again- u know I'm not a pro) ever heard of that. I was and still am a Pontiac and Chevy man and even a couple of Fords over the years. This is very my first Mopar. All of my Mopar buddies from High school who aren't dead or in prison ( Heh, Heh) always talk about how simple Chryslers are to work on. And l think they are in many respects. No trouble w/ the bottom end. But the heads? - I've never done so much reading only to find myself more confused than ever. Lol. Everyone's at adds on what to do about these mysterious Chrysler heads. I thought "a rocker bar?" and "no valve guides" - "Great!". But then all of this "rocker offset" "what heads are they?" Is it .450 or .650 and I still couldn't even tell what the stock rocker arms offset is. Even now... I only have a rough idea of what the stock offset is. Hard to measure those stamped steel rockers and get an accurate number. I'm sure there must be an accurate way to measure them but I couldn't figure it out, and I'm no dummy. Well, I guess that's debatable. Lol And not one of my Mopar guru buddies knows either. Dudes w/ bad-*** cars who have no idea. I thought that would be a simple question but no one seems to know. People just quoting part #'s and saying this part # is stock offset. Or even Less than that, just saying "this should work for you're application". But that doesn't answer the question. I still don't know if I have the correct offset. But very confident that I do. It's just bugs me not to know exactly. It's been very frustrating for me. The main reason I joined B Bodies was for advice. Both give and receive. It's been all receive to this point. And I appreciate everyone's input. I hope I can contribute myself one day and help someone else. You really sound like u know what you're talking about too. thanks
 
BD I've had to fix lotsof guides and trashed engines from roller tip rockers
Either get the B3 type kit or do not use roller tip rockers
on the road racers and high lift dodges we machined the pedestals off and made blocks like the early BBM and Max Wedges
would not have done it if we did not have to
good move Guido get B3 kit or forget it
some try lash caps if not too far off but that just hides the problem
and X2 on just using shims
those with long valves or larger springs or both like for 2" Battleship springs can get themselves in real trouble
some grind the underside of the rocker and some of those break rockers
beehive springs and their smaller retainers appear to solve the rocker/ retainer problem but again that just hides the real problem of fulcrum being too low
cheers
if you do work with mike ask about 1.6 on intake only I do not see where they help on the exhaust without a blower or nitrous
 
Thanks again for writing. I'll leave it be. These Chrysler heads are the most complicated heads I've ever dealt with in my 35 years of wrenching on cars. You sound very smart and I appreciate your help very much but it's ok the way it is. I got a lot more punch outa my 455 Pontiac with a similar cam lift, duration, separation, ect. But a different trans and rear end, so it's difficult guess. Have great day bro.
 
Yep, lots of fixed guides. But no correlation to the roller rocker tip. Way more worn out guides from conventional rockers. Lots of reasons for wear, original guide clearance, guide material and quality, poor oiling, spring pressures, cycles.......

Be interested in seeing your data that demonstrates the statistical difference in valve guide wear for a basically stock hydraulic motor with roller rockers.

Please explain in more detail the trashed engines you've experience due to roller rocker geometry.
 
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