? Valvetrain Geometry ?

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FASTBACK340

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OK.... it's been confirmed that the noise after replacing the bad lifters is coming from the roller rockers. Apparently the rollers are almost running off of the edge of the valves. For the time being I'm installing a set of stock rockers and pushrods, which just may stay. But if I do decide I want to use the roller rockers, I have a question:

How DO I determine the needed lenght pushrod and what pattern am I looking for on the tip of the valve stem? I have an adjustable pushrod and calipers big enough to measure the adjusted lenght. Obviously I screwed up the first time (Hey, I make mistakes too....) and need to learn the right way, or at least be directed to a site that will explain it. My chemically-imbalanced old brain has a hard time grasping procedures more complicated than fork-to-mouth at times....

C`mon guys! I've done some searching and found explainations that weren't Mopar-specific. Help....

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Wow!! Them look worse than the ones I had. What brand are they John? Do you have a way to measure the valve stem height? That can also cause geometry problems. If the valve stem isn't high enough it causes the rocker to run off the edge. Stock heads valve stem height measures 1.9" from the spring seat to the tip of the valve.

BTW: The ones I had were rolling close to the edge too and I finally just put the stock arms and pushrods back on and they rolled perfectly center and made no noise.
 
To determine how long your pushrods need to be roll the engine over to where the cam lobe your testing is at the base circle and install the adjustable pushrod (shortened all the way up to start so your not compressing the lifter). Then slowly lengthen the adjustable pushrod until it won't spin easily with 2 fingers. In other words take out all the free play and your at zero lash. Remove the pushrod and measure it and add .030-.050 for preload and that's how long you need them. If your block has never been square decked you might want to measure all 4 corner cylinders and take an average. Hopefully that's clearer than mud.
 
Push rod length will have zero effect on the roller tip to valve stem relationship because its a rocker shaft system. You will have to run lash caps which will lengthen the valves and that will move the roller closer to the shaft side. But to run lash caps you have to have enough room at the top of the valve stem which means you may have to change your locks and possibly your retainers. Here is a picture of rocker arm geometry:

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Looking quick, the shafts are too low. What happens is the rocker tip ends up starting inside the center of the valve stem centerline, then as the rocker goes thru the lift motion, it gets to the outside and stops. The motion of the rocker is an arc. You need the arc reduced to just the part that is perpendicular to the centerline fo the valve. That's how you get the most lift action with the least power robbing friction, and the wear that accompanies it. It also cuts down on the pushrod rubbing and rocker/spring clearance issues on a lot of engines. The pushrod length is the last thing you check, and on my engines, the last part ordered are the pushrods.
 
John,

Moper is right, you need to shim the rocker shafts to pull the roller contact patch in toward the shaft. You can get shims from Hughes Engines. Pushrod measurement should done last and most roller rocker manufacturers recommend 1 1/2 to 2 threads showing under the rocker.
 
I've been in a battle with a good friend of mine whom has built a few high-performance engines. His arguement is pushrod lenght makes a difference and I said rocker shaft placement limits the actual sweep of the tip. Score one for the old guy..... I guess I'll order some shims and play with it at a later date. As for now, I picked up a set of stock rockers, shafts, and push rods yesterday. I'm headed over to the garage in about an hour to install it all. My mistake was not checking the actual roller movement across the valves when I had the engine on the stand. These mistakes is what eventually becomes experience..... Thanks for everyone's input. I measured right, just skipped a more important step first.

Hopefully later we'll have video of a happily running small block...... 8)
 
BTW: It's a Mopar Performance short block, new Edelbrock heads, Crane roller rockers, Comp Cam, Comp lifters, and Smith Bros. pushrods.


No junk in there.... just a botched assembly.
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lol.. your friend builds non-shaft rocker system engines. Geometry on mopars is not like ford or chevy at all that way. And you have no idea how common it is for it to be terrible...lol Too bad on the Smiths Bros..lol. Like I said "Last call..."
 
And my friend I'm arguing with builds nothing but small block Mopars. And his stuff stays together and produces POWER.

Go figure....
 
the pic(340sFastback)helped me most about a month ago. if your roller tip is outboard (exhaust side) then you would need to raise the valve or lower the shaft.
i have a bag of shims from mancini if you need'em
 
mrbill00 said:
the pic(340sFastback)helped me most about a month ago. if your roller tip is outboard (exhaust side) then you would need to raise the valve or lower the shaft.
i have a bag of shims from mancini if you need'em
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Another FABO member coming through. Love this site.

I have a valve tick in my 360 and I think it might be the roller rockers too. This helps. Hoping it is just a lash adjustment.

John I bet you'll be okay with the MP stamped rockers. My 340 has them and puts out over 400hp.

Can't wait to hear the next sound bite.

Dave
 
FASTBACK340 said:
And my friend I'm arguing with builds nothing but small block Mopars. And his stuff stays together and produces POWER.

Go figure....
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Maybe a bit of luck? He obviously doesn't understand how shaft mounted rockers work.
 
mrbill00 said:
the pic(340sFastback)helped me most about a month ago. if your roller tip is outboard (exhaust side) then you would need to raise the valve or lower the shaft.
i have a bag of shims from mancini if you need'em
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I agree. I went through this with a set of Harland Sharps when I put my 340 together. I ended up shimming the stands and ditching the HS rockers as they were really designed for longer valve stems. I ended up with MP iron rockers (which were junk, BTW). Those had the correct geometry, but had .010" clearance on the shaft. I sent them out to have them bushed and they're OK now. I should have stuck with stamped rockers.
 
lilcuda said:
I ended up with MP iron rockers (which were junk, BTW). Those had the correct geometry, but had .010" clearance on the shaft. I sent them out to have them bushed and they're OK now. I should have stuck with stamped rockers.
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That's odd. I have a new set of Mopar iron rockers here and they only have .002 clearance to the shaft. They had alot of side slop (over .120") so I shimmed that up to approx. .025. They also have real good geometry.

Were your iron rockers and shafts used?
 
FASTBACK340 said:
BTW: It's a Mopar Performance short block, new Edelbrock heads, Crane roller rockers, Comp Cam, Comp lifters, and Smith Bros. pushrods.


No junk in there.... just a botched assembly.
funny.gif
Click to expand...

Been there, done that. Sometimes we think just because we bought big name brand stuff we can throw it together and everything will be hunky dorey. I had the same problem with a set of Comp Magnum rockers a year and a half ago. I thought by your pics you had the exact same problem as me but apparently it was the mechanical opposite because shimming my rocker shafts made mine worse. Factory arms and pushrods did get mine in line alot closer. Been running them for 1-1/2 yr now with no problem.
 
lilcuda said:
I agree. I went through this with a set of Harland Sharps when I put my 340 together. I ended up shimming the stands and ditching the HS rockers as they were really designed for longer valve stems. I ended up with MP iron rockers (which were junk, BTW). Those had the correct geometry, but had .010" clearance on the shaft. I sent them out to have them bushed and they're OK now. I should have stuck with stamped rockers.
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valve stem length. i had the same crane gold rockers and eddy heads and found the same problem; to far out on the stem. i saw that you have already put stamped rockers on so its a little late for this info but i spoke with a crane rep. and he sad that their rockers are not compatible with eddy heads and thats them most info i could get out of him. so i bought a set of comp roller tips and they work fine, all nice and lined up.
 
Doesn't seem to be a "standard" when it comes to after market rockers. They all seem to be different lengths. The picture I posted above was my Comp Pro Magnum Rockers on my Edelbrock heads.
 
fishy68 said:
That's odd. I have a new set of Mopar iron rockers here and they only have .002 clearance to the shaft. They had alot of side slop (over .120") so I shimmed that up to approx. .025. They also have real good geometry.

Were your iron rockers and shafts used?
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Nope. Brand new in the box from MP. Another interesting thing about them is that out of the 16 rockers I bought, I discovered that 7 of of them were cracked. I discovered this after I had run them for a couple hundred miles and pulled them off to have them bushed. I saw what looked like a crack on one, then magged them all (I was working at a machine shop at the time). 7 of them were cracked. I still have them to remind myself how crappy MP parts can be. Can you say "lowest bidder"?
 
lilcuda said:
Nope. Brand new in the box from MP. Another interesting thing about them is that out of the 16 rockers I bought, I discovered that 7 of of them were cracked. I discovered this after I had run them for a couple hundred miles and pulled them off to have them bushed. I saw what looked like a crack on one, then magged them all (I was working at a machine shop at the time). 7 of them were cracked. I still have them to remind myself how crappy MP parts can be. Can you say "lowest bidder"?
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Wow, I thought those were actually made by Crane and were good quality.???
 
lilcuda said:
Nope. Brand new in the box from MP. Another interesting thing about them is that out of the 16 rockers I bought, I discovered that 7 of of them were cracked. I discovered this after I had run them for a couple hundred miles and pulled them off to have them bushed. I saw what looked like a crack on one, then magged them all (I was working at a machine shop at the time). 7 of them were cracked. I still have them to remind myself how crappy MP parts can be. Can you say "lowest bidder"?
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Is there any possibility they cracked because they were so loose on the shafts that you had to have them bushed please dont take it like I'm blaming you I dont mean that at all if you buy new quality parts they should be good out of the box and you should never have had the clearence issues in the first place I was just wondering. I don't know I was just wondering I'd like to order them for mine but with the horror stories you have I guess I will have to think this over a little more. Thanks for sharing Justin
 
lilcuda said:
Nope. Brand new in the box from MP. Another interesting thing about them is that out of the 16 rockers I bought, I discovered that 7 of of them were cracked. I discovered this after I had run them for a couple hundred miles and pulled them off to have them bushed. I saw what looked like a crack on one, then magged them all (I was working at a machine shop at the time). 7 of them were cracked. I still have them to remind myself how crappy MP parts can be. Can you say "lowest bidder"?
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Wow that is odd. I have never seen any sloppy or cracked and I've seen a few sets. Maybe made on monday morn by somebody with a hangover.:bootysha:

JJR426 has a good point too. Maybe since they were so loose the slapping around cracked them.

Sorry to hear about your bad luck with them.

Longgone said:
Wow, I thought those were actually made by Crane and were good quality.???
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That's what I thought too.
 
Longgone said:
Wow, I thought those were actually made by Crane and were good quality.???
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I don't know who made them, but they were not good quality. This was about 15 years ago, so things may have changed, but that experience, plus my dissatisfaction with the 280/.474 cam from them has soured my opinion of their parts.
 
jjr426 said:
Is there any possibility they cracked because they were so loose on the shafts that you had to have them bushed please dont take it like I'm blaming you I dont mean that at all if you buy new quality parts they should be good out of the box and you should never have had the clearence issues in the first place I was just wondering. I don't know I was just wondering I'd like to order them for mine but with the horror stories you have I guess I will have to think this over a little more. Thanks for sharing Justin
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I don't think so. They were not cracked in the same place on each one. I believe it was poor metallurgy. Also, on the adjusting screws, some were tight in the threads, others were WAY loose before they were run. It's a QA problem.

It's my personal opinion that MP "quality" is nothing more than marketing.

My apologies to the OP for hijacking this thread.
 
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