Any valve train geometry gurus here

[Cazman]

Plugging along on my 440 stroker. The block was zero decked, different lifters, 440 source heads, and the valves were sunk, so a few variables have changed in the valve train since stock. I also would like to keep the stock rocker arms and am using the method in this video to get the rockers to the correct geometry.. Basically, putting the rocker arm centerline 90 degrees to the valve stem.

I estimated the rocker centerline by matching the radius of the rocker tip against a 5/8" bar stock and found that center then drew a line to the center of the shaft bore. I used a laser level to plot a parallel line to the top of the spring retainer.

This would mean that I have to shim the shaft .250" to raise it. It seems like a lot. Maybe I have the centerline wrong.

 

[Davea Lux]

The question I have is why do you want to keep stock rockers on a performance stroker build? Stock rockers float on the rocker shafts and have a habit of tipping side to side at high rpms. At the very least this causes the valves to not fully deploy so some of the advantage of a high lift cam is lost. The tipping also puts considerable extra strain on the push rods which can cause breakage. Do yourself a favor and invest in a set of precision rockers. You will be glad you did. You also mention that you are running non stock lifters, you need to be sure that these lifters are even compatible with a stock rocker assembly.

Dave

 

[Cazman]

This is a high torque build. Max RPM will be 5,000. It's a mild cam too. I have done the screamer motors before, this is a smooth-running, move my 4,400 lb butt motor. No need for rollers unless the geometry is way off.

 

[Turboomni]

I am no engine builder as you both are but when I approached Mr Dwane Porter of Porter racing heads in VT I had the same idea of using stock rockers. I had thought that with a rather mild cam I wouldn't need anything more than stock rockers. Mr Porter convinced me to use different rockers. They didn't have to be the top of the rocker food chain. I think maybe it is because he also designed a roller cam to make the most of HP exhaust manifolds and had it cut for my application. Not saying one way or other as I am no authority. I am just relating my experience.Good luck on your build. I hope to get mine going this late spring.

 

[Turboomni]

This is a high torque build. Max RPM will be 5,000. It's a mild cam too. I have done the screamer motors before, this is a smooth-running, move my 4,400 lb butt motor. No need for rollers unless the geometry is way off.

That is exactly what I am after too with decent vacuum for brakes and torque to move my "Big Boned Gal" with ease with 3.23 rear and hit the highways too.

 

[Cazman]

Dwane did my cam. As you know he does wonders with the strictly stock racing. So, stock rockers, manifolds, etc. are no problem.

 

[Turboomni]

Nice man! I had heard such great things about Dwane and got a ride in FURYGT's Fury before he left for the Carolinas. HP manifolds stroked and that thing hauled ***! It was as impressive how the car handled the power ,very composed no wild antics ,it just went where it was pointed. After that I knew that was what I wanted. I met Dwane and had the Stealths shipped and he did his magic. I'm sure if Mr Porter thinks it's ok then it must be. He did do the cam for you after all. Keep us posted on your build.

 

[Davea Lux]

Plugging along on my 440 stroker. The block was zero decked, different lifters, 440 source heads, and the valves were sunk, so a few variables have changed in the valve train since stock. I also would like to keep the stock rocker arms and am using the method in this video to get the rockers to the correct geometry.. Basically, putting the rocker arm centerline 90 degrees to the valve stem.

I estimated the rocker centerline by matching the radius of the rocker tip against a 5/8" bar stock and found that center then drew a line to the center of the shaft bore. I used a laser level to plot a parallel line to the top of the spring retainer.

This would mean that I have to shim the shaft .250" to raise it. It seems like a lot. Maybe I have the centerline wrong.

View attachment 349812

If that measurement is right, .25" is way more that you would want to shim. Your machine shop should be able to tell you what shims are going to be need and usually it is not that expensive.

Dave

 

[Cazman]

I made a mistake in my measurements. On non-roller rockers, you are supposed to bring the centerline to the bottom of the rocker tip, not the center of the tip radius. That still requires a shim of over .125. I think way too many .030 shims. I do not know if people have never worried about this with 440 source heads or if there is variation, but using the mid-lift method for geometry these are off.

I may go with the Isky iron arms, as they were used for racing for years and are a copy of the MOPAR Hi Performance ones.

 

[MEV]

I used the 440 source heads, roller rockers, shafts and rocker shims (that go between the rocker arms on the shaft to center them left and right on the valve tip. Then i cut a 1'" section out of one of the stock pushrods and put a small section of all thread with 2 nuts on it to make an adjustable pushrod. I smeared the top of the valve tip with sharpie ink, and rotated the motor completely. I set the length to where the rocker arm roller was centered in the ink mark on the valve as the motor was rotated. it only took a couple of tries to adjust and re-ink the valve to get the right length. I measured the over-all length of the pushrod and called smith brothers and had them make me the right length pushrods. Perfect.

 

[Cazman]

That's how I used to do it, until I read the mid-lift method. A bit shocking.
https://www.crankshaftcoalition.com/wiki/images/c/c7/MILLER_ROCKER_GEOMETRY.pdf

 

[twostick]

Read the tech articles here. Everything you ever wanted to know about valve train geometry, a lot of which flies in the face of what some think they know.

B3 Racing Engines LLC - Performance Engine Building and Mopar Valvetrains

Kevin

 

[Cazman]

Yea, I have been through those articles. Like I said; shocking.
Here is one of their quotes:
"Talking about adjusters and pushrods reminds me of another problem I run into when talking geometry to some Mopar guys and girls. Some are choosing pushrod length based on max lift numbers, or centering the sweep on the valve tip. This is entirely incorrect, and will result in a very inefficient and unstable valvetrain." This is what most machine shops do.

Here is a picture of them fixing the geometry. Wrong, then fixed at no lift, then max lift. Look at the size of the custom shim they made. That's what I would need.

 

[Davea Lux]

Yea, I have been through those articles. Like I said; shocking.
Here is one of their quotes:
"Talking about adjusters and pushrods reminds me of another problem I run into when talking geometry to some Mopar guys and girls. Some are choosing pushrod length based on max lift numbers, or centering the sweep on the valve tip. This is entirely incorrect, and will result in a very inefficient and unstable valvetrain." This is what most machine shops do.

Here is a picture of them fixing the geometry. Wrong, then fixed at no lift, then max lift. Look at the size of the custom shim they made. That's what I would need.

View attachment 350016

From the photo, it looks like the crown of the push rod is still contacting the side of the rocker even after the "fix". The push rod and lifters should be able to spin freely so the cam does not go flat. Crown contact can also bend the push rods. Would want to see if a feeler gauge can be inserted between the crown and rocker body before firing this fix.

Dave

 

[Cazman]

The pictures only prove one point. They set up a bunch of manufactures' rockers and did the same thing just to show how the mid-lift method changes the angles. This is not the final solution. But, it shows how off all of the aftermarket rocker parts are for our MOPARs. It is all covered on B3 Racing's site.

 

[twostick]

From the photo, it looks like the crown of the push rod is still contacting the side of the rocker even after the "fix". The push rod and lifters should be able to spin freely so the cam does not go flat. Crown contact can also bend the push rods. Would want to see if a feeler gauge can be inserted between the crown and rocker body before firing this fix.

Dave

I think there is a relief machined into the rocker there but not sure. I've met Mike and I think he would have mentioned it if there was interference on top of the other issues.

Whenever I see a "Who makes the best rockers for a Mopar" post, the answer generally is, nobody.

Kevin

 

[MEV]

That's how I used to do it, until I read the mid-lift method. A bit shocking.
https://www.crankshaftcoalition.com/wiki/images/c/c7/MILLER_ROCKER_GEOMETRY.pdf

Hard to argue with my results, i doubt most guys here pound on their stroker like i do. These are after an 80-ish mile drive to the drag strip at highway speed. This is over a couple year period. I run 3:23 gears.

 

[Cazman]

Yea. Many a motor tearing it up with the traditional method. Just another learning moment, so I may as well try.
I think in a post a while back, I agreed with your build. Put it together and run it! That's what I always did and had good results.

I went down a rat hole with this motor. First time I have put in the best machine work - torque plate hone, bore lined, zero decked, etc. I even equalized (ground) the head chambers so they are all at 64cc. Have .046 quench. Used a Cometic gasket to dial in the exact compression. Dwayne Porter did a custom cam. I don't know what is happening to me.

 

[MEV]

Yeah, its easy to get down in the weeds. I had chris straub grind me a custom cam. I wanted super reliability. With the exception of a faulty comp cams roller lifter link bar rivet, it has been "fun'er than stomping baby chickens" to drive.

 

[Turboomni]

I went down a rat hole with this motor. First time I have put in the best machine work - torque plate hone, bore lined, zero decked, etc. I even equalized (ground) the head chambers so they are all at 64cc. Have .046 quench. Used a Cometic gasket to dial in the exact compression. Dwayne Porter did a custom cam. I don't know what is happening to me.

For me at least I want an engine that makes very good power ,lots of torque, decent idle ,power brakes, runs on pump premium ,is reliable and won't hurt itself easily that I could drive everyday or go anywhere without a trailer. Just routine maintenance and enjoy. I am at an age to not want to tackle this on my own. I think it is called laziness.