help with push rod length Erson rockers

[priobe]

hey all

I got the Erson rockers installed. I am running headstuds so I had to do some additional work to the studs and rockershaft mounts.

My question is I think the pushrods are too small. when mounted on the motor with proper lash , I removed the assemby and looked at the bottom of the rockers and I have 5 - 6 threads on the adjustment screw.

Should I figureout the additional length using the adjustable pushrod and make it so that I have 3 threads on the underside of the rocker?

I am trying to get my measurements for Monday so I can place the order to Smith Brothers or is what I have ok

Thanks

[priobe]

56 views and no response for help

[Bill Bess]

I don't know about your rockers, but I have dove roller rockers and had a problem when I backed off one adjuster bolt too far (less than 3 threads). The result was the cup on the push rod struck the inside of the alum. rocker resulting in a broken cup on the pushrod. Luckily it was an easy fix....just make sure there is plenty of clearence for the cup ends of the pushrods.
Bill

[priobe]

bill,

if I understand correctly, if you back out the thread adjustment it will in deed bring the pushrod cup to the back of the rocker.

what I have is more clearance 5-6 threads out with the cup being further away from the rocker

is this bad or is the 2-3 thread needed for proper length?

[diegokid]

I am in the process of building a extra engine for my car. I used a hyd roller in this motor so the lifters are taller, different pushrods needed. There are a lot of posts about the dove rockers breaking from pushrod interference in the cup area. I talked to dove and they said to make sure there is no interference in the cup, yours should be ok with the clearence you mentioned.

Since the pushrod length doesn't affect the geometry with shaft mounted rockers and you only have the 2 or so extra threads showing it shouldn't be an issue if you can properly adjust the rockers with the pushrods you have and still have a full engagement on the locknut.

If you insist on buying new pushrods just find an old fe rod, cut a section out and thread it to accept a 1/4 stud and make an adj pushrod to send to Smith Brothers at the length needed.

Just my 2 cents worth.

[vettestr]

The best bet is to follow the recommendation's of your component manufacturer. That being said .... are you looking for advise on checking the rocker tip to valve tip geometry? Several links on the web have very detailed instructions for checking push rod length that do a much better job than I could ever write.

I think you want more than just what is the ideal thread contact of a fastener but ???
A rule of thumb for fastener thread length is to match it's diameter or greater. If your bolt,screw or whatever is 5/16 in diameter then it should have that 5/16 of thread length as a minimum. In this case too long or longer than needed is just adding extra weight or mass that is traveling at 6000 plus crankshaft RPM.

The contact area of rocker tip to valve stem face is centered on the valve stem through the event. Seeing this area is tough but a light skin of grease on the stem face will show the contact at a given adjustment. I have made a few adjustable length pushrods copied from the old hemi days to make checking mock-up easier. Then measuring the pushrod to the thou. is done in stages as I don't have precision calipers or mic's beyond 6 inches. Jeff C

[vettestr]

Morning Diegokid,
Just checked your thread posted as I was hacking away with my blazing 1 finger method.
You mentioned.......... "Since the pushrod length doesn't affect the geometry with shaft mounted rockers and you only have the 2 or so extra threads showing it shouldn't be an issue if you can properly adjust the rockers with the pushrods you have and still have a full engagement on the locknut."

I agree that the length of the pushrod on a shaft mounted rocker is used to adjust the lash and will not correct the geometry. I do check the contact area though as a sanity check for valve length and pedestal height. With all the possible areas machined and component combinations possible I never underestimate the weird stuff.

[priobe]

ok,

just for me to clear things up because I dont want to get the wrong information.

running a pushrod with 5-6 threads at the bottom is ok as long as the tip of the roller is making good contact with the tip of the valve.

with shaft mounted rocker you cannot adjust up and down adjustment because the rockers are fixed on the shaft.

however, it is wise to check that the side to side clearance is good for the tip of the rocker to the tip on the valve stem.

Is this correct?

question #2


I set the lash on my valve and I am getting 5-6 threads. If I remove the rocker and take the other side rockers and adjust the threads to 2-3 and I measure the difference of the 2 shafts, then subtract them,

finally add the difference to the old measurement of the original push rod to get the proper length needed?

to put me in the ball park?

[concobra]

to Priobe

Have you finished with this pushrod length decision? At the risk of appearing to know it all (believe me I don't) I would be happy to discuss this with you and would consider sending you an adjustable pushrod made for this purpose. I also live close to Smith Brothers and know Greg and Pierre there well. I would be glad to help if I can.

Concobra

[priobe]

Concobra,

Thank you so much for the offer. I actually received the pushrods and installed in the motor. Apparently, the adjustments I made were right on the money. The threads under the body were 2 threads.

Also, since there is not much of anything else to adjust the roller tip is centered on the valve stem.

Now, as crazy as this may sound, after firing up the motor and letting it warm-up it sounds different.

I mean, it does not sound bad or anything but the pitch of the motor sounds just different. I had a chance to take it for a short spin and everything seems fine. I will keep an eye on the rockers for awhile.

Thanks for the offer.

[concobra]

That's great. Good luck with your engine.

Concobra

[Bobcat]

Priobe .... about the engine sounding diffident now .... not crazy at all . Now that you have the valve train geometry correct , the whole thing has less strain on it . Had the same thing happen on my 427 Galaxie where the guy who did my heads screwed them up on the valve stem lengths . After the correction ( shimmed the stands ) , the engine was a more "even" sound and not as "clattery " .
When the center line of the rocker coincides with the center line of the valve stem at 50% lift ... good things happen .

Bob

[concobra]

Priobe

You make an interesting point about the difference in engine sound. When you began this thread I believe you said you had problems with the Dove rockerarms. Given this I would assume that you also had their end stands. If that is true I have noticed that on every valve cover that I have used with the Dove end stands that those end stands make contact with the valve covers. This creates a situation where the valves covers pick up the valve train noises thus reverberating those noises. This is usually quite noticable. When switching to another rockerarm system this noise goes away and it makes the engine appear to run better due to the quieter valve train. I am not saying that the Dove's are bad because of this just that the contact point can create this noise issue. Looking on the bright side hearing the valve train making the right kind of sounds is good and you can pick up bad sounds quickly with the Dove system.

Concobra