Moparts
Pushrod length/adjuster threads
Posted By: Von
Pushrod length/adjuster threads - 08/17/10 04:37 AM
If you had no choice, would you rather have 1.25-1.5 thread sticking out of the bottom of the rocker or 3.5 threads?
Yeah, I know neither is right. But, money is tight (My employer is taking away my travel check (my fun money) so one of them will have to do) and I need to use what I have.
Thanks
Posted By: MR_P_BODY
Re: Pushrod length/adjuster threads - 08/17/10 04:51 AM
1.25-1.5... it'll be closer to the proper geometry
IF it still oils properly
Posted By: Bob_Coomer
Re: Pushrod length/adjuster threads - 08/17/10 05:30 AM
Whats the rocker arm manufacture say? Jesel calls for 3/4 thread as idea, no more than 1 1/2......If I am at 1 1/2 thread IMO its pretty good shape....3 treads is too much, and I would be looking at longer push rods, or at least adding lash caps and checking things out...
Again check with the rocker company..
Posted By: Big Squeeze
Re: Pushrod length/adjuster threads - 08/17/10 05:35 AM
Quote:
If you had no choice, would you rather have 1.25-1.5 thread sticking out of the bottom of the rocker or 3.5 threads?
Yeah, I know neither is right. But, money is tight (My employer is taking away my travel check (my fun money) so one of them will have to do) and I need to use what I have.
Thanks
Hey PVP......I've got a few extra sets of pushrods laying around.....Bring by what you have and we can see if I have something that'll work better........ 
Posted By: Von
Re: Pushrod length/adjuster threads - 08/17/10 06:05 AM
Quote:
Whats the rocker arm manufacture say?
The rockers are bronze bushed factory adjustables, so I have no idea what the factory spec is.
Anybody know?
Posted By: Von
Re: Pushrod length/adjuster threads - 08/17/10 06:08 AM
Quote:
Hey PVP......I've got a few extra sets of pushrods laying around.....Bring by what you have and we can see if I have something that'll work better........
I may take you up on that!! Ive got some rough measurements. Depending on which adjusters I use I need either 9.040 effective length or 9.140.
Got anything close?
Thanks, you big 
Posted By: Von
Re: Pushrod length/adjuster threads - 08/17/10 06:20 AM
BTW, by swapping adjusters (2 different sets of adjusters) I can get 1.5 threads with one set and 4.5 threads with the other set, same pushrods. Obviously the "number of threads showing out of the bottom" isnt that accurate.
Is there an optimum distance from cup to rocker, or is it "get in a ballpark measurement"?
Hope that makes sense.
Posted By: polyspheric
Re: Pushrod length/adjuster threads - 08/17/10 01:56 PM
Leaving out any oil or interference problem: the smallest possible adjuster has the highest rocker ratio. No threads at all is best, but you need some adjustment somewhere.
The actual distance from the rocker body to the adjuster ball or cup is what matters, not the threads. The number of threads is only important in that the adjuster is more likely to break.
However: it may push your geometry over the cliff.
Every time someone says "use lash caps" I get a headache.
I'd ask everyone who doesn't understand this to refrain from commenting - but everyone knows I'm not talking about them.....
Posted By: bigtimeauto
Re: Pushrod length/adjuster threads - 08/17/10 04:12 PM
Quote:
However: it may push your geometry over the cliff.
Every time someone says "use lash caps" I get a headache.
i'll bite how will the rocker adjustment change the geometry on a shaft system?
A lash cap will barely do it,after that you need shims or mill the head stands to change it. to many threads down will only break the adjuster or block oil from coming out of some screws.
Posted By: polyspheric
Re: Pushrod length/adjuster threads - 08/17/10 07:15 PM
Is that a question, or a statement?
Posted By: bigtimeauto
Re: Pushrod length/adjuster threads - 08/17/10 07:21 PM
Quote:
Is that a question, or a statement?
that would be a question about your statement
Posted By: polyspheric
Re: Pushrod length/adjuster threads - 08/17/10 07:29 PM
Fine, we'll do it your way.
Your first remark appears to be a question, but you followed it with a statement that pretty much says it doesn't.
It does.
your turn.
Posted By: bigtimeauto
Re: Pushrod length/adjuster threads - 08/17/10 08:04 PM
You want to play instead of answering my question thats fine.
"However: it may push your geometry over the cliff."
You said adjusting the rocker arm affects geometry, i asked why would you say that and asked for your reasoning.
Posted By: tboomer
Re: Pushrod length/adjuster threads - 08/17/10 08:10 PM
Quote:
You said adjusting the rocker arm affects geometry, i asked why would you say that and asked for your reasoning.
I am with Bob here...Poly...Maybe we can all learn something...
Posted By: Moparnut426
Re: Pushrod length/adjuster threads - 08/17/10 08:18 PM
Im curious also,,,
You would be raising, lowering the adjuster, just where the pushrod makes mechanical contact with the rocker. Changing the geometry would mean you would physically move the fulcrum up, down, inn or out changine where it makes physical contact with the spring, or changing the ratio by moving the adjuster in, or out from the fulcrum.
Kasey
Posted By: bigtimeauto
Re: Pushrod length/adjuster threads - 08/17/10 08:31 PM
Quote:
Quote:
However: it may push your geometry over the cliff.
Every time someone says "use lash caps" I get a headache.
i'll bite how will the rocker adjustment change the geometry on a shaft system?
A lash cap will barely do it,after that you need shims or mill the head stands to change it. to many threads down will only break the adjuster or block oil from coming out of some screws.
a simple i wasn't thinking clear is good for me
Posted By: 540DUSTER
Re: Pushrod length/adjuster threads - 08/17/10 09:08 PM
The old direct connection book says that the ball should be 5/16 from the rocker arm.Not all adjusters are the same.I have seen it with my own eyes that when the ball is closer to the rocker;the folcum will be closer to the shaft and will lift the valve more.Its not much but it happens.
Posted By: bigtimeauto
Re: Pushrod length/adjuster threads - 08/17/10 09:12 PM
Quote:
The old direct connection book says that the ball should be 5/16 from the rocker arm.Not all adjusters are the same.I have seen it with my own eyes that when the ball is closer to the rocker;the folcum will be closer to the shaft and will lift the valve more.Its not much but it happens.
nobody is talking lift we are talking geometry
Posted By: 540DUSTER
Re: Pushrod length/adjuster threads - 08/17/10 09:34 PM
If the ball is closer to the shaft ,the geometry changes.
Posted By: MR_P_BODY
Re: Pushrod length/adjuster threads - 08/17/10 09:37 PM
Quote:
Quote:
The old direct connection book says that the ball should be 5/16 from the rocker arm.Not all adjusters are the same.I have seen it with my own eyes that when the ball is closer to the rocker;the folcum will be closer to the shaft and will lift the valve more.Its not much but it happens.
nobody is talking lift we are talking geometry
What occurs when you change the adjuster is it starts
putting a lot of side load and reducing the lift..
it in i self(adjuster) doesnt change the valve/rocker
geometry
Posted By: 540DUSTER
Re: Pushrod length/adjuster threads - 08/17/10 09:40 PM
If you don't believe the geometry changes,then how about rocker arm ratio?
Posted By: MR_P_BODY
Re: Pushrod length/adjuster threads - 08/17/10 09:47 PM
Quote:
If you don't believe the geometry changes,then how about rocker arm ratio?
Its changing the ratio... why is the geometry changing
Posted By: 540DUSTER
Re: Pushrod length/adjuster threads - 08/17/10 10:21 PM
Mr P, You are right it doesn't change the relationship of the valve tip to the rocker;But if the adjuster ball is closer to the rocker,lift will increace.
Posted By: bigtimeauto
Re: Pushrod length/adjuster threads - 08/17/10 10:41 PM
Quote:
Quote:
Quote:
However: it may push your geometry over the cliff.
Every time someone says "use lash caps" I get a headache.
i'll bite how will the rocker adjustment change the geometry on a shaft system?
A lash cap will barely do it,after that you need shims or mill the head stands to change it. to many threads down will only break the adjuster or block oil from coming out of some screws.
a simple i wasn't thinking clear is good for me
waiting.......
Posted By: MR_P_BODY
Re: Pushrod length/adjuster threads - 08/17/10 10:46 PM
Quote:
Mr P, You are right it doesn't change the relationship of the valve tip to the rocker;But if the adjuster ball is closer to the rocker,lift will increace.
Yes you are correct that it will change the ratio
due to the distance of the contact point on the adjuster
up to a point... if you take a straight edge and go from
the contact point of the rocker/valve point through
the center of the shaft then continue to the push
rod side that point is where it would be at the
optimum for the adjuster to be at(point of contact
for the push rod and rocker)
Posted By: Hemiroid
Re: Pushrod length/adjuster threads - 08/18/10 01:07 AM
Quote:
Quote:
Hey PVP......I've got a few extra sets of pushrods laying around.....Bring by what you have and we can see if I have something that'll work better........
I may take you up on that!! Ive got some rough measurements. Depending on which adjusters I use I need either 9.040 effective length or 9.140.
Got anything close?
Thanks, you big
That's too funny. My crappy Crane rockers I bought for my hydraulic cam in my GTX has EXACTLY those same push rod dimensions. Half of the rockers were of a fairly new batch and the others were antiques with different adjusters. That being said, the distance from the beginning of the threads and the tip of the ball are different, so simply using thread exposure isn't always accurate.
Posted By: ahy
Re: Pushrod length/adjuster threads - 08/18/10 03:08 AM
1.25 - 1.5 sounds good to me. Check oiling with a drill motor and turning the crank. If OK you are ready to go.
Posted By: Performance Only
Re: Pushrod length/adjuster threads - 08/18/10 03:26 AM
technically speaking, adding lash caps does change the geometry. it doesn't change the fulcrum point, but it does change the sweep of the rocker tip over the valve tip. also, moving the adjuster farther or closer to the fulcrum to change the ratio, also changes the geometry since the force applied from the pushrod needs to be greater since it is closer to the fulcrum on that side.
think of a teeter totter for a reference. it's all basic geometry. now replace the kid at either end with a valve tip and a rocker adjuster at either end. any time you change the position of any of the three pieces, your changing the "geometry", regardless of how much and regardless of the effect.
Posted By: Bob_Coomer
Re: Pushrod length/adjuster threads - 08/18/10 03:57 AM
LOL, You guys would argue over the color of a black board.
I dont understand why were talking and even arguing about stuff that is irrelevant, doesnt matter and cant change LOL
-Push rod length doesnt effect geometry
-how much adjuster is hanging out doesnt affect geometry
How far the adjuster is located from the cup does change the ratio, how else would one change it?
It cant be changed unless you buy another rocker arm so why bring it up?
also with little to no thread protruding from the rocker arm can cause problems with push rod interference where the cup actually contacts the rocker body.
This isnt a problem with cup adjusters and ball end/ball end push rods...
I have no proof or hard evidence but I truly believe that cup adjusters and ball end/ball end push rods are better than cup style push rods from burning up etc. But thats another story and doesnt matter here either.
Lash caps will effect geometry a little. I have used lash caps on diff projects and engines over the years maybe a half dozen times. To be honest I it has really never made any significant changes either way.
Some engine builders avoid lash caps like a plague, but why?
I think they definitely serve a purpose, and in some cases save the engine builder a bunch of money.
i have heard horror stories about guys trashing engine or loosing lash caps, but IMO thats not the lash caps fault. If the lash cap is to deep and it pushes against the valve lock, its not the lash caps fault.
Bottom line if these are Isky, or Crane type Ductile type rockers anything from 1 to 3 threads showing will be just fine....
IMO 1 /2 thread is pretty idea...
Posted By: Sport440
Re: Pushrod length/adjuster threads - 08/18/10 04:25 AM
Oh , No doubt, the geometry is changed by both the adjuster length and a lash cap. The lash cap has a lessor effect,IMO over the adjuster length. Combined they can have a greater effect.
In the scheme of things though I wouldnt use it as a tuning device, Id be more concerned with the best valvetrain strength of the geometry aspects. Shortest adjuster length and best roller sweep over the valves tip. mike
Posted By: polyspheric
Re: Pushrod length/adjuster threads - 08/18/10 11:09 PM
I'd like to make a clear distinction in terms.
"irrelevant" (meaning, nothing to do with it) isn't true, all those dimensions affect geometry, lift, wear etc. - the question is in what way, and how much?
"doesn't matter" is actually true in many cases, you get an error but the effect is very small, or 2 errors almost cancel each other out. Sometimes an accidental change corrects an unseen error.
"Push rod length doesnt effect geometry": well, not directly (a fixed length hydraulic pushrod is always "right"), but will if you need more adjuster to make it up.
"how much adjuster is hanging out doesnt affect geometry": it not only changes the ratio (more threads = lower ratio), it changes the angle between the 2 rocker levers (pushrod side and valve side), which is part of the basic rocker design. The rocker's inter-lever angle is the total of the pushrod angle (not the tappet bank angle) and the valve stem angle (15°, 18°, etc.). If the pushrod is 0° (parallel to the cylinder) the angle is just the stem axis. If the lever total changes (as with too many threads), the arc of either the pushrod side, the valve side, or both cannot be centered, and the sweep and scrub increase.
Yes, it's a complicated subject.