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Re: 340 Engine... How to determine pushrod length?? [Re: B G Racing] #458159
09/04/09 03:11 PM
09/04/09 03:11 PM
Joined: Jan 2003
Posts: 74,904
U.S.S.A.
JohnRR Offline
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JohnRR  Offline
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Quote:

Using stock non-adjustable rockers and hydraulic lifters you need only bolt on the rocker assembly,find the distance(adjustable pushrod ball&ball ends)and at rest,valve 100% closed add your desired preload(start the plunger downward)Lock your adjustment on the pushrod and you have your proper length.Make sure you are on the(bottom) of the cam lobe at true basecircle.





Re: 340 Engine... How to determine pushrod length?? [Re: B G Racing] #458160
09/04/09 04:02 PM
09/04/09 04:02 PM
Joined: Jan 2005
Posts: 3,699
Newport, Mi
Evil Spirit Offline
master
Evil Spirit  Offline
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Posts: 3,699
Newport, Mi
Quote:

Using stock non-adjustable rockers and hydraulic lifters you need only bolt on the rocker assembly,find the distance(adjustable pushrod ball&ball ends)and at rest,valve 100% closed add your desired preload(start the plunger downward)Lock your adjustment on the pushrod and you have your proper length.Make sure you are on the(bottom) of the cam lobe at true basecircle.




And now for the real wrinkle.If whenever the valve job was done, if the heights of the valves weren't equalized (across the tops of the valves) you will have to check every rocker. If you drop a straightedge across the top of the valves and the heights are all over the place, you would either need different length p/rods for each rocker, have to have the ends cut to the right height, or adjustable rockers.


Free advice and worth every penny...
Factory trained Slinky rewinder.........
Re: 340 Engine... How to determine pushrod length?? [Re: Evil Spirit] #458161
09/04/09 05:11 PM
09/04/09 05:11 PM
Joined: Jan 2003
Posts: 16,122
Grand Haven, MI
patrick Offline
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patrick  Offline
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Joined: Jan 2003
Posts: 16,122
Grand Haven, MI
Quote:

Quote:

Using stock non-adjustable rockers and hydraulic lifters you need only bolt on the rocker assembly,find the distance(adjustable pushrod ball&ball ends)and at rest,valve 100% closed add your desired preload(start the plunger downward)Lock your adjustment on the pushrod and you have your proper length.Make sure you are on the(bottom) of the cam lobe at true basecircle.




And now for the real wrinkle.If whenever the valve job was done, if the heights of the valves weren't equalized (across the tops of the valves) you will have to check every rocker. If you drop a straightedge across the top of the valves and the heights are all over the place, you would either need different length p/rods for each rocker, have to have the ends cut to the right height, or adjustable rockers.




aren't we overcomplicating things here? Isn't that part of what the hydraulic lifter's function is for, to soak up the tolerances in the valvetrain? yes, check every position with a length checking pushrod like johnahhahh suggests making (or just buy one) for 0 preload on the lifter plunger, and then look through the summit catalog to find the nearest length pushrod not shorter than that number, and you'll be fine. on a mild hydraulic cam, you won't have aperformance difference if you have .010 preload or .080 preload. it's just not that critical.


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Re: 340 Engine... How to determine pushrod length?? [Re: patrick] #458162
09/04/09 09:32 PM
09/04/09 09:32 PM
Joined: Jan 2005
Posts: 3,699
Newport, Mi
Evil Spirit Offline
master
Evil Spirit  Offline
master

Joined: Jan 2005
Posts: 3,699
Newport, Mi


aren't we overcomplicating things here? Isn't that part of what the hydraulic lifter's function is for, to soak up the tolerances in the valvetrain? yes, check every position with a length checking pushrod like johnahhahh suggests making (or just buy one) for 0 preload on the lifter plunger, and then look through the summit catalog to find the nearest length pushrod not shorter than that number, and you'll be fine. on a mild hydraulic cam, you won't have aperformance difference if you have .010 preload or .080 preload. it's just not that critical.




The one time you don't check it is the time it bites ya. I've seen heads that were converted to 2.02's that the intakes weren't set deep enough in the heads - they were .080 lower (from the top side) than the exhausts. Exhaust valves were used, and the seats were deep. It's not that hard to toss a straight edge across the tops and at least see if more attention is needed.


Free advice and worth every penny...
Factory trained Slinky rewinder.........
Re: 340 Engine... How to determine pushrod length?? [Re: JohnRR] #458163
09/04/09 11:22 PM
09/04/09 11:22 PM

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Quote:

Quote:

Some of you guys are confused. PUSHROD LENGTH is adjusted to maintain VALVE CLEARANCE "lash" when adjusting valves AND to maintain decent rocker arm geometry. IT HAS NOTHING TO DO with piston to valve clearance. Pushrod length is set WITH THE VALVES CLOSED






The only person confused here seems to be YOU , no one said anything, anywhere, in this thread about adjusting piston to valve clearance with the length of the pushrods till you brought it up .

If you go back and reread you'll see he was told to use a HEAD GASKET SHIM to regain his piston to valve clearance .




!!!! REALLY?????!!!!!

From the OP's very own words:

"Basically you lengthen and shorten the adjustable push-rod to achieve the correct imprint on the top of the valve. (Then use that length to order new ones of that length)."

Re: 340 Engine... How to determine pushrod length?? #458164
09/05/09 09:03 AM
09/05/09 09:03 AM
Joined: Jan 2003
Posts: 74,904
U.S.S.A.
JohnRR Offline
I Win
JohnRR  Offline
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Joined: Jan 2003
Posts: 74,904
U.S.S.A.
Quote:

Quote:

Quote:

Some of you guys are confused. PUSHROD LENGTH is adjusted to maintain VALVE CLEARANCE "lash" when adjusting valves AND to maintain decent rocker arm geometry. IT HAS NOTHING TO DO with piston to valve clearance. Pushrod length is set WITH THE VALVES CLOSED






The only person confused here seems to be YOU , no one said anything, anywhere, in this thread about adjusting piston to valve clearance with the length of the pushrods till you brought it up .

If you go back and reread you'll see he was told to use a HEAD GASKET SHIM to regain his piston to valve clearance .




!!!! REALLY?????!!!!!

From the OP's very own words:

"Basically you lengthen and shorten the adjustable push-rod to achieve the correct imprint on the top of the valve. (Then use that length to order new ones of that length)."




You still aren't seeing it ... ... he said the imprint on TOP OF THE VALVE , meaning ROCKER TO VALVE TIP GEOMETRY ... which is the wrong line of thought for pushrod length because that doesn't move anything on a SHAFT MOUNTED SYSTEM ... I'm still trying to figure out how him saying rocker scrub across the TIP OF THE VALVE is being TRANSLATED into PISTON TO VALVE CLEARANCE ???

Reading is funDUHmental

Re: 340 Engine... How to determine pushrod length?? [Re: JohnRR] #458165
09/07/09 02:20 PM
09/07/09 02:20 PM
Joined: Apr 2004
Posts: 589
Waynesboro, PA
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cuda_tim Offline OP
mopar
cuda_tim  Offline OP
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Joined: Apr 2004
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Waynesboro, PA
Ok, I think I finally got an answer. Thanks, guys!

Just to reiterate, by using an adjustable pushrod, I can determine the length that I need. I do this with the valves completely closed (lifter on the true base circle of the cam lobe). I just need to make sure that the lifter has some pre-load.

Then I use the measured length and buy new ones at least "that" length.

BTW: My machine shop did make sure that all of the valve tips were at the same height (cutting was necessary in many cases). I probably should still check the length of one push rod on each head.

Just to be clear, the valve to piston clearance was not the reason for getting new push-rods. I only want to make sure that the push-rods that I'm using (or need to buy), are the correct length.

Thanks!

Tim...


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Re: 340 Engine... How to determine pushrod length?? [Re: cuda_tim] #458166
08/14/10 04:44 PM
08/14/10 04:44 PM
Joined: Sep 2009
Posts: 69
Menomonie,wi
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menomoniemopars Offline
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menomoniemopars  Offline
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Joined: Sep 2009
Posts: 69
Menomonie,wi
Got the same issue right now , need to find proper length pushrod

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