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Push rod problem!

english_man_in_norway

Contributing Member
Hi there,some of you will proberly remember I had problems getting some rocker arm studs a couple of months ago,well I got some specially made In the end back in the uk at a machine shop,but I now have a new problem. I have a 1993 4.3 Mercruiser & when I tried to set the push rods the nuts in the rocker arm were 'bottoming' out before a full turn & I was able to still twist some off the push rods,In the boat manual I have It states that the Intake valves & the exhaust valves have differant length pushrods,but mine are the same length! Anyone had a simular problem :confused:.
 
Precisionally mark the studs, and watch to see if any are backing out of their bores.

Remember, you will be setting the depth of the cam follower plunger/piston within the bore of the cam follower.
If these are now dry, this would be the time to set all of them, IMO.

If memory serves me, some 4.3l's call for full down on the adjustment nuts.
Do a search on this..... make sure to use the correct procedure for the year model.

Use the 6 stop method over that of the 2 stop method.
Then perhaps go back through them dynamically.
 
Hi there,some of you will proberly remember I had problems getting some rocker arm studs a couple of months ago,well I got some specially made In the end back in the uk at a machine shop,but I now have a new problem. I have a 1993 4.3 Mercruiser & when I tried to set the push rods the nuts in the rocker arm were 'bottoming' out before a full turn & I was able to still twist some off the push rods,In the boat manual I have It states that the Intake valves & the exhaust valves have differant length pushrods,but mine are the same length! Anyone had a simular problem :confused:.

Ayuh,... Yer just supposed to zero out the lash, no more up/ down...

If ya crank 'em down so's ya can't Twist 'em,...
You've collasped the lifters, to Solid...
1 turn passed can't Twist 'em, is mostly Wide Open valves...

Loosen 'em all, up, 'n start over, get it runnin', 'n do it again...
 
English Man, have you primed the oil system yet?
If not, then the cam follower (aka lifter) plungers are dry.
When dry, and at bottom center of lob, you will be able to push the plunger down with the push rod, and with very little force.
(the spring pressure is very lilght)
There will be approximately .100" plunger travel within the cam follower.

If you have primed the system, now the plunger is resting on a cushion of oil.... IOW, hydraulically locked.
Finding zero lash is only a portion of this.
The goal is setting the plunger depth!
You must first find ZERO, as Bondo suggests, then the additional % of the rocker nut turn sets the plunger depth.

When doing this statically, it will make a difference as to whether or not you have already primed the oil system.

To avoid any confusion, you may want to go through them dynamically.

.
 
Thanks for your imput guys,I havn't primed It,so I'l go through the basic settings again & take It from there,no one mentioned the length question on the pushrods,are some models the same length or can someone have installed the wrong ones,at some stage?
 
Thanks Ghost,Its very confusing sometimes,with all the differant boat manuals with their very differant Ideas & specs! Hopefully just a simple set up again then & fingers crossed, them long awaited revs once more!!
 
First. Adjust the rocker until there is zero lash(NO PLAY UP AND DOWN) Then turn the lock nut one complete turn and you are done. Never adjust the rocker arm by rotating the push rod. This method is inaccurate.

Second. All the push rods are the same length.
 
First. Adjust the rocker until there is zero lash(NO PLAY UP AND DOWN) Then turn the lock nut one complete turn and you are done. Never adjust the rocker arm by rotating the push rod. This method is inaccurate.

Second. All the push rods are the same length.

Just to clarify one statement, ((Adjust the rocker until there is zero lash(NO PLAY UP AND DOWN))

This is what confuses people the most. This adjustment means when the valve is completely closed and you are sure the lifter is on the BASE CIRCLE (non lift area) of the cam, you tighten the rocker arm nut slowly until there is just a very small amount of resistance when spinning the pusrod with the TIPS of your fingers. Once this resistance is felt STOP. Now turn 3/4 turn more and done, move on to the next one.

Hope this helps.....Just a bit of clarification.
 
Two Differant methods here,but I'm sure both are good,I was just tightening the nuts a bit too much,I didn't realise that the rocker arms should be so loose,I'm surprised In 'theory' the nuts don't vibrate off! Thanks again for your confident advice guys,a break in the weather & I'l be back down to her to give It another go.
 
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