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Discussion Starter · #1 ·
Hi all - im working on a dreaded mercruiser 470 which has a ford 426/460 style head with non adjustable rockers and the manual calls for a combination of 4 various push rod lengths!! The lifters are hydraulic, if I convert a sbc 3/8 fine thread to 3/8 to half a turn (which is my goto) of a turn I get about 15 - 20 thou correct?

Im going to use a margin for setting these things so i can move on.. would 15-30 be an acceptable amount?

Basically just going to torque down rockers and check with dial indicator using various push rods I have on hand to get each one close..
 

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. As long as you get the pushrods in the correct orientation, have good lifters and springs, all you need to do is apply the proper torque.

Been covered a few times over the years. The below threads will give you a idea. But I highly recommend you invest in a quality service manual with part numbers. With a car if you have a issue you call a tow truck. A issue on a boat can lead to a very bad day real fast.

You may look at the cost of a "engine service" from a quality marine mechanic. Normally I am pro DIY and I believe people can learn anything with enough determination. But that does not mean they won't make mistakes while learning. A bit of knowledge can lead to costly mistakes.

If you go forward having the proper tools like the proper "shop" service manuals and any boat related tools will lead to better results.


You need to log in to see the 4 diffrent lengths and colors of the pushrods.

 

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Discussion Starter · #4 ·
. As long as you get the pushrods in the correct orientation, have good lifters and springs, all you need to do is apply the proper torque.

Been covered a few times over the years. The below threads will give you a idea. But I highly recommend you invest in a quality service manual with part numbers. With a car if you have a issue you call a tow truck. A issue on a boat can lead to a very bad day real fast.

You may look at the cost of a "engine service" from a quality marine mechanic. Normally I am pro DIY and I believe people can learn anything with enough determination. But that does not mean they won't make mistakes while learning. A bit of knowledge can lead to costly mistakes.

If you go forward having the proper tools like the proper "shop" service manuals and any boat related tools will lead to better results.


You need to log in to see the 4 diffrent lengths and colors of the pushrods.

I personally bore and rebuild my customer engines.. The manual asks to bleed the lifter down with a special tool and a: that tool is not easy to come by, 2 is to leave lifter on valve open to apply pressure - sometimes the lifters dont even bleed down and require dismantling..

The manual which i have read lists 4 different length push rods and a spec of 100 to 200 thou on a collapsed lifter which seems ludicrous - how do you know when its fully collapsed.. Bear in mind this darn engine has 40% leak down loss and just need it to fire up for a broke customer - all this is just side info.. bottom line is I checked some push rod lengths, ordered a few from the melling catalogue and will work over the valves till they are close enough..
 

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If you have a lifter out then you can measure the plunger travel from full up to fully compressed. If there’s oil in it getting to full compressed will depend on how fast it leaks down if at all so enough disassembly to get the plunger out so all the oil can be drained from under it.

The lifter will function at any preset that is between full up and full down. Most factory settings try for the mid point. The only thing the plunger is concerned about is where in its available travel it encounters the resistance from the closed valve. It will hold that point. The things you’re trying to avoid is a push rod so short that the plunger is riding against its top retainer or so deep it’s bottomed. At the retainer if a gap was to appear in the valve train oil pressure under the plunger could pop the retainer out spilling the plunger into the valley. Running the plunger on the bottom allows too much space for pump up if operating gaps appear in the valve train which then requires too much recovery time from a pump up so the affected valve will be unable to seat for a long time period. So somewhere around the mid point favors minimizing risks from the extreme conditions.

Bogid
 
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