I'm about to put the head on my engine and hopefully start wrapping up my build. I searched all over the site but I can't find an explanation on how to check lifter preload a slushy motor. The machine shop says that I will probably have to get custom pushrods. I think the final numbers came out to 40 off the block and about 30 off the head. He said the head was a pain because it was warped, so he had to take off more than he would for a non warped head.

So in a nutshell, can anybody give me a procedure to check my lifter preload?

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

Jeb, I wonder about your machine shop. Thirty off of the head is nothing to worry about. Many times I have gone ninety off the head with no problems, use the stock pushrods and don't worry.

Yeah I wonder about my machine shop too. I'm going to CC my chambers this afternoon, and I should then be able to accurately determine how much he chopped off the head.

Remember I also had 40 whacked off the block.

The reason why I ask is because this engine already had a lower than normal deck height. Most 225's seem to be at least .170 in the hole, mine measured .150 stock.

So back to the original question, how do I check my lifter preload?

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

Jeb, I came up with a method that works great. All of the cam companies recommend a specific preload dimension to allow the hydraulic lifter to function properly. The dimension that they recommend for optimum performance and adjustment is between .025" to .045" of preload. You can easily make a fixture to measure how much the pushrod pushes the plunger down inside the lifter when you tighten down the rocker shaft using a magnetic base dial indicator and a flat plate bolted down to the valve cover rail.
Over-compressing or over-preloading a lifter can damage the valving inside of them and cause other issues that might not be apparent initially and will no longer provide optimum performance or adjustment.

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There's no such thing as too much cam....only not enough engine!

Make or purchase an adjustable pushrod and use that to take measurements and set the preload distance.

It is best to take a few measurements, at different locations along the engine's length... check intake and exhaust positions at #1, then #3 & #6, then average the readings.

You will need to know the type of thread used on the adjustment screw. (TPI or threads per inch)

I make my own adjustable "test" pushrod using a 1/4 - 20 tap so with that TPI, one full turn is .050 of length change.

To test, get the cam positioned on the back of the lobe, (base circle) install a lifter, the test push rod and the rocker shaft w/ rocker arm. Tighten your test pushrod, until it just makes contact. (no lash) Go one full turn more, (.050) then remove the test push rod and measure it's length.
DD

http://www.fordmuscle.com/archives/2000/03/quicktips/

when working through hydraulic lifter preload scenario's as part of the planning for the build for the 83 D-150,, I too had seen numerious internet postings suggesting .030 to .040 hydraulic lifter preload.

When I disassemble the 83 slant motor I had checked the lifter preload by
scribing a line in the crud on a couple of pushrods,, in line with the machined valve cover mounting face. I then loosened the rocker arm mounting bolts and let the pushrods float up,, held them reasonably straight and scribed a second line..to check the lifter pre load with this method the lifter(s) will need to be on the heel of the cam with both valves completely closed.

measured the distance between the lines and got .090 to ,.100
a lot different than the reported .035 avg.

so I disassembled a lifter, to drain the oil,, and measured the components, The lifter pushrod seat has a travel potential of .180

so the factory .090 to .100 of preload was right in the middle of the overall possible preload travel of .180.

for my build I cut something like .045 from the head, a skim cut on the case so there is another .005 to .010,, which should put the lifter pushrod seat deeper into the lifter,, but I also have a re ground cam,, which would put the lifter lower on the cam and in effect raise the push rod seat.
so maybe they balanced out.
I want to pull the valve cover, remark the push rods and see how the preload has changed.

bottom line is my experience says that the slant six hydraulic lifters have a lot more than .035 preload from the factory.

Thanks for the advice everyone. Looks like I'm making an adjustable pushrod.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

In my experiences with Smith Brothers Pushrods...I've locked my adjustable pushrod and sent it to them to make 12 of this length and configuration. That way they don't have too many questions, they just match the tube, ends, and length and ship it all right back to you.

-D.Idiot