440 rebuild pre-load and pushrods

[Dukes2fast]

How do I check pre load with hydraulic lifters and non-adjustable rocker arms? or is it necessary?
If the block is milled to acheive zero deck and a higher lift cam (MP .509) is installed can I still use the stock length pushrods?

[rumblefish360]

Hey Duke;

I would get a pushrod length checker in a length that puts the stock 440 length at the extended range of the rod.
Collapse the rod and install it with the rockers installed above it. Open it up until the lifter is depressed no more than .050. Thats your rod length.

Not depending on how much the block was milled but defenitly a huge factor, clay on top of the piston will tell you if you have room or not.
Spin the engine around with all cam/valve train componets installed to see if you have valve to piston clearance.
It's really the best way to know unless theres a been there done that present with a milled block and your pistons and cam combo.

[Dukes2fast]

I have piston to valve clearance.

I followed these instructions to meausure my pre-load

http://www.holley.com/data/Products/...al/INST150.pdf

they say it should be between .020 and .060. Well, first of all this is not an easy measurement to take. But anyway I get .090 to .100, I measured three different sets.

If the push rods are 9.295 I would assume a shorter one will reduce the pre-load?
So, does this mean I need special cut pushrods? 9.245 ?? I thought hydraulic lifters eliminated the need for this?
Help

[dust]

Originally Posted by rumblefish360

clay on top of the piston will tell you if you have room or not.

Where do you get this clay?

Duke: if you interested, there is alot more info on this topic on this tread,
http://www.moparchat.com/forums/showthread.php?t=97166

[Dukes2fast]

I have stock non-adjustable rocker arms. I still don't know what the solution is.

[rumblefish360]

Originally Posted by dst

Where do you get this clay?

Duke: if you interested, there is alot more info on this topic on this tread,
http://www.moparchat.com/forums/showthread.php?t=97166

DST, good man. That link is perfect.
I get the clay at a local art store.

Duke...

I would assume a shorter one will reduce the pre-load?

Yes it would.

So, does this mean I need special cut pushrods?

Yes. But it's no more expensive than off the shelf, regular length P-rods.

I thought hydraulic lifters eliminated the need for this?

Yes, the Hyd. non-adjustable rockers are designed with that in mind. However, if the P-rod is to long or short, it can not do it's job. To long is to long. No preload and to much pre-load is a bad thing. The lifter can not do it's job then.

[Dukes2fast]

Thanks for the replies. Is it common to have to get custom length push rods after a rebuild? Most I have talked to don't seem to think it is much of an issue or even check this

[B1owner]

Originally Posted by dst

Where do you get this clay?

Duke: if you interested, there is alot more info on this topic on this tread,
http://www.moparchat.com/forums/showthread.php?t=97166

DST,
I use Play-Doh. Not kidding, it works great. You can also use silly putty!

[dust]

Originally Posted by B1owner

DST,
I use Play-Doh. Not kidding, it works great. You can also use silly putty!

They did that in a magazine I read about a year ago, CarCraft I think... I don't get why Play-Doh is not more popular than clay, PD is easier to find and edible in case you get hungry while building your engine.

[rumblefish360]

Originally Posted by Dukes2fast

Thanks for the replies. Is it common to have to get custom length push rods after a rebuild? Most I have talked to don't seem to think it is much of an issue or even check this

There idea of non-issue is only because there engine hasn't been milled on the deck or heads with or without a larger cam. It should be checked if you mill something more than .040 and use stock thickness gaskets.

Also, it's not there engine. Nor there money.

[DartGT66]

If I remember correctly, for example competition cams offers pushrods in .050" length differencies, so the correct length isn't any rocket science. I wouldn't be too worried about the correct length, mopar lifters usually have a wide adjustment range and nearly anything goes. With a big cam, by playing with the preload adjusting it to or close to zero, you often can see some benefit at high rpm, but otherwise it doesn't matter much. We have our rockers at a pre determined height, so no changes in valvetrain geometry with the chnage of a pushrod length, and the lifter adjustment range is way bigger than for exmaple in chevy lifters.

[dust]

Originally Posted by DartGT66

If I remember correctly, for example competition cams offers pushrods in .050" length differencies, so the correct length isn't any rocket science. .

Yup, that's what I got.
Makes it real easy...

[Scatpack1969]

on my 400 my lifter preload was .135 ( i first put the stock pushrod in marked it compressed into the lifter, and then loosened everything up and marked the pushrod again it was about .135) so i went to summit racing and looked up 8.450 length pushrods instead of the 8.550 stock length. i found a set of trick flow pushrods discounted to 45.00 (awesome deal) the only differance is they are drilled for a oil passage.

[Satty71]

According to comp pre load on a hydro can be .050 to .130. I would check it man you don't want to bending rods. The check tools are pretty cheap. A lot cheaper that pulling the engine back apart. I think (scarey) one rotation of the nut equates to .050 of preload with your check tool. I ran mine down until contact, spun it one full turn and it was money. This is all based off of memory so please double check!!!!

[Scatpack1969]

go to summit racing , type in the length you need,

[pishta]

I dont know why more people dont use adjustable rockers, Way stronger than the pressed cup design, the cost is not that much more (isky or crane ductile rockers in Ebay) are rebuildable and you can get the correct pushrod off the shelf. Preload has always been an issue with my motors (decked or shim gaskets, etc) so I just went with adjustables. Plus you can get some real monster 3 piece 440 pushrods ( I run a 383/400 stroker and B mechanical pushrods are not that easy to find) and cut them down too, just press the cup back in.

[Rdrunner72]

Rube Goldberg would be proud but I fixed up a way to use a dial indicator to check mine. True, I had adjustable rockers but this will accurately determine the preload and lift with any rockers or pushrods. Remember though this is pushrod movement, so the valve movement will depend on the rocker ratio. So for the valve/piston clearence thing, good 'ol clay was used. (I had no issue with that as the heads and pistons were stock, but I still double checked them)

After positioning the dial indicator (which is held by a magnetic base) I put a parallel clamp on the pushrod. As the pushrod moves the dial indicator which is resting on the parallel clamp reads the exact distance to .001 inch.

Again, kind of Rube Goldberg but once I got it set up the whole process of all 16 valves didn't take very long. Been a while ago but I think I set mine to .050" but would have to go back and check my notes to make sure.

[daredevil]

I milled my heads and zeroed my block and i made shims for my pedestals out of .040 brass shim stock . just cut little squares and drill for the rocker bolts. Make sure to drill end holes where oil feeds a little larger than the bolts. Shim stock was 2 bucks at ace and worked great .Really cheap fix with a little craftsmanship.