360 Pushrod help...

['66Cuda]

Using a pushrod length checker, in my .060" over 360 with J heads that have been milled .008", I measured the pushrod length to be 7.480". That is with .030" preload on the new, non-pumped up Howard's hyraulic lifters, with lifters lubed and sitting on base circle.

Can I use the standard 7.500" pushrods safely and effectively?

I have read where some guys preload to .050" anyways to begin with. How much will the extra .020" effect geometry, if I use the 7.500" push rods?

Thanks!

 

[AJ/FormS]

That should work.There is lots of travel in the plungers.You wont have an answer as to geometry, until you adjust your pushrod to that length and plug it in with a set-up lifter.
Now heres the kicker. If you rev the engine to the point that the springs can no longer control the valve train, the lifters will pump up. You better make sure the valves dont get into the pistons.It depends on where the pistons are and what the cam is doing.With just .050 preload you should be fine.Hughes Engines lists .080 to .095 as standard preload on some of their cams.
But the engine wont idle with .050 pump-up, and may be extremely hard to restart.Put some good springs on it,stay out of pump-up, and you'll be fine.

I run adjustable rockers and 3/8 to 1/2 turn of preload.The engine revs to 7200 on a regular basis. If the lifters have ever pumped up , I sure havent noticed. I adjust them every spring.I used to run 1/4 T preload. It didnt make it through the summer. I forget the tpi on my adjusters. Ima guessing 28 threads per inch, so that would be about .036 per turn. So I'm running about .014 preload. At .050 you would be running the equivalent of .050/.036= 1.4 turns.That is quite a bit.

 

[Rapid Robert]

I'd get a junk HYD lifter & jbweld the cup .050 below the snap ring then mockup & check the wipe pattern with some light springs. First tho I would mockup with the longer pushrods you have & measure the actual preload cuz the lifter/p rod ain't in a straight line & JB the cup at the actual dimention (might not be .050"). I'm a bit OCD but right is right & I want to know EXACTLY what I have

 

['66Cuda]

Thanks for the responses. One of my lifters had a casting void, and I got a replacement overnighted. I tried mocking the bad one with .030" preload, by placing washers under the piston, and came up with the 7.480". After writing this post, I went back out and mocked it with zero preload, then measured and got 7.449". I added .030" for preload for a total of 7.479" pushrod length. My machinist suggested going shorter rather than longer, so I ordered some 7.475" long. I had to order oil through rods. I did some research and most thought they work good. I have the factory stamped rockers for now, and may go adjustable in the future. Do you see any issues with what I am doing?

 

[mopowers]

Did you check more than one cylinder? I know when I did my 340, the lengths varied side to side and front to back by about .020"

 

[winstoninwisc]

we went thru that problem and that .01-.02 can just be in the block not squared off to start with , my cam is way too small rite now iwanted to use a 557 lift that had around 285
@.050 what cams are you running ?? my pushrodscame out to be 7.375 with hydrolic
lifters with roller rockers so 7 1/2 should be goodfor using the stock rockers there not close to a true 1.5 . but yes the mock up and dial messure various holes is the only way to do it

 

[Rapid Robert]

I added .030" for preload for a total of 7.479" pushrod length. My machinist suggested going shorter rather than longer, so I ordered some 7.475" long. I had to order oil through rods. Do you see any issues with what I am doing?

7.449" got you 30 preload & you went 5 tho less for 25 preload?. (1) installed,see what you get for preload (2) check wipe pattern (as said check more than one for 1 & 2). Ideally I'd like to use an adjustable p rod/get the preload you want/measure it/order em. Post how things go. dont forget checking the wipe pattern

 

['66Cuda]

7.449" got you 30 preload & you went 5 tho less for 25 preload?. (1) installed,see what you get for preload (2) check wipe pattern (as said check more than one for 1 & 2). Ideally I'd like to use an adjustable p rod/get the preload you want/measure it/order em. Post how things go. dont forget checking the wipe pattern

Yes...I used an adjustable pushrod checker and measured the .030" with a wire feeler gauge between top of cup and retainer spring on lifter. Then I mocked the lifter with no preload, used adjustable pushrod to get no lash, measured and added .030" for preload. That measurement was 7.479". My machinist told me he would rather go .004" less than .020" more preload. Hughes Engines recommends .022" - .030" for a medium performance application.

Can I still check the wipe pattern with the factory stamped rockers, like you do with rollers? I wasn't sure that would work correctly because the load bearing surface is so large on the factory rockers.

Thanks for the input!

 

['66Cuda]

Here is my wipe pattern with stamped rockers. It may not matter at this point though. I ordered 5/16" pushrods. They don't fit in the cup of the rockers like the factory pushrods. I am getting more than .040" preload (wire feelers only go up to .040"). I started the day with an EZ out. Not my day...

Build your own motor they said....it'll be cheaper and it'll be fun they said....

 

[Marcohotrod]

use stock pushrods, I bet they measure slightly less than 7.500". the head gaskets U are going to use are probably .008" or so thicker than stock. hydraulic lifters are not as sensitive to lifter preload as some think, search the dyno test steve dulcich did on a big block mopar a few years ago. there is also a thing such as lifter bleeddown, the opposite of pump up

 

['66Cuda]

My head gaskets are .028" thick, which is .017" thinner than the Fel-Pros that come in the rebuild kits. I still don't understand where I gained the extra length.

 

[dano]

I still don't understand where I gained the extra length.

Deck height, Valve stem height, head thickness, base circle diameter, different brand lifter, variations in the rocker, head gasket thickness, shaft stand heights, and Sasquatch.

 

[Marcohotrod]

so your head gaskets are approximately stock thickness. heads cut .008" = insignificant. what extra length did u gain. and pushrod length does not affect rocker geometry on shaft mounted rocker engines. what was stock lifter preload on 340s and 360s? cuz I have revved and beat the hell out of stockers with no problems

 

['66Cuda]

The "gain" came from my measurement of 7.475" on my adjustable pushrod tool, that should have given me around .025"-.030" of preload. Instead I have over .040" (my wire feeler only goes up to .040"). I have a bigger wire feeler gauge coming today, that will tell me what I actually have. At this point, I may just leave it. I am not real sure its worth trying to knock off another .015" of preload. Hughes Engines lists a preload of .022" -.042" for bracket racing. I definitely won't be doing any bracket racing, so I might be fine. Thoughts?

 

[j par]

I bought 273 adjustable rockers with cup & ball pushrods for $ 100 shipped from a FABO member. I had to get pinch nut adjusters for $50, but it was a good upgrade. Food for thought ......:dontknow::dontknow: