Hey guys i need some guidence here. I'm building a 512 and was talked into switching to a roller cam not realizing what all was involved in doing that, I bought a Howards 565 lift hydraulic roller can and i ordered 1.5 Harland Sharp Roller rockers. I need to figure out pushrod length and i have no clue how to go about it. from what i understand you have to have an adjustable pushrod tool right? Well it looks like there is different lengths? How do i figure all this out. This roller can stuff is all new to me. I've been running a 292 purple shaft for 30 years. Im an old school guy and just sticks with what works. Any help would be greatly appreciated. The pushrods are the only thing left before i can finish the motor. Anyone? I'm an old school guy and don't like change and man have i paid for it...lol

The adjustable pushrods have about a 1/2" of adjustment so "close" will work.

Snug down a bank of rockers. Pick a rocker and adjust it so there are two threads showing on the bottom. Get the corresponding lifter on the cam base circle. with the rocker firm against the valve, use a thin tape measure to measure from the pushrod cup in the lifter the the bottom of the adjuster. Whatever that measurement is you'll want an adjustable pushrod with that measurement at the midpoint. This will give you wiggle room either way to determine the exact length you're going to need.

Take one of your old pushrods and try it. It will most likely be too long but it will give you an idea. If you have a buddy with some tools you can turn an old pushrod into an adjustable pushrod. You just cut it in half and then thread it and use a long set screw as the adjuster.

Contact Trend and see if they have some checking pushrods for your application

Not sure if you have old pushrods but when switching to solid roller I took a couple of the original flat tappet pushrods, removed the cup, slotted the end (so could easily install/remove cup) and ground them down until they were the right length.

I was going for 2 threads below rocker lashed.

I then used head shrink around the pushrod to determine max diameter that would fit.

Comp Cams 7719 it adjusts from 8.8 -9.8. $ 37.95 from Summit. That's what I use 511 RB with Indy Ez and Harland Sharp rockers.

The proper way is to buy an adjustable set of pushrods used for determining pushrod lenght. They come in a set. You pick out the correct lenght and it has a range of adjustments with two jam nuts. It’s made of aluminum so don’t turn the motor over with springs on the heads. It will bend them. Make sure you have the correct preload on the lifter with the proper amount of threads showing on top and bottom of the rocker. Then you remove this pushrods and measure it with a dial caliper. Manton or Smith Bros can build you the correct lenght pushrod.

The better way is to purchase the push rod tool that with adjust to the proper length and configuration, both end type and diameter (ball/ball, ball/cup, 5/16, 3/8 etc) most are etched with a scale to determine the change in length from nominal (ie. purchase a 10" nominal push rod and every turn is some know value) When doing so the adjusters in the rockers should be set so if the oil squirt hole is slightly above the intersection of the push rod/adjuster. Then set your preload as normal using the measuring Push rod. Now using the nominal length and the amount of adjustment added, that will be your required push rod length. It is preferable to use a test spring to run the valve thru its range of motion to ensure no issues are present and also check multiple location both int and exh.. the $37 spent on the tool is well worth it

On my 512 RB stroker with a Comp hydraulic roller and HS 1.6:1 rockers on 440 Source stealth heads, the pushrods I bought were just a bit short of 8.5".
Looking at my notes, I think 8.4750"? I used the Comp cams adjustable pushrod, with light checking springs on the valves. I used Smith Brothers 5/16", and fairly sure the 0.083" wall pushrods.
I came up with a range of pushrod lengths for between 0.020 and 0.040" lifter preload, and the minimum number of adjuster threads (where the pushrod / adjuster starts getting oil from the rocker), to about three turns down (any more and the oil to the adjuster starts getting cut off.)

Your measurements might be different. My block was cut to zero deck the pistons, and used a 0.040" Cometic MLS head gasket.

I made an adjustable push rod by taking an old one and cutting it in half at the proper spot, threading both ends with a die, then threading them into a coupler nut. After I have adjusted it to the proper length, I measure it with a dial caliper.

Once you have an adjustable push rod, you can determine the exact length you need to create proper load on the center of valve stem. If you're unsure how to do that, make sure you ask or you look into it. It's not hard, but you do want to keep the rocker tip centered on the stem at peak lift / open pressure.

So i ordered the pushord length checking tool. Ive been watching videos on youtube on how to do it. Some say you need to pull off a valave spring and put on a checking spring? but then ive been told its no necessary? I get the whole concept but its very confusing and i dont want to screw it up.

I ordered push rod checking ones from Smith Brothers.
They were cheap so got 2 even though you just need one. As someone borrowed mine (never gave it back) I allways say no more loan a tool but.

Package was at my door in 3 days.

It'll be much easier with a checking spring and probably more accurate.

Contact Hughes engines, they will send you and adjustable pushrod checker. You set it to length, remove it and send it back and they will have some Smith bro's push rods made for you

ok i ordered the comp cams pushrod length checking tool 8.8 to 9.8.. went to try to figure this whole mess out and it looks to be way too long! Either that or im missing something. look at the pics. This whole process is a complete confusing pain in the ass and im kind of over it. One step forward 2 steps back.

Well, your rocker shaft isn't tightened down...

the utube vid "engine tech valvetrain geometry" by "straub technologies" may help. EDIT & UTG had something on preload amount for hyd lifters, probably not valid here but I wanted to throw it out there. he was loosing alot of power till he corrected it.

I mentioned, the pushrods should be about 8.5" so you could get the correct length checking pushrod.

The OP shouldn't be playing with mechanical things !!!