[67gtospud]

Went to finish putting my engine together today and adjust the rocker arms and. . . The pushrods are too short. With my poly locks all the way down its just that there's a slight pressure on the rocker arms. I had the block zero decked and 0.015" was removed but I installed screw in studs in the head. I'm having a difficult time finding somebody nearby to borrow an adjustable pushrod. Ugh, this is a bummer of a start to my weekend.

[max 93]

Where in WI are you ? I have an adjustable pushrod I would let you borrow.

[67gtospud]

Originally Posted by max 93

Where in WI are you ? I have an adjustable pushrod I would let you borrow.

I'm in the southern part of door county

[max 93]

That's about 3 hrs from me

[fiedlerh]

An adjustable pushrod is pretty cheap from Summit or Jegs.
Sometime the screw-in studs are a bit too long, especially if they are aftermarket. Maybe one of the engine builders can chime in on the best fix for that.

[chuckies76ta]

Make sure you use checking springs to check for pushrod length if you have hydraulic lifters.

Just a thought.

[critter]

Maybe this will help on the pushrod front.

[67gtospud]

Thanks, I will use the checking springs and I have a set of old solid lifters. And I will have to use one of my old pushrods to make a tool. What thread is it?

[Schurkey]

Originally Posted by 67gtospud

I have a set of old solid lifters.

Is the pushrod socket at the SAME height as the hydraulic lifters you plan to use, when the hydraulics are preloaded the amount you intend to run? Any difference in the height of the pushrod sockets has to be accounted for in the pushrod length measurement.

Don't forget that there are at least three different ways to measure the length of a pushrod, and you need to use the same measurement method as the pushrod supplier you're buying from.

[67cruiser]

You are starting out on compression stroke to start with are you not????

[MNBob]

As an admitted newb here, this thread is confusing me. I have this job in my future. A few questions:
1. Why wouldn’t you just use the hydraulic lifters (roller or flat) you will use to measure the length?
2. Are the checker springs so that the spring in the hydraulic lifter is strong enough to depress them without deflection?
3. Where do I get checker springs?
4. Isn’t the pushrod length just the distance from tip to tip? How else would you measure it?

[Joel Koontz]

It would probably be a good idea to check for correct pushrod length, but I do not think you would need a longer pushrod after the changes you mentioned.

Moving the head closer to the cam should not require a longer pushrod.

If the pushrods were the correct length before the block was decked, they should be (slightly) "too long" now, but probably not enough to be concerned about.

It sounds to me like all you may need is some hardened washers under your poly locks.

[67gtospud]

Yes it is on the compression stroke. I did move the head closer, however I installed screw in studs in place of the press in studs. With the screw in studs the pushrod guideplate is located under the new studs which raises them up.

Checking springs can be bought at summit or jegs. You only need 2. I could use the hydraulic lifters im going to use in my engine but the solid ones have the same measurements. Comp cams has a good read on their site about the different ways of measuring pushrod length.

[Joel Koontz]

Raising the position of the rocker stud is not going to require a longer pushrod.

It just means that the rocker needs to be positioned further down on the stud.

[fiedlerh]

Yes, but you can run out of adjustment room on the polylocks

[LATECH]

Jkoontz has the right idea. I did that on my build.Zero decked,.045 off the heads screw in studs.I used hardened washers and it worked nicely.

[Cliff R]

Use the hydraulic lifters that you are going to run when measuring for pushrod length, or you will have to take one of them apart (not recommended) and shim it up to where you are going to run it to make the measurements.

What we do here is to set the pre-load where we are going to run them, then bottom out the lifters and measure the additional travel. With the lifters bottomed out, mark the valve tip and adjust the pushrod (adjustable) until you determine the ideal pushrod length. Then subtract the additional travel from your measurement, and you have the correct pushrod length.

Look for the narrowest pattern as close to being centered on the valve tip as possible. This may take some time, but it is worth the effort.

For example, the 455 we just finished use HR lifters that had a total of .140" travel. this was apprx 1.5 turns with the locknuts. We set the pre-load at .070", or about 3/4 turns down from zero lash. We bottomed out the plunger then did the measurements, then subtracted .070" from the result.

The pushrod lengths required on these engines are all over the map these days, due to the different items used with the valvetrain, and decking/squaring blocks and milling heads. Just going from one brand of rocker to the next will typically come up with a different length.

Other items in the mix change the length required as well. Cam base circle, brand/type of lifter, type of head, valve length used in them, and brand/type of rocker arm.

The shortest we've used to date have been 8.900", and have needed clear up to 9.850's for a few engines.

I would also recommend going to heavier wall pushrods if you find yourself buying a custom set, unless it is a near stone stock set-up with stock spring loads/small cam, and will never see much past 5000rpms.

Although we've never had any failures with .080" wall pushrods, they few engines we've been back into that used them had "witness" marks on the pushrods where they were flexing around quite a bit and rubbing where they go up thru the heads. This problem does not happen with the thicker wall pushrods, as we've been checking several engines used for street/strip action that we built here in the past few years, including my own.

Another problem we run into as it relates to this topic, is not enough engagement with the locknuts. I will not assemble one of these engines and put it in service with at least 5 full turns with the locknuts. We've had to get longer studs or shim up the ones supplied with the heads on occassion. The length of the locknuts also has them hitting most stock covers, so we find ourselves using thicker gaskets, or getting shorter locknuts or machining down the set supplied in the lathe for the needed clearance......Cliff

[MNBob]

After I posted yesterday, I did a lot of reading on this subject. There are about 4 methods suggested by others for dealing with hydraulic lifters when measuring push rod height. I also read the Comp Cams literature about the different ways to measure a push rod.

The first method was converting a hydraulic lifter to a solid by taking it apart and filling it with something. The problem with this one was getting it right. One guy had used tin foil which subsequently collapsed somewhat. I would imagine that even with washers it would still be hard to shim it exactly. Also, it was mentioned that you could not take apart hydraulic rollers because of the pin. Scratch this method.

The second was to use a solid lifter in place of the hydraulic. This method didn’t sound good to me because why would a solid be the same height as a hydraulic so your measurement would be off by the difference. Maybe you could measure both lifters and push rod and difference the two measurements.

The third was to use checking springs. One poster said he was skeptical of this method because you always get some deflection in the lifter. Still, this method must work or they wouldn’t sell checking springs. This method requires you to buy or rent a valve spring tool.

The fourth was the method mentioned by Cliff above. It was stated that it is fairly easy to determine when the lifter bottoms out. This method only requires the adjustable pushrod and uses the intended lifters. The only question I had with this method is how to measure the total travel. Is that done by adjusting the nut and counting the turns and knowing there are X threads per inch?

Thanks for the patience guys, I am learning here.

[Joel Koontz]

The Comp Cams High Tech Pushrod Length Checker, extends or retracts .050" per turn. IMO it is well worth the slight additional cost over a normal checker.

The pushrod length checker is not as strong as a normal pushrod. It MAY(I would research/ask Comp Cams to be sure) be OK to use it with a fairly weak set of stock springs, but I definitely would not recommend using it with a stiff set of valve springs as you may damage it and/or get inaccurate readings.

A lever type valve spring compressor should work OK on stock type springs and are on E... for under $15.

A checking spring is something you can probably get for under $1 from a local hardware store.

[MNBob]

Thanks for the input. The Comp Cams High Tech Pushrod Length Checker seems well worth it for little additional money. I was planning on buying a set of assembled KRE D-ports, I am not sure how strong the springs are.

If they are too strong for the checker, then the checking springs would have to be used. I would feel more comfortable using the spring’s from Jeg’s or Summit designed for this purpose.

I have never used a valve removal tool. Would I have to use it, install the light springs, bolt on the heads, measure, take the heads off and replace the heavy springs?