Hi all,
In my quest to have my engine assembled before I deploy, I seem to run in to all sorts of problems. Of course, that's the fun of the game!

Anyways, I have my 250 (230 block, 250 crank, 307 pistons) with my head (Tom's work, lump ported, longer valves, etc etc) and roller rockers (Comp Cams). I am trying out the Ford 300 pushrods (10.14 length) since I could get them overnight and can return them if need be.

I went to set my pre-load and when twisting and tightening they would stop, but after a couple seconds be loose again. I could do this for about a full turn before they would no longer loosen after setting. I had put some assembly lube on the lifter & rocker, my thinking is that it was pushing that out of the way and once the oil moved the pushrod would spin again.

After getting to where the pushrod wouldn't spin, I backed it off slightly to get it to just spin, then went a full turn as per manual.

However, I swear the rocker was pushing the valve slightly down when I was doing the final turn. After doing a bunch of reading, it seems like the full turn is heavily debated. I do have a very mild cam in it, not sure if that's causing it.

Anyone have any suggestions? Any way to physically measure the preload vs doing the spin & tighten drill?

I preload one half turn past zero lash. Seems to work well.If you are worried about the valve being opened with the preload you are using, you could apply air pressure at the spark plug hole and listen for leaks. I`ve been told one half turn is .030 down.

I do what sparks does, loosen til they clatter, then tighten just til clatter stops, then another 1/2 turn (or less).

If you want to do it w engine off (good way to start off anyhow), set each cylinder at TDC compression stroke, make sure each lifter is right up against its snap ring ie at the top, with free lash. Tighten just til you still have about .002" lash ie some, not zero, then go another 1/2 turn and STOP. At first the pushrod wont turn, then after a minute or so it will turn - its supposed to - but youre DONE after 1 shot.

Sure, if the engine is new, never milled, etc, you can go down 1 turn or more - but that is why a lot of us use 1/2 turn - too many valve jobs, milling, gaskets, ground cams, etc - 1/2 turn is enough and it allows for stackups over the years/decades.

The engine won't be running anytime soon, so checking them while running isn't an option. I'll try resetting them to 1/2 and keep an eye on the lifter to see how much it's moving.

Did some research and it seems like the lifter should collapse .020-.060 according to Crane Cams, other sources say .030, which is also what Sparks had mentioned.

Since I have my side covers off and it's on an engine stand, I'm just going to use my calipers to measure the preload on the lifter. Should be able to set them without worrying about 1/4 turn or 1/2 turn or full turn or....!

Hi, just curious, where will you be deployed to and for how long?
Mark

Head to Pre-Mob for 2 months in August, then Kuwait for roughly 9 months. Haven't seen any official dates, that's just what we roughly hear.

My machinist told be to set zero lash and 1 full turn for pre-load. He's done it that way and said he's never had issues. Did that with mine but may back everything off a 1/2 turn just for the heck of it. Least until break in is over.

That's the way the manual states as well. However, my engine was pushing open the valves when I did that. With easy access to the lifters I am just going to measure. The full turn is supposed to set the preload to .030, I'll just measure the .030 and know it's right!

We salute you for what you do and your sacrifices!

I plan to do nearly the same rebuild to my 230 that you've done to yours. I'm selfishly hoping you get it done before you deploy since I'm learning the gotchas (like buying new pushrods of different lengths). But if you don't you can learn the final tips from me this winter. One difference is that I'll have a machine shop do the majority of the work.

Good luck finishing it up and with the deployment!

My machinist told me that's normal. If you were to come back a little while later you'd notice the valve closed because the lifter bleeded out. Like said, I'll find out. lol I think for break in I will set no load on the lifters and maybe even a slight clearance. Then after break in set the preload and see what happens.

I don't think my lifter will bleed out, it doesn't have oil in it yet!

I just did some work on it today. I can tighten down my rocker nut by hand and it will start preloading the lifter! Before I must have been maxing out the lifter and then setting it another turn, which was turning the valve. I suppose with all new lifters, pushrods, roller rockers, etc there just isn't enough resistance. Even with the .030 preload I can spin the pushrod easily, however the vertical movement is gone so I know I'm at or past zero lash.

Mshaw230, nice to know someone is following my build! My current problem is with the longer pushrods I don't have enough thread engagement on my rocker arm nut to feel comfortable (less than 1/4"). I have marked the tip of my valves and rotated the engine, it seems to be wearing perfectly centered with the Ford 300 pushrods, so I don't really want to go any shorter to get thread engagement as I would sacrifice rocker geometry. I asked Tom if I can space my rocker arm studs a bit to gain some thread engagement, just waiting to hear back now.

I know it won't run before I leave, but if I can have it assembled and looking good, I'll be happy!

Then you will be reducing the thread engagement of the stud into the rocker bosses if you space them. You need a rocker stud that is longer on the rocker arm side to provide more engagement of the adjusting nut. Since your using longer valves, and now longer length non-stock pushrods you also have to use longer length rocker studs, especially if the rocker stud bosses have been machined down also.

Tom responded that it shouldn't be a problem and that there is plenty of threads. I do understand what you are saying though. Does anyone know of an actual spec for how much thread engagement rocker arm locks need? It's a 1" long nut with a roughly 3/8" lock inside. Some of the videos I've watched on valvetrain geometry seem to have their locks down inside of the nut a ways as well. Maybe I'm freaking out over nothing.

You should have as much thread engagement as the thickness of a stock rocker nut.

That's kind of what I was thinking as well. I just thought maybe some company had a spec of their own.

There is no spec for thread engagement, but the more the better. Since there is no real application specific screw-in rocker stud available because these engine never came with them from the factory, some aftermarket ones work better than others, but you want the set screw inside the rocker nut to be as close to the top of the nut as possible, not recessed way down inside of it like your describing.