Beast96Z

iTrader: (21)

Well, after checking, it looks like Tony is right. I have .110" on the intake side of the valve, and .040" on the exaust side of the valve. Looks like it is time for a shorter PR and thinner shims. Thanks for the advise Tony.

JF WS6

Do the Morel lifters have as much preload variation tolerance as the stockers? Where would your preload/turns past 0 lash be if you just went with the 7.350 Pushrods and no shims do you think? Just wondering.

Beast96Z

iTrader: (21)

The Morels are not supposed to be as sensitive as the Comp R's. They should be more like stock tolerences, but in a better lifter. As for the turns past zero with the 7.350's, I'm not sure. I'd say maybe 1 full turn since we talking .050" shorter. I'm sure Ill do like Tony said and use the 7.350's and a .025 shim to get me back to the .075 that I started with, but this time the valve tip will move back to the center instead of being so exaust biased.

RX-Ben

iTrader: (7)

Let me take a stab at this, with respect to the Holley/Lunati instructions and what Tony has said. Please make any corrections as necessary:

1. Pushrod length and valvetrain geometry are independent of each other, because we use hydraulic lifters. If we used solid lifters, like in the Holley article, pushrod length would dictate geometry.

2. In a hydraulic lifter engine, pushrod length is strictly for adjusting pre-load on the lifter. The lifter can accept a range of pushrod lengths, though the difference will be the amount of turns of the rocker stud to achieve 22 lb/ft. More turns of the rocker stud = more preload. Stock lifters are more forgiving that Comp Rs in this regard. Looking at the 2 extremes- a pushrod that is too long will either not allow the rockers to be fully seated (essentially pushing them up) or will not allow the requisite number of turns to achieve the proper pre-load. A pushrod that is too short will take too many turns of the rocker stud to achieve 22 lb/ft. If a pushrod is too long, you can place a shim between the head and the rocker plate. This will allow the correct number of turns for pre-load, but will also affect the rocker geometry and cause the lopsided "wipe" issues. If a pushrod is too short...buy a longer one.

3. Valvetrain geometry is governed by the rocker height. Altering the rocker height will change where the rocker tip and the valve stem contact each other. As Tony said, geometry is more important that the pushrod length. This would be because of the forgiving nature of hydraulic lifters, which will accept a range of pushrod lengths. Geometry is not forgiving, the geometry is either right or wrong as evidenced by the "wiping pattern" on the valve stem.

4. Lifter pre-load and valvetrain are interrelated. If a shim is needed to fix the geometry, the lifter pre-load will be affected as well. If you shim the lifter to fit in a longer pushrod (to decrease the number of turns to achieve 22 lb/ft), you'll alter the geometry. As Tony said, this is not the way to do it. Put the cart before the horse- address the geometry first and then get the correct pushrod length.

Sound correct? I'm just trying to put together everything on this thread (and from other threads) to make sure I have everything straight.

Thanks
Ben

Beast96Z

iTrader: (21)

In my case, I'm using the shorter PR to get the correct geometry and "wipe", and the shim to get the proper pre-load. Although pre-load will be effected by the shorter pushrod, it is not the way to change pre-load. In my case, it is just a bi-product of the correct geometry. Now my wipe will be correct and the shims will be thinner, giving me closer to a "factory" angle, which should be about right. I'm glad I decided to check. It wouldn't have taken much for the rocker to come off the head of the valve the way I had it.

Tony Mamo @ AFR

iTrader: (13)

Your welcome.....LOL

Mirek

PDD: That Sucks How much you got in that thing!!?
RX-Ben: Good summary
Thanks again, this turned into a very useful post.
I figure I'll use a shim to assure the proper wipe pattern (geometry)and torque down to 22ft/lbs there is no preload adjustment. Everything sould be zen then because they are stock non adjustable rockers -preload should be automatically after 22 ft lbs right ?

Beast96Z

iTrader: (21)

Actually, I think you got it backwards. Your gunna use the PR to get the correct "wipe" and then use a shim if you need one to get the right pre-load. With your heads being cut .030", you should be in the same boat as me. A 7.350 PR should get you your correct wipe, and if you have stock lifters, you can shim if you want, but shouldn't have to.

AFTICA

iTrader: (8)

I think I disagree. Like Tony and RX-Ben stated PR length will not change wipe or geometry just preload. So Beast I think you have it backwards.

Lets try to get Mirek where he needs to be. He's right the stock PR is 7.38. His aftermarket cam is .030 smaller.(use 1/2 of this for PR length figures) He's also using a 7.40 PR. So before he puts these heads on his PR's are .005 too long. Now he's going to have the head .040 closer. So he would need to have a .035 shim to keep the geometry proper, correct?? I believe the stock lifters have .090 travel in them so he should be OK with preload, correct??

Once we get this straight, this will be a very informative thread.

Beast96Z

iTrader: (21)

I guess I'm missing something here. My set-up is almost identical. .030 smaller base circle, heads milled .024", and the same pushrods. If this is supposed to be correct, then why is my wipe so far off?

JF WS6

Your wipe is off, but you are using shims correct? Maybe I'm wrong, but it seems to me with NON-adjustable rockers you'd want to just get the preload right or within tolerance with custom pushrods and use no shims. The shims are what shifts the position of the rocker over the valve tip correct? I don't understand how just bolting a stock or stock replacement rocker down on a head at proper tq. spec would have an improper "wipe" pattern on the valve.

Maybe it's just me, but it seems this thread has become more complicated than necessary. If I'm wrong, somebody please correct me.

AFTICA

iTrader: (8)

Beast.. Get your geometry (wipe) correct with or without shims, then see what length PR you need. JF WS6 is correct. Bolting a stock rocker on a head should give you the correct geometry....it's just like stock. But when you mill the heads you need to make the preload correct. So the two most common ways of doing this are custom length PR's or shims. The problem when you use shims is that geometry is effected, so ideally you should figure out what length PR to use and use it with no shims. However with only 7.40 and 7.35 PR's readily available sometimes you need to use some shims to make the compromise.I would use the closest length PR and the least shims as possible to make up the difference.
Remember PR length effects only preload, shims effect geometry and preload.

Mirek

ok, I bought both .030 &.060 shims to use with the 7.4's. I'll check the wipe pattern before using them and then choose which one based on what the wipe pattern tells me. The lifter should be able to accomodate the varience but it is possible that my wipe pattern look fine even without any shims if the lifter has enough ability to accomodate the varience in length (at the expense of too much pre-load). Which brings me to full circle with:
How many turns (after the bolt is finger tight not allowing the pushrod to move) should get me to 22 ft/lbs ?

Beast96Z

iTrader: (21)

After everything these guys have told me, It looks like you WILL need shorter PR's. I guess it more or less depends on how much pre-load you want in your lifter. I can tell you now that the .060" shim will put you on the wrong side of the valve tip. The .030" might be OK, but I'd check first. The 7.350 PR should put you right were you want to be with no shims. I guess you could get away with having alot of pre-load, but you don't want your lifters to bottom out because you have them set-up so tight. In my set-up, no shims netted me 1 1/2 to 1 3/4 turns past zero to 22 ft. lbs. In my opinion, that is far to much. I prefer to run about 1/2 past zero to 22 ft lbs. The 7.350's and a .020" shim should get me to were I need to be.

Tony Mamo @ AFR

iTrader: (13)

Guys...

Quickly to summarize so new people reading won't get confused...

First and foremost is to achieve a centered "wipe pattern" on the valve stem tip. This is achieved by changing the height of the rocker arm pedastals with shims (IF necessary). Pushrod legth in ANY pedastal style (LS1) rocker set-up DOES NOT altar that geometry. (Only in a conventional "stud mount" set-up is that the case).

Once you have achieved the correct stand height and wipe pattern, THEN you install the appropriate length pushrod that will give you the desired pre-load with your hydraulic lifters. Best way to do this is with an ajustable pushrod that you will end up measuring when you have achieved the pre-load you are shooting for making sure the lifter is on the basecircle of the camsahft.

Once again, the correct "wipe pattern" dictates the pushrod length (other variables being cam base circle diameter, shaved heads, etc.)....NOT the other way around.

Also, it is always best to check these dimensions on YOUR individual set-up for optimum results. Don't take your buddies word because his heads were milled .030 also that you will need "X" amount of shim and "X" pushrod length. Use that as a starting point and confirm its best on your set-up as well. Blueprinting and correctly building performance engines is time consuming....making assumtions and taking "short-cuts" ineveitably leads to less power AND reliability (or worse).

Tony M.

Mirek

Excellent.
And for the benefit of those reading in the future....how much pre-load (turns past zero lash to 22ft lbs) is "recommended" with stock lifters ?

JF WS6

According to JMX's LS1howto.com no more than 360 degrees or 1 full turn from 0 lash (from the Yella Terra rocker install.)

Straight up question Tony, have you ever seen a situation with a stock or stock replacement LS1 rocker arm that is non adjustable where it needed shims to achieve a proper wipe pattern? I've NEVER heard of that personally.

Most any reference I've seen to "shimming" is trying to get the preload right without having to buy another set of pushrods, not to get the geometry or wipe pattern correct. I thought it was a given that bolting a stock/stock replacement rocker to the head with no shims would achieve the proper geometry since it's just like stock (or should be anyway.)

Tony Mamo @ AFR

iTrader: (13)

To be perfectly honest....I don't know (I'm running "stud mount" on my personal vehicle).

I would like to THINK "stock" gives you the perfect wipe pattern, but I wouldn't bet my life on it, and if I were building the engine for myself, or anyone else for that matter, I would check and see if "stock" didnt need a little different situation. Keep in mind that most guys doing this might have just installed a camshaft that lifts the valves close to .100 MORE than a "stock" situation....that can, and will, effect the wipe pattern and might end up requiring shim etc. to correct for it.

As far as preload, I have seen close to 2 turns with a stock GM lifter set-up. I noticed that when I took my engine apart. I would say anywhere from 1-1.5 turns would be fine. By the way, I did some dyno testing with my "R" lifters and from .010 preload (valvetrain making a racket) to .055-.060 preload (lifters MUCH quieter), I saw ZERO difference in power anywhere in the curve. Guess where I run my Comp "R"'s ?? (hint: think "quiet").

P Mack

iTrader: (6)

Tony, when checking your wipe pattern, do you just eyeball it while you turn the engine over by hand?

Beast96Z

iTrader: (21)

You remove the rocker, color the head of the valve with a black marker, re-install the rocker, then rotate. You can now remove the rocker and see where the tip rides at. I measured what wasn't removed with a caliper to see how far off I was, although it was very obvious. With these rockers being pedestal style, it makes more since that the pushrod dosen't effect wipe. I've been stuck thinking about stud type rockers. I've got it down now.