So I just set the lash on my new engine. First time with roller rockers, but more less the same as several previous times setting lash. I've always heard 1/2 to 1 full turn for small blocks, and I've always used a nice safe 3/4 turn. ....after I was finished (of course) I see CompCams recommends 1/2 turn for my Ultra Golds. ....does that 1/4 turn extra that I gave em matter? I wouldn't think so, and my gut just likes that 3/4 turn I've always done. ....but....my brain still is stuck on following directions.

Am I over thinking?

 

Not really...

Recommendations run all the way from 1 full turn (factory... glue the valve covers back down and don't touch em for 100k miles) to ¾ turn (typical Chilton's etc.) to ½ turn (typical aftermarket "street" cam, where higher RPM w/o pump-up from float is desired) to ¼ ("street/strip", even less "pump-up" but maybe more frequent maintenance) to near zero (no pump-up ever, reset every few runs).

What rockers you use, doesn't matter. No doubt Comp's thinking is, if you have that product, odds are, you're not doing an el cheeeeeeepo stock rebuild.

Take your pick.

 

I need a "Red Phone" directly to you, sofa! LOL thanks...

....actually, I went back and set 'em all to 1/2 over zero, per the instructions. If I blow this thing, up, I don't wanna tell anyone I completely, and knowingly disregarded the instructions! Ha!

 

Should be perfectly fine.

 

If you want to get really picky, it depends on how much preload is required for the lifter. The majority of hydraulic lifters require around 0.030" from zero lash on the base circle of the cam lobe. For most engines, that's right around 1/2 turn from zero lash. You can get high tech and use a dial gauge to measure the adjustment but hydraulic lifters are very forgiving and should work just fine anywhere in the 1/4 to 3/4 range.

After you've adjusted the rocker, the lifter will bleed down and the pushrod will feel loose again. This is normal. DO NOT overtighten.

 

Anyone can look it it for themselves but no one does. The stock 1 full turn reduces the plunger travel before push'n on the p-rod and provides not only more margin for vlv train wear but provides the most lift or more correct it is to say it has the least lift loss. But this allows the most amount of plunger pump up at higher rpm that would hold the vlv open the most if pumped up solid.

The smaller 1/4 turn adjustment then has the greatest lift loss as the plunger travels the most before pushing up the p-rod. But if the lifter can no longer bleed down fast enough it will hold the vlv open the least once pumped up solid and the plunger cannot move down/bleed down.

After adjusting only 1/4 turn for years i now adjust 1 full turn as i just dont spin to 6,000 rpm if i can help it.

Comp sells a hyd roller lifter that uses a very short plunger travel so u have to make a tiny preload adjust but it gives u the best of both worlds. Problem is to few seem to be able to adj them correctly and they kinda fell out'a favor.

Hope this helps.

 

Wow, that's funny. I have the exact same question. I put a stud girdle on my valve train just yesterday and took them all down 3/4 past zero lash. Later to find out 1/2 turn past is recommended per the instructions.

MY question is...., now that the valves are set and locked at 3/4 past, can I just go and loosen the lock nut and back off each one a 1/4 turn as it sits?

Or do I have to back everything off, find zero lash on every one and then do the extra 1/2?

I know it was mentioned that I'd probably be fine at 3/4 past, but like Abubaca says, i'd rather just do what is recommended.

Thanks!

 

Yup...

"Zero" hasn't moved (one can only hope), so anything referenced off of it is still the same.

 

 

IHO they are good to go at 3/4 turn preload. If u are using rollar rockers and u try to move the poly lock 1/4 turn back the poly lock will get loose. U need to re-set the preload again if u want to go back to 1/2 turn preload. Loose rocker arms cam destroy the motor in short time.

 

After further thought, that's what I'm thinking I'll do, just re-do it so i know its right. Thank you for the info.

 

You can loosen em ¼ turn and re-tighten the Poly-lock. No need to turn em the full ¾ turn back to 0, and then tighten em back ½ turn (or whatever the details may be in any given situation). The nut doesn't care which direction it was turned last or how much.

 

I went back to zero, but I'm a rookie at this. Didn't wanna get confused!!!!

 

I don't know how it'll run, but it looks nice!!!!!

 

1/4 turn FTW

 

You tell that it is normal that pushrod came loose again after adjusting them? I did it this week because of a thickling sound coming out somewhere of the valvetrain. So i put the covers down and adjusted all valves. (searching for zero lash by turning the rods until i felt a slight resistance and then a additional 3/4 turn). I then doublechecked all settings and found some rods loose again. But according to your post this doesn't matter?

Thanks for a short reply

 

That's correct. When you rotate the crankshaft (and the camshaft) over after adjusting the valves, the valve spring pressure will collapse the lifters and the pushrods will be loose. Don't adjust them again. If you do, when you go to start the motor, the oil pressure will pump up the lifters and the valves won't fully close....no compression....no run. Made that mistake before. Took a while to figure out what I did wrong.

 

Old thread, but since it was revived, My valves were adjusted "by the book" wiith a full-turn of preload. Every valve was held open and no compression. Re-adjusted with 3/4-turn. Same problem. Backed them all off 1/4 but haven't tried to start it yet. I don't trust it. My plan is to re-adjust (AGAIN) with 1/4-turn preload. It's been quite frustrating.
Comp cam & lifters...

 

Sounds like most likely, they were well past zero lash before the preload was added. Maybe the "twist the push rod" problem?

Try setting your zero lash setting with the "jiggle the push rod up and down" method instead.

 

Yes, that's exactly what I'm gonna do next...

 

If you can see the top of the lifter where the pushrod rests in the cup, then you can see exactly when the cup breaks free from the snap ring. Right there is ZERO lash.
Then add your desired preload.

 

Yeah, but too late for that now. Intake is on, and I ain't pulling it back off...

 

If the holes between the pushrod slots are
large enough, then you can see the tops of the lifters.
Some heads have small holes - others are larger.
My World Products 305 Torquer heads have huge holes.



So large that I was able to use a magnet to swap out all 16 lifters by using a magnet WITHOUT REMOVING THE INTAKE MANIFOLD. You get them out and in through the distributor hole.
This magnet: https://www.grainger.com/product/5C5...P7A1P:20501231



Back driving the car in 1 hour.

 

Anyone adjust lash on a running motor any more??? I had some cool little clips that would prevent me from getting an oil shower, just ran the engine at low idle, and adjusted the valves while it was running. Worked quite well.

 

It's not gonna run at all if you don't adjust them first...

 

The trick is, to get them 'close', then run it, and do the fine adjustment......

 

Yes I know. The problem. I've been having is getting them close to begin with...

 

Well, as far as that goes, just back em all off one full turn, then adjust em running... back em off some more, one at a time, until they clatter, if you need to; tighten back one at a time until they quit, as fast as you can, all 16; then shut off and add your desired preload to all 16. Efff the extra work of adjusting them sitting still. Pointless other than an educational exercise.

 

Yeah, I know what needs to happen. I'm just surprised at how easily the lifter plungers bottomed out...