Qiken

Ok ready to install the comp 1.5 roller tips after cam install and lt4 springs
zz4 cam.
1. How much of a turn do you tighten after resistance felt on pushrod.

2. how often is shimming normally required on valve springs,seem pretty even to me?

2. the brown and white connectors for the dissy,which colour installed closest to the firewall(brown one?)..its on an 89.

oldalaskaman

#1 . with engine not running , till theres no movement, and then down one more turn. with engine running, 1/2 to 3/4 after noise stops. #2. probably should measure a little more precise then ,'seems pretty close'.#3 . closest to the firewall is usually the power wire, turn your ign. key on and check for voltage, its usually the thicker of the two, on mine its black. You'll have others stepping in shortly with other more scientific ways to do it

oldalaskaman

he's disconnected his dist. and the front two wires will fit either place

engle1147

The "brown" wire used to be "red" (12 volt source for the coil) it more than likely has discolored with age/heat...or you've grabbed it with dirty fingers too many times. The connectors should only plug in the correct spots if the plastic connectors/cap are still in good shape. To answer your question the "brown" wire is closest to the firewall and the "white" (tach wire) will be further.

JrRifleCoach

After installing a CompCams 262 and their springs, lifters, 1:6 roller tips, we used 1/2 turn past "contact/zero". Sounds like it should be checked again after 5K miles. I'll be interested to find out if they need adjusting again.

Qiken

Yes that's what I thought,just wanted to confirm,this will have the brown wire connector hooking up to the red wire from the coil.

oldalaskaman

do yourself a favor and turn the ign sw.on and check that wire for voltage

coupeguy2001

#3..... white wire is tach and pink/red is ignition battery.
Distributor is marked tach and B+ where they plug in. Use a light and read it on the connector cover.

JAKE

Remember, it's SLIGHT resistance; don't forget the SLIGHT part - which many do. If you go beyond SLIGHT, you will be beyond Zero Lash and will actually be adding preload.

SLIGHT is hard to define - what's SLIGHT to one isn't to another - so many are now using the 'up and down' method instead of the 'twist the pushrod until slight resistance is felt" method.

"How much of a turn do you tighten . . . " After a lot of reading on this, I've concluded it depends on the lifter. Different make lifters call for different amounts of preload in order to correctly position the plunger in the lifter body.

Some, like some of CompCams lifters, only call for .020"/.040" of preload which translates into 1/2 turn or so. Others call for as much as .070" which calls for twice as much. Although they may look the same, lifters do vary. Plunger mechanism, pushrod cup height, oil hole position, etc.

After so many back and forths on this over the years I now recommend following what the lifter manufacturer recommends.

Jake

mseven

I agree with the above, and also it depends on the total amount of plunger travel for a particular lifter (specs from the mfg. are usually available).
The .040 shown by comp. translates to approx. 3/4 turn. When given a real measurement the amount of pre-load can be determined by the threads per inch (on the stud)....or you can always put a dial indicator on it.

JAKE

Shbox.com's site has the numbers. Depending on the number of threads per inch on the studs, using the info he posted you can calculate how many turns (partial turns) will result in how much preload in inches.

My 96 GM FSM recommends one full turn, plus or minus one-quarter turn. That tanslates into anything between one and one quarter turns from Zero Lash on the high end to three-quarters turn on the low end. Anything within that range is in factory spec. What's important is for Zero Lash to actually be Zero Lash; correctly found.

Shimming the springs to recover lost pressure isn't something that's usually done on street driven engines. Some may but I believe most don't. How often depends on how hard the springs have been worked; whether the valve train has been subjected to valve float, etc.

You'd need a spring pressure tester, made by different companies, and an assortment of different thickness shims. You'd also have to be careful of coil bind too if you add thicker shims.

Adding thicker or add'l shims eats up what precious little coil spring clearance there is. Installing new springs may be the only option if the pressure falls off beyond a certain point. Don't skip the correct spring break-in procedure which extends their life-span.

Jake

mseven

I never needed a 'site', the math is easy...guess I was not clear. ARP along wth other mfg.s list the stud dimensions (including thread pitch etc.) along with being .005 concentric thread pitch to thread pitch.
Once zero is truly established, and depending on the stud used,
a 3/8 fine thread is 24 threads per inch, which equals 0.042 inch per 360 deg turn of the poly lock, a half turn would then equal .021
7/16 fine thread is 20 threads per inch, which equals 0.050 inch per 360 deg turn of the poly lock, a half turn would then equal .025

Comp recommends 1/2 turn (.030" ?) preload without stipulating stud size. Is there a geometry issue that increases the pre-load at the plunger of the lifter ?
.021 x 1.5 (using 3/8 x 24 as an example and a half turn times rocker ratio) equals .0315". Fairly close to .030". Take .030" and divide it by the .021 and you get 1.428571... that would be real close to the ratio of stock stamped steel rockers.
Again, if there is any doubt when using a real measurement setting pre-load it can be double checked using a dial indicator.

This has been discussed before and currently on another thread. What I do not understand is why anyone would set the pre-load any differently than what the mfg. suggests. I've read the claims and reasons for different amounts of pre-load, yet I've never had an issue at higher rpm when using the mfg.s recommendations.

I'm not sure why you went on to discuss shimming the spring..I don't recall recovering spring pressure being asked.

JAKE

Sure glad to know you've got a handle on crunching the numbers though. Now I/we know who to track down when it's number crunching time.

OP, did you get all that? mseven's your guy when you want to play the numbers game! LOL

Question #2 started it for me -(well since he has two posted as #2 you'll need to read both of them) - and sent me down that "shimmng" path.

Jake