Which timing chain?

**VinnieGTP** · 01-14-2008

Originally Posted by SyntheticShield

Okay, Im not feeling any love here guys, you're raining on my parade, LOL

I was planing on getting LS6 springs for my Comp Cams 1.7 Roller Rockers. But now Im reading that if I do that I need a double roller which I am just NOT going to do, staying with a single roller or OEM chain was one of the major deciding factors in staying with the lower ration rockers, that and I want roller rockers for a slightly different reason than most and it also leaves the door open for a mild cam should I ever decide to go that route.

So, that stated, what spring do I need with these 1.7's. I have 117k on the engine, so Im dead set on replacing the springs. Now, do I need new or low mileage stock springs or what aftermarket spring do I need?

I just want to be absolutely sure I dont get valve float now or in the future but I want to stay away from the double roller. If I cant run the 1.7's without going to a double roller chain then I might as well put them, the comp cam push rods and next to new lifters I have up for sale.

You do NOT need a double roller with LS6 springs. 130lb. and above needs it.

**Bio248** · 01-14-2008

if you break or stretch a double roller, then you my friend have a grand prix that is faster than everyone elses car out there.

im pretty sure the zzp ttgt has just a jp double. i have had no problems to date with mine and its been there for a year, and im only running rockers.

**VinnieGTP** · 01-14-2008

Almost EVERYONE who has 1.9 rockers is using LS6 springs and most of them are still running a stock timing chain.

**Toasty** · 01-14-2008

and to throw another monkeywrech into the works... those of you considering the ls6 springs @90lbs, you might consider going to the 105lbs springs. since they arent progressive rate, they're not as hard on the rest of the drivetrain.

**SyntheticShield** · 01-14-2008

So the Comp Cam 105 springs would be better for the rockers Im going to be running than the LS6 ones? Could I still stay with a stock timing chain with those?

**UR LOSN** · 01-15-2008

yes stock chain will work. its just when you get 130# and above you need a double....or have a different cam.....with high lift/duration

**Reptile** · 01-15-2008

Originally Posted by scooz14

with the ls6 springs, i HIGHLY recommend a dual chain.

final seat pressure is somewhere in the neighborhood of 130#, due to the fact that they are a progressive rate spring.

if you want to stick with the stock timing chain, get a whole new set( i have a 2000 mile set if you want it) and stick with some 105#'s

Actually, they're 90lbs closed and 294lbs open to be exact.

**whitcomb** · 01-15-2008

Spring rate determines how much pressure the spring will have when the valve is open. This is very important because the spring pressure when the valve is opening determines the force needed to open the valve. The more force needed, the higher the stress on the timing chain system. In our case, the stock timing chain dampener. This means that the higher the spring pressure during valve opening the more wear on the stock timing dampener.

The LS6 spring increases in pressure faster than the Comp 105 or the Comp 130 (which has the same spring rate as the 105). By the time you get to .300 lift, the yellow LS6 spring has passed the Comp105 in pressure. At valve lifts of .500 (close to what a 1.9 rocker gives) the LS6 spring is up to 275#, while the Comp105 is only 250# and the Comp130 280#.

that is right from ZZPs site and look how comparible the 90#s are to the 130#'s , and someone said you dont need a double roller tillyou run the 130#'s well they are only a 5# difference opened, thats close enough to convince me to run a double roller..

**SyntheticShield** · 01-15-2008

Since Ive had my GP, Ive always read; run this rocker, use this spring and it you run this high of a spring you have to use this timing chain. Obviously this is a product of some testing and first hand experience. However, is there any way to determine what you should run? That is to say, are their formulas, charts, cross references and such that would say you need this amount of spring with this rocker to keep from getting into valve float?

Now I know shift points play into that, but I dont want to put on new OEM springs if they are going to wear out over time and be the reason for valve float down the line and I dont want to run a bigger spring if I dont have to. This is an area of mechanics I dont entirely understand well (if you couldnt tell already) so Im just trying to find out what would be best to do without having to rely on "This is what I ran and everything worked out good" or "This is what I did and I never had any problems". Thats all well and good, but I like data to back things up. If its there, fine, if not then I'll fall back to what has historically worked.

**scooz14** · 01-15-2008

Originally Posted by Reptile

Actually, they're 90lbs closed and 294lbs open to be exact.

actually, you are wrong

open in 90#

they are a progressive rate. i know a lot of people do it.if you really want to stick to a stock timing set recommend,that , to get 105s. i really don't like the single roller , as they require a tensioner. the stock tensioner is not designed for that type of chain, and will wear out very fast.

why would you upgrade to 1.7's. do you have a cam?? if you don't and are intent on going with 1.7's, just get new stock springs. more then enough for .1 change lol

**Reptile** · 01-15-2008

Originally Posted by scooz14

actually, you are wrong

open in 90#

they are a progressive rate. i know a lot of people do it.if you really want to stick to a stock timing set recommend,that , to get 105s. i really don't like the single roller , as they require a tensioner. the stock tensioner is not designed for that type of chain, and will wear out very fast.

why would you upgrade to 1.7's. do you have a cam?? if you don't and are intent on going with 1.7's, just get new stock springs. more then enough for .1 change lol

No....I'm not wrong. It's pulled from GM's Alldata. They measure the spring pressure at the seat pressure when the valve is closed. You're right about the springs being progressive...but do you honestly think that 90lbs of pressure open will snap a valve shut at 6000 rpm?

Every spring manufacturer measures their spring pressures at the specified installed height whatever it will be with the valve closed.

Taken from ZZP for instance:

For the 3800 there are a few choices of valve springs:

Stock –tested at ~70# pounds seat pressure @ install height of 1.72

LS1 –tested at ~70# seat pressure @ install height of 1.80

LS6 blue –tested at ~90# seat pressure @ install height of 1.80

LS6 yellow –tested at ~90# seat pressure @ install height of 1.80

Comp 105 –tested at ~108# seat pressure @ install height of 1.80

Comp 130 –tested at ~135# seat pressure @ install height of 1.80

Comp dual spring-tested at ~135# seat pressure @ install height of 1.80

Comp 150 -tested at 155# seat pressure @ install height of 1.90

They all explain that they are tested at seat pressure, not open.

I"m not trying to bust down on you....but I know what I'm talking about.

**IndeedSS** · 01-16-2008

Yes, there is a timing difference between the L67 and L36, we forget the exact number of degrees. That's why the cam gears differ between the 2 - one has triangle hole and the other has round holes so the assembly line could easily tell them apart. I believe the L67 had the triangles, but it's been a long time since we've looked at one. You can simply compare the stock cam gears and determine the degrees of difference.

We haven't kept up with what's available for the 3800 - what's the rollmaster and jp timing chain sets? Are they stronger or double roller or something?

This is a reply to an email I sent to Thrasher, inquiring about the cam timing differences between the L36 and L67. Remember the guys that started up Thrasher were GM engineers.

**IndeedSS** · 01-21-2008

I called JP in Australia today and spoke with Stan in their machine shop. He told me the JP 5619 single roller and JP5620 double roller was designed for the Holden VR-VT non supercharged engine and not any US engines.
According to him the timing would be off installing it straight up on a s/c V6.
I mentioned what their website showed for a Pontiac and he said they need to change it to say excluding supercharged.

We already know that Rollmaster is the same way.

**Bio248** · 01-21-2008

awww maaaann..so right now im -2* retarded or so? i dont care to take the front cover off, screw it.

**IndeedSS** · 01-21-2008

Originally Posted by Bio248

awww maaaann..so right now im -2* retarded or so? i dont care to take the front cover off, screw it.

-2* will give you better top end. Unless you need more low to mid power, you are better off. Plus travelling on the hiway you should get better mpg at -2*. I on the other hand have the XP and plenty of top end and would like more low to mid range power.

**newfie** · 01-22-2008

I'm looking at getting the Rollmaster Double Chain, I am running the L67 with a Turbo, will this knock me out 2*, or can I adjust it when I tune?

**IndeedSS** · 01-22-2008

Originally Posted by newfie

I'm looking at getting the Rollmaster Double Chain, I am running the L67 with a Turbo, will this knock me out 2*, or can I adjust it when I tune?

At this point in time it appears if you install it straight up you will be retarding the timing by 2*. Yes you can adjust it to +2* at install. However, I'm not sure if this has been done yet. Trannyman is going to give it a go on my car.