Which timing chain?

**whitcomb** · 01-13-2008

so i have LS6 springs springs wich are 90# springs and a equal lift/duration cam.. .507 lift / 234 duration , do you think i will be ok with a new stock chain and tensioner or should i go to a double roller... im really leaning towards the stock setup as many have been fine with it with the VS and S1X cam so i should be fine...just wanted to get atleast a hanfull of opinons before i buy... thanx in advance............

**UR LOSN** · 01-13-2008

you wont need a double unless you go with 130# springs or above.

for your setup the stocker will work. but...the double is added protection....

**J_Ferguson** · 01-13-2008

I read some were when installing the double chain,
you must also do some work on the inside cover
were the chain will rub .....
I'm sure someone that has done this will jump in to
explain this better..

John

**UR LOSN** · 01-13-2008

you have 2 options when it comes to it. I chose the second.....

1. add 2 gaskets to the front cover..this will space it away from the oil pump plate.

2. machine the oil pump plate and bolts down .002 to avoid contact with the chain.

I was lucky enough to buy a machined plate from FlynGTP in chicago. he has a machine shop shave them down for him....

**Bio248** · 01-13-2008

Originally Posted by UR LOSN

machine the oil pump plate and bolts down .020 to avoid contact with the chain.

its gotta be machined down 20 thousandths.

the jp is a better chain compared to the rollmaster, a few less have broken or caused problems. i would just get the double roller to begin with since you will never have to crack open the front cover again for the pure fact that the tensioner is gone.

**SyntheticShield** · 01-13-2008

There also was a huge discussion on the other site about some issues with the double roller as well. I believe Rollmaster has a single chain replacement that might be a bit better than the OEM one, Im not sure.

**whitcomb** · 01-13-2008

yea i read something bout the double streching??thats why i wanting to double check on runing just a new stock one..im know ill be fine i just wanted to get a hand full more opinions on it...thanx for the input so far...i know 90# wont be bad on the chain ive seen some guys run 105# on the stock so yea..

**IndeedSS** · 01-13-2008

I chose the JP single roller, but if I had to do over I would have gone stock. Most of this is because of more recent discussions about the Rollmaster and JP wearing ridges in the tensioner versus the stock chain. The other thing brought to light in a thread here, is that the Rollmaster with the timing on 0 will retard the cam timing on an L67 as it was designed for and L36. It appears the JP is the same. I guess knowing this you could advance them 2* to compensate...fwiw this is from others who know what they're talking about, and not me.

**UR LOSN** · 01-13-2008

sorry, I typed it too fast. you are rigth with the correction.

**scooz14** · 01-14-2008

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

**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.

**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.

**newfie** · 01-14-2008

I'm getting a double set-up also...just want something in there that will last longer than stock, and keep it's strength. I havn't heard anything about the double roller stretching?

**Bio248** · 01-14-2008

a couple people have broken doubles with a lot of horsepower or it rubbing on the oil pump cover. stretching doesnt seem to be a problem that often either.

**newfie** · 01-14-2008

Originally Posted by Bio248

a couple people have broken doubles with a lot of horsepower or it rubbing on the oil pump cover. stretching doesnt seem to be a problem that often either.

So will I have a problem when I do the upgraded cam and springs?