trex-carb-single plane- timing?
Thread Starter
Launching!
Joined: Jan 2010
Posts: 201
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From: NJ
trex-carb-single plane- timing? I am running a 2002 carbureted ls1 with a trex cam, roller rocker arms, long tube headers, 3200 stall, th-400 trans, with a victor jr manifold with the msd box. It is running pretty good but I was wondering if anyone out there has a similar set up or would have an idea where my timing table should be. Right now I have 24* degrees inital timing at 1000rpm then climbing up to 36* with it dropping down in the torque curve at 26* and then back up to 36* It seems to be running pretty well but it is the only curve I have tried so far. I guess my question is this curve look good or should I make changes? I was wondering if 36 degree is too much timing for an ls motor or not?
36 is SBC timing and can be a little much for an LS1 motor, but it can depend on your timing trigger.
If you are using the stock-ish timing arrangement (reluctor wheel to crank sensor to PCM) then I would try and keep it at 32 max. Through peak torque you should only have to reduce a couple degrees.
I would have peak timing (~32) in by 3k and see if you can hold that all the way out till the end.
The car will let you know if you need to reduce through peak torque or not. It will ping. Then drop a couple degrees in that RPM range.
If you are not using the stock timing arrangement, then I would get it to a dyno and hit it with a timing light because your timing is going to vary depending on how good your trigger is.
If you are using the stock-ish timing arrangement (reluctor wheel to crank sensor to PCM) then I would try and keep it at 32 max. Through peak torque you should only have to reduce a couple degrees.
I would have peak timing (~32) in by 3k and see if you can hold that all the way out till the end.
The car will let you know if you need to reduce through peak torque or not. It will ping. Then drop a couple degrees in that RPM range.
If you are not using the stock timing arrangement, then I would get it to a dyno and hit it with a timing light because your timing is going to vary depending on how good your trigger is.
Thread Starter
Launching!
Joined: Jan 2010
Posts: 201
Likes: 0
From: NJ
Thanks for your reply. I am not using the stock PCM my car is carbureted and I am using the msd ignition for ls1. I lowered my peak timing from 36* to 32* and I noticed the car pulls harder down low but I feel like it revs slower and from rolling start is slightly slower. I def need to get on a dyno and find out what the sweet spot is. but until I get there I may try bumping up to 34* that way it will be in the middle of my old and new setup.
This is my timing curve now let me know what you think: initial @1000 rpm 18* ramping up to 32* at 2000 rpm dropping down to 30* at 5500 rpm and riding out at 30* until 7000 rpm.
I was thinking about going back up to 32* at 6000-7000 rpm what you think?
I saw in your post you told me to be at 32* by 3000 rpm do you think that will change anything from me having it all in by 2000 rpm?
Thanks for your help sorry for all the questions.
This is my timing curve now let me know what you think: initial @1000 rpm 18* ramping up to 32* at 2000 rpm dropping down to 30* at 5500 rpm and riding out at 30* until 7000 rpm.
I was thinking about going back up to 32* at 6000-7000 rpm what you think?
I saw in your post you told me to be at 32* by 3000 rpm do you think that will change anything from me having it all in by 2000 rpm?
Thanks for your help sorry for all the questions.
TECH Apprentice
Joined: Jan 2008
Posts: 366
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From: Gladstone, Queensland, Australia
No, the cam in yours is not big enough to run that much lead down low. I think it would ping, but atleast try it, until you have around 250 degs of duration, then you can consider locked timing figures.
