Exactly how hard and fast can you add timing on a cammed car?
02-09-2005, 09:24 PM
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Exactly how hard and fast can you add timing on a cammed car? Like the title says, how hard and fast can you bring up the timing on a cammed car? When cruising, can you bring the timing up into the 40s as low as 1000 rpms without blowing anything up? I know some of the truck PCMs are programmed to bring the timing in pretty darn fast.
jes
02-10-2005, 02:24 PM
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You can check out my stock and modded tables up on Horist's site...
At cruise, I think these vehicles are under more of a load than the cars, so they might 'look' like they run more timing, but I don't think they do.
I normally see from 27-32* at light throttle, constant speed, on level ground, under 55mph.
25% throttle at ~1,800 = 26*.
Average timing when on the throttle looks to be around 22-24*.
Timing drops right off when the throttle is let off at low speeds, but will maintain the higher 30's at speed. I have readings of higher 40's at higher RPM / deceleration instances...
At cruise, I think these vehicles are under more of a load than the cars, so they might 'look' like they run more timing, but I don't think they do.
I normally see from 27-32* at light throttle, constant speed, on level ground, under 55mph.
25% throttle at ~1,800 = 26*.
Average timing when on the throttle looks to be around 22-24*.
Timing drops right off when the throttle is let off at low speeds, but will maintain the higher 30's at speed. I have readings of higher 40's at higher RPM / deceleration instances...
02-10-2005, 04:42 PM
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Originally Posted by marc_w
You can check out my stock and modded tables up on Horist's site...
At cruise, I think these vehicles are under more of a load than the cars, so they might 'look' like they run more timing, but I don't think they do.
I normally see from 27-32* at light throttle, constant speed, on level ground, under 55mph.
25% throttle at ~1,800 = 26*.
Average timing when on the throttle looks to be around 22-24*.
Timing drops right off when the throttle is let off at low speeds, but will maintain the higher 30's at speed. I have readings of higher 40's at higher RPM / deceleration instances...
At cruise, I think these vehicles are under more of a load than the cars, so they might 'look' like they run more timing, but I don't think they do.
I normally see from 27-32* at light throttle, constant speed, on level ground, under 55mph.
25% throttle at ~1,800 = 26*.
Average timing when on the throttle looks to be around 22-24*.
Timing drops right off when the throttle is let off at low speeds, but will maintain the higher 30's at speed. I have readings of higher 40's at higher RPM / deceleration instances...
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02-11-2005, 08:06 AM
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Originally Posted by Another_User
I have downloaded and looked at pretty much every tune on horist's website. I think the most interesting one (for this topic) is the 5.3L tunes, particularly the 2005. Look at how fast they bring in 40 degrees of timing, and run up into the 50s at light cruise.
02-11-2005, 08:20 AM
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Nevermind, I just looked now... 
I copied and pasted the 5.3 HO timing table over my stock one, and with a casual one-over, it looks like I've actually got more overall timing than that it does. The thing is, I don't know what g/cyl ranges those trucks operate in...
It appears the 5.3 brings in 50* under deceleration at lower RPM's, but in my accesible places in the timing table, my 6.0 runs at least a few degrees more.
Here's a few 'specs' I quickly grabbed off a log:
Idle - 20g/cyl.
Very light throttle cruise, at ~30mph, 30-38g/cyl.
30% throttle - in the 50g/cyl range.
Deceleration down long grade at 40mph - 14g/cyl.
I copied and pasted the 5.3 HO timing table over my stock one, and with a casual one-over, it looks like I've actually got more overall timing than that it does. The thing is, I don't know what g/cyl ranges those trucks operate in...
It appears the 5.3 brings in 50* under deceleration at lower RPM's, but in my accesible places in the timing table, my 6.0 runs at least a few degrees more.
Here's a few 'specs' I quickly grabbed off a log:
Idle - 20g/cyl.
Very light throttle cruise, at ~30mph, 30-38g/cyl.
30% throttle - in the 50g/cyl range.
Deceleration down long grade at 40mph - 14g/cyl.
02-13-2005, 04:06 PM
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Wow...my car really liked the extra timing in the .24 and below area. I only noticed a hint of bucking, but I didn't get to test as long as I would have liked. It seems like a few more degrees at really low RPM might do the trick. For anyone that isn't following my idea here, I am trying to advance the timing down low to keep the cylinder pressure up in an attempt to eliminate at least most of my take-off bucking issues.
01-05-2006, 12:45 PM
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My cruise portion of the table is really aggressive, I have a 99 5.3L w/01 PCM & OS. On 93 octane the very top portion of the table reaches 60* in a couple points, but most sticks in the mid to high 50's. It helped w/low-end acceleration problems when I installed my LS6 cam. I have some WOT KR but I havent dialed in my VE so thats most likely where that came from (running lean). I command 26* WOT but get 28-29* w/my AFR adder.
Chris
Chris
