Interesting cam question
06-22-2020, 08:02 PM
#31
@00pooterSS
After driving it and massaging the spark table as much as I can, I think the cam is to big for the converter.
It almost bogs a little off the line but once above 2k it pulls good.
The new converter is really tight. I’m having to lean on the brakes a little more now at a red light.
Gears or cam swap? The current cam is an off the shelf Comp, 222/224 @ 112+2.
I have the gears and cam but don’t know which would be better.
thoughts?
After driving it and massaging the spark table as much as I can, I think the cam is to big for the converter.
It almost bogs a little off the line but once above 2k it pulls good.
The new converter is really tight. I’m having to lean on the brakes a little more now at a red light.
Gears or cam swap? The current cam is an off the shelf Comp, 222/224 @ 112+2.
I have the gears and cam but don’t know which would be better.
thoughts?
The reason I suggested the gears first (besides the fact that it would really help with off the line more that the cam itself), is the combination of a smaller cam with 12.5:1, and tall overall ratio could be a little much for pump gas. Having the gears means the engine doesn't have to work quite as hard to move the heavy truck. So if you did that first, and still it's not enough, it'll help stave off detonation if/when you go to an earlier ICV. Plus you might find the gears is more than enough to not bother changing cams.
The 3.90s today with 34" tires are like running 3.55 with the stock 31" tires. Couple that with the shallow 2.48 of the 4L80E, you don't have much 1st gear ratio to get the truck moving. Your 1st gear/rear combo with the taller tires is effectively 8:8:1. Something closer to 10:1 would be a big improvement.
Last edited by 68Formula; 06-22-2020 at 08:19 PM.
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00pooterSS (06-23-2020)
06-24-2020, 11:32 AM
#32
What is the new cam?
The reason I suggested the gears first (besides the fact that it would really help with off the line more that the cam itself), is the combination of a smaller cam with 12.5:1, and tall overall ratio could be a little much for pump gas. Having the gears means the engine doesn't have to work quite as hard to move the heavy truck. So if you did that first, and still it's not enough, it'll help stave off detonation if/when you go to an earlier ICV. Plus you might find the gears is more than enough to not bother changing cams.
The 3.90s today with 34" tires are like running 3.55 with the stock 31" tires. Couple that with the shallow 2.48 of the 4L80E, you don't have much 1st gear ratio to get the truck moving. Your 1st gear/rear combo with the taller tires is effectively 8:8:1. Something closer to 10:1 would be a big improvement.
The reason I suggested the gears first (besides the fact that it would really help with off the line more that the cam itself), is the combination of a smaller cam with 12.5:1, and tall overall ratio could be a little much for pump gas. Having the gears means the engine doesn't have to work quite as hard to move the heavy truck. So if you did that first, and still it's not enough, it'll help stave off detonation if/when you go to an earlier ICV. Plus you might find the gears is more than enough to not bother changing cams.
The 3.90s today with 34" tires are like running 3.55 with the stock 31" tires. Couple that with the shallow 2.48 of the 4L80E, you don't have much 1st gear ratio to get the truck moving. Your 1st gear/rear combo with the taller tires is effectively 8:8:1. Something closer to 10:1 would be a big improvement.
It pulled those grades way better than I thought. I was locked in 2nd gear at 50mph the whole time and didn’t have any issues.
Trans temp was under 200 and the engine temp got up to about 190.
The new cam I have is a 212/218 @111.
I think I’ll do the gears.
I do need a tow rig but I’m presently happy with how the truck is doing.
I kept it at 50mph because I have the fans set to turn off at 55. I used 50mph to keep the fans on to help keep temps in check.
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