tbichips.com (Brian Harris). Useful or Not?

[Steveshow]

If the LT4 Hotcam was not making torque it had a bad tune or was timed wrong. That cam will BOIL tires off even at lower RPMs. In an engine under 10:1 it needs to be advance 3° and installed on a 106° ICL.

I have a Ramjet cam and 1.7 rockers in my Express van and even pulling my 6,000 lbs Jayco travel trailer I find it lacking above 4,000 rpm which I spend ALOT of time at. On steeper hills the 4L80E is in 2nd gear at 70 mph, spinning 4,500 rpm with my foot on the floor.

With my old G-van I had a 10.5:1 Vortec head 383 with TPI using SLP runners that had been siamese ported and tri-y headers. I ran a 232/240 @ .050 cam on a 110° LSA and towed heavy with it. It had a 4L60E and 3.08 gears. Only ran a 2,600 rpm converter in it. 70 in 3rd gear was only about 2,700 rpm.

Im not sure what the compression ratio of the stock vortec was, but the cam was in fact installed straight up. I did consider doing as you mentioned and advancing the cam to increase torque, but when asked,Brian only told me "it should work as is". Of course comp cams is in the business to sell cams, not give advice on how to make an existing cam work, so i guess i shouldnt be surprised that they didnt suggest advancing the existing cam.

btw, i know that a cam can be installed advanced or retarded by moving the timing gears, but how do you "alter" the centerline? This is how the cam is ground...


on a related note i dont think any cam would make a used vortec 350 with tbi in a 4x4 3/4 to. Truck with 265 70r16 all terrain tires "boil the tires"...

[Fast355]

Im not sure what the compression ratio of the stock vortec was, but the cam was in fact installed straight up. I did consider doing as you mentioned and advancing the cam to increase torque, but when asked,Brian only told me "it should work as is". Of course comp cams is in the business to sell cams, not give advice on how to make an existing cam work, so i guess i shouldnt be surprised that they didnt suggest advancing the existing cam.

btw, i know that a cam can be installed advanced or retarded by moving the timing gears, but how do you "alter" the centerline? This is how the cam is ground...


on a related note i dont think any cam would make a used vortec 350 with tbi in a 4x4 3/4 to. Truck with 265 70r16 all terrain tires "boil the tires"...

When you advance or retard the cam you change the intake amd exhaust centerline in relation to the crankshaft. The LSA or LCA is what is ground into the cam and cannot be changed.

My cammed L31 BOILS the 255/70R15s in my heavy Express van despite having a 4L80E with a very tall first gear and 3.73s.


This was the aftermath of a burnout on dry concrete.