91 350 Rebuild

I would suggest starting with

"KV" wrote: > Does anyone know of a trailer-towing (torque) cam that is ok > to use in this > engine and still be compatible with the original ECM? > It is a two bolt-main block and is being bored .040 over, and > is out of my > 91 GMC C1500. I tow a 30' Jayco 4 or 5 times a year. > Thanks in advance. > Kevin

Personally I would focus less on a cam and more on gear ratio as that is what makes or breaks a tow vehical. If you are running stock tires, you want 4.10 gears for that sized trailer and if you are running over stock tires size, try a 4.56 and you will not be disapionted in the towing improvements. ONe more comment if I may, the factory 10 bolt is not the strong of a rear axle and would no be my first choice for towing that much weight a lot wear wise. If you plan to keep the vehical for a while you should consider finding a 9.5 inch 14 bolt semi floting rear axle that they used in LD 3/4 ton trucks of that body style. Same hub lug pattern and a much stronger axle that will handle that towing with little effort. I have a 2005 Z71 loner will my truck is in for ABS warranty work. It has a 310hp 5.3 with 3.42 gears and the sticker even say HD towing package too. It is a DOG in OD and not to much better in 3rd at speed. I can only imagine how bad it would suck towing with those gears too.

Thanks guys I will check out the Crane website. I thought, since the engine was apart anyway, I would try to find out if there was a cam out there that might help a little. As for the rear-end ratio, prior to the engine and tranny trouble I have had recently, I had noticed a driveline howl that I suspected may be coming from the rear end. When I look into that I will definitely consider switching ratios. Any idea if the speedo can be corrected after this is done? Thanks again Kevin

Not sure if the 91 is the same as a 92, but the shop that did the tranny on my 92 burb said they couldn't be calibrated easily, if at all. Somthing about them being electric. I could be off in this, but figured it might give you a starting point.

Good luck...

Brian If your 92 Burb has the 700R4 (non-electronic), you and I have the same tranny. If that's the case then reprogramming mine ( or whatever is req'd) isn't likely to be easy. Thanks for the info Kevin

Why reprogram it? I have a 89 burb with a 700R4 and 172K on it to and it still works great and I would not change a thing about mine and I which my 2000 4L80E in a my K3500 shifted as predictably and reliably as my old 700R4.

Sno What I meant was somehow reprogramming the ecm to correct for the speedo error after changing the rear-end ratio. Have a look back at some of the previous posts in this thread for clarification. I agree with you...the 700R4 was very predictable etc. right up until the day it spun. Now for some upgrades - Corvette spool, shift kit and a couple other goodies. Kevin