Don Terrill’s Speed-Talk

donforeman wrote: ↑Thu Feb 13, 2020 10:25 am Yes I have a close friend with two of the Jet DST. They are finicky. Lots of horror stories of bricked pcms and Jet is very limited on support. Even when they are free licenses, the DST not worth it to me to mess with it. Hp Tuners I am much more comfortable with.

Why not do the plenty tried and true 0411 pcm swap on your 1996 7.4? Find a 2001-2002 pcm and use a 2002 express van calibration. The 2002 express van was still using the 5.7 vortec engine, and it also used the 0411 pcm. Then you can tune with efilive, hptuners etc. Way more support and table to modify than jet dst. It is also a newer pcm than the vortec pcm, more memory faster process speeds etc.
Do a search on 411 pcm swap you can read for days on it. You repin your harness to the 411 pcm. Very straightforward. Takes about 4 hours. I have done a few. You will need the pcm swap file which tells you what wires go where in the 411 pcm. You need to contact lextech as he is the keeper of the files still.

Thanks, I do have the pinouts for a few years of GMT400 to LS PCM. I am just not that motivated. Its a stock engine that runs just fine with the stock tune. The only thing I really wanted the tune access so far was to lock it in 3rd gear for the chassis dyno pulls as a base line. The kickdown really messes up the pull. Even then it was just messing around, not a big deal either way. If I changed some stuff from oem then the tune would be a bigger priority.

I figured out why the 8.1 felt so similar to the 7.4 when towing a trailer, power wise. The 8.1 has 3.73 and the 7.4 has 4.10. They are rated to pull the exact same weight trailer from the factory even. The 8.1 felt slightly better. I asked the seller before purchase and just assumed it was the 4.10 with the 8.1. The build code says different.

My opinion, give it 7 or 8 lbs of boost and be done.

Being that this thread is still coming up I have a quick question. What is the max lift you can get with the factory lifter system (assuming 1.7 rocker ratio)? Looking to use a gen 6 block for a truck build and would like to use the factory lifter/dog one setup. I looked around and was not able to find a clear answer.

Paul

FC-Pilot wrote: ↑Sun Feb 16, 2020 2:08 am Being that this thread is still coming up I have a quick question. What is the max lift you can get with the factory lifter system (assuming 1.7 rocker ratio)? Looking to use a gen 6 block for a truck build and would like to use the factory lifter/dog one setup. I looked around and was not able to find a clear answer.

Paul

Never mind, I found it. I googled crap for hours and in five minutes using the search of speedtalk I find the answer. Kinda feel like a doof.
https://www.speed-talk.com/forum/viewtopic.php?t=46943

Carry on.

Paul

If you are using the factory heads remember from the factory they are non adjustable rockers. Not sure of how much lift you can run with that?

econo racer wrote: ↑Sun Feb 16, 2020 6:35 am If you are using the factory heads remember from the factory they are non adjustable rockers. Not sure of how much lift you can run with that?

If I do go this route, I doubt I would be using the gen 6 heads. Looking to go aftermarket or maybe a set of 049 heads I was thinking about porting. Just looking at options for a basic truck engine to go in a 72 Chevy 4x4. I have converted the non adjustable rockers to standard big block stuff on previous builds. I have just never personally used the factory roller lifters. Being they were designed for long term use, and being my intended application would have a relatively modest rpm range it looks like a reasonable route. I have to build this thing for my sister and brother-in-law so it has to be idiot proof.

Paul

I currently have a 8.1 with 4:11 gearing. Thier is no comparison stock for stock.
On the 7.4, large oval intake, large oval heads with intake valve up sized and stock size stainless exhaust valve and cam specs most wouldnt believe. They never idled smooth but pulled like a freight train.