Don Terrill’s Speed-Talk

donforeman wrote: ↑Wed Jun 06, 2018 9:37 pm Thank you for the replies. The truck I was looking at has some overheating issues that were not mentioned in the ad. So I am back to looking at want ads. Yes the van does fine if you slow down, but you cant do that too much or you become a traffic hazard. The 4l60e was rebuilt by me with all the towing upgrades, so who knows how long it will last. Its no 4l80e though. I took down the pan last week and it was spotless inside even after towing pretty often for the last few months.

Someone already mentioned what you need. A cam, springs, converter and trans cooler. Don't be afraid to give the engine rpm on the hills. It's betterb than lugging it in overdrive trying to great a mountain. Simply downshift it and let her sing 4k rpm isn't a big deal.

I never tow in OD with the 4l60e. Like I wrote before 3rd and 2nd are the gears I use when towing. I did purchase a take out 14097395 roller cam (196/206@109) from a marine engine for the van in case the block happens to be roller comparable. If its not then, I will figure something else out and I can get rid of the roller cam easy for what I gave for it.

donforeman wrote: ↑Thu Jun 07, 2018 1:44 am I never tow in OD with the 4l60e. Like I wrote before 3rd and 2nd are the gears I use when towing. I did purchase a take out 14097395 roller cam (196/206@109) from a marine engine for the van in case the block happens to be roller comparable. If its not then, I will figure something else out and I can get rid of the roller cam easy for what I gave for it.

I wasn't trying to say you do. But many guys think they need the power to do so.

You can run that roller cam in a non roller block just do the retainer plate modification if it is a stepped nose cam.
That may be a dandy cam for the purpose.

FWIW the 95 I had was roller compatible but it had a flat tappet hyd. in it. It was a 1500 Sierra.

77cruiser wrote: ↑Thu Jun 07, 2018 10:16 am FWIW the 95 I had was roller compatible but it had a flat tappet hyd. in it. It was a 1500 Sierra.

Thanks for all the help.
TBI Chips lists the 94-95 truck blocks as sometimes only partly machined - missing drilled and tapped holes etc.

However in some 93, all 1994 and 1995 engines GM stopped drilling and tapping the bolt holes in the those provisions in the block

So Its a look and see sort of deal. I really hope mine is OK. If I took the engine completely out for a rebuild, the missing holes would be no problem. That's not the plan though as the lower end is at 108K and has no problems.

donforeman wrote: ↑Thu Jun 07, 2018 1:44 am I never tow in OD with the 4l60e. Like I wrote before 3rd and 2nd are the gears I use when towing. I did purchase a take out 14097395 roller cam (196/206@109) from a marine engine for the van in case the block happens to be roller comparable. If its not then, I will figure something else out and I can get rid of the roller cam easy for what I gave for it.

Try a vacuum gauge to watch how the engine is loaded in each gear. Got one on the dash of my camaro right where most will mount their aftermarket tachs. Now I can see the engine load even on small grades (just compare to idle vacuum) and I know when the engine is lugging. You can also see the condition of your cylinders in real time and you will know right away if you burn a valve. I think everyone every tow vehicle should have one. It's a large 3 inch gauge with color marks for good and bad economy. But now I know when to down shift out of overdrive when I would never know this w/o a vacuum gauge. Don't know where you can find the larger 3" gauges now but the dail marks are what I would shop for. And I verified the calibration was good at work with a calibrator there.

cardo0 wrote: ↑Thu Jun 07, 2018 11:52 am

donforeman wrote: ↑Thu Jun 07, 2018 1:44 am I never tow in OD with the 4l60e. Like I wrote before 3rd and 2nd are the gears I use when towing. I did purchase a take out 14097395 roller cam (196/206@109) from a marine engine for the van in case the block happens to be roller comparable. If its not then, I will figure something else out and I can get rid of the roller cam easy for what I gave for it.

Try a vacuum gauge to watch how the engine is loaded in each gear. Got one on the dash of my camaro right where most will mount their aftermarket tachs. Now I can see the engine load even on small grades (just compare to idle vacuum) and I know when the engine is lugging. You can also see the condition of your cylinders in real time and you will know right away if you burn a valve. I think everyone every tow vehicle should have one. It's a large 3 inch gauge with color marks for good and bad economy. But now I know when to down shift out of overdrive when I would never know this w/o a vacuum gauge. Don't know where you can find the larger 3" gauges now but the dail marks are what I would shop for. And I verified the calibration was good at work with a calibrator there.

the knock sensors can pull a bunch of timing, pulling 20-30hp out if it hasnt been tuned.

MTENGINES wrote: ↑Thu Jun 07, 2018 12:10 pm the knock sensors can pull a bunch of timing, pulling 20-30hp out if it hasnt been tuned.

I do have a 1320 Electronics 12 Pin ALDL OBD1 Bluetooth Scanner. I cant say enough good about that company. They helped me when I had an interference problem with the aldl. I can plug in and view and record data on my android phone. knock counts are low. The stock 1995 spark table is a little better than the early versions. Does anyone have a proven spark table for the 193 heads for truck use? I have a few saved that I have gleaned off the internet, but I may not use them as the stock table looks better. They look way too aggressive for even medium towing. I can adjust the table and recheck on the dyno, but burning chips and retesting is a slow process. If I had a head start, it would be a little less work.

Don, are you burning UV eraseable EPROMs? If so, which one? If it is a 27128 or 27256 there are EEPROMs that will drop right in that let you skip the UV step, at least. The stock ECM in my 86 TR uses a 2732 so I made a little board with a ZIF socket to hold a 27128 EEPROM with a DIP switch to select one of 4 images to map into the 2732 address space. I put a plug on the end of a shielded ribbon cable so I had the board in a box where I could reach it from the driver's seat so I could change images or burn a new chip without pulling the ECM. It's been a long time since I did that so I'm a bit fuzzy on part numbers but I can dig it all out if it would help you.
EDIT - Oops, I used a DS1225 which is a battery backed up SRAM, pin compatible with a 2764 so it held 2 2732 images. The larger chips were available I just wanted a minimalist change.

Thank you. Most of what you said was too advanced for me. I don't do any of that.
The van is a 1995 so it uses the faster 16197427 ECM. I removed the factory prom from a core and use a soldered in chip holder. The chips I use are SST 27SF512 eprom. I use http://www.tunerpro.net/ and the files found there and on gearhead-efi to burn the proms. The burning of the proms is pretty easy inside the software, its just harder and more time consuming than working with a system like Holley efi.

Just a side note. Billy Graves was a transmission software employee for GM in the 90s and he checked some of the trans files for me. He said because the way the program works, reverse engineered, not from the factory code. There are a lot of faults in the way tunerpro changes the binary code for the transmission. It can cause the trans pressures to not do what you tell it to in the software. So I left the trans pressure tables untouched, altering only the speed vs tps tables that he said were probably safe to alter.

What software allows an end user to change major fuel and spark tbi parameters? And then write the changes to the chip?

The same software tunerpro. I just mentioned the trans problem for info as it can cause failure and most people cant double check the results.

I've known John Howie at TunerCat ( http://www.tunercat.com/ ) for many years so I've never tried tunerpro. I use an emulator so I can program in real time, then when finished, save the file and burn the chip. You definately want to be careful with the trans parameters, can be easy to fubar the up/down shift tables and TCC lock/unlock and kill a trans in short order if you aren't careful while learning.

I was doing this before software and cheap emulators(Early 90's). All adjustments were made in hexadecimal, then correct the checksum and burn. It was a HUGE learning curve and VERY time consuming

I applaud your effort, it's very rewarding doing it yourself, lot's of reading.

94-95 350 4L60E
4168-4288 = Main Spark Table, Open Throttle
428C-43AC = Main Spark Table, Closed Throttle