Starting to Learn on 95 G30 5.7 for Towing

**Fast355** · 06-17-2018

This is the timing map I had in my 7730 TPI ECM that was running a stock TPI intake on a 1-ton 8.8:1 350 TBI engine with a LT1 F-car cam in my 1983 G20 van. PE spark is high at the top rpm because the TPI runners and swirl port heads are choking off the airflow by that RPM. More timing kept the power from falling off quite as noticeably. It had good power to ~5,200 rpm.

**donf** · 06-17-2018

Originally Posted by Fast355

This is the timing map I had in my 7730 TPI ECM that was running a stock TPI intake on a 1-ton 8.8:1 350 TBI engine with a LT1 F-car cam in my 1983 G20 van. PE spark is high at the top rpm because the TPI runners and swirl port heads are choking off the airflow by that RPM. More timing kept the power from falling off quite as noticeably. It had good power to ~5,200 rpm.

Thanks for the ignition map! That is helpful. I will mess around this summer, but I am not going to do the cam swap, bowl blend until late September. I keep having to tow the dyno places when the weather is good. I did look at the dyno runs on the van and there were some leaner areas at low rpm with the stock fuel map, not crazy though, if anything its too rich in the higher rpm ranges but I only run it to 4000.

**donf** · 08-05-2018

A picture I took yesterday. The van has been towing fine all summer. One thing I never thought about when I rebuilt the 4l60e is the 3rd to 2nd gear spacing. Its not that great for towing. If I had to do it over agian I would have found a core 95 4l80e to make 2nd a little more usable. The 4l60e trans durability wise is fine so far.

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**donf** · 10-11-2018

I have some questions about the program that some say they use to generate shift points, Blue Cat trans table generator. The information it exports seems to be made for another tuning program (HP Tuners) leaving a lot of tables to the imagination. The lockup tables seem abbreviated, it generates something called shift slope, and the Vss ratio is in a very different format than TunerPro $0D. I ended up not using it at all but I am still curious just to learn what all the fuss was about when using it for TunerPro.

**donf** · 10-26-2018

I tore the intake/timing cover off last night. The block is fully roller compatible. So the my 14097395 cam will work. I have also been able to pick up a GMPP vortec intake and an Edelbrock 3704 for less than the cost of a cheap tbi plate. I am waiting to have my heads checked for cracks to see what manifold I use. Torque from 2000 to 4500 is what I am looking to improve. I really do not care about anything above that for this application.

**Fast355** · 10-26-2018

Originally Posted by donf

I tore the intake/timing cover off last night. The block is fully roller compatible. So the my 14097395 cam will work. I have also been able to pick up a GMPP vortec intake and an Edelbrock 3704 for less than the cost of a cheap tbi plate. I am waiting to have my heads checked for cracks to see what manifold I use. Torque from 2000 to 4500 is what I am looking to improve. I really do not care about anything above that for this application.

Under 4,500 rpm, I would stick with the swirl ports. If you wanted to make power to about 5,000-5,200 run the Vortecs.
Get some GM 0.028" compressed head gaskets rather than the Felpro .038 or 0.43 that are typical of the rebuilder gasket sets.
I am guessing your engine has the dished pistons with long bath tub shaped valve pockets that are 18cc total dish.
If you mill about .010 or .020" off the heads and run the .028" composite gasket with the 18cc dished pistons you should be able to get close to 9:1.
With the Ramjet cam that should work very well on 87 octane in the lower rpm ranges.
Also no matter what else you do, the old GM pellet box cat needs to hit the scrap bin.
Replace it with a modern cat that actually flows decently, the one on my 305 was not clogged and swapping the smog exhaust for anOEM 80s 1-ton van dual exhaust without cats with the OEM tubular manifolds was like unhooking a trailer from behind the van.

**donf** · 10-27-2018

Thanks for the heads up. The converter has been changed to a recent 3" but it has a few goobers stuck to the bed. It may get left off for now, to be replaced in the future. No bathtub pistons, the standard ones that all light duty vans have. No ridge and very little carbon build up. My van is 800 lbs short of the heavy duty GVW. I found it has a replacement passenger side exhaust manifold made in China. The front port has the entire top half blocked off with some excess iron.