Squeezing more from my 4.3 TBI

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12-10-2023
Unc's Van

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Squeezing more from my 4.3 TBI

Newbie posting for the first time. Been lurking for a few months reading and marking threads that seem relevant to my build and informative in general.

Have a 1994 G10 window van with 4.3/4l60e 16197427 PCM with what seems like an odd ball bin file in BDSD. Running $0D XDF in tuner pro. Have been working on tuning it for a while due to modifications like an edelbrock 2111 intake, TBI spacer, TBI "ultimate mods", egr delete, raised fuel pressure to 13psi, 205 degree thermostat (it's pretty chilly here in WA state and this definitely boosts btu output from the heater).

Currently chasing knock counts ( an ongoing task since even before any modifications) and wondering how in the world this bin file ran well compared to others I've seen for SBC TBI motors. It used to knock badly at hwy cruise speeds during low rpm/high kpa. Been working to eliminate that but it's been interesting finding other references from various TBI bins. The BDSD has some interesting characteristics compared to other 4.3, or even 5.7 bins from trucks. Mainly what sticks out is its timing curve. Been chasing knock at high KPA's since it was stock and despite 92 octane and tactical reductions in timing it still occurs on occasion.

Attached the bin file and would love some feedback on it from folks here. Any guidance on tuning it for my application wouldn't hurt my feelings either. haha

Glad to be here and very grateful more knowledgeable folks than I have got together to collect this information for the benefit of others.

~Uncle
12-11-2023
Fast355

Quote:

Originally Posted by Unc's Van

Newbie posting for the first time. Been lurking for a few months reading and marking threads that seem relevant to my build and informative in general.

Have a 1994 G10 window van with 4.3/4l60e 16197427 PCM with what seems like an odd ball bin file in BDSD. Running $0D XDF in tuner pro. Have been working on tuning it for a while due to modifications like an edelbrock 2111 intake, TBI spacer, TBI "ultimate mods", egr delete, raised fuel pressure to 13psi, 205 degree thermostat (it's pretty chilly here in WA state and this definitely boosts btu output from the heater).

Currently chasing knock counts ( an ongoing task since even before any modifications) and wondering how in the world this bin file ran well compared to others I've seen for SBC TBI motors. It used to knock badly at hwy cruise speeds during low rpm/high kpa. Been working to eliminate that but it's been interesting finding other references from various TBI bins. The BDSD has some interesting characteristics compared to other 4.3, or even 5.7 bins from trucks. Mainly what sticks out is its timing curve. Been chasing knock at high KPA's since it was stock and despite 92 octane and tactical reductions in timing it still occurs on occasion.

Attached the bin file and would love some feedback on it from folks here. Any guidance on tuning it for my application wouldn't hurt my feelings either. haha

Glad to be here and very grateful more knowledgeable folks than I have got together to collect this information for the benefit of others.

~Uncle

Likely the reason it is knocking is that an iron head engine needs a 170F thermostat to keep the engine around 176-180F at its hotest.
12-11-2023
Unc's Van

Thanks for the input. I've read many threads on here about your experience with TBI motors. I'd like to get the thermostat swapped asap, but looking at local parts places, the in stock options are 160 or 180 degree. Is it safe to assume thermostat temp would be like a spark plug range, that is, generally the colder the better to prevent detonation?
12-11-2023
Fast355

Quote:

Originally Posted by Unc's Van

Thanks for the input. I've read many threads on here about your experience with TBI motors. I'd like to get the thermostat swapped asap, but looking at local parts places, the in stock options are 160 or 180 degree. Is it safe to assume thermostat temp would be like a spark plug range, that is, generally the colder the better to prevent detonation?

Given those choices I would run a 180F. 195F will also work, 205F is baking those heads and combustion chambers. I tested my heat in my 97 Express on a 20F morning with a 170F and it gets to 150F out of the dash vents. If your heater output is weak, may need to gently reverse flush the heater core to blow out accummulated sediment. I have had several G20 vans as well and the heater will cook you out on a 0F morning. We get some cold weather here in north Texas even. New weatherstripping, glass runs and window felts are inexpensive for the GM G-vans and preventing air leaks into the cabin makes a huge difference. I recently did all of the weathe atripping on the 87 G20 I have. The only weatherstrips that nobody reproduces is oddly the wing vent windows. Since I never used them, I sealed them off with the aluminum tape like you seal duct work off with. I am actually about to do an interior build on that. I will be insulating the front floor past the front drivers seat with an aluminum backed adhesive foam insulation and spray foam insulating the rest of the walls and roof.
12-11-2023
dave w

Gearhead-efi link for $OD Information: http://www.gearhead-efi.com/Fuel-Inj...Information-0D

Sometimes comparing other 4.3 liter .bin files is helpful.