4.3L to ?? swap.

89 4.3L NON-Vortec TBI 5-speed, RCSB. I'll get right to it. I don't think there's much life left in that NON-Vortec 4.3l.

Before anyone suggests it, there will be no LS swaps in this vehicles future, just because of the OBD-I to OBD-II wiring issues.

That said, there are plenty of Vortec 4.3L to V8 whatever swaps out there, and information for such... but not so much for the pre-Vortec V6's.

Ideas?

5.7 TBI is the natural choice. Should be pretty easy (even easier than Vortec V6 to V8 swap due to less electronics.) I'm not too familiar with TBIs, but can you get a chip burned for your computer? Several folks here are very knowledgeable on TBIs, hopefully they can offer good advice on the electronics.

The 5.7 will bolt directly to 700R4 (or TH400 in case yours came with that.)

What's wrong with your engine?

I have a 5-speed manual, not a slushbox th400. Thanks for the info, though.

What's wrong with my engine? Let's see.... it failed a compression test (low compression on cylinder 1), has a miss, yet passes a cylinder balance test, and spews oil all over the passenger side of the engine, under throttle. Besides that, I have no desire to go digging into it and possibly never finding the problem(s).

#fedupwiththis.

EDIT: I should also mention that I do have a lead foot, lol. I guess I'm just not getting the power I want out of a V6 with only an RCSB. Who the Hell knows anymore.

@PlayingWithTBI was commenting yesterday regarding some other member's TBI 5.7L (thread is linked below), he seems to have been down the road a time or two with regard to those engines. Perhaps he'll comment...

Upgrading to the slightly newer computer would be a benefit (GM p/n 16197427 ECU, used at least in the 1994-1995 TBI engines) on account of its enhanced data logging capability and tunability, but I don't know if that upgrade is Really Easy or not.

I upgraded a 1995 4.3L to a 5.7L and it was quite simple, just a mod to the knock sensor wiring, a different, GM-issue MEMCAL in the ECU (16197427 ECU was OE on that 4.3L, so that was nice), a different TBI / injector set from a donor engine... oh, and the 5.7L engine, air filter, and other hard parts.

Funny you should mention the air filter. I happened to have picked up the 5.7L air cleaner assembly from a junkyard truck. It does NOT fit the 4.3L. It will drop onto the TBI, however, it won't clear the upper radiator hose. To fit properly, it would require a totally different radiator hose - and one that would mate to a much narrower radiator.

I know this because I pulled the radiator hose from the same truck in the yard. I'm 99% sure that the yard truck is electric cooling fan, not a clutch fan. Hmmmm.

Big block.

If we're talking stock, 5.7 TBI over the 7.4 TBI. I had a 454 in my old '88 mated to an SM465. It had enough torque to start in direct, but I'd say the 350 in my '89 matches it acceleration wise, while netting me more than double the fuel economy. If OP puts a big block in that truck, he'll also have to upgrade the trans, whether he plans on it or not haha.

0xDEADBEEF said:

Big block.

Click to expand...

454ci? Yeah.... find one compatible with OBDI.

1998_K1500_Sub said:

Upgrading to the slightly newer computer would be a benefit (GM p/n 16197427 ECU, used at least in the 1994-1995 TBI engines) on account of its enhanced data logging capability and tunability

Click to expand...

Yep, the '7427 runs 8192 baud where the '7747 is 160. The '7427 has expanded VE and SA tables too. There are wiring changes/re-pinning but there's so much info on a 7747 to 7427 swap around, it s/b a no-brainer. You still have to find a way to flash or burn your calibrations on it though.

Another route to go, is the EBL Flash-II, it's just as fast as the 7427, has expanded tables, automatic VE learn, WBO2 tuning capability, and 8 flash banks for easy tuning. Even comes with its own USB cable. It comes with all kinds of documentation and support. You data log with its own What's Up Display (and a laptop), tune the .bin with TunerPro RT, then flash your new .bin with WUD in about 4 seconds, drive around some more, rinse and repeat He uses your old ECM and modifies it with his proprietary daughter board, IIRC you only have to re-pin one wire, otherwise it's plug and play (except for the WBO2)

DeCaff2007 said:

454ci? Yeah.... find one compatible with OBDI.

Click to expand...

They exist