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02-27-2006, 03:22 PM
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#1 |
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Senior Member
Join Date: Aug 2004
Location: Everett, WA
Posts: 2,316
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4.3 TBI to 305 TBI ?
I browsed the engine and drivetrain and didn't find much info so I'll try here.
Looking at an '87 2wd with a 4.3 and manual transmission. The V6 runs pretty shabby but I have an '87 with 305 that runs good. My question(s) is what will I need to bring over from the V8 truck? I know motor mounts, exhaust, etc, but my big question is about the computer and related items. Will the ECM (or whatever it is called) from the V8 truck plug into the harness on the V6 truck or do I need to switch the harness too? Are the fuel pumps (dual tanks) on the V6 truck the same as the V8 truck or do I need to switch those? Any thing else I should consider? Secondly, my 305 is backed by a 700r4. Will this engine mate to the manual or is there some pilot bushing problems or ?? I've went from manual to auto before with no problem but the only time I've went auto to manual was putting a factory dual quad 425 from a '65 Riviera GS into my '65 Skylark GS with a manual and we had to come up with a custom made bushing.
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2009 Honda Fit CfC (bsf 44.9 mpg) 2000 Tahoe Limited 1991 GMC CrewCab Dually 2wd, will end up swb, not dually and replace CCswb below 1991 GMC CrewCab Dually 4x4, just going to fix things up for now 1982/1989 K5/GMC Jimmy 2wd 1987 GMC 1/2 ton swb 2wd Crew (sold) |
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02-27-2006, 08:04 PM
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#2 |
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Registered User
Join Date: Dec 2004
Location: New Lenox, IL
Posts: 442
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Re: 4.3 TBI to 305 TBI ?
I believe the computer should be the same, but you will need a chip for the 305 motor.
The motor is the same bolt pattern, but you may have an issue with the pilot bushing in the crank. I heard the crank from an auto won't have the provision for the bushing. motor mounts should either be the same, or an easy swap. A 4.3 is kind of like a small block missing the front two cylinders. Might be the only 6 cyl or one of the few with the same bolt pattern as a small block. The fuel system should work as far as the tanks, pumps, and i think the Injectors themselves. I had an 87 Monte Carlo that was originally a 4.3 tbi (only motor with fuel injection in a Monte back then) It had a 305 dropped in its place and used the same ECM and wiring for the most part. It was cool because not many others had a fuel injected v8 in one of those, and it fast passed emissions while still testing as a 6 cyl. I did have an issue with overheating occasionally on a hot day with the a/c on in stop and go traffic. It was the 4.3's radiator with an electric fan. So it may be worth swapping that Good luck. Should be a nice swap. -Jeremy
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79 Jimmy slammed AKA James Down |
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03-03-2006, 06:56 PM
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#3 | |
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Senior Member
Join Date: Aug 2004
Location: Everett, WA
Posts: 2,316
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Re: 4.3 TBI to 305 TBI ?
Quote:
I bought the truck and took it to a local shop and they said without digging too deep into it, the engine is dead - flat cam or other major problems. I have a complete '87 lwb with a good running 305 TBI that I would like to bolt onto the manual tranny. If not I'll put engine and tranny in (700r4). Bought for $700 out the door, they were asking $1500. Looks like ex-forest service truck. Straight, clean, spartan. The interior is decent, but tan. I have complete except door panels Silverado dark grey interior.
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2009 Honda Fit CfC (bsf 44.9 mpg) 2000 Tahoe Limited 1991 GMC CrewCab Dually 2wd, will end up swb, not dually and replace CCswb below 1991 GMC CrewCab Dually 4x4, just going to fix things up for now 1982/1989 K5/GMC Jimmy 2wd 1987 GMC 1/2 ton swb 2wd Crew (sold) Last edited by kevinr1970; 10-04-2007 at 11:39 PM. |
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02-27-2006, 10:41 PM
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#4 |
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Professional Grade
Join Date: May 2003
Location: Fort McMurray, Alberta
Posts: 7,915
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Re: 4.3 TBI to 305 TBI ?
Yep, everything but the knock sensor, spark timing module, prom and rom chips and the injectors should interchange
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1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap) |
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03-04-2006, 12:52 AM
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#5 |
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huh ???
Join Date: Nov 2002
Location: Fredericksburg,Va.
Posts: 3,368
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Re: 4.3 TBI to 305 TBI ?
A crankshaft is a crankshaft, they don't offer one for an auto and one for a standard trans. All you have to do is pick up a pilot bushing for the crank...
Chuck
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90 Blazer Silverado 350w/ 700R4 and 32" Kelly's "I am a bomb technician. If you see me running try to keep up!" |
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03-04-2006, 02:20 AM
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#6 | |
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Senior Member
Join Date: Aug 2004
Location: Everett, WA
Posts: 2,316
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Re: 4.3 TBI to 305 TBI ?
Quote:
Looks like I know what I'll be doing in the next few weekends... PS, will the flywheel of the 4.3 be the same for a 5.0?
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2009 Honda Fit CfC (bsf 44.9 mpg) 2000 Tahoe Limited 1991 GMC CrewCab Dually 2wd, will end up swb, not dually and replace CCswb below 1991 GMC CrewCab Dually 4x4, just going to fix things up for now 1982/1989 K5/GMC Jimmy 2wd 1987 GMC 1/2 ton swb 2wd Crew (sold) Last edited by kevinr1970; 03-04-2006 at 02:21 AM. |
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03-04-2006, 05:21 PM
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#7 | |
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huh ???
Join Date: Nov 2002
Location: Fredericksburg,Va.
Posts: 3,368
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Re: 4.3 TBI to 305 TBI ?
Quote:
Chuck
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90 Blazer Silverado 350w/ 700R4 and 32" Kelly's "I am a bomb technician. If you see me running try to keep up!" |
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03-05-2006, 12:52 AM
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#8 | |
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Registered User
Join Date: Feb 2006
Location: Birmingham,Alabama
Posts: 260
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Re: 4.3 TBI to 305 TBI ?
Quote:
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1969 c10 stepside 250 inline six, 4speed granny tranny, 4.11 posi rear end |
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03-05-2006, 01:09 AM
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#9 | |
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huh ???
Join Date: Nov 2002
Location: Fredericksburg,Va.
Posts: 3,368
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Re: 4.3 TBI to 305 TBI ?
Quote:
Chuck
__________________
90 Blazer Silverado 350w/ 700R4 and 32" Kelly's "I am a bomb technician. If you see me running try to keep up!" |
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