4.3 87 to 92 parts interchange with 93 to 95

i have a 87 to 92 4.3 175 hp 2 brl with a cracked block (winter Freeze) (origional motor in this boat) and an operating 93-95 4.3 205 hp4 brl ( Installed now). i would like to swap out the intake manifolds and carbs getting rid of the 4 brl. will the intake manifold match up. other than a slight loss of power and a gain in operating economy am i looking at any problems.

Jim 1951 said:

i have a 87 to 92 4.3 175 hp 2 brl with a cracked block (winter Freeze) (origional motor in this boat) and an operating 93-95 4.3 205 hp4 brl ( Installed now). i would like to swap out the intake manifolds and carbs getting rid of the 4 brl. will the intake manifold match up. other than a slight loss of power and a gain in operating economy am i looking at any problems.

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Yes manifold will match up but id check it for cracks and rot in water crossover below thermostat.

why would you want to get rid of the 4 bbl? If for fuel economy it is more determined by how much you push the throttle down.

Ayuh,..... I'd stick with the 4bbl,..... The primary bores are smaller than the 2bbl, 'n the fuel economy could be better,......
Gas mileage goes downhill, only when the secondaries are used,.....

Agreed on the 2 bbl vs 4 bbl, I’ve always been amazed how economical my 1988 4.3 Cobra with the 4bbl Quadrajet is. The QJet has a spread bore design with small primaries and huge secondaries so the effect is even more pronounced than square bore carbs like the Holley 4160 and Edelbrock 1409. With the 2 bbl these were rated at 175 hp with the 4 bbl at 205 hp. That’s a lot to give up.
As a practical matter you can cruise on plane on the primaries only at 3500 rpm and get great fuel economy but if you want a blast of power open it up and the top end response is much better than with a 2 bbl. I don’t think the secondaries on mine open till about 4,000 rpm.
The intakes should be the same up to 1996 when they changed from the pre vortec (12 bolts holding down the intake) to the vortec (8 bolts holding down the intake). They also eliminated eliminated the exhaust crossover on the vortec intakes so you can’t use the well type or or divorced choke the vortec style has to use an electric choke.

Thank you for your replies.......the primary reason i wanted to switch back to the 2 brl is/was i had the parts and the 4 brl needed to be rebuilt in the worst way. as it turns out the carb issues are the least of my problems. i think i bent a piston rod and locked up the motor while cranking it over......it has always been difficult to start. i think the 4 brl with the elec fuel pump loaded up a cylinder and got the worst possible result.........does anyone in the upper midwest have a good short block that will be work with my existing 2 engines?

Because the 4.3 was used in many gm cars and trucks you can probably get a runner at a wrecking yard or find a local machine shop they may have parts laying around

If you hydrolocked it check the exhaust manifolds you may have gotten water in via the exhaust