96 C1500 engine swap question

Swapping from a 4.3 V6 to a 5.7 V-8...do the mounts line up or do they have to be moved???

From what i have heard the have to be moved as do the tranny lines and such refer to http://www.automotiveforums.com/vbulletin/showthread.php?t=325119 this previous post

I am not entirely sure, but i heard that the 4.3 is just a 305 with the front 2 cylinders chopped off of it. That is why you see so many chevy minivans with the 350 conversion in them , 305 and 350 same engine mounts, 4.3= a 305 with the front 2 cylinders gone. I do not know if it is true or not but i do know that there is alot of minivans around with 350's in them..... <shrugs>

4.3 has the same bore and stroke as a 350. You can use 350 parts to build a 4.3L

The engine mounts have to go forward.The wiring harness,computer are the same.All the computer has to to is compisate for the 350

You will have to change the prom in your computer. You wont have to move your mounts, you will have to buy the ones for the v8. They are not that expensive and they will bolt right in. The v6 mounts are opposite of the v8 mounts.

You might also want to change your radiator, shroud, tranny lines, oil cooler lines, fuel lines, lengthen the knock sensor wire (v6 is rear drivers side engine, v8 is front driver side engine).

Thats just a start ...

~Russ

Alright ya'll.... now I'm confused. Some of ya'll say mounts are the same and some of you say they have to move (forward). I plan on swapping my 4.3 as well so I like reading these threads so that I may plan ahead. So, whats the deal??? Do the motor mounts line have to come forward or not? From the knowledge I have obtained, I could understand how the mounts don't need to be moved since the 4.3 (262)has the same block as a 5.7 (or 350 motor). As others have mentioned the only difference is the front 2 cylinders chopped off. By the same token, I could also understand why the motormounts have to be moved. I would think if the tranny will line up with either motor, the mounts could possibly stay. Yet if the tranny is replaced, I could definantly understand why the mounts would need to be moved (forward)
So for those who have done this before, please help those whom are confused know the real real Hollifield!!

Oh yeah.......of course when you do something like this there will ALWAYS have to be modifications and maybe even custom fabrication to make it all work. Some of you mentioned many other things that will have to be modified, however, I don't recall anyone mentioning suspension mods. Wouldn't it be necessary to beef up the suspension to support the extra weight??

I just did this a few months ago...you can find my post about it somewhere on here if you search for it. Buy the motor mounts for the V-8. They bolt right into the same area on the frame, but they shift the point's that attach to the motor forward. The tranny mount is the same. You will also wan't to buy a new upper and lower fan shroud, if you want everything to look stock up front. Also, a larger radiator is usually used for the 350, and if you replace the shroud, the larger one will fit perfectly. There might be a few little fab things you need to do, but it's not that bad. Good Luck

OK, but what about suspension, is it neccessary to make modifications on front end suspension to support the extra weight????

I'm pretty sure the factory suspension is the same for a 4.3 or a v8

You'll need to torque the torsion bars up about 1/2 an inch, and new HD shocks wouldn't hurt.. but other than that it's the same.