I have an '84 4x4 Suburban with 350 4bbl. 700r4 trans. I would like to install a 455 Buick and a stronger trans. I don't want to go and buy a pro built super expensive redone 700r. Trying to keep it low with parts that exist naturally. 350 or 400 Turbos with an adapter for the engine a good idea? I'm not worried about the 3-4 mpg from the OD. It has 3.42 rears now. Any help is greatly appreciated. Daryn
The adapters for the bellhousing aren't all that expensive from what I've heard. I haven't priced them out myself though. I assume you're considering the adapter to run a Chevy-pattern trans due to the transfer-case tailshaft on the transmission? A couple of options for you: If you're not towing heavy loads & don't run it hard, a TH350 should survive. You could crossbreed the Buick TH350 case with the Chevy 4x4 TH350 tailsection & then not need an adapter at all. Any trans shop should have the core parts available. If you need the TH400, tranny shops can get a 4x4 tailsection to fit it. I've discussed that option with a local shop already. Again, just bolt on that tailsection to a BOP-case Th400 & you're good to go with no adapters required.
From looking @ parts that I have it seems like I could just remove the tailhousing off a BOP 350 and it would bolt to the Transfer case. I'm not 100% sure if the shaft length is the same. Or the splines. I'm sick of messing with these 700r's. I do use it for towing.
Exactly. Like you, I don't know the internals well enough to know what all would be involved. You may have to completely tear down the trans to switch to the transfer case style output shaft. The case should be the same though, so the BOP case would work. The 400 would be a better option for you though if you're towing. The 3/4 ton 4x4's should have 400's; at least the one I just bought does.
Goodluck with your switch! And smart move as far as I'm concerned. Go Buick!!!!!! Oh and use a th400 if you can.
700r4 and th350s use alot of the same internals, the output shaft on both 4x4 and 2wd have the same spline count between the trannys. The real difference btween the two is how long the case is, the 700 is about 3 or so inches longer than the 350 because of the overdrive gear. If you bolt up the transfer case to the 350 you might have to drill new holes in the frame farther up for the cross member and you will have to shorten the front driveshaft and legthen the rear one, or probably the easiest thing to do is that most tranny stores have a kit that you can swap a 350 in place of a 700r4. I'm not real sure what all comes in it but I do know that it has an adapter that is the 3 or 4 inches long that goes between the back of the trans and the transcase, so I think that all you really need is a short tailshaft 350 not a 4x4 350. Hope this helps. :TU:
Please keep us posted on this one! I was going to do this a while back but after taking a good hard look at the bottom of my truck, decided it needs a cab more than an engine!! My truck is a 78 K20 with the TH400 and I was going to make up an adapter plate as the tranny is really in good shape and I could build an adapter in less time than pulling two trannies apart and putting all my parts in a BOP case. I also figured if I ever got tired of the truck but wanted to keep my motor, it would be easy to switch it back to a SBC. My big thing was that the truck has 35" tires and even with 4.11 gears, the small block just doesn't have the grunt that I wanted. I bought the 455 carb to pan and tore it down in hopes to do rings, bearings, gaskets, and a timing chain but found a cracked piston skirt and a well worn cam so I'm now saving it for a good rebuild some day when funds allow!! Ken
