i have a 1995 gmc sierra / old state vdot truck/ 165000 miles runs excellent except ,a dead miss that might get very expensive,, anyway,,how much trouble to put in a350 sbc. ??will it bolt right in /motor mounts/?? can i use same torque converter and tranny?? its, a700r4 i presume ,3 spd.with overdrive in a half ton truck,, i presume i,ll need a wiring harness too . i thank you all for your expert advice..rick
09-19-2008 08:29 PM
6.5 diesal 350 sbc swap ???
does it need to go through emission's test ?
09-19-2008 08:34 PM
I'd have to imagine the diesel got a 4L80E. I might be wrong but a 700R4/4L60 might be a little on the weak side.
09-19-2008 09:13 PM
thanks, i can slide thru the emissions ,, and it could be a 4l 80e /trans pan is square like a 350 turbo ,,and it will power spin both whells on concrete bridges big time ,,any way i want all that computer junk out complety ,it even has a computer on the throttle , but the 350 sbc is in a 1979 gmc with hei ignition, mainly i justwant the ignition to work ,, or i can rig my own under dash if i have to i want to strip out everything that i can and and have clean engine bay with a 350 ,thanks,
09-19-2008 09:46 PM
The 4L80E will not run without a computer, period. But there is good news... I'll get to it in a minute.
The 6.2/6.5 family of engines was designed to basically bolt in place of any chevy engine, so the SBC swap should be a super easy breeze. Just confirm that the motor mounts are the same (or buy the proper mounts) and drop it in place. The bellhousing bolt patterns are the same. Two things you'll want to consider; 1) the diesel typically uses the large bolt pattern on the torque converter, so you'll probably need the larger (168-tooth) flexplate on the SBC. and 2) the diesel torque converter is a low-stall unit that won't be optimized for a gas engine. It will physically work, but it might seem a little sluggish off the line. For that reason you might want to get a stall that is properly matched to your 350
The good news I promised... Hotrodders for years have tried to find cheap easy ways of gettting a 4L80E to work in their old cars. One of the ways they have discovered is to use the computer from a 6.5 diesel. It has to be modified internally somehow, but do a search on some diesel forums and you'll find that the diesel PCM is one of the ways to get a 4L80E to work behind an old-school engine. I don't know the details, but someone in the tranny forum might.
But... I'll say it again, because I know your next question is going to be, "can't I just shift it manually?" or "how can I get it to work without the computer?" You can't. Period. The only thing you can do is install a race-type manual valve body along with some other modifications and then shift it manually.
09-20-2008 09:54 AM
To add a little detail to Curtis73, you will see on the driver side of a 4L80E trans a little shaft poking out, on which a shifter linkage is connected/can be connected. You cannot just connect your truck shifter to this shaft to run the trans, it will not work: this shaft is just a switch, allowing you (with your traditional shifter) to tell the computer in which gear you want to be; the actual gear shifting is then done by the computer, inside the trans.
09-20-2008 10:52 AM
If needed, there are also aftermarket transmission controllers. They aren't cheap though.
thanks,, everybody for your replies and great advice, i think i,ll stick a 350 turbo in it , modify driveshaft ,,a floor shifter and keep things simpler,, and less expensive , thanks again FOR YOUR TIME