Inliners International Forums General Discussion Drive Train 250 cid inline six needs overdrive

I prefer a manual setup, but also interested to know if anybody makes a conversion kit to mount a 700r4 to an inlne chevy 250 (1970 vintage). I know about the old electric Borg Warner overdrive units, but am looking for a modern setup for driveability and reliability.

The 700R4 will bolt up to the 250 no problem. Just have to check your flywheel so that it will bolt up to the 700R4 torque converter. A little bit of wiring, a different driveshaft and mount and you should be ready to go.

Cool, I would like to keep it all simple, and continue to run the Rochester MV(I think thats what it is) carb on the 250. Am I assuming correctly that there is linkage available for the carb that will take the cable from the 700r4 without issue? I know the 700r4 flexplate is different than the THM350(holes for torque converter in different location) Is a 700r4 flexplate from a small block useable on the back of the 250? or is there a balance issue?

Also,would you use the torque converter that's on the 700R4 or are there options depending on planned usage?( towing)

Any internally balanced pre 86 SBC flexplate will work as long as it is the dual pattern. Do not remember which set of holes, but had no problems mounting the converter to the flexplate.

I am not familar with the MV carb, but Bow-Tie makes on of their TV ez kits for a Rochester 3x2 set up that may work for you.

You can use a vacumm switch from a mid 80's GM to signal when to lock up the convertor. If your doing this for fuel economy you will pick up a little bit but maybe not as much as you think. The reason is that in OD the airflow is reduced and thus the venturi signal - you may find what was a crisp carb response in drive not to be as good in OD. After you do the swap let me know if this is the case...

The linkage out of a mid '70's nova with a TH350 should work, the 700r4 does need the linkage to be set properly otherwise the trans will cook from low line pressure. Installing a line pressure gage on the main pressure port above the trans thottle linkage is a good idea while setting things up - you'll need a 0 to 300 psi gage and hose good to 300 psi - check local hydraulic shops.

Have you thought about a 200-4R? Check the length of your current tranny. 200-4R is shorter than a 700R4 and you may not have to change the driveshaft, just the yoke. Same TV setup as the 700R4. Just my .02.

Ted

You mentioned that you would prefer a manual set up. By that I assume you mean 5 speed or 6 speed manual transmission.

I just installed a Tremec TKO500 in my car this spring. It is an easy & reasonably priced swap & the results are great. (Although I do need a bit more rear gear now, but a new rear end was in the forecast for this winter already.)

Contact Classic Chevy 5 Speed, ask for Jim & tell him McGoo sent ya.

Paul

Don't know if this will help, have you thought about the New Venture 4500 (5 sp) or 5600 (6 sp) that is in the newer trucks? I don't know if they will fit, but it's my understanding that Chevy puts this behind their 8.1L Big Block, so the bell housing might fit.

Thanks for the input gentlemen. Right now I'm leaning towards the 700r4. I have experience with them, and I'm not afraid of them when built properly. I have one behind a diesel in a one ton van. I'm just not familiar enuf with the 200r's to be comfortable putting one in. The price on the TKO 500 kit was a bit more than I want to spend on a tranny.
If I were to shell out the cabbage for an NV4500, I'd likely put that behind my diesel. It's a heavy duty application. I'm just trying to build a fuel efficient driver with this '70 GMC SWB 1/2 ton. It wont tow anything and a few bags of groceries probably the heaviest thing it'll ever haul(besides me, that is), and I'm not going to the races.
I'm adding another thred to get opinions on my plan to build a MPG buggy.