zuhi

iTrader: (1)

Hi Members!

We craned out a 83 CFI 5L and we want to do a carb swap. But we found a TH350 behind the LU5. Don't know how and when gets there.

We just want to know if we swap the LU5 to carb. (600cfm 1406Edelbrock and 2101intake in the palns) how the Echonomy MPG was possibly change compared to the first version 700R4 which sholud be there? (yes i know if it was there i must need to install lock up corrector) but now this is not the actual situation.

I would like to know what is the logical way for runs right, echonomy, to keep the TH350 (if its working) or try to get a used 700R4.

Thanx for any info.

bubusmc

I have a 91 converted to 350 from 4.3. I went with a th350 transmission with a 3000 stall. I started with 3:73 gears. I could not do over about 55mph on the highway without my car overheating due to the high rpm's the motor turned. I switched back to stock 3:23 gears. I can now keep it about 60-70mph, but it still turns some pretty high rpms. My guage doesn't work for some reason, but I think it is because I changed the motor and left the stock v6 gauges. That's another hick-up. I am wondering what people would do in my situation. I need an overdrive gear. Would a different th350 with a lock-up or taller gear ratio help with the rpms? Or do I need to convert to a 700r4. Would a 200r4 work? I need to be able to drive it on the highway. It isn't a race car, but I'd still like to keep the low end power for the most part.

Any and all feedback is welcome

bubusmc

its a factory shifter. however, i do have a b/m shifter to install, but havent done it yet

vetteoz

iTrader: (13)

Both trans had a 1:1 ratio in 3rd gear but the 700R4 has a 70% O/d in 4th so you get much better fuel economy
or if you want to accelerate fast, it lets you run a low diff ( 3.73 > ) gear while still having some fuel mileage in 4th

Read
http://forums.corvetteforum.com/1568185079-post21.html

You can do your own MPH / revs comparison here
http://www.bgsoflex.com/rpmmph.html
For top gear use 1.0 for TH350 and 0.70 for 700R4

johnny55555

hey so im new on this site and i need some serious help?!?! there is this horrid clunking sound coming from the passenger side of the axle. Just had the wheel bearings replaced the yokes for the driveshaft were inspected and passed, just replaced sway end links, the springs are pretty worn could that be it?? maybe the isolaators?? someone please help!

vetteoz

iTrader: (13)

Start you own new post describing your problem ;this one is about fuel economy and gearing

rob 86 firebird

With the 350 tranny you can gain more build ability however the 700R will crush it in fuel economy and driving comfort. I built my 700R with a shift kit and 2500 stall and it handles the .40 over built 350 in front of it perfectly and still delivers 16 MPG in overdrive on highway trips.

rob 86 firebird

mine has a 700r in it that has been built. 3:23 gearing in the rear end. In overdrive 60 MPH on the highway it only turns 1600 RPM and holds steady at 170 degrees.