3.73 vs 4.11 ?

[Bubba4spd]

Trying to get clear in my mind which way to go on my 68. Going to pull the 327 w/automatic (no original) and put back a 250 I6 with spd 3 OTT (factory set up) mostly for the novelty of it. The existing truck has 4.11 posi unit in it now and considering using a 5 lug no posi 3.73 just to improve the highway rpms on the occasional commute to work. Any suggestions/ideas if the 3.73 would be the best option?

[my67c20]

Unless you figured out some secret to gaining massive amounts of MPG's, i don't think either is really going to matter too much. Personally, with an inline, and being that they have good torgue, i would look at something like a 3.08, and slap some bigger tires on it. Everything is dependant on how quick, and how long you plan to get to and be at "highway" speeds.

[Bubba4spd]

11 miles to work, 10 of which consist of 55 and 65 speed limits with no lights.

[Mike C]

10% reduction in RPM. You would be happier with the 3.73 for sure. 3.42 would be even better and not completely neuter the truck.

If it were mine, I would be looking at doing a floor shifted T5 from a 4.3 equipped truck and keep the 4.10.

[Bubba4spd]

Originally Posted by Mike C

10% reduction in RPM. You would be happier with the 3.73 for sure. 3.42 would be even better and not completely neuter the truck.

If it were mine, I would be looking at doing a floor shifted T5 from a 4.3 equipped truck and keep the 4.10.

That would be a clean solution, thanks Mike.

[Jason Banks]

I have no problem running my 250 inline 3OTT down the highway at 65-70 mph with 4.11 rear gears. 75 is pushing it but still feels doable.

I love the T5 idea, but would never get rid of the 3OTT

[jocko]

I'd sure keep the 327. 3.42 better than 3.73 since your focus seems to be mpg and drivability. T5 an easy upgrade and an enjoyable driver once completed if you're not gonna run around flooring it all the time. T5 gives you good perf off the line AND at highway speed, rear end swaps have a trade off at one end or the other.

[Bubba4spd]

Originally Posted by Jason Banks

I have no problem running my 250 inline 3OTT down the highway at 65-70 mph with 4.11 rear gears. 75 is pushing it but still feels doable.

I love the T5 idea, but would never get rid of the 3OTT

Originally Posted by jocko

I'd sure keep the 327. 3.42 better than 3.73 since your focus seems to be mpg and drivability. T5 an easy upgrade and an enjoyable driver once completed if you're not gonna run around flooring it all the time. T5 gives you good perf off the line AND at highway speed, rear end swaps have a trade off at one end or the other.

Excellent suggestions fellas. Need to hear this stuff to make a decision. Actually fuel mileage is not much of an issue as I have a 99 (five speed) and a 16 model Silverados already. This is just for fun, may even have the doors painted with an old co. logo from the past (70 year old family business).

[Mike C]

The ONLY reason to not do the T5 IMO is you regularly have 3 abreast in the cab. And even that wouldn't deter me.

The biggest things late model vehicles have going for them is overdrive transmissions. More speeds over a wider range make for better acceleration, passing, cruising, etc.

I find more than a 30 minute trip in my 69 with its 307 and TH350 and 3.07 gears to be about my limit at 70 mph so find it hard to believe a 6 banger and 4.11 make for much of a road tripper.

T5. Hot Rod Power Tour. The truck will do EVERYTHING better with the T5

If you spend any time on off road message boards the biggest change they make is more gear. Usually they have plenty of motor and I feel the same about your 250 powered truck. You will not regret the lower first gear and overdrive combined with your 4.10 diff you will have the best of all worlds.

[jocko]

well, if you're interested, here's the complete swap, soup to nuts (in a 66, but same applies). Fun project and much more fun to drive. http://67-72chevytrucks.com/vboard/s...d.php?t=482069

[Bubba4spd]

Originally Posted by jocko

well, if you're interested, here's the complete swap, soup to nuts (in a 66, but same applies). Fun project and much more fun to drive. http://67-72chevytrucks.com/vboard/s...d.php?t=482069

Thanks jocko! Yeah at my age, I take fun whenever I can now. I'll start my search for a T-5 that fits the bill immediately.

[Bubba4spd]

Originally Posted by Mike C

The ONLY reason to not do the T5 IMO is you regularly have 3 abreast in the cab. And even that wouldn't deter me.

The biggest things late model vehicles have going for them is overdrive transmissions. More speeds over a wider range make for better acceleration, passing, cruising, etc.

I find more than a 30 minute trip in my 69 with its 307 and TH350 and 3.07 gears to be about my limit at 70 mph so find it hard to believe a 6 banger and 4.11 make for much of a road tripper.

T5. Hot Rod Power Tour. The truck will do EVERYTHING better with the T5

If you spend any time on off road message boards the biggest change they make is more gear. Usually they have plenty of motor and I feel the same about your 250 powered truck. You will not regret the lower first gear and overdrive combined with your 4.10 diff you will have the best of all worlds.

Getting more stoked about the build now that I'm getting some of these decisions resolved. Thanks for the advice.

[mike16]

my 72 is a 3 speed/307 and i have 373 gears. i get about 12 mpg and i'm always going for that next gear. a friend has a 350/350 with 308 gears. he gets about 17mpg. my 373 gears are very useful about 10% of the time. i would not trade them for anything that 10% but i pay dearly the rest of the time

[Bubba4spd]

Originally Posted by mike16

my 72 is a 3 speed/307 and i have 373 gears. i get about 12 mpg and i'm always going for that next gear. a friend has a 350/350 with 308 gears. he gets about 17mpg. my 373 gears are very useful about 10% of the time. i would not trade them for anything that 10% but i pay dearly the rest of the time

Mike, have you ever considered a five speed conversion?

[Bubba4spd]

Originally Posted by Jason Banks

I have no problem running my 250 inline 3OTT down the highway at 65-70 mph with 4.11 rear gears. 75 is pushing it but still feels doable.

I love the T5 idea, but would never get rid of the 3OTT

Yeah I know what you mean, I have fond memories as a boy driving my elderly fishing buddies 66 chevy stepside down to the lake and being the after school pharmacy delivery boy in a 3OTT 65 ford fleetside swb. I didn't even ask for my weekly pay. Driving that truck around town since it was so well known and cool to drive was plenty payment enough.

[Bubba4spd]

Originally Posted by jocko

well, if you're interested, here's the complete swap, soup to nuts (in a 66, but same applies). Fun project and much more fun to drive. http://67-72chevytrucks.com/vboard/s...d.php?t=482069

Jocko, I called my small town junk car dealer and he said he hasn't seen any S-10 T-5's lately but has seen a few NV3500's. Would it work almost as well? I do realize I would have an electronic speedo to deal with. I have plenty of time to locate a proper T-5.

[mike16]

Originally Posted by Bubba4spd

Mike, have you ever considered a five speed conversion?

i have. but its all origonal and when I bought it 6 years ago it only had 71k miles on it. I have thought long and hard about a 4500. it needs an od but i dont want to comprimise its origonality

[old Chevy guy]

Good luck finding a good t5 in a junk yard. We spent over a year looking for a good T5 to put in my sons first generation S10. IF you can find one be prepared to pay through the nose for it. IF you get one drive it like its your moms car, they won't take a lot of abuse ,nice and easy, don't be trying to spin the tires and such or you will be sorry. We couldn't even find parts to fix a broken one. Finally he stumbled on to one in a local yard the guy was using for his yard truck and he bought the whole thing to get the tranny and then still sent it out to a shop to have it checked out before he installed it. Previously he had gotten one from a junk yard that turned out bad and the guy didn't want to refund the money and said he would get another one for us. He searched everywhere and after a week gave him his money back. Lots of those trucks got crushed a few years ago when scrap was high, the rest already got bought up by people putting them in older hot/ rat rod stuff . It's a lot of money but if your going that way your money's probably better spent on the NV 3500 conversation. We are looking to build a K 20 soon and that's the route I hope to go. Probably not as expensive for two wheel drive but I haven't looked into that yet. Anyway That's my two cents and it's barely worth that I'm sure.

[Bubba4spd]

Originally Posted by old Chevy guy

Good luck finding a good t5 in a junk yard. We spent over a year looking for a good T5 to put in my sons first generation S10. IF you can find one be prepared to pay through the nose for it. IF you get one drive it like its your moms car, they won't take a lot of abuse ,nice and easy, don't be trying to spin the tires and such or you will be sorry. We couldn't even find parts to fix a broken one. Finally he stumbled on to one in a local yard the guy was using for his yard truck and he bought the whole thing to get the tranny and then still sent it out to a shop to have it checked out before he installed it. Previously he had gotten one from a junk yard that turned out bad and the guy didn't want to refund the money and said he would get another one for us. He searched everywhere and after a week gave him his money back. Lots of those trucks got crushed a few years ago when scrap was high, the rest already got bought up by people putting them in older hot/ rat rod stuff . It's a lot of money but if your going that way your money's probably better spent on the NV 3500 conversation. We are looking to build a K 20 soon and that's the route I hope to go. Probably not as expensive for two wheel drive but I haven't looked into that yet. Anyway That's my two cents and it's barely worth that I'm sure.

Thanks for your input. Do you know if the S-10 T5's are basically the same for both the 4cyl and 2.8 v6 ?

[Overdriven]

With Chevy T5 availability not being all that great and them being weak I was looking into alternatives other than the much more expensive Tremec. One I found was that QuickTime has a Chevy Bellbousing with a Ford trans bolt pattern. Ford T5's are practically a dime a dozen, then there's the 5spd that they used behind the 4.6 (tr3550?) as well. I'm not sure if you'd need a clutch with a Chevy pressure plate and a Ford splined clutch disc. But even if you do a quick call to your clutch supplier solves that easily enough and total cost would still be lower than going with a new Tremec. Assuming that's all that needs to be done, haven't looked too deep into the input shaft length and pilot bearing/bushing diameter yet. I'm sure QuickTime would be able to answer those questions but again, I have gotten that far yet.

[In The Ten Ring]

4.11's are for real men, everything else is for the modern (girly) man.

I'm just kidding! My truck is a 250 I6 and 4.11, 3OTT. It got 10 mpg last time I remember (1993).

So KUDOS to you for trying to go back to original and double props for wanting the novelty of the column shift manual. It is rather fun to be different.

I live in hill country, so a 3.08 is definitely out. My dad told me about a guy back in the 1960's that bought a new car but it "ain't got no power!" Dad asked what gear ratio he had. There was his problem. We have hills here, some are long, big, and there are lots of them.

Now GA is pretty flat as I recall......so you could probably do OK with a higher ratio. If I ever change mine, it will be to a 3.73.

Edit! Did you decide against the 3OTT? I do wish my truck had a higher gear but the bench seat and no floor shifter makes for a great date truck. :-)

[old Chevy guy]

The 2.5 4 cylinder and the v6 I believe is a 2.8 are suposed to be the same. The 4.3 is different I'm told.

[BlackedOut67shorty]

4.3 shares the same bell housing as the sbc and inline sixes. The four bangers and the 2.8 are different .

[Bubba4spd]

Originally Posted by In The Ten Ring

4.11's are for real men, everything else is for the modern (girly) man.

I'm just kidding! My truck is a 250 I6 and 4.11, 3OTT. It got 10 mpg last time I remember (1993).

So KUDOS to you for trying to go back to original and double props for wanting the novelty of the column shift manual. It is rather fun to be different.

I live in hill country, so a 3.08 is definitely out. My dad told me about a guy back in the 1960's that bought a new car but it "ain't got no power!" Dad asked what gear ratio he had. There was his problem. We have hills here, some are long, big, and there are lots of them.

Now GA is pretty flat as I recall......so you could probably do OK with a higher ratio. If I ever change mine, it will be to a 3.73.

Edit! Did you decide against the 3OTT? I do wish my truck had a higher gear but the bench seat and no floor shifter makes for a great date truck. :-)

No I haven't totally given up on the 3OTT yet, it's still in the mix. Yes we have a lot of flat country down south where I am for sure. North Ga has a mountain range running through it, the reason I ordered my last truck with a 3.42 rather than a 3.08 which would work just fine with the auto 6 spd in south ga. Keep me posted on the Ford T5 route.

Originally Posted by old Chevy guy

The 2.5 4 cylinder and the v6 I believe is a 2.8 are suposed to be the same. The 4.3 is different I'm told.

Thanks....one thing I need to learn is the diameter of the input shaft where it goes into the pilot bushing. I know from 4 to 8 they are different sizes.

[Bubba4spd]

Originally Posted by BlackedOut67shorty

4.3 shares the same bell housing as the sbc and inline sixes. The four bangers and the 2.8 are different .

thanks BlackedOut67shorty. Would you know if the case on the 4/6 is the same as the 4.3?