Stubby686

I installed a different tranny into my 1980 C3 vette. I'm going to a local guy next week for some final tuning & dialing in now that I'm done with the major things I wanted to do. He asked me on the phone what my final drive ratio was (along with some other info) so he could ballpark some carb settings to start out. How do I figure this out ?

Old stock tranny ..T-10
1st 2.88
2nd 1.91
3rd 1.33
4th 1 to 1

Current tranny Doug Nash / Richmond 4+1
This is what I found online for ratios for this tranny
1st 3.28
2nd 2.14
3rd 1.57
4th 1.24
5th 1 to 1

Rear gears are 3.07 / tire size 255/60-15

qwank

I would guess he wanted to know the rear end gears. did you tell him 3.07?

63mako

First gear final drive ratio is important for your tune. A 10 to 1 ratio is the goal for off the line performance. Your new first gear final drive ratio is 10.07 to 1. Many factory first gear final drives are bolow 8 to 1. A perfomance build with a 8 to 1 first gear final drive would be sluggish off the line and careful tuning can compensate for this somewhat. With your new gearing you can do a full performance distributor curve and get everything out of your existing engine possible as far as bottom end power is concerned. You multiply your first gear ratio by your rear end ratio to figure first gear final drive ratio

Stubby686

Perfect !! Thank you so much !!

The guy is really good but is a tad grumpy and gets annoyed when he asks a question and it's answered with 'Huh?' Just hope we can get along for the time he spends with me on the car lol. Not to many people are willing to tune a motor while your there helping also to learn how things work so I'll get a better understanding for future tinkering on my own.

scottyp99

Ya know, way too many people do not realize the potential of the internet. A lot of people say "You can't learn everything by reading.....", and that is true, but, it's also true that you can learn an awful lot by reading. Anything that you are interested in, carb tuning, engine building, suspension tuning, building a birdhouse, whatever, just type it into Google, and you will be amazed at the resources at your disposal! And, of course, you have us, so you got that goin' for you, too!

Sometimes, with the old grumpy guys, (I know this because I am 46, and just starting to get a little bit old, and a little bit grumpy!) they are kind of annoyed by the "Huh?" accompanied by the "deer in the headlights" look. Substitute it with furrowing your eyebrows like you are giving what he said careful consideration, and say something like "OK, I don't understand what you mean by (fill in the blank).". No guarantees, but it's worth a try.


Keep the shiny side up!
Scott

iokepakai

The Richmond trans with that 1st gear matches well with your 3.08 rear gear.Got the ROD in my car and really like how it pulls out in 1st.Hit second and your going at a pretty fast pace,well spaced ratio's on that trans.Once I got the dist,& carb issues all worked out and things in tune ,man what a difference! Vette is scary fast now.....Good luck on the tune......

Stubby686

I'm 41 myself so I'm not far behind you lol. The guy that will be messing with it is 60ish & after talking with him it came to that he worked with my father back in the 70's at a dealership when I was filling up diapers. I lost my dad when I was 20 and sorry to say I was to cocky with the know it all attitude to pick up the things that really matter when it came to tuning motors. I've 'tinkered' with motors my whole life but it's just that ... tinkering otherwise known as trial & error. I have gotten the carb , dist curve/advance & timing close but I'm also the type that is never happy with anything. I know all to well even a bit off on a tune can leave double digit HP numbers on the table. I'm just looking for every bit that can come to life. Sorry to say I'm also the type that picks up faster & far more info going the hands on route. However this car was a 180hp (maybe 70 RWHP ) POS that would stall if the clutch was dumped along with a ton of non-working things when we got it. With this forum and the internet it has come close to a complete 180 turn-a-round. Best part is almost everything was done right the first time with the right parts