Anyone here made the switch in a say 3300-3500 lb. car?
kind of curios on your results?

Not of much help I don't think but I've been running the 2.75 low gear set in my Coronet for over ten years.

But, I weigh 3950 in a B-Body

11.30-11.40 in the 1/4 with 3.54 gears in the Dana.

Mike

I did back in the day, no help. In fact get the correct converter and you'd be surprised how little overall starting line ratio you need.
Doug

I'm seriously considering it, for the Barnyard Viper...but like the Coronet above it's very heavy.
I understand exactly what Doug is saying but in a heavy street car, where it's preferable to run less gear for street driving, I think it could be a worthwhile advantage.

The car I tried one in was a 426 wedge 63 Dodge. Car ran 4.88 then 4.56 with both standard and low sets. All combos ran about the same, low 11's. Later it got a 498 with a factory cross ram. Ran the same with 4.56 and a 4.10, low 10's.
Doug

^^^ This is along the lines I was thinking, being able to keep my 4.10's gear but increasing my 1 st gear ratio and maintaining my 2-3 gear ratio. which bring up the question. what do most consider a heavy car here?(weight wise).

I think some would say anything over 3,300 poinds is heavy.
Most tell me mine is a yacht.
The best i've ever sixty footed is 1.57....but mostly 1.58-1.61 with the 3.54's

Speaking from 904 land but its close I guess. I ran a low gear 904 with a nitrous 360 that ran 11.30s. It usually 60'd 1.52-1.53. I changed from the low gear 904 to a standard ratio 727 and it lost .1 in the 60 and .3 overall(slower). So take into consideration some of that ET was lost to the 727 but I bet that .1 in the 60 was the low gear set. I used the same converter buy just had Turbo action make it fit a 727. My car at the time scaled 3525 with driver.

My old A/SA stocker had to weigh 3520 with me in it to race legally, I switched it from the stock 2.45 Mopar OEM 1st gear set to the Mopar 2.77 helical low gear set and swapped the rear gears from 4.89 ratio to 4.56. That change picked the 60 fts up and it made the car go into high gear sooner due to the lower 1st and 2nd gear ratios, which was not a bad thing
If your not spinning the tires now I would swap them in a heart beat
I did the math on the starting line ratio (2.45x4.89=11.98, 2.77x4.56=12.63 plus the torque converter multipication, which remained the same on both gear sets) before doing the swap, that car was a 1963 Plymouth Belevedere two door sedan with the low compression 415 HP motor and steel front end, it had right at 50% weight on the front and back tires with me in it
This was in 1988 before radial drag tires had been made and sold, that car was on bias ply 9x30 drag slicks and hooked up very well, 1.48 60 ft times best is what I remember now
I'm putting a 4 speed street car together right now and I did the math on using either a standard NP 833 with the stock 2.66 1st gear ratio tranny with a 3.73 rear gear ratio Dana 60 or use a NP 833 O.D. tranny with the 3.09 1st gear ratio and .64 in overdrive, I went for the fuel mileage and less RPM going down the road when crusing Hopefully it won't be a big tire spinner in 1st gear

My 71 weighs 3825, add me and we're at 4100. Yeah I'm a big guy!
I have a CRT tranny with a low gear set. My tank runs 10.60's in the 127 range. 60 foot is 1.47-1.48 most of the time. I have 60'd as low as 1.44. The old girl leaves pretty hard for the size. I have a 9.5 converter from Lenny and a 4.30 Dana on a 30x10.5 Hoosier radial slick.
I never had a regular gear set with this combo to compare. But this is what my car is doing now.

I have them in my gtx for years now. Had them in then out then back in about .100 better but leaves way better and better second offset by big drop in third.

Without starting a new thread on this , i'll just bring this back up.For the guys that have made the switch did you all experience excessive tire spin ?Guess i'm trying to figure how much of a 1 st gear change there is between 2.77 and 2.45.And also what are the other options for 727 1 st. gears?

I discussed this with John Cope and One of the guys at Southlands way back when. I really wanted to change them but...... "If you have a marginal / inconsistent 60ft this may make things worse or, make the wheelstand worse" (SLR). I stuck with the standard ratios
I do know folk who have changed and picked up in the 60ft and et. I know it worked on our small block and 904...... but if that motor has more than 320hp I'd be surprised.

2.77 to 2.45 is a fairly substantial change in SLR. 12-15% depending on rear gear. Try it. Swapping low gear ratios and testing will teach you some things.

Changing SLR 10% and finding the sweet spot made a big difference in my situation. Big. 60s, reaction times, consistency. All of it. Suspension adjustment is key in all of this. SLR is extra important if you lack the adjustability to tune to the gear ratio (4 link, good shocks, etc).

According to Wallace cal's right now with 2.45x4.10=10.05 they say you want to be in the 9,10.11 rang the car is pretty consistent .with 2.77(2.77x4.10=11.35)seems i'll be on the edge of spinning. Some have talk about stroke and converter slippage when discussing low gear sets and i can see that having a effect on the low gear mortification.Trying to figure out how aggressive the 2.77 is over the 2.45.

I did that to my 1963 Plymouth 415 HP M.W. NHRA Stocker in 1988, switch the rear gear ratio from 4;89 to 4:56 and swap the stock 2.45 low gear set and the second gear to the Mopar helical 2.77 low gear set and the 2nd gear ratio that set up came with.
I'm sure it help the car run faster and quicker but that swap was not a A/B/A test, the car had set for 4 yrs after me blowing up the motor really bad in 1984 and letting it sit until November of 1987 before fixing it and racing it again in 1988.
The new motor, trans and gear sets were all installed at the same time
I have one of Pro Trans older SS/AH 727 in my shop, it has all of the tricks used back in the early 1990s, aluminum drums front and rear, straight cut custom ratio gear sets and so on, hopefully I'll be able to use it soon

Thanks Cab......if i'm reading this right you say you swap the first and second gear set to 2.77?

3800@line RR, 11.35 SLR, 2.77x4.10, 10x29 Hoosiers, c-trac/mono's, dead hooks and picks them up to 1.43 60's to date f/braking, its only a 10.35 1/4ET car, the converter is somewhat tight@3600-4200 max torque is@4400 , seems to work ok, whether we'd go faster with a 2.45 and a looser converter is debatable, I know we'd pick up with more flash as it is now.

Thanks for that info your car is a little heavier than mines but Good info.

Here's the car on a hit with only a handful of runs on it early season....watch from 2hr. 43min. 20secs in and again@9hrs 40 mins>

https://www.youtube.com/watch?v=l7eQ4wVUEzs