big block with 2.73 gears and 400 turbo? [Archive] - Team Camaro Tech

: big block with 2.73 gears and 400 turbo?


68zz502fi
Apr 8th, 07, 09:47 AM
just trying to get some input from anybody that is or has run a 400 turbo trans and 2.73 gears (prefferably a big block chevy). the question's are, what stall converter size are you running? what type of 1/4 mile performance do you get? what type of mileage do you get? also is your 400 trans stock gear ratio. or do you run a (low gear set) in the trans?
just trying to get a feel of what im in for with this combination.

thanks!:beers:

zdld17
Apr 8th, 07, 10:20 AM
This is not really a performance gear set. More of a cruiser. Try looking at some of the 3 series gears like 3:55 , 3:73 if you want to move that car with a th 400 in stock form convertor.

novaderrik
Apr 8th, 07, 10:41 AM
with a big block, you don't need gears to make it move.
even the stock 350 in my Monte moves it around ok with 2.73 gears- a big block would be right at home.

68zz502fi
Apr 8th, 07, 11:48 AM
:thumbsup: thanks for the replys so far.. I am aware that 2.73 is hardly considered a performance gear, that wasnt my question or objective here. I have had experience with 4.10 gears a 350 turbo 4000 stall converter and a mild 327. I know how this combination performs... it screams!

that was years ago and I have since calmed my need for snap your head off launches and 1/4 mile jaunts. dont get me wrong, I still want/enjoy a car that has high performance. I just want some better street manners, some actual drivability and dare I say gas mileage? I want to actually drive this car on the highway without taching @ 4000 rpm, that obviously is not practical.

my new set up is this.. a zz 502 big block (502hp/567tq) a 12 bolt posi w/2/73 gears. and im considering a 400 turbo with about a 2000 stall converter. this is the basis of my post. I just wanted some imput from a few people that are running the same gear and a comparable engine/ trans combination.

pdq67
Apr 8th, 07, 11:52 AM
Sound's like a real winner to me!!

In your case no shorter than 3.07's, imho....

And I'm sure some even run the 2.56's too...

pdq67

oger
Apr 8th, 07, 12:48 PM
My old Elky had an oval port 427 a 400 with the stock SS convertor and 2.73s. It worked just fine but people though the speedo was wrong when it would shift out of passing gear as the speedo went off the end.

DOUG G
Apr 8th, 07, 01:02 PM
With old combo 406 sbc, th350, and 2.73's I could do 80 in 1st @ 6000rpm, which would surprise a few ricers :yes:
The best ET was a 13.51 @ 101.7 using only 1st & 2nd (2.0 60's all day w/ street tires)

BAMiller
Apr 8th, 07, 06:13 PM
I used to run my vert with a turbo 400 with a non pozi 2.73 rearend and a mild 327 with 64 cc heads and a 350hp/327 chev grind cam and would run 14.60's in the 1/4 @ about 95 mph. That was comeing off the line part throttle to get traction and I would not get into 3rd gear the whole 1/4 mile. With all that torque I think it would make a nice driver. Would be cheaper that 3.73 gears and a overdrive trans.

Tinkerr
Apr 8th, 07, 06:28 PM
I would think the 2000 stall converter is going to be slipping alot with 2:73's and making the converter run hot!

bigblockgirl
Apr 8th, 07, 08:02 PM
I don't have all the specs you are looking for but maybe the info I do have will help. I have a BBC with a stock TH400 hooked to a TCI Saturday Night Special (2000) stall converter. The engine is .30 over and I have a mild cam (.280/.520). Until this afternoon, I was running the stock 2.73 gear. This gear is Great on the highway. I would run around 65-70 or so which turned about 25-2700 RPM. I could only do a one-wheel peel which would nearly burn the back right tire clean off but would go only straight. The 2.73 gear didn't really make the car want to jump out of its tracks or anything but if cruising at low RPM is what you want, this combo works great. My gas mileage wasn't bad at all but since I never measured it, I can't give any details.

BTW, just got finished with installing a 3.73 and it feel like i might twist the darn car apart. Woo Hoo...there goes my gas mileage. :cool:

*added - i have short tires and was only doing a one-wheel-peel...sorry for the mispelling.

South Side Goons & Hitmen
Apr 8th, 07, 08:12 PM
When I built my first car years ago (a 1969 Camaro) I had a well built screaming 396 & a THM 400. The stall was 3,000 10" converter I think. The car had a 10 bolt open rear end w/ 3:08 gears. The car was great on the highway. If you want nice street manners the 2,000 stall will be fine. Make sure you run a HUGE trans cooler. Eventually I put a 3:73 12 bolt in that car.

The 400 trans had the stock planetary gear set. I don't think anyone offered low gear sets 15-16 years ago.

speedshifter
Apr 8th, 07, 11:13 PM
My old Elky had an oval port 427 a 400 with the stock SS convertor and 2.73s. It worked just fine but people though the speedo was wrong when it would shift out of passing gear as the speedo went off the end.
I know what you mean! I put an M22 and a 396 in an '80 Camaro that originally had an auto/V6. That car had the 2.56 gears, but that mean rat would redline in high gear. My 85 MPH speedometer was useless!

sirstude
Apr 9th, 07, 08:59 AM
I just joined this forum, for the 12 bolt information, and found this question while looking it over. I am running a ZZ502 in a 65 Impala, I know it is a heavier car, but here is my info. I also have a Richmond 5 speed. I am running 2.56 in it now. I used to have a 3.08 but shredded the ring gear. Anyway, with the gears in it now, if you are running it hard, you will fall out of the power band between gears. With th 3.08's it was pretty good at staying in the power band, but I would think with the t400 with only 3 gears, you won't be happy if you want to mash the pedal a bunch. Realize that the ZZ502's have all the torque and power in the world, there are still some considerations at the back end. I am assuming that you are going to use a ZZ502EFI from your signin.

DOUG G
Apr 9th, 07, 12:34 PM
Run what you have and you can always change it if you want :yes: or when money frees up.

67RS/SS396
Apr 9th, 07, 01:35 PM
My sons 68 vert has a 396 40 over, a comp cams 268(?) w/68 corvette 3x2 oval port, turbo 400 2000 stall 3:08 open rear. Cars sound really good but, doesn't really start pulling hard til about 3500 and at 65 mph it tachs at 3000 rpm. gas milage forgetaboutit.

namz111
Apr 9th, 07, 01:51 PM
I have a 30 over 396 with a 400 trans 2000 stall and the 2:73 gears its a great cruiser but thats all it is. I take this car out a few times a year so I really dont need a cruiser I want more out of it so this year I am changing the gears to a 3:90's as for gas mileage I really dont think its going to matter what gears you have in it gas mileage suxs! ;)

fotoboy
Apr 9th, 07, 10:58 PM
your end result is different from what most people what so take that into cosideration. I know my 87 c4 Vette ran a 2.59 gear which was perfect w a 700r4 and a tuned port motor. W a 502 there is alot of tq to pull that car w any gear. my current car is a 502 ramjet w 550rwtq off the spray, the gear I run is a 3.89 w a 31 in tall tire. The car cruises at 65 at 2800 rpm w a tb400. w the tire size OF 25in tall be running it will prob be 2400rpm.

DOUG G
Apr 10th, 07, 01:24 PM
My sons 68 vert has a 396 40 over, a comp cams 268(?) w/68 corvette 3x2 oval port, turbo 400 2000 stall 3:08 open rear. Cars sound really good but, doesn't really start pulling hard til about 3500 and at 65 mph it tachs at 3000 rpm. gas milage forgetaboutit.


Must be a very short tire or somethings wrong. I only pull 3000 @ 65mph with 3.73's,10" 3000 stall, and 27.5" tall tires.

BTW, I have a speed warning to show it :D

Z15CAM
Apr 10th, 07, 08:03 PM
This is my idea of a touring with a BBC: 2.73’s with a 266H-10 cam. 3.08’s with a XM278H-12 or perhaps a 288AR-10 or XR274R-10 cam. A Holley 80511-1 830 Annular Booster over and RPM Edlebrock Oval Port. Tranny is up to you, I prefer Muncie.

A 150 mph speed-o is totally useless.

We are a sick lot – lol