finish line rpm vs launch

[Jim Wahl]

I agree, the 5.13 I think would work better. Lower the shift point by 200 and with the 5.13 should put you in the sweet spot. My Volare has a 4.88 and it weighs in at 3500+ with normal trap rpms at 7200-7400. That is using the 30" radial. I'm thinking that 383 was all out of steam before the 1000' mark at 7400. Jim

[Eric Merryfield]

Originally Posted by Jim Wahl

I agree, the 5.13 I think would work better. Lower the shift point by 200 and with the 5.13 should put you in the sweet spot. My Volare has a 4.88 and it weighs in at 3500+ with normal trap rpms at 7200-7400. That is using the 30" radial. I'm thinking that 383 was all out of steam before the 1000' mark at 7400. Jim

my 383 stocker motor(old school 1993 motor) with 2.45 727 and 4.56 would go through the traps at 6200.......by comparison....4speed jericho, 5.13 7000-7200.....109-111 mph either way.....not running out of steam, but with the 4.56 seemed like it wanted it to be a 1/3 mile race! With the 70 you are limited by your 600 cfm holley a bit.

Exhaust with 4.56 dead hooker supercomps, and dynomax ultraflow, with stick TTI's.....nothing sexy.

My vote for the combo with a auto would be 4.88....unless you have done work to the motor and carb and exhaust system to let it make hp that much higher.

Or you could just put the stick in it and not have to learn all about the automatics!

Eric

[GTX JOHN]

While you were in the Garage, I would leak down the engine and make sure it is in top shape. I have seen similar big block mopar with that head and compression spin easily that high ( As I recall Steve Wann told me
he rouitinely spun his big block 383/440 stockers to 7700 and laughed at me by being a Sissy).

I do agree that a 488/513 gear would be better unless you are at altitude
like Denver for example.

If I read your posting correctly @ 102 Mph.....I would be also check you
valve train and spring pressure. At 12.70 and 102 8 your speed/ET is about
what I would expect in a Heavy Stocker that was not real high HP.
My kids wagon @ 4000 ft when it ran 12.8 would run 102/03. @ 3700 Lbs
when it was making in the low 310-320 Hp range and it appears you big block
is a bit high torque and maybe a bit better midrange on the track.

I can not recommend enough putting a light low drag racing transmission with
straight cut gears (Probably a 263 low or so) like Pro Trans (Palmdale Calif.) is a heavy lower class stocker.
It is expensive but it Really makes a big difference (Dave does not pay me to say that).
It helped Jr.'s stocker 06/07 in 60 and about a tenth a Half. the 727 with 904 guts is
Even more Dramatic in performance difference. It sounds like you car is struggling on
the index and it is no fun to get in bad Summer air and not be able to play .
I know very well...... it hurts to spend to money, but if you can swing it---Buy the
Best and Only Cry Once.

[Todd Boyer]

Originally Posted by 4spdJohnny

I am in the process of going from 5.38 to 4.88 gears in a j/sa 70 Sport Sattelite wagon 383 is shifted at 6400 goes thru traps at 7400. Building a trans with a lower first 2.45 to a 2.77. Thoughts keeping the same basic gear multiplication down low and more in power band down track. Does this seem like a move in the right direction or is it normal to "over rev" a stocker that much? It sure seems out of breath last 300 ft. Is that to much of a jump?

Would this be the red Satellite stocker wagon that was on Racing Junk a while back ???

[GTX JOHN]

That would be the one according to what Johnny told me.

[Chris DeGidio]

From experience,I think the 4.88 is the right way to go.We used a 29.5" Firestone/Phoenix in a 70 Road Runner with 383,both 4-speed and 727 were used,4.88 gear was perfect for that combo.I know the wagon is a bit heavier,but with the 2.77 first,I think that will work great.

[GTX JOHN]

I checked my #1 son Robbie who runs a H/I/J SA Roadrunner with a low compression 400. He runs 488 @ Sea Level and has run 513 at altitude sometimes (4000plus ft. ) He shifts around 6200 and goes thru lights @7200.
He normally runs 11.3/11.4 @115 to 116 at sea level(Usual showing 2000ft.)with the 4.88 @3650LBs. He thinks the 513 are probable a push at sea level ......but a littleharder on the engine.

Again I would look at condition of your engine and maybe try another converter. 102/103 Mph is not a lot of speed for a big block car even with a 625 carb. I believe you might be able to run the 735 Holley on that combo as I have seen Don Wann's 70 383 Roadrunner run the Holley some years ago............................................... ............
and it was (Like all their stuff) way FAST!.