AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 25,870
- Reaction score
- 13,175
Look, I know you guys need some love.
So I'm gonna give you what I think is the best advice anybody can ever give you.
Are you ready? it's Torque multiplication.
For as long as you continue to run a stock transmission combo, your engine is constrained by that all-wrong-for-318performance-combo. and
As long as your engine has the stock deck height, and factory heads, no matter how big a cam you put into it, it will be a dog until the rpm climbs up into the Power window which could be as high as 3800 rpm, just to tickle the powerband. With typical 2.76 gears and a TF, that will be ~43mph; and full power will not arrive until ~60mph.
The question is this; Are you willing to put up with that?
Of course not, and you know the solution is a higher stall to get closer to where the power is, like a 3800, right? I mean that's where the Powerband begins right? Well yes and no. You might want to be there, but that makes a lousy streeter.
So the next thing to consider, is to get rid of the 2.76s. The right gear for a street teener is almost always more than 3.91s; which will get you ~65@5000. Put a 2800 stall on that, and you have a nice street transmission ...... except in Drive, 65=3160 plus or minus slip. So now unless you are building a City-Only car, you need an overdrive.
Ok so the point is, no matter what you do to your teener, yur gonna need a convertor and an overdrive for her to be a true streeter.. Plus of course the usual upgrades to your TF to make it reliable, etcetera.
So, if you cannot do this work yourself, it's gonna cost you a lotta lotta money to get this done. But if you don't do this first, your budget-318 hop-up will be a dog for like 95% of the time.
So, my advice is to do these things first, so that you can enjoy your stock 318 until you have the money to at least upgrade the compression ratio.
Now, lemmee tell you about my transmission, and judge for yourself if you think it could help your street-teener.
BTW
I'm not telling that this is what you should build. I am telling you that it took me many years to get to where I am, and thousands of dollars.
but it will still not hurt my feelings one bit, if you chose another path. Remember, I take no offense if you're not interested.
Are you ready? My combo is;
Commando A833/Gvod/3.55s/ clutch. The ratios are
3.09-1.92-1.40-1.00-.78od. and splits are .62-.73-.72-.78, but, I shift into overdrive
after third and then into 4od, making the splits .62-.73-.78-.71. Check out how progressive those first 3 shifts are.
Now, here comes the neat part; I wired a bypass on the GV controller, so I can splitshift. With full 12 volts going to the shift solenoid, the GV shifts like lightning. Here is the neater part; Split-shifting between 1st and 2nd, and after Second, the ratios are
3.09-2.41-1.92-1.50 ..... for splits of; .78-.80-.78 ..............
IDK if there is anywhere on God's Green Earth that you can find three splits that tight.
Effectively, this is a very progressive 5-speed trans, that is well able to be a Six on the street.
Shifting at 5500, the rpm drop is to 4350, a powerband requirement of just 1155 rpm.
On the street, I like to gear this with 3.23s so that 1.92 Second hits 65@ 5020, which I can do because I have a modest-cammed longer-stroke 367 engine. Whereas if I had a 318, I might use 3.73s for 60=5370, which would run well with a 5000rpm powerpeak, say a 223@050 cam. That's a pretty small cam, and, with 3.73s you cruise rpm is 65=2350, and
if I was a betting man, I'd bet with the right cylinder pressure, you could tune that deep into the 20s mpg.
Now, that's a streeter.
Well, except now you still have to build your hi-pressure 318;
Or well, you know, a factory 318 with just a 4bbl, and say 3.23s would be a pretty good combo, @ 65= 2040.
And the best part, you don't have to dink around with convertors or shift kits or stinking governor weights; and you will NEVER burn out that Commando/GVod combo, and honestly, your clutch discs with a 318, should just keep on going and going and going. And so, it's like a one time deal.
Oh and you got that variable stall thing, called a clutch. Even the factory 2bbl, 8/1 318 should get rubber in first, and may even blow thru First-over, as well, lol. I know my winter-engine, a factory smog318, with 4.30s had no trouble.
Now, to conclude, this is Torque-multiplication at it's finest. This is the culmination of five years of throwing stuff at my combo, to see what sticks. My combo has seen every small-input, A833 ratio, that Mopar ever built, and every rear gear from 2.76 to 4.30, plus 4.88 and 5.13s, and except 3.73s. Not until I got the GVod did I have a winning combination, and I finally settled on 3.55s, which allowed my 367 to trap 93mph@6150rpm in Second-over, lol.
The only engine advice I can give you in this post, and it's harsh, is this;
If your 318 only has 135psi cylinder pressure in stock form, and you slide a big cam into that;
have you heard the expression; "garbage in=garbage out"?
So I'm gonna give you what I think is the best advice anybody can ever give you.
Are you ready? it's Torque multiplication.
For as long as you continue to run a stock transmission combo, your engine is constrained by that all-wrong-for-318performance-combo. and
As long as your engine has the stock deck height, and factory heads, no matter how big a cam you put into it, it will be a dog until the rpm climbs up into the Power window which could be as high as 3800 rpm, just to tickle the powerband. With typical 2.76 gears and a TF, that will be ~43mph; and full power will not arrive until ~60mph.
The question is this; Are you willing to put up with that?
Of course not, and you know the solution is a higher stall to get closer to where the power is, like a 3800, right? I mean that's where the Powerband begins right? Well yes and no. You might want to be there, but that makes a lousy streeter.
So the next thing to consider, is to get rid of the 2.76s. The right gear for a street teener is almost always more than 3.91s; which will get you ~65@5000. Put a 2800 stall on that, and you have a nice street transmission ...... except in Drive, 65=3160 plus or minus slip. So now unless you are building a City-Only car, you need an overdrive.
Ok so the point is, no matter what you do to your teener, yur gonna need a convertor and an overdrive for her to be a true streeter.. Plus of course the usual upgrades to your TF to make it reliable, etcetera.
So, if you cannot do this work yourself, it's gonna cost you a lotta lotta money to get this done. But if you don't do this first, your budget-318 hop-up will be a dog for like 95% of the time.
So, my advice is to do these things first, so that you can enjoy your stock 318 until you have the money to at least upgrade the compression ratio.
Now, lemmee tell you about my transmission, and judge for yourself if you think it could help your street-teener.
BTW
I'm not telling that this is what you should build. I am telling you that it took me many years to get to where I am, and thousands of dollars.
but it will still not hurt my feelings one bit, if you chose another path. Remember, I take no offense if you're not interested.
Are you ready? My combo is;
Commando A833/Gvod/3.55s/ clutch. The ratios are
3.09-1.92-1.40-1.00-.78od. and splits are .62-.73-.72-.78, but, I shift into overdrive
after third and then into 4od, making the splits .62-.73-.78-.71. Check out how progressive those first 3 shifts are.
Now, here comes the neat part; I wired a bypass on the GV controller, so I can splitshift. With full 12 volts going to the shift solenoid, the GV shifts like lightning. Here is the neater part; Split-shifting between 1st and 2nd, and after Second, the ratios are
3.09-2.41-1.92-1.50 ..... for splits of; .78-.80-.78 ..............
IDK if there is anywhere on God's Green Earth that you can find three splits that tight.
Effectively, this is a very progressive 5-speed trans, that is well able to be a Six on the street.
Shifting at 5500, the rpm drop is to 4350, a powerband requirement of just 1155 rpm.
On the street, I like to gear this with 3.23s so that 1.92 Second hits 65@ 5020, which I can do because I have a modest-cammed longer-stroke 367 engine. Whereas if I had a 318, I might use 3.73s for 60=5370, which would run well with a 5000rpm powerpeak, say a 223@050 cam. That's a pretty small cam, and, with 3.73s you cruise rpm is 65=2350, and
if I was a betting man, I'd bet with the right cylinder pressure, you could tune that deep into the 20s mpg.
Now, that's a streeter.
Well, except now you still have to build your hi-pressure 318;
Or well, you know, a factory 318 with just a 4bbl, and say 3.23s would be a pretty good combo, @ 65= 2040.
And the best part, you don't have to dink around with convertors or shift kits or stinking governor weights; and you will NEVER burn out that Commando/GVod combo, and honestly, your clutch discs with a 318, should just keep on going and going and going. And so, it's like a one time deal.
Oh and you got that variable stall thing, called a clutch. Even the factory 2bbl, 8/1 318 should get rubber in first, and may even blow thru First-over, as well, lol. I know my winter-engine, a factory smog318, with 4.30s had no trouble.
Now, to conclude, this is Torque-multiplication at it's finest. This is the culmination of five years of throwing stuff at my combo, to see what sticks. My combo has seen every small-input, A833 ratio, that Mopar ever built, and every rear gear from 2.76 to 4.30, plus 4.88 and 5.13s, and except 3.73s. Not until I got the GVod did I have a winning combination, and I finally settled on 3.55s, which allowed my 367 to trap 93mph@6150rpm in Second-over, lol.
The only engine advice I can give you in this post, and it's harsh, is this;
If your 318 only has 135psi cylinder pressure in stock form, and you slide a big cam into that;
have you heard the expression; "garbage in=garbage out"?
Last edited:
Cruise 75 mph all day if I wanted to also 
