If you are interested in fuel-economy;
After all is said and done, yur still gonna want to get rid of the 3.23s.
The ratios in the A833od are 3.09-1.67-1.00-.73od. Some say these ratios are horrible(see above) And you won't hear me disagree. They can be made to work by carefully coordinating your combo; I have done that.
Now, with the 3.23s and 29s, 65=1777 rpm in od/2430 in Direct. Either gear will get about the same fuel-economy. Unless you can figure out how to give the engine the cruise-timing it needs at 1777, actually, 2430 is likely to be better. That will be the First challenge.
>The Second challenge will be getting the fueling right at those rpms. There is no 4bbl that will operate at a decent AFR, pulling that brick, at 65=1777rpm, until you make it so, and then it will be wrong the rest of the time.
>The Third challenge is driving it slow; chugging along at 650 in Low gear is 5.6 mph. That's about as slow as she'll drive before losing it.
>The Fourth challenge is that 30 mph is; 1123rpm in Direct, 1875 in Second, and 3470 in First gear. As you can see, there is no good gear to use in stop and go traffic.
So here's my point;
Since you gotta change the rear gear anyway, why not do it now, while the slanty is still in it? ........... well I mean , you don't gotta but it don't make any sense to me to try and cruise 65=1777, in a "cheaper than dirt combo"............
The secret to running that transmission is to select the right rear gear, such that Second gear works right, and then building your engine to pull that gear, and let the rest be what it will be .
My combo likes a Second roadgear of ~6.00 corrected to a 24" tire. to get that in your combo with the 29s and 1.97 Second gear, will take a rear ratio of
{6.00/(24/29)}1.67=4.34; rounds to 4.30s With that gear your speed will be 12 mph per 1000 rpm. so;
2000=24, 3000= 36, 4000=48, 5000=60mph, 6000=72mph
Knowing this now; there is NO SENSE putting a big cam in this 318, which will only sacrifice power at 2000, to get it on your budget. Just leave the 318 cam in there and instead, punch up the cylinder pressure.
So what are your other roadgears?
My math says 13.29-7.18- 4.30-3.14 but with 29s, as compared to a car with 27s, this will feel like ;
11.81-6.38-3.82-2.79 almost perfect.
With 4.30s and 29s; 65=2365
IMO, this is altogether acceptable now, which is why I used to run my combo with this gearing.
Now all you have to do is build your 318 up pull that Second gear, hard enough to satisfy your need for acceleration.
First gear at WOT will get you to
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At the 1-2 shift, the Rs will fall to 2700rpm. So your teener is gonna need some grunt down there, or just do what I did, run first gear up to 5500@36 mph, and Second will come in at ~3000, Thus your powerband will have to start at 3000.
Since most Passenger car cams will be hard pressed to have a powerband much wider than 1500, this points to a cam that power-peaks around 4500, which points to a stock-type duration. But since you gotta wring it out to 5500 in First, your heads are gonna have to make that work.
Aaaaaaaannd, now you know why this transmission is such a PITA , or as
@sireland67 says, "it has horrible ratios" .
So by now, your dirt budget is looooonng gone.
What I'm seeing here is a high compression short block, with a re-balanced crank, built to survive 6000rpm blasts, with fancy heads to pull mid-range power out of that tiny engine. It'll probably need a high-lift, fast rate of lift, Solid-lifter cam, adjustable valve gear, good valve geometry, etc. .
what's that all about?
Well, that's about making that very low first gear, (11.81 corrected) get the engine onto the cam, in that very high (6.38), Second gear, so you can have some Second-gear fun.
Do you have to run the 4.30s?
No, you can put a stock 440-2bbl into your truck and forget everything I have said so far. Or
you can do what I did; which was to swap a buncha pumpkins into the back, until I eventually, 4 years later, I landed on the 4.30s, and that was that, with that combo.
The point is that you get the benefit of my experience with that PITA transmission, and it's free.
Ok start saving for heads.