Questions from a newbie...
Comments inside the quote
Argh, AJ!!! You give me too many ideas, I literally can't decide.See, I knew you mighta jumped the gun!Take your time;think it thru. From what you have been saying, it is easy to see that you are still formulating a plan. You can do it your way, by just throwing money out there,and have the makings of a real nice auto-crosser.It will have to burn 91 gas, idle a bit lopey,be scary fast in first gear, and then it's over, cuz you are speeding. It will need special tuning skills,and may not like cold mornings. It may even be prone to overheating,especially in traffic.
>You can put that fancy front end under there. But to do what with? cruise it around town? That's about 3 to 5 years gas money!
>How old are you? Married?Got kids?I'm assuming this is a just-for-fun car, and that you already have a DD.How old will you be in 10 years or twenty. Will you have teenagers turning 16 soon? Have you ever driven a 450/500hp car with 563 ftlbs of torque? Do you know how incredibly fast things can go wrong with something like that? Who will take care of your family, while you are recovering in hospital? assuming you live thru it.
>Stick cars are fun when the shifters work. Are you prepared to reset the freeplay once in a while? To rebuilt the shifter when it piles full of gravel? Reset the neutral gate when the nuts come loose. Replace the brass or the clutch,when they wear out?; they don't last forever.
> Automatics, by contrast are a set it and forget it kindof deal. Yeah you only have three gears. But you only need 3. You need 1 to go Zero to 60,and one to cruise with,and one to use as a filler in between.See?
Race cars with little engines or big trapspeeds need more gears, a streeter does not.
This is a major project;take some time to study it out.
So, this morning I see, a '72 Duster with 3 speed manual near me.V8 car? with disc brakes?and an 8.75? That would be a really nice find.The guy has a 4 speed to go in the deal too. Do not pay much extra for an od box, they can be had at swap meets for 50 to 150 Canadian,lol. I'm assuming the pedal set up and other components would work with the 4 speed, correct? Yes. Obviously, new rods/linkage would be required. Unless he has a complete shifter,too! Do not be tempted to buy anything but a street shifter with an H pattern Do you know of any problems going from the 3 speed to 4 speed? Disposing of the little boat anchor,lol. Actually this is likely to be an A-230, a much better piece than the A903. The A230 is actually worth some money to somebody.
At the risk of sounding like a dick, here is a reprint of post #17
Come out of the fog;Here's your recipe;
For a dual purpose machine that is more than occasionally going to hit the hiway;
5.9 roller, cleaned up heads,223/230MAXIMUM cam(050s), 8.6 Dcr,Oiling mods to live at 6800, springs to go there,HO mechanical fuel pump with 3/8 supply line, electronic ignition upgrades to support the occasional stomp to 6800.
HD-904 with semi-auto kit and 2800TC, Narrowed 8.75 with tapered bearings and 3.23s and LSD.
From a73 up V-8 A-body;Front K-member, UCAs, Disc fronts and 10x2" rear brakes, sway-bar.
HD rear springs;Relocated with the offset perches. 1.03 T-bars,and HD shocks all around,
Minimum tire sizes of 235fronts/275rears. 295s will be better.
Optional P/S,P/B,tilt steering column,frame connectors,
3.23s?! Yes 3.23s will get you 60mph@6200rpm, in first, with 5% slip, a one gear run
3.55s will get you 60@6800 in first.Quite a bit out of the cams happy place.
3.73s will be 7150, just doable with the oiling mods, but you are waaaay off the peak power,so not recommended.
If you do not care about hiway rpm,nor about ET,or Trapspeed; then consider a two-gear run to 65/70mph, and choose a smaller cam, cuz your average power during the run will be higher, and a shorter TC, cuz you are gonna have plenty of starter gear.With this combo you will not have to do the oiling mods, just try to keep the Rs down to 1000rpm over the cams peak,say below 6200. And you can run this on a 5/16 fuel line, if your fuel-volume-test supports your horsepower level.
I suggest 4.30s minimum, and the A999. These will get you 60@5200 in second gear.This will leave you some headroom, to redline. The starter gear is 11.78 so a stockish 2200 TC will be fine. You only need a little cam now, say between 215 and 223.This combo will make tons of torque down low, try to keep the smile off your face; people will think there's something wrong with you.You will need a traction aider. Below 60 mph the engine will not have to buck much wind, so all the power can be used to propel the vehicle, instead of using some or a lot of it to overcome wind resistance.
Use a spreadbore carb and any old manifold (like the 71 TQ stuff).I would order a small custom cam. maybe on a 108LSA; counter-intuitive I know but;We need to shed some low-speed torque, and we need some power up top, cuz the Rs are gonna be down. This cam will run well with long-tube headers. I suggest as much lift as the heads can support and the grinder is willing to supply.
Honestly,every morning,before you hit the key, take a few breaths,mellow out. Repeat 7 times; I will not smile, I will not smile, I will not smile,I will not smile, I will not smile, I will not smile, I will not smile.
I guarantee you can't make it through first gear without smiling.
The only way to cure that, is with a smaller engine. Perhaps a 273.
The downside of course is the 3500@65 cruise rpm. I solved that with a GVOD.The Rs will drop to 2700ish.
Now to add, for a 4 speed; You might consider the od box for use with 4.10s to 3.91s, with that smaller engine. Remember,on the street, you only need a 3plus1.
Do not think to use this box with the 408;the starter gear will be way to big, and by the time you get the starter gear right, then the od gear will be way too small. For example; The 408 will be happy with a 3.23, to perhaps a 3.55. If you put more gear than this behind her, you would have to shift it before 60mph.The od box will turn these final drives into 2.36,and 2.59. These will turn the cruise rpm at 65mph, into about 1840 and 2022. To cruise this low, the cam is gonna have to be pretty small, and it would work best with a small TC too. Almost nobody would build a combo like that. Typically we cruise at 2400ish, requiring a 2.94 final drive. With the od box, this is a 4.10 rear gear. That would make the starter gear 12.67, which would make a slanty very happy, a teener some happy, a 360 says WTH?, and the 408 blows the tires off and has to shift less than 100 ft out of the gate! Yeah so that 408 would need special consideration to run that Mopar od box. I mean you could run it,no problem, but there is no way to optimize such a combo, unless maybe it was in a tow-truck application.
So by now you might be getting the idea that the engine and tranny need to be well matched. And you would be right. Every tranny wants an optimized engine to get the best out of the combo. If your engine build does not stray very far from the stock specs,then the stock tranny will work. How well they work together,is a different matter.
If your application calls for a wide ratio tranny, then a 292/108 cam is not gonna make a happy combo. That cam wants a very close ratio tranny.
If your tranny has closely spaced gears and lots of them, then you can use a lot smaller engine with a very narrow rpm band.
> long story short, you need to focus your tranny needs now before you have built the wrong engine for it. I did that, and it was a very costly experiment.
The regular automatics are a wide 1-2 ratio, and a slightly less wide 2-3.
The low first gear automatics are an even wider 1-2, with an even wider 2-3 ratio.
The standard 4 speed has 3 closely, evenly, spaced splits.
The deep low, has a wide 1-2 split, and the others are same as the standard box.
The od box has ridiculously wide spaced 1-2, and a slightly less ridiculously wide 2-3 split, with a too-close od.
The TA tranny has closely spaced ratios, that preclude it's use for anything but roadracing, cuz it requires a huge rear gear to be fun on the street;like 4.56s or 4.30s, to get a decent starter gear.
From the factory, those are your choices.
>So with a slanty you have more or less 2 ratio choices. A teener, depending on the power band, like the 360, can use any except the T/A which is a special case. The more power you wring outta these little engines, the more focused your tranny choice needs to be. With BB power, we begin to see the choices narrow up again.
I would never again use the od box behind an HO 360. I would use it behind a low output hi-torque engine SBM, sure.
I would not use the wide ratio autos behind any HO SBM.
I gotta stop; this post is getting ridiculously long.