MX > C6 conversion. Wide-ratio and other questions.

[shady]

C6 is the king of the hill.
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwj2oIu56NXwAhVBM1kFHQtGDcgQFjAbegQIERAD&url=https%3A%2F%2Fwww.460ford.com%2Fforum%2F42-general-tech%2F118570-transmission-specifications-including-parasitic-hp-losses.html&usg=AOvVaw0vYSPOKScd5MHhviHZUqCH

[Rory428]

Jackal A reverse pattern valve body requires its own reverse pattern shifter such as a B&M or Hurst .I wouldn't want to attempt making a factory shifter work with a reverse pattern valve body but I suppose it could be done .Doug

Actually, when I had the reverse manual valve body in my Fairmonts C6, I used a factory Ford Floor shifter, from a 69 Mustang. I liked the stock shifter for several reasons, first off, it was laying around in the garage, so it was free. 2nd, having experienced aftermarket shifters where the plastic cable melted on the headers or exhaust, the idea of a sturdy steel rod was very appealing. Having also experienced the frustration of the detents on the aftermarket shifter not lining up correctly, because the shifter was designed for a GM application, and the detent spacing on a Ford is a bit different, so if you get it adjusted to fully go into the 1rst gear position, by the time you get into Park, it does not engage correctly. I also liked the factory look, plus I was able to retain the original C6 neutral safety switch on the side of the transmission. To make the stock shifter work with the reverse pattern valve body, I just ground away the detent that would normally be between "D" and "2". That way, if the shifter is in the D position, which is 1rst gear with the reverse pattern VB, and you want to grab 2nd, I would just pull the shifter handle down, until it hit the next detent, which originally was between 2 and 1, but is now between 2nd and 3rd. Then when it was time for high gear, I would just push the stock button on the side of the T handle, and pull it down as far as it will go, and, voila, you got 3rd. I raced the Fairmont with the C6 for the first 10 years, using that shifter, and it always performed flawlessly.

[cammerfe]

Comment regarding whittling on governor valves. When I was involved in such shenanigans, I was working at T&C Livonia. The QC Lab and Process Section was within a few feet of a small experimental section where they were set up to work on the governor valves. They used small grinding wheels on the interior circumference of the valves.Whittle out a bit of weight and then test the valve to see how much you'd moved the shift point. With the governor, it's actually the centrifugal force on the valve, acting against the spring. Modulation is done by the vac-pot. Replacements are adjustable. Turn off the vacuum supply and it's all controlled by the governor. (We used a tricked governor valve and a quarter-turn shut-off in the vac line on Brother Lon's '67 Mustang/427 TP street-race car. It was led into the interior of the car and the quarter-turn was mounted to the lower edge of the dash.

Those valves are through-hardened, and we had regular sessions of having to make minute adjustments of such valves, working in bored and reamed aluminum valve bodies. Unless the diameters of the holes and the valves were watched VERY closely, the valves became small broach bars and 'ate' the aluminum parts. Production specs called out the surface finish of the holes. Air gauges, reading, actually, the leakage of air between the gauge plug and the hole were the standard.

KS

[66FAIRLANE]

Like Rory I hate cable shifters, hate the 'GM' detents and wanted to retain the console. So as per the picture below I made my own detent plate with a sliding detent that locks the shifter in the forward gears. So 1-2 is a 'slap' shift against a stop, no button necessary. 2-3 is a button down shift against a stop. The lever is then pulled which drops this stop and allows you to shift into neutral and its the normal function then on to P. Of course the lever is pulled when going the other way to to drop it into D from N. Can all be done with one hand.

[Jackal]

Hmmm, 6R80 sounds interesting, but I assume pricey and I wonder about all the electronics.

EDIT: NEVERMIND, I missed page 3. :\ I have the data somewhere, but IIRC 25 HP loss w/ the FMX and 55 w/ the C6 prior to rollerizing. I don't think I've seen anything on a rollerized C6, but expect its back down to 25-30 HP.

[e philpott]

https://www.usshift.com/usq6.shtml this and a used 6R80 with a little bit of modifying , once you go OD you never go back

[Gaugster]

Hmmm, 6R80 sounds interesting, but I assume pricey and I wonder about all the electronics.

EDIT: NEVERMIND, I missed page 3. :\ I have the data somewhere, but IIRC 25 HP loss w/ the FMX and 55 w/ the C6 prior to rollerizing. I don't think I've seen anything on a rollerized C6, but expect its back down to 25-30 HP.

Here's my total spend for the retrofit. It comes down to value, future plans etc.... Probably 2X the cost of  C6 but.....the 6R80 comes with a 2400 stall stock, holds at least 650 HP stock and of course has 4 gears plus 2 overdrives. In relative terms I paid a premium for my 6R80. Some sell for much less but with more miles and no warranty.

Fyi - I did post a thread in the project section. I'll  bud out now. 

[Jackal]

That does sound nice. The 4R70W also sounds like something I could have considered. I just thought the C6 would be cheaper, easier, and of course I was aiming to stay close to '67 with mods.

I tried to attach some pics that I dug up of the '63 crossmember adapter plates, but it doesn't seem to be working. I was mistaken on my trans being an FMX. I think it's actually an MX.

[Dr Mabuse]

Others have covered your questions better than I can, but consider:

There is no such thing as a "6090-C heads" - most all FE heads have a "6090" (basic) pattern number (often) between the center 2 spark-plug holes. It is the prefix and suffix that are used to (usually) i.d. a cylinder head (such as the 1966-67 "poor man's" CJ, C6AE-R).

I understand "BT" (Blue Thunder) make nice Ford parts, but for less added expense, an Edelbrock might perform as well, and for less money. Your goal of 450 hp is easily accomplished.

The Truetrac differential is a good choice, along with new 31 spline axle shafts. Changing from a 3:00 gear to a 3:25 is such a small change, it isn't worth it, unless you need to buy a new ring & pinion anyway. Always use a solid pinion spacer - never the crush type.

You seem to be over-thinking much of you plans. The Crites C6 conversion bracket and isolator purchase is one example of putting the cart before the horse. The stock/OEM crossmember and a standard mount may work fine. You should consider ditching the idea of using a stock driveshaft, and plan on spending $500(+) on a new aluminum performance shaft. If the stock shaft is the wrong length, it's time to just get a new aluminum shaft.

You didn't mention chassis upgrades - especially brakes. Wilwood is probably the aftermarket leader, and they have many options available, from reasonably priced mild upgrades to big rotors and 6 piston calipers.

[ROBSREDFORD]

I’ve run 390 with 3.00 gear and a small cam for 30 plus years...not ideal but surprises folks as it just goes....55-60 in first,95-100 in second....heavy f100... for your application I know you want period correct but I don’t see reverspattern manual vb as period correct...I’d do junkyard 6r80 all day on this combo