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

[Jackal]

I hope this is an appropriate post here. If not, please delete and accept my apologies. I tried to keep as short as possible while providing enough information to get some assistance.

I have a '63.5 Galaxie 500XL w/ original Feb. '63 390 w/ 112k mi. and a '67 C6 that was behind a 390 in a Fairlane column shift. I want to start my transmission project in prep for engine rebuild in a year or two. I plan to take the 390 to 410 or 445, shooting for 450'ish HP using a BT 4v 427 MR intake and hopefully worked over 6090-C heads. This will be for street only, no special application, and I like bottom-mid torque and rarely live near red-line. I want a big lumpy idle, but not at the expense of driveability or power brakes. I will probably do something like a custom ground cam from Ken @ Oregon Cams. I currently have a 3.00, open, 9" rear-end, and I'm satisfied with the RPMs @ 70 mph. I'm not sure if a gear change is warranted or not, but do plan to install a TrueTrac diff. I also assume a mild stall converter will be in order.

I will probably build the C6 myself if I can get the shaft end-play sorted out without a big investment/gamble, and make sense of a straight forward rebuild manual that covers rollerization. I think I have decided to send the valvebody off to Broader to have it modified as a reverse, manual VB. This seems like it would work well with the stock console shifter and would allow deletion of the vacuum modulator, governor, and kickdown linkage and lever. (Curious what your thoughts/experience is if you have driven something similar. Maybe there is a performance shifter for this application that fits in the stock location that I should consider for safety or performance reasons?)

I bought the Crites C6 conversion bracket and isolator, but it sounds like this puts the trans at an unnecessary angle that even prevents getting the speedometer cable in place, so not knowing of any other source, I plan on going with the 1/8" plates to instead relocate the original crossmember. I'm not sure which isolator would be required at this point. I will also need some sort of slip yoke for the driveshaft. (Luckily I got the factory 1-piece shaft.) Not sure if I'd be better off swapping the column shift lever over to the console shift lever or just going with the TCI universal lever for extra adjustability.

This just leaves one last piece to sort out so that I can get started. I'm not sure if I should go wide-ratio or not, based on all these other aspects and what I THINK is my desired outcome. They add quite a bit to the cost of the build assuming my stock internals are in good shape. Any thoughts/input here is greatly appreciated. I have been hum-hawing over this for a year now. THANKS!

[Rory428]

In my opinion, a "big lumpy cam sound" in a big heavy car with 3.00 gears(convertor stall not mentioned, but with 3.00 gears, I wouldn`t recommend much over factory)is most certainly going to come at the expense of low speed performance and drivability. I also think that a reverse pattern manual valve body, with a tight convertor and tall  gearing will likely shift more harshly in normal driving than you may want. I only had the C6 low gear set in my 428 Fairmont drag car, over 20 years ago, so no idea how you will like it, but I would have to think it would help get a heavy Galaxie moving from a stop a bit brisker, I can`t really see a down side to it, other than cost. If you do a lot of freeway driving, I understand your desire to keep the 3.00 gears, but a lower ratio would really help get that barge moving.

[Jackal]

Thanks for your reply. Yea I know my preference in lumpy idle and low-end torque are in conflict. As long as she sounds somewhat NASTY I can deal. I over cammed a v-twin and it about ruined it for me, so I will take sound advice over my hard head in that respect. LOL

I know the cam, stall, gearing, etc. all has to work together. I've only removed maybe about 250 lbs. in total and might keep the iron heads. I'm not opposed to going a little steeper, and I spend more time on 45-55 mph roads than on the freeway, but I'm usually at 70-75 mph in both cases. Maybe the wide-ratio gears would help get me rolling while preserving the suitable highway RPMs, but I could also see this going the other direction where 1st. is nearly unusable and second would be more usable if not also reduced? The engine is clapped out so I don't rev too high right now, but I know that she sure wants to shift out of "L" at 25-30 mph. Not sure if it is better to invest in a new gear set, or the wide-ratio gears, or both.

[drdano]

After I grenaded my Cruise-O-Matic in my '62 Galaxie I went to a C6.  I also had the factory 3.00 with open diff.  I did the E40D wide ratio kit.  While a bit 'whiney', it did work nicely to get the barge off the line.  This was a factory z-code hydraulic 390, so nothing spicey under the hood.  I trimmed the factory trans cross member to clear the pan on the trans and drilled two new holes for the insulator.  It required a different length driveshaft I think, the factory column shifter did work, though didn't exactly line up on the column lines for P-R-N, etc.  Pinion angle had to be adjusted, but that could have been due to the car being slammed as well.

[WerbyFord]

If you're going that far into the C6, and want to keep the 3.00 gears then yes I'd say go for the wide ratio.
It WILL make a higher drop on the 1-2 shift, but not as bad as the GM 700r4 or Powerglide.

x2 what Rory said, a lumpy cam will kill that big car with 3.00 gears, BTDT. The biggest cam you want with that 3.00 gear is a Comp 270S, which is not very lumpy. Anything bigger will be slower.

For crossmembers, you can just turn the stock crossmember backwards, use 2 holes to mount it to the frame, which is plenty, and re=weld the E=brake bracket. A 50-year old trick, still works. Or make your own!

Why all the work to the C6 if it's just a street car as you say? Lots of cost, and a C6 will shift itself just fine with a little governor tuning, then just hook up the kickdown & leave it in "Drive".

For that money in that BIG car (4100 lb at least), adding more cubes would add more fun & make it less of a dog with any kind of cam. The 3.00 gear is nice at those freeway speeds so I can see trying to keep that. But in that case, the more inches the better ie go for 445cid or more.

[Jackal]

Thanks all.

Street car all the way, but I had to put a teardrop on it and tape off the headlights too like a true poser.

I like the idea of the manual VB because I am used to manual trans. plus it eliminates parts which I'm oddly drawn to. I had to fabricate an adjustable kickdown linkage when I switched to the 427 MR intake manifold, so I didn't want to have to fight that again or fab up a Lokar cable. It sounds like I should plan on going wide-ratio and if need be, once all else completed, change gearing to accommodate. I had read somewhere that the wide-ratio kit could actually slow you down in the 1/4 mi., but I don't plan on doing much of that anyway.

I don't THINK I'll have to change the driveshaft length, but time will tell. I hesitate getting projects like this started without some sort of bail out plan in place and I just don't seem to have much luck doing things "locally".

[frnkeore]

I'm doing something similar but, with a much lighter car 3300 lb. My specs are 2.73 x 26" tires stock converter and a 423 ci, 5500 rpm engine.

I'm a old road racer and I dislike wide ratio's because you loose part of your torque band, going into the next higher gear.

If you plan 5500 rpm as a shift point, here is what your looking at:

[blykins]

I'm in agreement with the other guys, you don't want a big radical cam in a heavy car with a tall gear.  It's a recipe for a turd. 

A compromise is a short duration camshaft that still gives you the torque and lower rpm powerband, but ground on a tighter lobe center to give a little bit of sound.  The short duration would work with a tighter converter.  Keep in mind that for everything to be *right*, you will not have a big radical idle, but you can have a little bit of chop. 

This is one of those situations where you can't have your cake and eat it too.  That's why you see a lot of guys going to deeper gears and overdrive transmissions.

[e philpott]

Have you considered a 4 speed auto or the newer 6 speed auto ? I've done a couple GM swapped to 4sp auto's and it's night day from a 3 speed , even with a 700R4's gear spread it's a big improvement over a T350 especially with lockup torque converter really knocks it out

[Jackal]

Thanks for the calc/chart and input guys! (Though I'm confused by the shift points. Maybe this is where an auto VB would shift into that gear w/o low vacuum?)

I think I could live with a Comp 270'ish chop. I definitely know better than to over cam again.

https://youtu.be/alWXQyBhKfA

[Jackal]

I couldn't live with a GM trans in my car, although I am running a Delco 10SI alternator. Maybe cool to stuff a massive 6R100 in there or something, but I would prefer to keep it fairly near 1967 era save the MSD and electric fan.

[chilly460]

Thanks for the calc/chart and input guys! (Though I'm confused by the shift points. Maybe this is where an auto VB would shift into that gear w/o low vacuum?)

I think I could live with a Comp 270'ish chop. I definitely know better than to over cam again.

https://youtu.be/alWXQyBhKfA

Man, what a fine looking machine that is!!!! 

I think a 270H will be ok in a 445 with the 3.00, but IMO it'll really like the wide ratio (my car was lazy with a 2.32 first/3.00 T10 combo but of course didn't have a convertor helping).  It should be fine at cruise @ 70mph, which I think is 2600rpm or so?  The 390 pulls 70mph @ 2200rpm in OD, which is a deeper final ratio. 

[Jackal]

OIC...lol. NICE ride chilly!

[e philpott]

I couldn't live with a GM trans in my car, although I am running a Delco 10SI alternator. Maybe cool to stuff a massive 6R100 in there or something, but I would prefer to keep it fairly near 1967 era save the MSD and electric fan.

I hear that , the GM I referenced were classic GM's converted to 700R4 and the difference before and after was huge , I wouldn't want a GM in my Ford either but it does have me wanting to convert my 63 Fairlane 4 speed top loader to 5 speed TKX

[Jackal]

I gotcha. Thanks for offering it up. I definitely haven't explored my options, I just fixated on a C6.

If I went 3.25:1, would wide ratio still be something I might want to consider with the bigger jump between gears and all? It looks like the gear set would nearly accomplish the same as the wide ratio kit in 1st, although I imagine all the fun happens in 2nd.

It looks like my original curb weight is supposed to be about 3,979 lb. or < a new Taurus. 


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For my reference and to help "visualize" the difference:
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If I grab a gear at 70 mph with a wide ratio & 3.00:1, RPM jumps from 2,600 to almost 4,000 and I'm only doing 88 mph @ 5,000 RPM. Dropping back into 3rd. it would jump down to 3,300 RPM.

W/ stock ratios, I would only drop down to 3,800 RPM, hitting 92 MPH @ 5,000 RPM, and grabbing 3rd. would put me at 3,400 RPM.

W/ 3.25:1 @ 70 mph I'd now be turning over 2,800 RPM. Grabbing 2nd. would put me over 4,100 RPM, hitting 84-85 mph @ 5,000 RPM, and grabbing 3rd. would put me just over 3,400 RPM.