I am wondering if I would be able to figure out what rear I have on my 1977 Cordoba, without looking at it, as it is in the back of my friend's shop, and I am nowhere near it. I can find the vin, it has a 400 cu in engine with a 727 trans.

I am once again trying to identify any possible weak links before they occur when I put the 440 in it.

 

I have the possible rears here: Standard; 2.4 Optional; 2.7, 3.2, 2.4 Sure Grip, 2.7 Sure Grip, 3.2 Sure Grip.

 

That's kind of what I figured, not much I can do from here anyways with that info, except to ask what would be the best with my setup?

I know 8 3/4 is a good diff as to what a good ratio would be, I am unsure of.

 

it all depends on how you plan on using it. if its going to be more street than strip, then I'd go with a 3.07 or so. If its more strip than street, then 4.10 is good. ifs its a mix of both, maybe around a 3.55. it also depends on the width and height of the tires that you plan on using.

 

So if I were to use it on the street with stock or similar tires, I may be fine with the rear in it now. But if I were to increase the tire size a bit in height and maybe take it on the track 3.55 would be fine?

Is that a standard rear, or with a spool?

 

Both. No matter what you deside to run for tires and if you run posi, locker, or a spool, you should use the right size gearing. If I were you, I would set my mind on one size tire and stick with that. Heck, I would even set my mind on one tire and stick with that. Then you can get a better idea what you want to runn for gearing and narrow your choices more.

E.I.: Let say you were going to run a 255/65/16 tire (i know its a bit big but hold on) on a 16x8 rim with posi. Let say that your motor is putting out about 425 HP and you plan on taking it to the strip once a month. I would then look at what companies had to offer for gearing betwwen 3.50 and 3.90.

If you have the same setup but plan on hitting the strip to compete for some money, then I would do a spool and something around 4.10 to 4.30.

If you are just doing it for street then I might do posi and look for something in the 3.00 to 3.30 range.

You need to sit down and think about what you really are going to do with this vehicle and stick to it. Trust me, its a lot cheaper having a plan than just winging it as you go. Let us know what size tire you want, what your looking at for numbers from your motor and how you plan on driving it and we can give you a better idea how we think you should go.

 

I have been looking at these Shelby Cobra series 427 by American Racing for awhile and that is the ideal rim to me, size 17x8. I am not sure on the tire size but somewhere with enough profile that it does not look like there is no tire, I believe 4.5 in profile will fit good. I do not know the max size that will fit on there, but that totals out to be 26 inches.

They also make a 17x9.5 and a 17x11, the 17x8 should interfere the least with turning and driving.

I would like to take it on the track max once a month, more for fun on the street.

As for what its going to be putting out, I am not sure the "desktop dyno" tells me about 400 hp with 550 ft/lbs of torque. I am more inclined it will be a little more as the cam data they have in there isn't too accurate.

I am also thinking about doing the B & M transpak to the 727.

To show you whats on there now, they are 15x? I think 8, with a wide profile.

 

That is a lot of torque to get to the ground through a small tire. I would definitely go with posi since you plan on being mostly on the street. With that kind of power and tire size I would stay around 3.25, depending on the rear axle that you have. That will still give you plenty of good gearing for street driving but enough top end as well when it comes to the strip. If you were looking at a larger size tire (like 28" or so) then I would say go with 3.45 to 3.55 gearing. 26" tires are a little small for that kind of power in my opinion. I would see about getting the widest tire possible though to get the best foot print on the pavement.

 

I got to figure out what the max size is before I get to involved in picking a tire, but I am going to pick the 17" rim. So should I go with the 11" or the 9.5" wide in the back, and 8" in the front, I am trying not to get it to look too extreme.

So what is the rev, and backside for example:
427P-Custom 17x11 Rev
1.25 – 4.00
427P-Custom 17x11
4.75 – 7.50

 

I was just looking around at other Cordobas and saw one with 265/35-22, which is a diameter of 29.3, and they say they have no lift. So they gives me multiple possibilities, which I think I will go with ?/40-17 with an 11" wide in the back, but not sure on the BS, saw one with 285/40-18 10" wide that said they should rather have used 5.5" BS. The same one had fronts with 245/45-16 8" wide, but they would have rather had 17"s with 4.5" BS, but I will keep the rim size in the front same as the back at 17".

So how big can I go with this combination, I couldn't figure this out if there were any bigger then 285, but then what to use in the front to keep them from looking like little tires, and to keep it good on the street?

 

I would go with the 17x8 up front and the 17x9.5 out back. As far as BS goes, I have no idea. I do know that if you have the middle of the tire on over the hub where the wheel bolts onto it, it will be a little easier to turn the wheel. As far as the back goes, see about a 265 to 285 tire. This will give you a nice wide contact patch on the pavement. As far as how tall, you'll have to do some meassuring.

 

That makes sense to me with centering it over the wheel, I really hadn't thought about that before.

I think that sounds like it would work well, 285/40R17 in the back with 9.5" wide rims, and the 245/45R17 in the front with 8" wide rims should have them look relatively the same from the side. The front will have a 4.34" profile and the back 4.48". It will have the nice slope to the front look, but not look crazy with different wheel sizes, plus its got the the stock air shocks that I can adjust too.

So with this combination in mind I should look between a 3.4-3.5 ratio?

 

your looking at a 25.9" tall tire. I would stay in the low to mid 3s, say 3.20 to 3.50 (max). you don't want too tall of a gearing so that when your going down the highway your doing 3000 RPM. I'd probably stay around 3.25 with that in mind.

 

Ok sounds good, next step to figure out what I got in there now.

 

Not sure which thread I had posted this in, but figured I'd hijack my own.

For the stall converter I need a new flex plate for the steel crank (internally balanced) TCI makes two one with 5/16 bolts (large bolt circle, 145700) and one with 7/16 bolts (small bolt circle, 1452000). The one with 7/16 is rated better, but which one is stock configuration for a 73 steel crank? I can look at the crank later this week when I get the engine back from the machine shop, but I don't know if that will help with the size of the bolt circle.

 

Ok, if I wrote down the number (3723599) off the bottom of the differential it is a 8 1/4, not the 8 3/4 I hoped for. I did find that it could be a 9 1/4 as they used them in Cordobas as well, the site I found said either 8 1/4 or 9 1/4.

Anyone have an opinion on the 9 1/4, or if I will run into problems if I use the 8 1/4?

 

The 8 1/4 will not hole up to a 440. Heck they don't even hold up to a 360.

If you have a 9 1/4 to swap in, I'd go that way. I have a 9 1/4 in my dakota from a durango R/T and love it. I never have to worry about it. It was originally gonna go behind my 383 in an 85 D100 that I had a while back and I was not worried about that.

If you can't find an 8 3/4 to put in then put in a 9 1/4. The 9 1/4 is pretty equal to a dana 60.

 

I found an 8 3/4 on Craigslist: http://philadelphia.craigslist.org/pts/922066695.html

Not sure what they go for, but I did e-mail him for some more info. I guess I also need to find out the width for my car, which would require the same method to measure them.

 

I am not sure what it is out of, but doesn't appear on that chart dart cuda posted, and according to that chart 57.8 is the flange to flange for the Cordoba. Hopefully it is out of a 71-74 B body as that would appear to be a direct fit.

 

I got a question about a rear a buddy of mine has, it is in an 84 Fury Interceptor I am assuming this won't fit, but it is not on that chart.

 

The the leaf springs and everything line up?

Sounds like a fun project you got there, hope you don't run into the same problems I have been asking about here.