Thread: Un-Building my Mustang

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Some of you may remember me talking about the 77 Mustang II I built before joining the site. I had hunted for several years for a nice Mustang II Coupe to drop a 351W (mildly built with Edelbrock heads and a few other goodies) and 4 speed into. Well I had finally found a rust free one with a blown up 302, C4 and 2.79 open rear end. It had nice paint and new interior so in went the 351, OD 4 speed and a 3.00 Posi. I used it as a daily driver until I got the El Camino done a little over a year ago when I just parked it.

The wife has been driving her 74 Mustang II all along, but the little 2.3 is about on its last legs and there are some other issues with it. It was/is a decent around town car but really not all that great on the highway. Even though I could go thru the 2.3 and take care of the other things it would still be an under powered 2.3. I mentioned week that it was probably about time to start hunting for something else for her. I was informed in no uncertain terms that she wanted a Mustang II.

Simple solution right.....toss her the keys to my 77 and park the 74. One problem she does not drive a stick (and believe me I have learned there are some battles you do not fight).

So over the next couple of months I’ll be finding a C4, and reinstalling the 2.79 open. I’ve got some future plans for the Edelbrocks, so I took a set of stock heads over to the machine shop Friday. It won’t be as much fun for me to drive, but I won’t get much of a chance to anyway but I guess it beats it just sitting in the back shed.

I always thought that was a bad move,when those poor little things got a 4 cyl..But at least theres enough room for a healthy Windsor..hmm,,sounds like a 347 stroker and auto for your wife....

The problem with her car being a 74 is that the core support (along with the hood and front valance) are a bit different and one year only. On the 74s you can have a V8 or you can have Air Conditioning but you ain’t going to have both. If it could be done I would have stuffed a V8 in hers a long time ago.



To a certain point I almost wish we had kept this ticket magnet, (this was Donna’s before I did the 74 for her).

It's been quite some time since I've seen a couple MII's! And those are some good looking examples. Was it a fun car to drive with the 351? I had one with a 302 and the frame/uni-body twisting was terrible. I can only imagine the added horsepower making things more interesting.

With gas going to 4 dollars a gallon, (maybe 5 we're hearing) that 4 cyl. might look better and better... 8-)

Mike, out of curiosity why are you going to the trouble of switching back to the open 2.79's over the posi 3.00? It's only about 100 to 150rpm difference at cruise, right? Just wondering...

".....I had one with a 302 and the frame/uni-body twisting was terrible....."

I've seen guys pop the hatch glass on the fastbacks on a hard launch. One of the reasons I always liked the Coupe over the Fastback is they are quite a bit more rigid. I also added some extra X bracing behind the back seat and built under the hood bracing to replicate the factory T Top braces which helped quite a bit. The tires are also very conservative to they really never bit that hard.

As far as mileage on the highway at 75 MPH the 351 coupe did better than the 2.3 coupe. They both have 3.0 gears but with the 2.3 runs a C3 automatic and a bit shorter tire and only managed around 20 (and was working itself to death especially with the AC on). With the OD in the 351 powered one it was just loafing and gets around 24-25 MPG.

I’d considered putting an AOD instead the C4 and gear change in the coupe, but there would be a fair amount of trans tunnel mods to make it fit. With any luck, it will still be around 20 MPG when I’m done though. I am really curious to see that going to happen going back to stock heads.

Roger you’re right about the RPM, running it thru the calculator it’s only about a 200 RPM difference.

The real reason for the change is after seeing my wife on a slick street with a posi rear end I can assure you it is not a pretty sight.

I have both 3.0 and 2.79 open chucks so I figure I might as well go with the highest ratio (as far as I know 2.79 is the highest ford made for the 8” ....otherwise I throw in something like a 2.4-2.5 especially with the short tires.



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Originally Posted by Mike P

The real reason for the change is after seeing my wife on a slick street with a posi rear end I can assure you it is not a pretty sight.
I have both 3.0 and 2.79 open chucks so I figure I might as well go with the highest ratio (as far as I know 2.79 is the highest ford made for the 8” ....otherwise I throw in something like a 2.4-2.5 especially with the short tires.

Yeah, I did not change the tire OD in my Excel spreadsheet, just looking at an approximate rpm change with the gears, and questioned the value of the added labor, which is really not much labor at all. So is it better to have the RR spinning on the slick street? I guess that the posi would tend to kick the rear end out and get it started fishtailing, huh? Had not thought of that aspect

I think the stock heads and automatic will make it a lot more driveable, Mike! I can imagine what a posi is like down there on the roads when it does rain, had a similar experience many years ago when Jackie decided she wanted to drive my Maverick (408, 4 spd, posi) once in awhile--til one of the days she drove it too work and it was a light rain when she left and 180'd the car pulling away from a stop sign at her usual brisk pace!!!!!!! She went back to driving her Caprice to work after that!

Yeah Dave, Donnna pretty much managed the same thing under the same circumstances in the little red Cobra II. If she hadn't I probably wouldn't be doing the swap.

Originally Posted by Mike P

".....I had one with a 302 and the frame/uni-body twisting was terrible....."

I've seen guys pop the hatch glass on the fastbacks on a hard launch. One of the reasons I always liked the Coupe over the Fastback is they are quite a bit more rigid. I also added some extra X bracing behind the back seat and built under the hood bracing to replicate the factory T Top braces which helped quite a bit. The tires are also very conservative to they really never bit that hard.

As far as mileage on the highway at 75 MPH the 351 coupe did better than the 2.3 coupe. They both have 3.0 gears but with the 2.3 runs a C3 automatic and a bit shorter tire and only managed around 20 (and was working itself to death especially with the AC on). With the OD in the 351 powered one it was just loafing and gets around 24-25 MPG.

Yeah, after jumping on mine once the doors wouldn't close right. Took about 3 days for it to settle down. That's good news about the mileage w\351! You know I'll be watching this when you get started.

Yeah, I'm wondering what the changes will do overall too. It was a fun little car to drive (and fooled a lot of people too ).

I'm figuring the mileage at 75 will probably drop to around 20 without the OD, but I really don't see too many long highway trips in it's immediate future, mostly 65 MPH secondary roads and around town driving.

I stopped by the local wrecking yard this morning to check and see what they had for C4s and to pickup an automatic brake pedal. I was really hoping to find something with a C4 I could throw some seals in and put it under the car. It sure wasn't like it was even 10 years ago......it looks like there will be a C4 rebuilding session in my future.....I also found out I don't fit under the dash of a Mustang II like I did 10 years ago

On the bright side I think I mentioned in my 37 Dodge build thread that when I bought the Dodge the PO had put a Mustang II rear end under it (the first thing I replaced when I got it home). When I pulled it apart yesterday to get the third member I found it had been completly gone thru.....new brakes and hardware, drums turned, new axel bearings, and new carrier and pinion bearings.

Well it’s probably time for an update. I’m not as far along with the Mustang as I figured I’d be by now. I’ve been top coating the roofs, installed a couple of skylights in the office, getting the swamp coolers going etc etc.

I got the Mustang out and did a final drive with the good parts.....man it’s a fun little car with the 4 speed and the way it is (was) set up.

I got the heads back from the machine shop and they are currently sitting on the shelf waiting to go on in place of the Edelbrocks. I had a few sets of stock heads laying around including some that would probably make almost as much power as the heads I’ll be taking off, but as this is for the wife I settled on a pair a 77 castings with the smaller valves and larger chambers as I’m thinking those might be a bit better for mileage (her concern, not mine LOL).

I got the Posi out and the open differential back in it. Of course it was a good excuse for another road test while the 4 speed was still in it (LOL)...... man did it ever turned into a peg leg wonder. As I have no immediate plans to build anything with an 8” and the shelf with the differentials and gears etc is already pretty full, I took the Posi to the swap meet and sold it last weekend to help cover some of the costs of converting the car.

The C4 is built and ready to go in. I didn’t have any luck finding a working used unit so I talked to by buddy at the tranny shop and he had good 1965 C4 core he built for me. The 65 was still a “Green Dot” tranny so in order not have to explain to the wife why she would need to drive in the D2 position instead of D, I just had him put in a 67 valve body so it would have the normal shift pattern.

Having fought building new cooler lines and installing them in car before, I decided to make it easy on myself this time and build a short pair of lines with couplers to put on the transmission before it goes up in the transmission tunnel.



I spent the last couple of days getting all the 4 speed stuff out..... and I’m glad I thought ahead when I built the exhaust and put a ball and socket joint in the head pipe when I built it as the pipe had to come out to get the bellhousing out. Changing out the pedals and pulling the clutch cable wasn’t a lot of fun 10 years ago and even less so now......but I did manage to still fit under the dash one more time.

I’m currently waiting on a new transmission mount to come in so it will probably be next week before it’s moving under its own power again.

Good plan on the lines, Mike. Detuning the mustang just goes against everything we've done over the years, huh????

"..... Detuning the mustang just goes against everything we've done over the years, huh????......"

You got that right Dave. I got the C4 in this week and put some miles on it. It's just not as near as much fun to drive. I also notice when I go to start it my left leg still hunts for the clutch pedal to push in

Next week I guess I'll get started on putting the set of stock heads back on it.

I already put the 4 speed stuff on craigslist, and will probably do the same with the Edelbrock heads once they are off. If they don't sell, I can live with that......I have engough stuff to put together another 351 and have been kind of thinking something like a first gen Falcon or Ranchero would be fun.


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