I keep seeing early/mid 70’s Thunderbirds with 429’s and 460’s in them, for sale. Some of them go really cheap because they have issues of one sort or another. I have this idea of picking one up for stupid cheap, like $1k, maybe $1.5k tops, and pulling the engine and trans to put em in my '68 Cougar.
First off, I know this is way beyond the scope of what I can handle on my own, like by a mile. I do have access to a couple guys that know cars well enough and have the equipment required to do stuff this involved. So my question becomes…
Will the 429/460 fit in a '68 without any major modifications? Or is it too involved to even really think about? New suspension, right? And my C4 won’t cut it, so I’d need the C6 from the T-bird also… is that a drop-in replacement? The other parts I’d need, can I get em from the T-bird? Or do I need to get a whole different drive shaft and etc? If the T-bird has a 9" rear end, can that come along for the ride? Or are there axle length issues coming into play?
I’m assuming there are too many factors to make this work easily. But exactly how difficult is it? Tremendously?
And then there’s the other question, even more important so I saved it for last… Is the 460 a better engine than the '68 302 4V in the first place? Sure it’s bigger, but is it actually better? More or less reliable, more or less power, and I’m not even gonna ask I’m just gonna guess worse fuel economy right?
I’m guessing it’s a dumb idea, but heh, I gotta ask.
Read that one and another I found using the Google. Neither makes mention of fuel economy, I have to assume it’s noticeably worse, no? The other one they did a bit of a rebuild, lotsa new parts in the engine, and were able to coax over 500 HP and 500 ft lbs of torque out of it (dyno, of course) which sounds pretty impressive. The stock rating of the engine doesn’t sound so amazing. Thoughts on that?
T-birds and Lincolns of the mid-70s use a c-6 with a longer funky tailshaft with a v-shaped rear mount. How do I know? Funny you should ask…
Back 25+ years ago, I had bought a '78 Country Squire with a clapped-out 351M/FMX/8.5" integral rear (similar to an 8.8"). Basically, I bought it just for the body. I found a cheap used 429, and a ‘it fell off the truck’ factory new C-6 and converter with a Livonia transortation plate bolted across the front that held the converter in place… Trans was a D2SE… it had the funky tailshaft and v-style mount. Well, I made it work. Also found a 3.00 ptraction lock 9". I got the 429/460 LTD frame mounts from a junkyard, and the LTD C-6 trans crossmember. The mount I made for the trans sat about 4" back of the ‘normal’ C-6 mount and still bolted to the C-6 crossmember. Not the optimal or most elegant solution but it worked. I also had to shorten the driveshaft going from the FMX to the C-6 anyway, so it needed to be shortened another couple of inches to fit the longer T-bird/Lincoln trans.
Anyway, although a 429/460 can be made to fit an early Mustnag/Cougar, it is work! You’d be better off trying to find a 351W that not only fits better, but can also use your existing mounts and transmission - or if you feel ambitious and still want more power - stroke it! For the money you’d spend to convert to a 429/460, you can build a killer stroked 351W! It’d be a couple hundred pounds lighter, to boot!
About fuel economy… I’m not so dumb that I’m thinking “how can I increase my fuel economy… Hmm… Oh I got it, an engine with 50% more displacement!!!”
I’m doing what the kids these days call cost benefit analysis. For example, if the 460 is gonna crank out double the horsepower and almost double the torque, and the fuel economy is going to be about 5% worse, then “hot damn!”. But if the 460 is gonna give me about 10% increase in HP and torque, but 50% worse fuel economy then “hell no!”.
I’m just looking at a possible alternative, comparing it to the “no action” scenario, and then making an informed decision from there, all while trying to identify and take into account all the relevant variables or areas of interest (cost, time, difficulty, performance, availability of parts, etc etc). It’s just how my mind works, which is a good thing since I do data analysis for a living.
If I wanted fuel economy an nothing else mattered, I wouldn’t even be looking at diesel, I’d be buying a Prius, or for that matter a bicycle.
In reality, I am torn between the “no action” scenario which is to just make my 302 4V run great, and two possible action scenarios, one where the 302 gets upgraded in some way(s), and another where the engine is swapped out for something else like a 428, 429/460, or whatever else presents itself as worth investigating.
As always, great input guys, and please keep it coming!
I’m not looking to open up that can of worms. If you stuff a 460 into a 3500 lb car, yes it’s going to be fast. And yes you can make a 460 perform, I’m sure that the Gearz Interceptor will prove that. But if bigger is always better, they would still be producing those engines. And just because you can do something, it doesn’t mean you should. If I had an unlimited budget and a shop with a million dollars worth of equipment, I’d probably build a V8 Interceptor myself. But for the average guy it’s all about the benjamins. If you want performance you can pull 600hp out of a 351W. That’s more than most guys would ever want in a car like a Cougar. And you can do that a helluva lot easier and cheaper than trying to go the 460 route.
I am running the 460 on 87 octane pump gas with a C6 and 3:25 rear gear. The C6 has the lower AOD 1st gear and 1:1 final drive. My highway trips to Carlisle I get about 16 MPG at 65 MPH. And I get to 65 VERY quickly.
Luckily Carroll Shelby didn’t look at the AC or Mustang and say “That 4 cylinder is fine in that little car and I can soup up the 302. No need to fit a bigger engine in either”.
With my 9.4:1 393W, I’m getting 480hp using 87-octane pump gas, and with 3.55 gears and the AOD I still get 15+mpg! A 4000-pound car that is almost in the 12s in the quarter-mile and still gets 15+mpg? Best of both worlds, I say! Tough to do that with a 460 even if you run one of those behemoth E4OD transmissions (or a stick w/ overdrive).
To answer the question about fuel economy - yes, you can impre economy by switching to a bigger engine. My race buddy’s 23’ Class C motorhome originally had a 351W that struggled to go up hills when towing an open trailer. He built a 501-inch stroked 460/C-6 and his gas mileage actually improved while increasing the towing ability… Oh, that mileage increase was from 7mpg to 9mpg. Not earth-shatteringly ‘economical’ by most standards, but that was a 20% improvement in mileage!! He’s thinking of putting an E4OD in there next…
Well looks like there’s a fine chance I’m gonna get to know the 351 anyway. 90-something percent chance I’m driving up to Michigan on Saturday to pick up a 2nd gen Bronco. So I guess the 460 is going to become less likely than a hotrodded 351, since I’d be able to share parts that way.