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I have the opportunity to pickup a 460 for dirt cheap. My '71 Mach 1 is an M code 351C with CC heads. If you had a choice which would you build for the '71? Any one been in this dilemma? I would be mating it to a 4 speed. 

If you ain't learning, you ain't living. 

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Most 460's are truck engines and built more for torque than horsepower, so you probably wouldn't get a big horsepower gain. If you go to a 460, you should also change the transmission to one with big input and output shafts, and the tail shaft would have to be the right length for a Mustang. The driveline yoke will be different for the big output shaft. You'll need a different radiator, and should go heavier front springs for the extra weight. If you have Ram Air, the air cleaner is different, IIRC. For no real horsepower gain, putting the extra weight on the front end, which will affect handling, and the expense of changing everything else out, I wouldn't bother.

 

Steve

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X2 on the Cleveland. The 460 is much heavier, the car should feel more balanced with the 351. That said, it depends on what YOU want to do with the car. If handling type performance the 351 for sure. For straight line performance it's a toss up. For a fun summer car, it's whatever floats your boat. 

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[align=left]Jeff T.

 

When I die I want to die like grandpa, peacefully in my sleep... not screaming, like his passengers. [/align]

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Keep the Cleveland. With all the money you save from changing everything over to fit the 460, you can put that into the 351. 

John - 72 Q Code

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I'm definitely not up on big blocks, but yeah for sure I would love a 429/460 in my Mach 1 instead of the M code, but there is something I recently learned and something you may want to consider if you plan on using your existing 4 speed box. I'm not saying you can't use that box, but the 429's use a RUG-AZ1 box with 1 3/8" input shaft. It is listed in the Marti Tag book plus I saw an ad on Kijiji in Ontario for a RUG-AZ1 box for sale for $1700 Cdn. It is also a close ratio gearbox. No idea if the bell housing is any different, something else to check on.

If too much, for sure keep the M code.

Geoff.

 I learn something new every day!

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I like going fast as much as any, and more than most, and like the power (torque) of a big block. However, I also like a car to handle well. Even with an M code the tail end of these cars is light, would be even more so with a 460. You can take the cost of converting to a 460 and build a 408 stroker that will rival the power of a 460 with stock heads, and still handle curves fairly well. That said, if you're going to build up the 460 with Kaase heads, I'd like to go for a ride with you when you're done.

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“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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Only way i would go with a 460 is if i was gonna do as Don said and slap on some Kaase  Boss 9 heads and build something crazy.  Otherwise, i am getting around 500ft lbs of torque out of my 408 Cleveland stroker  and 600hp.   Its fun to say the least. 

Kevin
1971 Mach 1

408C Stroker - C4 w/3,000 stall - 8.8" Rear w/3.73's - Disc brakes all way around.

 

 

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1 minute ago, turtle5353 said:

Only way i would go with a 460 is if i was gonna do as Don said and slap on some Kaase  Boss 9 heads and build something crazy.  Otherwise, i am getting around 500ft lbs of torque out of my 408 Cleveland stroker  and 600hp.   Its fun to say the least. 

................ and costly on tires too!

Geoff.

 I learn something new every day!

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I did the 460 (it was already built at the time and 351c was out to repair rear main leak and pull bad C6 anyway..).  429 mounts, 429 PI exhaust manifolds (simplicity, but better flow than 71 460 manifolds), had a big spline Torino toploader on hand already too.  Used the 71 Lincoln Mark 3 radiator and the 351c PS pump bolted to the Lincoln brackets. Install was not complex.

Standard smaller spline 4 speed is tough, but will be taxed similarly with either a stroker or a 460, so isn't a big factor between the 2 options presented, idt. If jacking up a 351c to approach 460 torque outputs, then similar power load either way.

Weight factor can be minimized with aluminum intake and aluminum 460 heads, moderate or high-buck versions.. Aluminum radiator and water pump if so inclined..

Downtime?  A year or more?  If the 351 is driveable now, it won't be once a stroker project is undertaken.  With the 460 you can continue to drive the 351 continuously until 460 is ready and you have acquired any needed conversion parts. And you can change your mind in the interim if you want...

Cost?  460 build with aluminum heads is probably in the same ball park cost-wise as a good stroker, but with likely more durability/longevity.

Keep the original 351c to sell with the car when the time comes (it will..).  The 351c is one of my favorite motors. I have 3 of them. But the bolt-in aspect and large engine bay built to take the big block has an appeal and ease that swapping a 460 into most other cars just does not approach.

 

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4 hours ago, Don C said:

I like going fast as much as any, and more than most, and like the power (torque) of a big block. However, I also like a car to handle well. Even with an M code the tail end of these cars is light, would be even more so with a 460. You can take the cost of converting to a 460 and build a 408 stroker that will rival the power of a 460 with stock heads, and still handle curves fairly well. That said, if you're going to build up the 460 with Kaase heads, I'd like to go for a ride with you when you're done.

+1 Build a 408 stroker out of the Cleveland.

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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I for one totally vote for the big block build idea... because I am so selfless and supportive I will happily come take that lame 351C with CC heads off your hands...

 

[sarcasm obviously... I love the Cleveland]

 

 

Lazarus

 

9-C51-EEB4-A25-A-4-F27-8-D01-0-EB879931296.jpg

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I would build the 351C with the CC heads and existing 4 speed. The stock 460 heads do not flow well as cast, the 351C do flow well as cast. The 351C is about 150-170 pounds lighter (all iron vs. all iron). The front to rear weight ratio is not great with the 351C but worse with a 460. Cubic dollars can improve both engines but the 351C M code has good heads and a decent intake (match the primary bores to the secondary and use a .5 inch open spacer). Unless the car was an original 429 cj/scj, the only time I'd use the 460 block is if I was going BIG and had the budget to buy all the good parts to take advantage of the cubic inches. You could buy the 460 "dirt cheap" and resell it for a profit to help finance the 351C build. This is just one gear head's opinion. It is your, car do what makes you happy. Good luck with whatever you build. Chuck

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I'd go big block.I'm building a Boss 429 powered 71 Trans Am Mach1.So yes,big blocks can go round corners too.

 

Edited by 71Rustang
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23 hours ago, rvrtrash said:

Most 460's are truck engines and built more for torque than horsepower, so you probably wouldn't get a big horsepower gain. If you go to a 460, you should also change the transmission to one with big input and output shafts, and the tail shaft would have to be the right length for a Mustang. The driveline yoke will be different for the big output shaft. You'll need a different radiator, and should go heavier front springs for the extra weight. If you have Ram Air, the air cleaner is different, IIRC. For no real horsepower gain, putting the extra weight on the front end, which will affect handling, and the expense of changing everything else out, I wouldn't bother.

 

Steve

I think after everything I'll stick with the 351C. I plan on stroking it to 393. The 460 is an 1988 block which apparently is not too good to start a build with. 

If you ain't learning, you ain't living. 

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