Need some engine advise

Heardatbeat

Well-known member
Joined
Nov 22, 2016
Messages
162
Reaction score
4
Location
Washington
My Car
1971 Mach 1
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. 

 

rvrtrash

VIP Members
Joined
Aug 28, 2011
Messages
656
Reaction score
34
Location
Spirit Lake, Id
My Car
1971 Boss 351, 1969 Fairlane 500 Conv., 1965 Sunbeam Tiger
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

 

turtle5353

VIP Members
Joined
May 15, 2011
Messages
3,417
Reaction score
244
Location
PA
My Car
1971 Mach 1 Mustang
Stick with the Cleveland! 

 

droptop73

VIP Members
Staff member
Moderator
Joined
Jul 5, 2010
Messages
6,381
Reaction score
178
Location
Grand Rapids, MI
My Car
73 Convertible
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. 

 

jpaz

VIP Members
Site Supporters
Joined
Dec 28, 2014
Messages
2,588
Reaction score
240
Location
Washington Twp. Mi
My Car
1972 Mach 1 Q Code
Keep the Cleveland. With all the money you save from changing everything over to fit the 460, you can put that into the 351. 

 

7173Vert

Well-known member
Joined
Sep 14, 2018
Messages
846
Reaction score
189
Location
Ontario
My Car
1971 Convertible, 1973 Hardtop
Nothing like a Big Block...

 

Stanglover

VIP Members
Site Supporters
Joined
Sep 12, 2015
Messages
5,394
Reaction score
616
Location
SW Ontario
My Car
1971 Mustang Mach 1, M code, 4 speed.
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.

 

Don C

Fords Forever
Joined
Jan 1, 2012
Messages
7,893
Reaction score
685
Location
Springfield, OR
My Car
1971 Mustang Sportroof M code
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.

 

turtle5353

VIP Members
Joined
May 15, 2011
Messages
3,417
Reaction score
244
Location
PA
My Car
1971 Mach 1 Mustang
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. 

 

Stanglover

VIP Members
Site Supporters
Joined
Sep 12, 2015
Messages
5,394
Reaction score
616
Location
SW Ontario
My Car
1971 Mustang Mach 1, M code, 4 speed.
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!

 

brushwolf

Active member
Joined
Oct 19, 2017
Messages
36
Reaction score
4
Location
Minnesota
My Car
73 Fastback Mach clone, 466, CJ Toploader
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.

 

tony-muscle

Well-known member
Site Supporters
Joined
Aug 14, 2014
Messages
3,360
Reaction score
365
Location
Madison, WI
My Car
1971 M-Code Mach 1 w/408C stroker
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.

 

Lazarus

Well-known member
Joined
Mar 19, 2019
Messages
188
Reaction score
69
Location
NC
My Car
1973 Mustang Convertible 302
1972 Mustang Convertible 351-2V/TKO600
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]

 

c9zx

VIP Members
Joined
Sep 30, 2010
Messages
5,337
Reaction score
272
Location
Mustang, OK.
My Car
1972 Mach 1 Q code
2007 GT
1969 Cougar Eliminator B302
CSX 7000 Shelby Cobra FIA
2020 Edge ST
2002 F250 V10
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

 

71Rustang

Well-known member
Joined
Mar 15, 2012
Messages
189
Reaction score
125
Location
Pennsylvania
My Car
71 Boss 429 Trans Am ,race car
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.

 
Last edited by a moderator:

Heardatbeat

Well-known member
Joined
Nov 22, 2016
Messages
162
Reaction score
4
Location
Washington
My Car
1971 Mach 1
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. 

 
Top