Build up 302 or drop a 460

Help Support 7173Mustangs.com:

Tataocb

Well-known member
Joined
Jul 11, 2016
Messages
67
Reaction score
0
Location
Houston, TX
My Car
1973 Mustang Convertible 351C 2v, auto.
I recently bought a 73 Grande with a 302 2v engine, auto tranny, power steering and A/C. I am in the process of rebuilding the carb because it wasn't really driveable with how the carb was performing. Anyways, I used to own a 69 Mach I with a 351w and 4 spd manual transmission, so the loss in power is noticeable. I am wondering whether it is better to build up the 302 or drop in a 460.

If I were to build up the 302 I would probably start by changing the heads to increase the CR. I would probably start with 351w heads as I do not want to start by spending $1k+ on heads. I would probably then look to change the intake and carb to go to a 4 bbl carb. Then possibly headers and a dual exhaust system. I would like to get some boom tube mufflers to make this loud. I would also upgrade to electronic ignition. I might even get a cam in there. I would take this one step at a time as I want to be able to still drive the car and do not have the money to get this all at once. Can you get enough hp/torque out of a 302 to compare it to a "not so modified" 460 just with bolt ons?

I have seen a couple of videos of the 460 and read that they are not too difficult to drop into one of our cars. I have checked CL and found a couple of 460 options. I am not sure of the hp/torque numbers on a stock 460 and I know it will depend on the year. I know there is a chance the 460 will also need an aftermarket intake and carb; and maybe even heads to get some real power out of it. Regardless of which option I go with, I would still do the dual exhaust as it currently has single exhaust system. So far, I found a restoration shop who will install a rebuilt 429 for $3500 and a 460 for $3000; or they sell the 429 for $1500 and the 460 for $1000. They are both disassembled and include block, crank, pistons, rods, heads, and intake. They are both early 70s engines according to they guy I talked to (hopefully they are not 72s). This does not include transmission. There is another person selling a 460/C6 combo out ot a motorhome with 40k miles for $750 (but it is a couple hundred miles away and still in the vehicle). Honestly, it seems like I could do a lot to the 302 with the kind of money the restoration shop is asking for.

I plan to keep all the current accessories including power steering and A/C. I will most likely use this car as a weekend cruiser or something to take to the supermarket, or to drive to work on Fridays. It wont be a race or track car, but I want it to put a big smile on my face anytime I hit the gas. Sorry for the long post. Any input or suggestions on the topic are appreciated from such a knowledgeable group of people.

 
Joined
Jan 7, 2015
Messages
8,032
Reaction score
490
Location
Western North Carolina
My Car
Multiple Mustangs!
Remember it is not just unbolt the 302 and transmission and drop the 429 or 460 in. Lots of other things have to change. The front springs are different for the BB cars, drive shaft, rear end, rear leaf springs, staggered rear shocks that came with competition suspension. Wire harness changes, radiator etc.. You need to search the forum there have been several that have done the swap I am sure. Members have put everything from 6 cyl. to Boss 429 and the new coyote engines in these cars. About anything will fit that Ford made in a 71 - 73 so lots of options. Some of the new engines and transmissions might be a better choice more HP and much better gas mileage but not just a simple swap either. Go to a totaled vehicle get engine, transmission and all the wiring and computers for sure. Can be much less cost than finding one of the old engines and building it and still have less HP and very poor gas mileage. It is only original once so if you change it does not matter what you do. It is your car and you are the one that needs to be happy.

 
Joined
Sep 19, 2010
Messages
1,675
Reaction score
50
Location
CT
My Car
73 Mustang Convertible
The cheapest course of action is to hop up the 302 but torque is where its at on the street and a warmed over 302 will never equal even a stock 460 for torque output.

Its all about what you want and what you want to spend.

 

Tataocb

Well-known member
Joined
Jul 11, 2016
Messages
67
Reaction score
0
Location
Houston, TX
My Car
1973 Mustang Convertible 351C 2v, auto.
I honestly had not considered swapping a more recent motor in there. I know in earlier Mustangs the strut towers need to be shaved and the suspension needs to be changed, but have not checked for the 71-73 models.

I thought since the car was already a V8, I would not need to change the suspension or the rear end. I will read some more on how others have done their swaps.

 
Joined
Jan 7, 2015
Messages
8,032
Reaction score
490
Location
Western North Carolina
My Car
Multiple Mustangs!
I honestly had not considered swapping a more recent motor in there. I know in earlier Mustangs the strut towers need to be shaved and the suspension needs to be changed, but have not checked for the 71-73 models.

I thought since the car was already a V8, I would not need to change the suspension or the rear end. I will read some more on how others have done their swaps.
Your car probably had the 8" rear in it. If you look under the car and the back center portion of the housing is a smooth sphere it is. If it has an offset bubble out it is a 9" and there are different sizes of U-joints in them and locking and not locking. The front springs have to be heavier to support the heavier BB engine. Pretty sure if a Boss 429 will fit that the new engines will fit also. I put one of the 4.6 SOHC Ford engines out of a highway patrol car in a 1950 ford and it fit in there. I also have seen the double cam motors out of the Mercury in them also. Had to cut the firewall to move it back far enough and changed the front cross member also. Not many engine swaps are easy and boom it is done.

The new engines put the old ones to shame on HP and mileage. Find a crashed new Shelby and you can push them to 1,000 hp with right upgrades and still be dependable and street able.

 

barnett468

Well-known member
Joined
Nov 3, 2014
Messages
1,097
Reaction score
10
Location
us
My Car
i have a collection of mustangs
351 heads wont gain you much power unless you at least port the exhaust.

if you use a bigger cam than stock or stiffer springs, you must either pin the rocker studs or install screw in studs.

 

red351

Well-known member
Joined
Oct 6, 2013
Messages
269
Reaction score
11
Location
Carlisle PA
My Car
72 mach 4sp PS AC PBdisc ramair started restoration in 1995 to 1999
460's from trucks or motorhomes are low torque engine and can go through a tank of gas faster than you can imagine. Good for rock climbing, not high speed performance.

 
Joined
Jan 1, 2012
Messages
8,171
Reaction score
928
Location
Springfield, OR
My Car
1971 Mustang Sportroof M code
Big blocks are good for a straight line, forget about nice handling and turning corners when the road is slippery. You'll find out what the NASCAR drivers are talking about when they say their car is tight.

You can always go 351 Windsor or Cleveland, stroke it and have plenty of power and torque, and still have a decent handling car.

 
Last edited by a moderator:
Joined
Dec 24, 2010
Messages
2,888
Reaction score
43
Location
U.S.A.
My Car
1972 Q code Mach 4spd
2004 350z
2005 Corvette
1971 Camaro SS/RS
Big blocks are good for a straight line, forget about nice handling and turning corners when the road is slippery. You'll find out what the NASCAR drivers are talking about when they say their car is tight.

You can always go 351 Windsor or Cleveland, stroke it and have plenty of power and torque, ans still have a decent handling car.
:goodpost:Best advice yet ..I had a 460 in my car with every aluminum piece you could buy..Ditched it for a 351 best move ever :D

 

Tataocb

Well-known member
Joined
Jul 11, 2016
Messages
67
Reaction score
0
Location
Houston, TX
My Car
1973 Mustang Convertible 351C 2v, auto.
Thanks guys for all the input. I finished rebuilding the carb, drove it around, and I definitely want some more power. I also own a 98 LS1 Trans Am (which I am trying to sell) and can definitely feel the difference (obviously the 98 is a lighter, more powerful car). The exhaust leak sounds bad. For now, I think I am going to focus more on the transmission and rear end before deciding what to do with the motor.

I found an ad for a 1980 F150 which supposedly has a 1972 351C 4v CJ motor, C6 tranny, and 9" "posi" rear end for $950. Sounds like a good starting point considering most of the built 351w I have found locally start at $2500. I know the Cleveland engine does not have nearly as much aftermarket parts as the Windsor, but still looks like an option to consider.

Is there a kit out there to swap an 8.8" rear into a 71-73 Mustang? It seems like a good option to get rear disc brakes.

What gear ratio is numerically too high for some highway driving and an original C4/C6? Anything over 4.0? If I am going to focus on transmission and rear end, maybe I should go with a T5 and lower gears? There are so many options to consider...

 
Joined
Sep 19, 2010
Messages
1,675
Reaction score
50
Location
CT
My Car
73 Mustang Convertible
Be careful when you go and look at so called CJ or Boss engines in late model cars or trucks. It often turns out they are actually 351M's or 400's which to the untrained eye can be difficult to distinguish.

 
Last edited by a moderator:

barnett468

Well-known member
Joined
Nov 3, 2014
Messages
1,097
Reaction score
10
Location
us
My Car
i have a collection of mustangs
3.25 is a good performance and highway gear for a non overdrive trans . add a 2000 rpm stall converter if it has a stock or slight cam if you want to spin the tires.

3.50 are the numerically lowest gears i use with a non overdrive trans for a car that sees a lot of highway/freeway miles

if the cleveland has open chamber heads, they are not ideal.

 
Last edited by a moderator:

Tataocb

Well-known member
Joined
Jul 11, 2016
Messages
67
Reaction score
0
Location
Houston, TX
My Car
1973 Mustang Convertible 351C 2v, auto.
I have found a complete 460 D1VE block engine (don't know head castings), supposedly off a 74 Torino, for sale for $300. It probably needs to be rebuilt as it is partially dissasembled, with the heads still on, but everything else has been removed. It includes manifolds and alternator/power steering pump, but no carb. Quick question, will the AC Compressor and power steering pump from my 302 work with the 460?

I have seen a couple of late 80s/early 90s 302 longblocks (already rebuilt) going for about $500. I am thinking one of these newer 302s will have a higher CR than my current engine, and is cheaper since a full rebuild kit usually goes for $500+ and I would need to add the machine work cost. I am checking on a couple of 351w as well.

 
Joined
Sep 3, 2015
Messages
634
Reaction score
50
Location
AZ
My Car
1972 Mach 1
1971 Ranchero
That 460 will be like night and day compared to your 302. You would prefer to have C8VE, C9VE, D0VE, or DO0E-R heads on that block. I mentioned the D0OE just in case...not likely they will be on it. The worst heads would be the D2VE's....they are both low compression and more constricted exhaust.

As for the compressor and pump...those items, in and of themselves, will work fine with the 460. As for the mounting bracket compatibility, someone else will have to answer that question. You'll also have to deal with crank and waterpump pulleys and a larger radiator.

 

Mister 4x4

Too Big to Sneak
Staff member
Administrator
Moderator
Joined
Aug 12, 2010
Messages
8,114
Reaction score
351
Location
San Angelo, Texas
My Car
1971 Mustang Mach 1
The biggest thing I've noticed with the other guys stuffing in 460s, is that they run short of options for performance parts that will actually fit into the car without great expense or modification [to the car]. Headers is one of the biggest issues, as well as getting the right motor mounts. They're out there, but be prepared to pay $$$ for the good stuff. Don't know what kind of budget you're looking at, so I just thought I'd toss that out there.

Like Scott mentioned, ditching the 460 for the 351C was actually an upgrade for him. Probably lost some weight in the deal, along with opening up more affordable performance options. Stroking a 351 to big-block displacement numbers is not a bad way to make power as well, is affordable, and keeps things manageable. I know rebuilding with a bunch of performance goodies and some minor machine work has my 351C-2V pushing somewhere around 400hp - not a bad upgrade from the factory rating of 245.

The only 'bad' thing I can see about the '72 Truck deal would be to make sure the axle width is right for the car - truck axles tend to run wider than car axles, as well as the spring perches might need to be relocated.

Same thing with the late-model 8.8 axles - a buddy of mine was only half-listening when I mentioned the possibility of upgrading to an Explorer 8.8 for his '66 coupe... now his 245/60R15s on 15x7 rims stick out a full 2" on each side in the back. The 8.8 might need some narrowing, or you might be limited to late-model style wheels with more positive offset/back spacing.

Lots of things to consider. Good luck and have fun with it.

 

Hemikiller

Well-known member
Staff member
Moderator
Joined
Jul 12, 2010
Messages
3,649
Reaction score
901
Location
Killingworth, CT
My Car
71 Mach 1
65 coupe
Simplest upgrade is to go to a 351W or 351C. Just about everything from the 302 will work, sans maybe a couple accessory brackets.

I found an ad for a 1980 F150 which supposedly has a 1972 351C 4v CJ motor, C6 tranny, and 9" "posi" rear end for $950. Sounds like a good starting point considering most of the built 351w I have found locally start at $2500. I know the Cleveland engine does not have nearly as much aftermarket parts as the Windsor, but still looks like an option to consider.
351C didn't need a whole lot of aftermarket parts to make horsepower. There's a lot more available now than there was even just 5 years ago.

I would seriously investigate the truck, for $950 that doesn't sound like a horrible deal if it's a good runner and is actually a 351CJ.

 
Top