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351 or 302?

  • Thread starter Thread starter brandywine_pony
  • Start date Start date Jun 30, 2010
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brandywine_pony

New Member
Jun 30, 2010
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Spokane, WA
Jun 30, 2010
#1
  • Jun 30, 2010
  • #1
I'm looking at a '66 convertible (project). It has a 351w and a C4.

My first question is, if I want to make this a daily driver (for the summer at least, as we get a fair bit of snow here 'round wintertime), would it make sense to track down a 302 for the gas mileage, and maybe a 4bbl carb for some extra oomph?

And secondly, how tough would it be to throw in a 5- or 6-speed? Normally I'd just wait til one showed up that already had the 302/5-speed set up, but the price on this is just too good ($8400, runs and drives).

Any input in addition to this would be welcomed. Thanks so much for your help!
 

Rusty67

20+ Year Stangneter
Dec 3, 2002
3,749
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109
LA, CA
Jun 30, 2010
#2
  • Jun 30, 2010
  • #2
Nothing wrong with a 351. You can provably get the same gas mileage out of it that you can get out of a 289 or a 302 as long as you don't sink your foot into the floor all the time.
 

Wildbill3

New Member
Jun 10, 2009
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Jun 30, 2010
#3
  • Jun 30, 2010
  • #3
Thers alot of threads posted on the 5 speed conversion also do a serch,sounds like a nice car any pics?
 
1

1968-coupe

New Member
Mar 28, 2010
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Deep East Texas
Jun 30, 2010
#4
  • Jun 30, 2010
  • #4
Honestly you wont get enough better fuel mileage to make the swap, unless you trade even and spend nothing on the swap you will lose money. Say you spend $1,000 swapping to a 302, thats 384 gallons of gas at $2.60. Lets say you get 20mpg. 16 with the 351. Thats a 4 mpg difference, and it would take a LONG LONG time to save the money you spent swapping, evern longer to see and savings from it. 351 is a good engine, more torque, if it runs good leave it in the car.
 
2

2+2GT

10 Year Member
Apr 25, 2009
3,333
10
79
Southeastern Pennsylvania
Jun 30, 2010
#5
  • Jun 30, 2010
  • #5
True. I'd reckon 5-10 years to break even on the cost of the changeover vs. price of gas.
 

mudbilly

Member
Jun 3, 2005
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South County, Maryland
Jun 30, 2010
#6
  • Jun 30, 2010
  • #6
the 5/6 speed might be worth it, if you do alot of highway miles.........??
 

Rusty67

20+ Year Stangneter
Dec 3, 2002
3,749
37
109
LA, CA
Jun 30, 2010
#7
  • Jun 30, 2010
  • #7
A 351 will eat most basic T5's for lunch. You may need a T5z for it to hold up.
 

tx65coupe

Active Member
Nov 29, 1999
1,551
1
37
Jul 1, 2010
#8
  • Jul 1, 2010
  • #8
Since its an automatic car, you could also do an AOD conversion. Either way I will also vote for an OD transmission swap.

I would keep the 351 since its already there. I doubt you would see much if any mpg difference with normal cruising.
 
6

65coupe408w

Member
Mar 26, 2010
192
0
16
Jul 2, 2010
#9
  • Jul 2, 2010
  • #9
my 408w which isnt exactly built for economy still pulls 18mpg on the highway with a T5...thats with a 3.70 gear
 

68stang351

Founding Member
May 16, 2002
850
9
39
Savoy TX
Jul 2, 2010
#10
  • Jul 2, 2010
  • #10
I recommend the 351w (obviously). If you use a 302 you will always wonder how it would've run with a 351. I have a 351w and a T5 in my 68 and to be honest, it really isn't bad on gas at all. That engine barely has to work to move a car that light around, and with overdrive it's even better. I barely touch the pedal in normal driving.
 
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brandywine_pony

New Member
Jun 30, 2010
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Spokane, WA
Jul 7, 2010
#11
  • Jul 7, 2010
  • #11
thanks, everybody! i appreciate all the responses!
 
B

brandywine_pony

New Member
Jun 30, 2010
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Spokane, WA
Jul 7, 2010
#12
  • Jul 7, 2010
  • #12
something else just occurred to me - with the additional torque from a 351, would it be in my best interest to beef up the frame if this hasn't already been done?
again, thank you all!
 

tx65coupe

Active Member
Nov 29, 1999
1,551
1
37
Jul 8, 2010
#13
  • Jul 8, 2010
  • #13
I would stiffen up the chassis with either setup. I would go with one piece export brace, a monte carlo bar, and subframe connectors.
 

68stang351

Founding Member
May 16, 2002
850
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39
Savoy TX
Jul 8, 2010
#14
  • Jul 8, 2010
  • #14
tx65coupe said:
I would stiffen up the chassis with either setup. I would go with one piece export brace, a monte carlo bar, and subframe connectors.
Click to expand...

+1.

That's what I put on my 68, and it definitely stiffened it up a lot.
 
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