Im new to all this and i dont know too much about cars yet. Im trying to convert my car to a V8 but i dont know if i HAVE to switch rear-ends from the 8" to the 9" or can i just change the axles.
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The factory rearend for 66 inline sixes cannot handle a V8. You can go with either an 8" or 9" rearend. Most 9"s will need to be cut to fit the 65/66 width. The 8" can handle a lot of power and is lighter...just a suggestion. What transmission are you going to put behind the V8 and what size V8 are you dropping in?
The idea i have is to get a 302 engine from a 88 to 92 fox body and the keep AOD transmission that it comes with. So i will have to get a different rear-end for my car
Firstly you don't have a V6 (unless someone has swapped it in) you have an I6, and you need a solid plan on what you want to do and how much you have to spend. But you will need engine, trans, wiring, suspension, rearend, springs, fuel lines, steering, hubs, wheels, drive shaft, and a ton of other stuff.
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Mike
I've had 60 cars....most of them Mustangs :-)
you also need to have a budget in mind will you be leavin the 5.0 stock doing new heads injectors figure out how much you are willing to spend on the project before diving in (im working on a simular swap into my car and the car is now 8000 over the original budget I planned lol
Before you go through all the trouble of switching form a I6 to V8 take a look over at fordsix.com and classicinlines.com. They carry a lot of good stuff and good info for the inlines. Beside the is more to a V8 conversion than changing out the engine and rear end.
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Dare to be DIFFERENT. Stay INLINE
1966 Mustang Vert., 200 CID I6, Autolite 1100, Candy Apple Red, black interior with black power top, C4 Auto Trans (was 3 speed manual), Scarebird 4 lug front disc brake conversion, dual MC in process.
1976 Cobra II, 302 CID, C4 auto trans. Blackjack headers, white with blue stripe and blue interior. Restoration and mod in process.
Changing the rear end is not a must. I had a 351w in my 68 with the 7" rear for a long time with no trouble. If you want to go 5 lug, you have to change the whole thing though. I have never seen 5 lug axles for that rear end. If you change the rear to an 8" or 9" you will have 5lug in the back, so you will need to change the front brakes to have 5 lug in the front. On the 65/66 the v8 spindles are different than the 6cyl, so you will need to change the spindles while upgrading the brakes. Or you could just leave it all 4 lug. Must changes are the motor and frame mounts, radiator, and the exhaust. A front suspension upgrade would be a good thing to do too. If you change your spindles, you may as well put some v8 coil springs on there. The added weight of the v8 will make the 6cyl suspension float around a little.
I am not too sure but i think the rear end on my car is a 9" i looked at some websites about how to tell and my rear end has a hump on it. Any other visual things i can look at to tell the difference in rear-ends. Also, i want to rebuild the rear seats that i got but not too sure what kind of foam to use.
What areas of the rear seat need building up? Dad and I used foam from a cloth store and an electric kitchen knife to fill in the sides. Make sure you do not put too much or it will be difficult to stretch the upholstery over the sides.
I want to put new foam in it and of course upholstery becasue if not i will have beige front seats and blue and white back seats . Do you have to get the front seat seat foams for it?
+1 on the Classic Inline. I'm currently working on hopping up my i6, looking to put on their aluminum cylinder head within the next year.
Although I admit I have been thinking about going completely mad scientist and putting a V8 from the 05-09 line in it. The engine isn't that much bigger than the 302 Boss. Probably just needs the shock towers shaved.
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1966 Mustang V6 to V8 Conversion 
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