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Discussion Starter #1 (Edited)
Alright, at least a few of you would like to see the build of my 327 Miata. So, I'll keep the thread updated. The project started with a '91 Miata that I picked up cheap three years ago. I was commuting a long distance, and that little bugger got 30+ mpg even at a sustained 90mph. I bought it with 180K miles on it, and it now has 230K.....and is very tired. I pulled the drivetrain in preparation for the 327 conversion. I've include a shot from the rear with the new rubber. The one pic shows the old rubber compared to the new.
 

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Discussion Starter #4 (Edited)
I'm getting some of my pics organized to catch the thread up to where I am now. The 327 bottom end was donated by a friend of mine. The motor had eaten a cam, and was replacing it with a crate motor. I replaced all the bearings and had the crank polished. You could still see the hatching on the cylinder walls. The pistons are flat tops. The heads are 64cc Edelbrock Performers with 2.02 Intakes and roller rockers. I'm running a Isky 20 solid lifter cam. Intake and carb are both Edelbrock Performer as well.

I'm running a dual friction Centerforce clutch with hydraulic throwout bearing mated to a Muncie 4sp (M21). The drive shaft will be a couple of feet long and hook to a Ford T-bird diff w/3.27 gears. The diff is held in place by a custom hanger that hooks to the stock miata diff mounts. There is also a torque plate that is to be welded to the miata subframe. The axles are T-bird half shafts with shortened chromoly tubes. The miata hubs were broached to accept the T-bird axles.
 

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Discussion Starter #6 (Edited)
As I was building the motor, I discovered that the crank bolt that was used on this motor was actually a main cap bolt. The problem is that the crank threads should be 7/16-20 and the bolt was 7/16-14. I figure that someone used it to bind the bolt in the old damaged threads. It probably worked.....once. I fixed it with a helicoil, but it took a long time to tap those threads by hand. I suppose that it could have been done more quickly, but I was worried about breaking off the tap. Well, I got her together, and engine fit-up in the miata will probably occur this weekend. I'll check run-out on the bellhousing before I do too much more. I'm also considering setting up the engine, clutch, and transmission on my stand to properly shim the hydraulic throwout bearing before it goes in the car.

I used tape on the drill bit to indicate when I have drilled deep enough. It worked well. My cast tap handle broke......instead of the tap which is good. I switched to a crescent wrench and the tapping when much more quickly. The 327 is nearly together.
 

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Discussion Starter #11 (Edited)
I'm betting that new rubber will look like the old VERY quickly!!!
It will help that I am running the 3.27:1 gear, and I have a pretty tall 1st gear (2.20:1) in the Muncie. That puts me at 67mph when I hit second gear with a 6500rpm shift.

Yeah, solid cam and roller edit:rockers (1.6). No roller cam.
 

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How much more does the 327 weigh over the stock motor? where does the new motor sit in comparison to the front "axle"? I imagine that a bit of the extra weight is going to be forward of the axle, in an already light vehicle. I bet you'll suprise yourself at how easy it will be to break the rears loose (or how hard it will be to get them to not slip)


Travis
 

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Discussion Starter #17
How much more does the 327 weigh over the stock motor? where does the new motor sit in comparison to the front "axle"? I imagine that a bit of the extra weight is going to be forward of the axle, in an already light vehicle. I bet you'll suprise yourself at how easy it will be to break the rears loose (or how hard it will be to get them to not slip)


Travis
The whole conversion was going to be about 250lbs over stock evenly distributed between the front and rear with some of the difference being in the transmission and mount. With the aluminum heads I'm taking another 40 or 50lbs off the front (wild guess.....I've not weighed the cast iron heads). The rears are 10" wide, and I'm pretty sure that they are going to break loose pretty easily. I'm toying with the idea of some mounts near the diff where I can hang lead and experiment with weight vs. traction in the rear.
 

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Discussion Starter #20
So is the T-bird 8.8 diff swap a common swap for Miatas? That bracket looks manufactured, not home built.
The t-bird line used both 7.5 and an aluminum cased 8.8. Both can be swapped in the Miata. Some fabricate their own hangers. I bought mine from a guy in CA that makes them. The hanger accepts the stock (or is it stalk?:D) miata diff bushings, and saved me a bundle of time and probably material cost.

As for being common. It is not. There are around 200 V8 miatas running around the States. Most of those will have either the 7.5 or 8.8. Some are using the S2000 rear, and others are using the RX-7 twin turbo rear. I liked and chose the Ford for the availability and affordability of gears through Summit (~$160).

The non-V8 miatas are swapping the late model 1.8 rears. The original 1.6 liter motor had a 6.5" ring gear and was prone to failure even on a stock 100hp car. The 7" late model rear holds up much better and is the common swap in miatas.
 
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