200ci - 1966 Mustang coupe pre-build thread (2024)

Hi All. New guy here both in terms of Ford L6 engines and the forum community. At the outset I realize that 99.9% of what I am about to ask is most likely covered in this forum in some shape or form. Digesting everything is quite a task for a newbie so here goes.

I have a 1966 Mustang Coupe with a bone stock (small log) motor and automatic transmission (and all the other OEM accurate bits and pieces). The car chassis/interior were completely restored sometime in the 90's (judging by the hairdo's in the resto photographs that came with the car), and well maintained since the restoration. Unfortunately I do not know if the engine/transmission were rebuilt or just repainted. The motor runs fairly well but as you know not much in it and kind of scary to drive on the highway. The transmission is, well, "jerky" comes to mind; needs a rebuild or some service.

I want to address the power deficiency in stages to ensure I don't "disable" the car for long periods and do a parallel engine build. In addition, I'll be swapping the jerky auto tranny to a manual. The ultimate end goal is to build a balanced crank unit with a mild degreed cam, VI aluminum head and 4bbl carb mated to a T5 trans. I will be buying a used "donor" motor/trans to have parallel parts to work on during my staged build (see bottom of thread for potential donor that is currently available to me)

Stage 1: Use a donor large log head to perform a 2V conversion, valve job (upgrade the exhaust valve size and seats), and rocker arm with a 1.6:1 ratio - install onto the current stock motor and equip with 2 barrel carb and the required distributor upgrade using the donor distributor. Install exhaust headers.
Stage 2: Install the donor manual transmission - 6 in the trans code indicates an

a Borg Warner T4 with a T5 compatible bell housing.
Stage 3. Procure the VI aluminum head - build as needed. Rebuild donor block, balance, degree new mild cam. Swap the assembly into the car mating to the previously installed donor manual transmission. Install a 4 barrel carb and a decent distributor. Install new exhaust headers.
Stage 4. Procure a T5 transmission and install into the car.

My questions is: is the below donor power/trans unit suitable to carry out my genius plan; I could not get better pics of the trans.
My follow up question is: do I need to keep the clutch master cylinder and linkages or this requires a new setup?
My follow follow up question is: will this trans and, eventually the T5 even fit in my 66?

Donor out of a 1981 Foxbody

TrickSix said:

I'm no expert on the later model low-mount starter 200s. But if you don't have a copy of the Falcon Six Performance Handbook already, get one. Pretty much everything you have brought up is addressed there.

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I do in fact just got it last week and haven't had a chance to read yet.

drag-200stang said:

It is hard to see but this one is a high mount.

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Doing more reading a seems that 1981 Fox Bodies with 3.3 T4 were all high mount blocks

Mech4niq said:

I do in fact just got it last week and haven't had a chance to read yet.

That's a low mount starter.

Doing more reading a seems that 1981 Fox Bodies with 3.3 T4 were all high mount blocks

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Yea, I was having a hard time interpreting that picture's perspective. When I saw the different dipstick location, I went low. Even as a high mount starter block, does it have the same bellhousing bolt pattern on the back as your older block? If I understand your sequence of events, you plan to install the newer bellhousing and four speed onto the older block. I never read that section of the book much, I don't know off the top of my head.