'71 vs '81 200.

[xpsnake]

I have a 1981 Mustang with the late 200 in it. The car has A/C, PS, PB, and the emissions garbage, with a c4 auto. It only has about 77,000 miles on it, but it sat for 3 or 4 years right before I got it.
After a brake job, I've determined that the dampner or timing chain has slipped. The engine runs smooth at RPM, but has a hard time at slow speeds and idle. It also shuts off when going over hard bumps. Most importantly, it uses a pretty absurd amount of oil and I put a lot of miles on it. I am considering just doing a timing chain and head job on it, and seeing where I am at.

Ideally, I'd like to remove all the emissions garbage, put a header on it, put a progressive 2bbl on it, and a few other things. The car itself is mint with no rust or body damage.

Overall, I want to build this motor for maximum MPG, whatever that may be. My question is, is there a difference between this engine and the complete 200i6 I took out of my '71 Maverick? Can I just build the head on the maverick and then slap it on the mustang? Would this be optimal?

 

[Asa]

the '81 will have an upgraded ignition system, and should have hardened valve seats

those should be the only significant differences between the two, the engines didn't change very much throughout the years

 

[Inliner]

Someone correct me if I'm wrong, but didn't some "big-bell" 200s come out in '81 (E1BB casting code)? IIRC, you can also just look to see if the starter is located above or below the bottom of the block. Above is small bell (like your '71 engine) & below is big bell.

 

[Asa]

Someone correct me if I'm wrong, but didn't some "big-bell" 200s come out in '81 (E1BB casting code)? IIRC, you can also just look to see if the starter is located above or below the bottom of the block. Above is small bell (like your '71 engine) & below is big bell.

'80 apparently
http://fordsix.com/tech/engine/bigbell.php

forgot about the big bell

 

[Eric Rose]

the '81 will have an upgraded ignition system, and should have hardened valve seats

those should be the only significant differences between the two, the engines didn't change very much throughout the years

Don't forget the short/long water pumps too. The '71 will have the short pump and the '81 will have a long one. I'm not sure if they will interchange.

 

[Bort62]

the '81 will have an upgraded ignition system, and should have hardened valve seats

those should be the only significant differences between the two, the engines didn't change very much throughout the years

Don't forget the short/long water pumps too. The '71 will have the short pump and the '81 will have a long one. I'm not sure if they will interchange.

They will swap back and forth. It's the same block.

 

[xpsnake]

Other than the valve seats, which I would be redoing, there's no advantage to the later head? If this is the case, I will get the '71 head redone, get the adapter, 2bbl, and header, and do the head replacement and conversion in a weekend.

 

[Eric Rose]

They will swap back and forth. It's the same block.

What about the crank pullies? The '81 will probably have a 3 groove pulley, and the '71 will probably have a single or a double.

 

[xpsnake]

Would there be bolt pattern differences on the pulleys? Otherwise I'd just swap them too.

 

[CZLN6]

Howdy Bruce:

The '81 head has larger intake valves 1.75" vs 1.68", It also has a larger intake tract volume, if that matters to you. The '81 will have hardened valve seats. Larger late model valves and hardened seats can be added to the '71 head, just costs more.

Adios, David