1966 Sprint differences
 

After checking numbers, I found my 1967 LeMans has a 1966 Sprint engine. I've read here that the 1966 year engine (as well as '69) is unique. I know it has aluminum cam belt covers, but what else makes it different?

'66 Vs '67 4BC ENGINES
 

As noted the 1 year only upper and lower Aluminum Belt Cover.

Harmonic Balancer/Damper.

Intake Manifold. ( No heat crossover within the carb mounting surface)

Another 1 year only, Pancake Breather with a Tall Neck Base.

And the Painting detail on the Cam Housing and Belt Cover.
'66 was the only year to get this then it abruptly went away. My guess, Cost.

Nothing else comes to mind but I'm sure there are a few other little details, otherwise, they are the same engine.

One year only louvered “pancake” air cleaner. Similar to GTO. Also the 207hp rating.....

Internal differences...
 

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I see the differences in the harmonic balancers, but are they functionally interchangeable?

Yes, the crank snouts are the same size.

Small crank snout / 230 (1-1/4”)
Large crank snout / 250 (1-5/16”)

Also the 66 Sprint Exhaust manifold only bolts up to the 66 Intake manifold due to the difference in the exhaust heat passage shape.

Also unique camshaft, remember the 66 4bbls OHC-6 was rated at 207 HP, and most 67-69 versions were rated at 215 HP. Partly due to the 66 using the "B" Camshaft, and the 67-69's using the "E" camshaft.

Those are the only other differences I am aware of that haven't been covered y previous Posts.

I didn't even think about the exhaust man changes. Camshafts are almost equal, per the spec sheet posted, here's another straightforward spec sheet.

Another minor outward difference was the amount of fuel hose used on the '66, the '67 changed over to full tubing.

I forgot that the "B" and "E" cams are basically the same grind, I wonder what the difference is that justified the different P/N and stamping?

Thanks for reminding me.

I recall the spark plugs and the holes being short on the 66, long on 67 - 69.