[romax]

Hello, I have 1966 Mustang that was ordered in fall 1965 and built on Nov.9th 1965. The engine in it has these codes:
4K1
C5AE-6015E
front block under head casting:
-4K7

It's one owner car and I'm told it's all original. Car was for export {Japan}.
How likely is it that this engine IS the original from factory in yours opinion {possible -maybe-impossible}?
Thank you all as always.

 

[bronzepony66]

Date codes indicate November '64, so I'd bet the motor is from a '65. Should also have a 5-bolt bell housing,

 

[romax]

Date codes indicate November '64, so I'd bet the motor is from a '65. Should also have a 5-bolt bell housing,

Ok, thx. '66 bell housing would be different?

 

[bronzepony66]

I may have mixed this up...(again!)
After researching this more closely, the early 64-1/2 289s had the 5 bolt bell, starting in about July '64 this was changed to a six bolt pattern ("change level 5").

Does your engine still have the tag? It would read something like this:
289 65 5
4 - K 551-J

 

[caveeagle]

If I remember correctly, its pretty easy to tell a 5-bolt motor from a 6-bolt. Right behind the intake manifold, you will either have one bell housing bolt at the center of the block (5-bolt). Or, you will have two bell housing bolts, with a flat area directly behind the manifold.

That was the easiest way for me to tell the difference while installed in a car.

 

[awhtx]

K is October in the date code because the letter I was not used. The 5 bolt blocks ended with the end of 64.5 production around the end of July 1964 and 6 bolt blocks began with production of the 65 in August 1964.

 

[bronzepony66]

Hey, at least I had most of it right (the second time)!
romax, look for that engine tag!

 

[Mitch70769]

I wonder why there would be a 64 date coded block in a 66 car unless it was replaced with a donor motor at some time? These cars were being produced so fast that the dates on the blocks and cars were very close and they ran the Sprint promotion because they were short on V-8s from what I have read.