Topic: 1966 Mustang I6

[Turnall]

Just wanting to make sure that the engine in my 1966 is NOT original.  It only has 3 freeze plugs on the starter side of the engine.

Engine Block - C6DE  6015-A

6T07T235364

684   

C31   6T07T235364

65A  8  26

Thanks, Allen

[Turnall]

Can someone confirm that this cannot be a 200cid engine and therefore can't be original?  Or on the other hand, could it be original?

[jwc66k]

The casting number you refer to is for a 200CID I-6 engines used in Mustangs in 1966 and 1967. There is no sure way to determine if the engine is the original to the car except by casting date code and engine assembly date code, if they preceeds the car scheduled assembly date by a week or up to six weeks. The date code should be the same as a V-8 and in the format 5M25Z (5=year, M=December, 25=day, Z=inspector). I don't know where the engine assembly date code is located but I would assume the casting date code is near the casting number. See http://www.fordsix.com/ for some  more info for your engine. I don't know how many freeze plugs are used or where they are located.
Jim

[C5ZZ]

It may be a 170 engine because of the 3 freeze plugs.
Mustangs did not use the 170 after the 64 1/2's but
Ford still used the 170 in Falcons and then the Maverick
up until about 71.

As mentioned check Fordsix.com website, more info
than you will ever want on the six.

[Turnall]

Ok, I had the engine out so decided to go ahead and pull the head off of it.  It's a 170 according to classic inlines (got there from the above website).  Not only with the 3 freeze plugs, but also by the pistons.  This engine has flat pistons, 3.50" in diameter...

"Pistons: All 144/170ci engines have cast aluminum flat top pistons with a 3.50" diameter, while the 200/250ci engines utilized a dished piston with a 3.68" diameter. "

Anybody got a '66 200 lying around...

Thanks for the help,

Allen