428 V8 or 390 V8?

[JamesB]

Hello,

I am an Internet Manager at a Local Used Car Dealership.
I am suppose to identify a 1966 Ford Thunderbird before posting it up for sale.

I have an issue with the VIN# and type of engine.

1. The engine is too small for a 428 V8 (ref: from one experienced Manager/Mechanic).
2. The Vin# is either 6Y810123920 or 6Y81Q123920 (Information from the Driver side door plate and stamp on the frame of car upside down under the hood).

The First image is an enhanced image of plate.
The second image is a normal photo. (I am a Professional Photographer)

 

[JamesB]

Photo of Engine

 

[boaterbob]

It would be a Q, The only other letter that would be in that position would be a Z. Z designates a 390 Q designates a 428. They look identical. It would be a 428 unless someone change the engine. Measure the stroke if you want

 

[JamesB]

It would be a Q, The only other letter that would be in that position would be a Z. Z designates a 390 Q designates a 428. They look identical. It would be a 428 unless someone change the engine. Measure the stroke if you want

Boaterbob, Thank you for the response.
Let me clarify what you are saying, The 390 engine and the 428 engine will appear to be identical in size. Is this a correct statement?

So far, that is all we have... "it looks to small to be a 428".

 

[boaterbob]

Yes, Identical in size. Going by your pics engine looks correct! You could take inspection plate off bottom front of bell housing to look and see which flex plate it has or measure stroke.

 

[JamesB]

Thank you BoaterBob...

ooooboy... Office Politics, I have to go sneak to find the flex plate.
Don't want to hurt the expert mechanic's ego.

BTW, if it is a 428 V8 engine... does it worth more money than a 390 V8 engine Tbird???

 

[kevindeluca66]

The general rule is to add 40%to the value of the car if it has the 428.

 

[JamesB]

Thank you very much for the help.

But Office Politics dominates, my manager/expert mechanic says there is no way that is a 428 and doesn't want to be liable for misrepresenting this car.

So the price stays the same as if it is a 390.

 

[Nitrous Bob]

boaterbob,
How do you tell the difference by the flexplate? Really new to FE motors.

 

[Animute]

428's and 390's are identical externally except look for an extra separate weight on the harmonic balancer Q-code serial nos will tell you what was original but after 50 yrs who knows.