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More on engine size

Discussion in '1955 - 1966 Classic Ford Thunderbird' started by Poppy Red, Aug 13, 2017.

  1. I read that it is also possible to determine the engine size from numbers on the intake manifold. Numbers on mine are: 6E20, which I interpret as 1966, March 20. Also on the runner is: C6AE, and 425-G

    Another question for those with knowledge. I recall the 390 engine in the first 66 I had, had flat topped rocker covers. The engine in my 2nd car has rounded rocker covers, with "Powered by Ford" in raised/stamped letters. I know that is not a guarantee of engine size, but, if those covers were stock, it may help.
  2. captrick

    captrick Well-Known Member Lifetime Donor

    Hey Red, if you think that the engine has not been changed and it was built in the car the 5th digit in the VIN should be the engine code. If it is a "Y" it would be a 390 at 265 hp, if it is a "H" it would be a 390 at 270 hp, if it is a "Z" it would be a 390 at 315 hp. Also look on the spec tag on the door and the 5th digit there will show the engine size and hp. If none of those letters appear then it is a 352. I am sorry I don't have that code for the 352. Good luck Rick
  3. Rick
    The VIN number of the car clearly states that is was built with the Q code, 428cu option. As I said, I was told by the 4th owner, that the original 428 engine was for some reason removed, and a 390 installed. Later, the 390 was removed and a 428 CJ was installed. My question, is, how can I determine if the engine in the car right now, is a 428. I don't care if it is a CJ or not, I would like to know the size, if I need to purchase parts, etc.
  4. captrick

    captrick Well-Known Member Lifetime Donor

    The only way to tell for sure is to pull one of the heads and measure the bore. The bore should be 4.13 give or take .0030 inches for the 428. Most of the parts other then the pistons and bearings are all interchangeable in all FE big blocks. On some performance blocks there in a casting in the back of the block behind the flywheel that designates the cubic inches. The 428 Cobra Jet engines also used the 427 Lemans Rods which have cap screws to hold the caps on and not nuts and bolts. Other then that it will very hard to tell what the engine is. Sorry I can't be more help Rick

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