some 1968 GT500's with stock 390's?

Re: some 68 GT500's with stock 390's?

I've heard it but I'm yet to see one. I think more likely it is a rumor started due to the fact 68 500s got the same "S" VIN designation as their little brother 390s. Ford actually sent out a TSB on this so techs wouldn't be confused.

 

Re: some 68 GT500's with stock 390's?

I heard the same rumor a few months ago. And when i asked i got two different answers: Tim's answer of a mix up with the "S" designation in the VIN and yes it happened. However, i am yet to find or have someone admit that their car has a 390. Could be just another urban myth like alligators in the sewer....

 

Re: some 68 GT500's with stock 390's?

There are no 30' alligators in the sewers?

 

Re: some 68 GT500's with stock 390's?

If you haven't seen the service bulletin, I have it here:

http://www.thecoralsnake.com/engbull.html

 

Re: some 68 GT500's with stock 390's?

Common belief during the 70-80's but just an urban legend (with a basis as Pete offered)

 

Re: some 68 GT500's with stock 390's?

That reference text also has a mistake where it says the "Paxton option was returned from 66" ... they didn't know it was a 67 option as well so who knows what they are making up. Probably written by a Chevy owner.

But, not to change the subject very much:

Is there a way to tell a 428 from a 390 when looking at a car. Recently I saw a 390 Mustang advertised with 428 transplant. How could you easily verify that?

 

Re: some 68 GT500's with stock 390's?

I am sure someone smarter then me knows but the only way i could tell the difference was by pulling the motor apart and examining the block. However, i assume if the 390 came from the factory it would have 390 heads. If you pulled the heads, the 390 valves would be smaller then the 428 valves.

 

Re: some 68 GT500's with stock 390's?

There really isn't any absolute way to tell externally. The 428 PI uses the same heads as the 390 so even the part # would be identical. I pretty sure you could tell the difference driving them though.

 

Re: some 68 GT500's with stock 390's?

There were a few mistakes made in 1968 I believe it was more then a urban legend. The first 67 GT500 was discovered to have a 390 in it also ,probably due to lack of cordination between the assemblyline and the engine plant.The magazine people deduced it first by the dismal performance in the test.So if it happened then plus the providence of the service bulliton in 1968 it could happen in a 68 GT500. A 428 block will have 428 cast into the block which can be seen after removing the freeze plug on the passenger side I believe.You could pump the engine like is done by scrutineers in SCCA and many other racing groups to check displacement or removing the heads and measureing the bore.Bob

 

Re: some 68 GT500's with stock 390's?

Probably a lot of GT500's received 390's, but not from the factory. I know of one 67 that did. When the cars were "used cars" and were getting thrashed those 428's would let go on occasion. Many times the owners were not rich back in those days and these cars were daily drivers. A call to the junkyard got the answer " no we dont have any 428's but we have 5 390s to choose from..." and then a few years later the collectors started taking them apart and found 390s.

Looking at a GT500 for sale is another scenario where it would be good to be able to easily verify a car has a 428 vs 390. Any other ideas along those lines.

 

You can always remove the front spark plug, drop a length of rod down the bore. Turn the motor over and measure the stroke. 3.78 for 390's vs 3.78 for 428's

 

sorry 3.98 for 428's

 

Wonder how old that article is and who did the research. Could have found better examples of stock production cars but most viewing the site will likely not chance the stuff or think it correct.

Thanks for sharing

 

I have always heard that early in production of the 68 GT500's that there was a two week period where 428's were not available due to a Strike. I tend to believe it was possible.

 

I remember being criticized back in the early 80's by an "expert" at a show because I didn't even know that Ford had trouble supplying enough 65 K code engines for the cars sent to Shelby that they assemblied the K code fastbacks with 6 cylinders.

According to that person the 6 cylinders were pulled by Shelby and the Hipo engines (which were shipped from Dearborn) were installed before they were sold to the public.

Forgot to as him if some of them were over looked and delivered to the buyer with the 6 cylinders still in them

Lots of years, stories and people that heard ..... Got to love em