6.5 Liter vs 390 CT


I have a '68 Cougar XR7 with 6.5 liter badges on the front fenders. I know that it was built that way from the factory, the serial number shows that it is an X code car. The 2V intake and carb have been removed and replaced with a Ford S code iron intake and a 80457-10 Holly carb which runs great.

My question is: what other difference is there in the 6.5 liter and the 390 motors of the same year?


Bob Seeds
Apopka FL.

the 6.5L option allowed you to get either the X-code 390-2V or the S-code 390-4V GT engine (which is what I have). The X-code Premium Fuel and S-code 390’s have the higher 10.5:1 compression ratio. There is a 390-2V non_premium fuel w/ 9.5:1 compression ratio listed in my shop manual but that was for another product line.

The GT package option allowed you to order either the S-code 390-4V or the R-code 428-4V CJ engine (Apr 1968).

The GT package also included some suspn upgrades along with engine chrome goodies under the hood, like chromed air cleaner lid, oil dip stick handle, Power by Ford valve covers, etc… There was also a slightly different free flowing exhaust system as well.

I have chrome valve covers on my '68 S-code 6.5Litre. But if it came with the x-code I believe those would have been painted Ford blue.

The S code and X code both share the same dual exhaust system. The X code has a milder cam than the S code. Still the X code engines are a blast to drive. Lots of tire shredding torque!

Royce, I have to ask you because you’d know this. Why would anyone order a 390 big block with a two barrel carb? Some suggest because they wanted fuel economy. If that’s the reason there were better options…like a J-code.

Here is a link to the CCOA’s website with a great description of the 6.5 Litre and GT option:


Just guessing here, but I would think it’s a matter of how they all look on paper. If you wanted a HP and torque upgrade, the X code sticker price was only $20 more than the J code and had significantly higher power numbers. The S code was three times as much as the J code.

More than one manufacturer had a 2 barrel version of a big block back then.

I know in the case of an uncle of mine, his father-in-law had a large boat he needed to tow so needed a vehicle with torque. He wasn’t interested in performance per say so he opted for a 2v big block car.

Probable helped a little with insurance costs also.

  • Phillip

It was a matter of matching up with the competition. And the X code did get a bit better mileage than an S code but still delivered a lot better performance than a J code.

Pontiac and Oldsmobile both offered 400-2V engines in their GTO / 442 cars, These were seen as direct competitors for the customer who might buy a Cougar in 1968.Sure the difference in gas mileage might be from 12 MPG to 14 MPG comparing the 2V version to the 4V version. That argument might be just enough to convince wifey to let a guy have a big block.

Following up on memories Royce triggered, I actually saw one of the 265 horse 2-barrel GTOs in the flesh late spring '68 when helping my late Father car shop for a LeMans. It was the wrong color, so he moved along the line of cars, but it briefly made his eyes twinkle while looking at the 350 cars. Never saw or encountered another.

The Pontiacs used the mildest of all V8 cams in their 2-barrel, too. Intake didn’t even make a full .400 net lift. I don’t want to hear another word about Ford cams being conservative.

As for the Ford 390 2-barrels, I rode with a few contemporary full-size Fords with the lower compression Galaxie/Country Squire engine, and they were quite the fun from stoplights in those 2-ton jobs. The X-Code must have been a real right rear smoker with 500 pounds less.

Ford had a massive hole in the engine line up in '67. Ford had nothing in between the 289 and the 390 GT. The 351 would not be available until 1969. The 1968 2V 390 was the stop gap to answer the 327 and 350 in the Camaro, the 326 and 350 in the Firebird, the 318 and 340 in the Barracuda, Even AMC was in the mix with a 343 and a 360.

Basically the 390 2 was a pricing exercise. It was $77.80 more than the base 289 or 302 2V. The 390GT was $158 and required at least the $79 heavy duty 3 speed manual trans. The J code 302 was just $20.19 less money than the 390 2V. If you could afford the gas then the 390 sure looked like a good value.