C2 1966 425 HP or 390

[Guest]

Hi

Recently purchased a late 1966 Coupe that was an original big block. This is evidenced by the correct dated BB Rear, gas line, Hood prop, tach, oil pressure, fender flags, correct radiator, heavy duty half shaft flanges, etc. Without owner history is there any way to determine if this was a 425 HP car or the 390 HP car. Car had been stored since mid 70's. I've heard that on the passenger side firewall if it was a 425 HP car there should not be the 4 rivet/holes for the overflow tank. I have four indents, but no see thru holes. Is there any truth to this? Thanks

[Duke W.]

Where does the tach redzone start? *NM*

[Guest]

Re: Where does the tach redzone start?

6500 - but as folks will point out these things can easly be changed.

[Michael H.]

Re: C2 1966 425 HP or 390

Eric,

The presence, or lack of, holes for the expansion tank only indicates big block or small block. Small blocks would have had the tank but big blocks did not, so a correct big block car would have had only the dimples, or drill starts, that you mentioned.

If the car was originally equipped with transistor ignition, it could have been either 390 or 425 HP but if there is no sign that the car ever had this system, it would have to have been a 390 HP as TI was a mandatory option with 425 HP. Look for the amplifier, or possibly the three holes in the front of the LH fender skirt where an amplifier may have been. There are several other subtle changes in the engine wiring harness that will help decide if the car was/is equipped with this system.

The tachometer redline is another clue but that's easily changed so I wouldn't count to heavily on that.

If possible, look at the back of the instrument cluster and find the tag that would have been attached. Post all of the part numbers and we'll be able to tell you more about which engine the car came with.

Michael

[Guest]

Re: C2 1966 425 HP or 390

Forgot to include that car does have K66 and unit is still mounted on car. I will check instrument panel and get back with numbers.

[John H.]

Re: C2 1966 425 HP or 390

The four rivet holes in the RH inner fender for the expansion tank bracket were pre-drilled by A.O. Smith (who molded the part) in every inner fender, and both plants filled those four holes with bond on big-block cars - usually quite apparent when viewed from the tire side of the panel.

[Mike M.]

Re: C2 1966 425 HP or 390

seem to recall(not at home to check) that all 425's came with F-41 but not all F-41's were 425HP. mike

[Guest]

Re: C2 1966 425 HP or 390

Instrument cluster has following information:
Blue ink "JUN 1966 D15" - This is correct as car looks to have been made in first week of July. Most parts have been dated June.

Sticker with following information:
Beige sticker with Red writing - Large "LB"
Cluster 6457984
Speedo 64???67-W Hole for odometer cable is in middle of these numbers
Tach 6412223-W
AC - Made in USA

[Guest]

Re: C2 1966 425 HP or 390

Car has front and rear sway bars, no markings on springs, and replacement shocks.

[Michael H.]

Re: C2 1966 425 HP or 390

Yes, John is correct. I should have been more specific on the description of the holes. Early production 66 big block cars had just the drill starts while the rest of the 66 run had the holes filled with bond. I believe it was Mike Mccagh that has an early car with just the drill starts. The holes in my November car are filled with factory bond.

[Michael H.]

Re: C2 1966 425 HP or 390

Mike,

Someone mentioned yer name in a post (directly above). Hope I remembered the info correctly.

F40 HD suspension was only available on the 425 HP cars in 66, and was optional, not mandatory.

[Mike M.]

Re: C2 1966 425 HP or 390

mike hanson has the suspension info down pat. i shouldn't post from memory as the betz cells are dying off. mike

[Michael H.]

Re: C2 1966 425 HP or 390

Eric,

That's a good piece of information. That would indicate that the instrument cluster was originally installed in a 425 HP car. No other car/engine combo used a 6412223 tachometer for the 66 model year. While this alone isn't proof, I would certainly say it's reasonably convincing. Sounds like you're on your way to a 425 HP! Photograph everything in sight, before restoration. Good luck with your project,

Michael

[Michael H.]

Memory...

Actually Mike, I don't remember any of this stuff either but I make up everything as I go. Amazingly, some people actually believe some of the ramblings that I post. CRS set in a few years ago.

[Guest]

Re: C2 1966 425 HP or 390

Thanks for the information. Wasn't sure about the 4 rivet holes myth and confirmation of the tach is helpful.