66 carb date

[Michael R.]

Could someone give me some information as to how the carb date for a 66 425hp motor relates to the build date of the engine and also to the build date of the car? Thanks, Mick

[John H.]

Re: 66 carb date

Mick -

The 3-digit OEM Holley date code is in year-month-week of the month format, and the 4-digit service replacement code is 3-digit Julian date followed by calendar year format. The carburetor was installed at St. Louis, not at Tonawanda, so the carb date doesn't relate directly to the engine assembly date, although 99.9% of the time the carb pre-dates the engine. The carb date needs to be prior to the car's build date, as that's when it was installed.

[Michael R.]

Re: 66 carb date

Thanks John for the information. My confusion was whether the carb was installed when the engine was built or whether at the time the car was built. My next question is, how far can the carb pre-date the build date of the car? Thanks again, Mick

[Patrick H.]

Re: 66 carb date

Mick,

Usual NCRS guideline is 6 months.

For "precision dating," check serial #'s similar to yours in Noland's guide, or contact the 66 Team Leader and see if he has info on surveys performed to see which date(s) are usually seen on 427/425 cars built near yours. As carbs are "batch built" there is most likely one or two dates which would be "most correct." That's what I did to find out what date should be best for Tom's 72 LT-1.

Now, next time you're over, I'll show you my original August 1970 water pump from my June 1971 car...

Patrick