NA9 for 1970

[Stan F.]

I've been doing a lot of background research on my 1970 LT-1 in preparation for restoration and have hit upon a question that I don't have a clear explanation for. According to very reliable information I received, this car was delivered to a dealership in Los Angeles, California which would suggest to me that the car should be equipped with option NA9. During inspection of the car it is apparent that it was never equipped with NA9 - no lines, charcoal canister, inner fender mounting bracket, etc. The car has some wear, but is relatively original so removal during a previous restoration is not a possibility. I have a couple of ideas, none of which has any evidence to support it, but I'll put them out there for your comments.

1. The information that I received was inaccurate and the car was never delivered to California. While this appears to be the most obvious answer, let me mention that the information on the delivery location came from the NCIB database through a third party. Another car I checked at the time was in agreement with documentation that I had so I am inclined to believe what I was told. The Build Order Copy is still in place on the fuel tank and will hopefully provide some supporting evidence when the tank is dropped.

2. The car was ordered out of state and simply drop shipped to California. The US was still involved in Viet Nam in 1970 and perhaps an individual in the service ordered a car from a hometown dealership to be picked up in California upon return to the US. I'm not sure if this would change the requirement for NA9 or not; perhaps a veteran who did this can comment?

3. NA9 was not available at the time the car was built. This particular LT-1 is a very early car (00538) with a January 9 trim tag date. I'm afraid that I am unfamiliar with the NA9 option, so I don't know how plausible this explanation is.

I'd appreciate any comments or ideas you might have that would explain the lack of NA9 on a California delivered car. Thanks in advance for the help!

Regards,

Stan Falenski NCRS# 24272

[Loren]

Re: NA9 for 1970

Did these NA9 cars come with a different carburetor?

[Loren]

Re: NA9 for 1970

Did these NA9 cars come with a different carburetor?

[Stan F.]

Re: NA9 for 1970

The 1970-1972 TIM&JG calls for a different carburetor when NA9 is installed. For a 1970 LT-1, the standard carburetor is a Holley 4555 while a Holley 4489 is used in NA9 applications. I am unaware of how the two carburetors differ, although I would guess that the NA9 Holley is jetted a bit leaner to reduce emissions. I do know that my car has the Holley 4555 which is in keeping with the other aspects of the car that I mentioned in the initial post; that is, the car appears to have never had NA9 to begin with.

Regards,

Stan Falenski NCRS# 24272

[Stan F.]

Re: NA9 for 1970

The 1970-1972 TIM&JG calls for a different carburetor when NA9 is installed. For a 1970 LT-1, the standard carburetor is a Holley 4555 while a Holley 4489 is used in NA9 applications. I am unaware of how the two carburetors differ, although I would guess that the NA9 Holley is jetted a bit leaner to reduce emissions. I do know that my car has the Holley 4555 which is in keeping with the other aspects of the car that I mentioned in the initial post; that is, the car appears to have never had NA9 to begin with.

Regards,

Stan Falenski NCRS# 24272

[Terry M.]

Re: NA9 for 1970

Stan,

The List 4489 is obviously different thn the 4555. The NA9 #4489 has a vent pipe on the primary float bowl with a 3/8 inch hose (I think that is the size, it is a big fat bugger) running to the vapor canister. I have only seen one in my years of looking at LT1's, but my distance from the Golden state may account for that.

I have seen several NA9 equipped cars that were NOT originally delivered to California most were without the proper carb. Thase were Rochester equiped vehicles and the installed carb had a correct date code and the cars appeared reasonably original. One even showed the NA9 option, but there was no charge for it onthe selling paperwork. These have all been late build 1970 cars.

My thought is that they were using up the supply of NA9 parts before the end of 1970 production, but at least some of those parts became standard on 1971 Corvettes. So there are some holes in that thinking.

Could a Corvette have been delivered in California in 1970 without NA9? Emissions rules were new and my guess is the enforcement mechanisms were less sophisticated back then.

Just more of those fun mysteries.

Terry McManmon

[Terry M.]

Re: NA9 for 1970

Stan,

The List 4489 is obviously different thn the 4555. The NA9 #4489 has a vent pipe on the primary float bowl with a 3/8 inch hose (I think that is the size, it is a big fat bugger) running to the vapor canister. I have only seen one in my years of looking at LT1's, but my distance from the Golden state may account for that.

I have seen several NA9 equipped cars that were NOT originally delivered to California most were without the proper carb. Thase were Rochester equiped vehicles and the installed carb had a correct date code and the cars appeared reasonably original. One even showed the NA9 option, but there was no charge for it onthe selling paperwork. These have all been late build 1970 cars.

My thought is that they were using up the supply of NA9 parts before the end of 1970 production, but at least some of those parts became standard on 1971 Corvettes. So there are some holes in that thinking.

Could a Corvette have been delivered in California in 1970 without NA9? Emissions rules were new and my guess is the enforcement mechanisms were less sophisticated back then.

Just more of those fun mysteries.

Terry McManmon