66 chevelle carb question

[maliburacer78]

Hi, I am thinking of running my 66 chevelle in stock eliminator. On NHRA's web site under engine specifications, it shows a 275 hp 327 to have a holley carburetor (also the 300 hp). Is this correct?? I always thought it would've had a q-jet. Also do you have to have a factory bench seat in the front if it came with one??

Thanks, Brian

[Bill Belden]

327/275 is a Q-jet motor
Bucket seats were optional, must use original not aftermarket


1100 I/S

[Chuck Norton]

Brian,

I believe that the '66 327, 275 hp combination is relatively unique in that you have a choice of three carburetor manufacturers. Sub-note #8 on the tech page indicates the availability of:

Alt carbs - Cart AVS-4027S/SM 4028S/PG Roch 4MV-7026203/SM 7026202/PG

It is my recollection that the overwhelming majority of Stock and S/S cars running this combination use the Quadrajet. Having said that, you clearly have the option to use either the Rochester, the Holley, or the Carter.

c

[bsa633]

chuck...was there a midseason change at chevrolet that year or....396-325 also have the holley option that year of 66?

[maliburacer78]

Thanks everyone!!

[Chuck Norton]

633,

I can't claim any particular expertise as a automotive historian of that era. However, to the best of my admittedly fuzzy memory, I recall that 1966 marked the introduction of the 275 horsepower combination and that most of at least the early cars were Holley equipped. Cars that were delivered in California weren't necessarily equipped the same as cars in the other 49 states. We even had the A.I.R. systems to complicate things. Obviously, the Holley was the originally specified carburetor because it is in the primary spot on the spec sheet. The Carter AVS was basically viewed as a re-engineered version of the AFB and many racers initially tended to approach the "air-door" carburetors as being less desirable. I personally never saw an AVS equipped 275 horsepower 327. Also, there may have been some factory equipped Q-jet cars in 1966 but I don't remember them. Travis Miller could probably shed light on this point but I seem to recall that after the Q-jet was put on the '67 275, it may have been approved for the '66 retroactively. (Note the revision to the spec sheet dated 8/23/79.)

Earlier in the mid-sixties, I recall that the Chevy V8 combinations had used AFB Carters, Holley's various sizes in single-feed configurations or, in the case of smaller horsepower units, the Rochester 4GC. Exactly why GM spent the money to build molds to cast two different manifolds (apparently Holley and Carter carbs both used the same casting) for the same engine configuration is a mystery to me. On the 396 side of the ledger, in 1966 there is a manifold that has the name "Holley" cast into the unit and that motor carried ten more horsepower than the very similar Q-jet combination of 1967.

Having scrambled through what's left of my rapidly evaporating memory to dredge up the foregoing, I'm in no position to declare it as totally accurate or complete. Just the way I remember it.

c

[bsa633]

thanks Chuck! as always...a lot of meat! i'll take your "fuzzy" memory over mine...anytime....CYA

[Dwight Southerland]

Chuck -

My "fuzzy" memory seems to recall in days of yore that the different carbs were related to the car model the engine was installed in. Seems the Chevy II used to be restricted to the Holley carb, the Chevelle could use the Holley or Cater and the full-size car used the Q-jet. Like I said, this is fuzzy. But, for the early years of Stock-SS (up until mid-70's), you never saw a '66 Chevy II with a 327 becasue of the carb restriction. I don't know when or why it changed. This may all be just distorted synapses from years of packing data, not getting enough sleep and stress that has accumulated into a total fabrication, too.

Does anyone else remember such?

Dwight Southerland

[Chuck Norton]

Dwight,

That makes sense. I do recall considering running a 275 horsepower combo in my '66 Nova stocker in about 1975 and going instead with a 283 for a variety of reasons, including the carburetor. Since I didn't pay a lot of attention to Chevelles and big cars, it could have been the case that they had different equipment. I'm sure that Travis knows!

c