What was the difference between the 325 HP and 360 HP engines in the SS 396 Chevelles in 1966?

The only difference was the cam. The 325hp's cam was VERY anemic. Something like .390 / .420 lift. Next to nothing! I can't remember if chevy put holleys on the 350hp/360hp versions on the 66, though...

Get the 66/67 Fact CD for all the external differences plus of course Everything You Ever Wanted to Know About 66/67 Chevelles but were Afraid to ask Mike!

Internal big difference was the camshaft profile

Q-Jet on 325, Q-Jet or Holley on 360. If car came with a Holley on the 360 it will have an "H" on the engine pad.

Ed...are you sure about that?? :D we have an edit button if you need it..pop in that CD ;)

See ...... gotta get the CD to know for sure :D
.. i beleive you will find a Holley could have been on both versions but without checking CD can't say for sure.

Well fill me in.

Mike,I guess I should stick to 67's

Let me help you out. The 325HP was available with a Holley (49 states) or the Q-jet (Calif.). The 360HP was Holley only in 1966. The Holley part numbers were different between the 325 and 360 (different jetting I think).

The distributors were different part numbers but the mechanical curve was the same, the vacuum module was different.

As stated previously, the cams were different. The 360HP was high lift with a bit more duration.

I didn't need the CD to answer this question, but I've got it and it's great! graemlins/thumbsup.gif

lest anyone think I was being a jerk..I was only busting on Eddie and he knows that... :cool:

and No, I wouldn't say you should stick to 67's...not at all...I mean, who knows...you could own a 66 SS some day and you would be way ahead of the game!! ;)

graemlins/beers.gif Bruce and Bill

hey don't forget the air cleaners were different and diff. stickers too graemlins/waving.gif

Yea there could be one in my future. I'll just have to ask my 67 if it's okay.

I should probably stick to '69's but I'm thinking valve springs were different too. At least in '69 the 325 hp used a weaker spring (96 lb seat, 230 lb open) than the 350 hp (106 lb seat, 327 lb open). The 350 hp spring was also used on the 375 hp 396. Of course this would have to be verified for a '66.

graemlins/beers.gif Bruce and Bill

hey don't forget the air cleaners were different and diff. stickers too

Yep but off course that's all in the CD ..... don't forget the breather too 325 had a pass side breather and 360 had an elbow into air cleaner pbly more, can't think of any more right now......got one ..... tach redline

Bruce, as a clarification on the 325 engines; are you saying that only the Holley was used in the 49 state market and the QJ was used only in CA?

Also, wasen't the closed crank case breather available as an option (although I forget the RPO designation at the moment) on the 325's?

Dan

I won't try and speak for Bruce...well., maybe I will :D I think he is saying that if you have a 66 SS 396/325hp, it could have a Holley carb or Quadrajet in every state, unless the car was a SMOG Car ( AIR ) ie., Calif. If the car was a 66 SS 396/325hp and had smog, it was a Quad carb. 360 hp 66 SS cars and 375 hp versions got Holley's no matter what state/Smog, etc..

Closed Breather air cleaner, were STANDARD equipment on all 325hp 66 SS's. I have found a very few exceptions to the rule where a 325hp 66 SS received a Open Air element cleaner. The Closed cleaner received a Chrome "AC" stamped breather cap, the open received the ELBOW with rubber hose directly to the cleaner. not sure this answers your questions...I make this stuff up ya know graemlins/waving.gif

Mike

I think he is saying that if you have a 66 SS 396/325hp, it could have a Holley carb or Quadrajet in every state, unless the car was a SMOG Car ( AIR ) ie., Calif. If the car was a 66 SS 396/325hp and had smog, it was a Quad carb. 360 hp 66 SS cars and 375 hp versions got Holley's no matter what state/Smog, etc..
And therefore, NO California 1966/325HP/396 cars should have a Holley, because ALL 325 and 360 HP cars were required by the State of California to have the smog equipment (both manual transmission and automatic versions). While their always are exceptions to everything, I think its doubtful that there are many, if any, exceptions to this rule because it was the first year for the AIR system, and not as many people would be familiar with the system, they would just be told it was required, and afterall, it didn't "officially" change performance (engines still rated as 325 and 360HP)... People could have ordered/bought the cars out-of-state and brought them in, but I think they wouldn't truly be a 'California' car.

The 375HP/L78 setup was actually "Smog Exempt" for California (as were the 425HP/427/L72 powered full-size Chevys and the AC Cobra, but I don't recall any Corvettes or Hemi's being exempt). I can't recall any other 1966 cars being exempt.

I have an older BAR book (Bureau of Automotive Repair- California State Agency that was responsible for the smog requiremnts) that mentions the exemption...

I do think its ironic that such high esteem seems to be placed on original California cars, with original "Black Plates" being a bonus, yet very few seem to be restored with the smog equipment, even in high dollar, thoroughly detailed cars...

Okay, sometimes the equipment gets "lost" (more likely tossed) over the years ;) I just find it interesting that if a car was restored to the level that included factory imperfections/overspray and assembly line markings, why wouldn't the smog equipment also be found and installed...

Sorry Mike, I just had to give you a hard time about it... Your cars so nice, I had to find something wrong just to make myself feel better tongue.gif

Yes Mike, your interpritation of Bruce's explanation of which carb might have been on a 325 engine is the way I understood it too; they could have either an H or R carb in all 49, unless it was a CA car (which came standard with A.I.R) or if the A.I.R option was specified in the rest of the 49. In the last two cases it got a QJ.

I also agree with the 325's receiving the closed element air cleaner as standard. What I was referring to was weather or not the 325's were available with the closed crank case ventilation - where the breather cap on the right rocker cover is replaced with an elbow and tube, plumbed into the bottom of the air cleaner (either open or closed element). Although I know the CCC ventilation was part of the A.I.R. set up I believe the CCC ventilation was offered as a stand alone option on the 325's, but I can't recall the RPO designation/description. I'll have to rummage around my info tonight.

Dan

Tony...I take the comments as a compliment and you would not be the first to POINT that out about MY 66! My reasoning is a simple as it gets.

I think the smog equipment looks terrible.

So, although I have had many chances to put the Lost equipment back on...had one guy say he would GIVE it to me... I have no desire to put it on. As PURIST as I am, I still retain my right to build my car to my own taste smile.gif

The way my car LOOKS right now...well, I wouldn't have it any other way!

also, I have retained the Black Calif Plates with even the CORRECT letter sequence for the model year, because the car was built there and owned there, not always, but at the start...if the car was built in Kansas and owned in Kansas, I would have the KAN plates on it.

But I digress :D and apologize for the soapbox, back to the topic at hand...lets talk about them 2 bolt main 325hp and 360 hp vs. the more rare 4 bolt 360hp ( 962 block ) tongue.gif

My reasoning is a simple as it gets.

I think the smog equipment looks terrible.Mike, I will agree whole-heartedly... Living here in California all my life, that was always the first thing to go on my Chevelles (if it was even still there in the first place)... In fact, I can recall only one 1966 396 Chevelle/El Camino that actually had it "original" smog equipment still intact...

lets talk about them 2 bolt main 325hp and 360 hp vs. the more rare 4 bolt 360hp ( 962 block So any ideas on just how many 360HP engines were built using the '962' block?

I know I have had several '962' EG blocks and seen several more, but I personally have never seen a '962' with a 360HP code (at least that I know of. I don't usually check casting numbers at shows)...

Originally posted by 1966_L78:
So any ideas on just how many 360HP engines were built using the '962' block?

No numbers I can feel confident in giving out as Gospel...I know I have seen/documented about dozen just in the last three years.

I have retained the Black Calif Plates with even the CORRECT letter sequence for the model yearCorrect sequencing: ABC123

So I would take a WAG that you plates likely start with letters between N & R... I have seen a few 66 plates starting with S and T, but I have also seen some 1968s stating with "T". I have owned a late 1965 Impala (purchased in Sept 1965 by my grandmother) starting with NKG ###...

I didn't see them posted on your sight...

I have some production numbers published by Mark Meekins and Fran Preve, of the National Chevelle Owners Association, in the late 80's,early nineties. Fran Preve worked at the Tonowanda plant. These production numbers (Chevelle 396s)indicate the number of engines built with each code and their configuration. Almost all of the engines with Rochesters were equipped with A.I.R. None of the Holley equipped engines had A.I.R. Only 325HP engines had Rochesters. The numbers of these Rochester equipped engines is low compared to the number of Holley equipped engines. It is my opinion that most or all of the Rochester engines were intended for installation at the Fremont, California assembly plant for the California market. That is why I call the Holley engines 49 state and the Rochester engines California only.

The 360HP engines were only equipped with Holley carburetors, with or without A.I.R.

The assembly manual does show a closed crank case system with a different RPO number from the A.I.R. RPO K19 system.

Also, someone mentioned valve springs yesterday. I was curious and looked in my October 65 parts book. The 360HP engine used the same springs as the 375HP engine. The 325HP springs were different. The cam and springs would account for the 500 RPM higher redline of the 360HP engine compared to the 325HP.

Somebody posted a question about a 66 360HP 962 block he had (a week or so ago). I read in Chevrolet By The Numbers that "most if not all" 360HP engines used the 962 block. Edit: Maybe that was "some if not most". Sorry, I'm at work and don't have my references in front of me. graemlins/clonk.gif

Tony:

This is the Rear Plate

Also the second page of web site for nice front view :cool:

http://www.chevelles.com/showroom/pic051.jpg

Isn't it amazing how one question can lead to so much information being shared smile.gif though I am not sure I would agree, no offense to the chevy by numbers book, that most all 360hp blocks were 962...but we must continue to share and learn and keep open minds...nice to see this thread discussed with respect for everyone and their own contributions. graemlins/thumbsup.gif

Mike...

How did you get a "1966" decal? Too cool...

I have some production numbers published by Mark Meekins and Fran Preve, of the National Chevelle Owners Association, in the late 80's,early nineties. Fran Preve worked at the Tonowanda plant. These production numbers (Chevelle 396s)indicate the number of engines built with each code and their configurationI have this book, and I really love it, BUT, it disturbs me that either the 1966 engine production does not add up, or there were NO 360 or 375 HP El Caminos...

I think (its been a while) I remember adding the numbers, and outside of the 1865 (##?) 325HP El Caminos that are mentioned as having "optional" 325 HP engines, there were exactly 72,272 other 396 engines placed in the 1966 A-bodies... Exactly the number of SuperSports with no additional engines for El Caminos... Either that, or only 1865 396 El Caminos total, which I do not believe, having owned 3 myself over the years...

Maybe my memory is off...

Tony,

The 1865 optional 325HP engines are all El Caminos. The 24,811 optional 360HP engines are for both Chevelle SS and El Caminos. There were 3,099 375HP engines that were installed in Chevelle SS and El Caminos. These numbers apparently come from Chevrolet production records, but there was no break down between the Chevelle SS and El Caminos.

Being an El Camino enthusiast, I tried to guesstimate how many of each of these engines might have been installed in El Caminos. I did this about 13 years ago and don't remember what assumptions I made, but probably based on ratios of Chevelle SS produced to big block El Caminos produced. These numbers are probably worthless, but I had fun speculating; I came up with about 1043 360HP El Caminos and 130 375HP El Caminos. So there could have been as many as 3,000 El Caminos total built with big blocks in 1966. Pure speculation.

I see what you mean about the overall totals. I think the number of total L35 cars would have to increase by the amount of 360HP and 375HP El Caminos. This leaves a larger amount of L35 cars and a smaller number of L35 service engines (a very small number of service engines; not realistic). So, is the 46,227 number of L35 cars a hard production derived total or is it a "calculated" number?

Here are the numbers for those of you who are wondering what we are talking about: (Edit: I originally entered the 46227 number as 46277. Sorry for any inconvenience. My daughter wanted to play a board game last night, so I skipped proofing my numbers. It gets me every time.) smile.gif

325 manual ED 28,430 Holley
325 manual EH 3,775 Rochester and AIR
325 PG EKR 21 Rochester
325 PG EK 12,592 Holley
325 PG EM 2,963 Rochester and AIR
47,781 Total L35 Engines
46,227 Total L35 Cars
1,554 Service Engines

360 manual EF 20,283
360 manual EJ 4,037 AIR
360 PG EL 1,179
360 PG EN 323 AIR
25,822 Total L34 Engines
24,811 Total L34 Cars
1,011 Service Engines

375 manual EG 3,167
3,167 Total L78 Engines
3,099 Total L78 Cars
68 Service engines

The total number of Super Sports is given as 72,272 hardtops and convertibles.

Thanks Bruce,

Thats what I was talking about... According to those numbers, there were only 50 cars not accounted for:

46277 (L35 cars) + 24811 (L34 cars) + 3099 (L78 cars) = 74187 396 powered cars

74187 - 72272 (SS cars) = 1915 396 El Caminos

1915 - 1865 = Only 50 El Caminos with L34 & L78 engines...

I would tend to go more with your speculated values...

Hey gang, I found some more information concerning the use of K24 (positive crankcase ventilation) and K19 (air injection reactor ) useage on 1966 325HP and 360HP engines. I have some old copies of Chevelle and El Camino ordering information dated February and March 1966.

Option K24 was available as an option on any 325HP engine. K24 was included (standard) on the 360HP and 375HP engines.

Option K19 was an option available on the 325HP and 360HP engines that also required ordering K24, except on the 360HP engine (K24 was already included).

Here is a quote from the ordering info:

"GM Air Injection Reactor: Approved by the state of California and exclusive to California registration only. Available only when closed engine positive ventilation is ordered. Not required when 375HP engine is ordered."

This indicates that smog pumps were only available for the California market; the other 49 states should not have smog pumps. But the PCV was apparently an option on any 325HP engine no matter where ordered and all 360HP (and 375HP)engines should have PCV.