Trim tag for 1966 396/375 (?) - Impala Tech
Tag Team De-coding tags & numbers

 
LinkBack Thread Tools
post #1 of 10 (permalink) Old 05-26-2013, 11:23 AM Thread Starter
BA.
Moderator
 
Join Date: Aug 2008
Location: Miamisburg, Oh.
Posts: 3,129
Blog Entries: 15
 
Trim tag for 1966 396/375 (?)

This was at the Springfield Ohio swap meet this weekend.
I think they were calling this a 396/375 motor but I don't remember that being available in a 1966 Impala. Was that a specially available option? Back door option? Wives tale?
Larry, did you see this one? Wasn't it being represented as a 375hp or did I mis-read something??

I took a picture of this body-tag just in case someone wanted to see it.

Sorry, no VIN!

HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
http://www.impalas.net/forums/blog.php?u=1432

Last edited by BA.; 12-10-2013 at 09:48 PM.
BA. is offline  
Sponsored Links
Advertisement
 
post #2 of 10 (permalink) Old 05-26-2013, 01:22 PM
Moderator
 
Join Date: Jan 2006
Posts: 12,361
 
Decals cost about $6 dollars. The 375 horse 396 differed from the 325 and the 350 horse 396 in the heads (only the 375 horse 396 received the HiPerf rectangular port head that is a dog on the street, the other two 396 engines used the much more practical and functional PASS oval port heads). The 375 horse 396 also used a solid tappet rough idling race cam designed for high RPM operation (NASCAR racing). And finally the 375 horse 396 has an aluminum high rise intake manifold (that saves 23 pounds) topped off by a 780 cfm Holley vacuum secondary carburetor. (If this 375 horse 396 was originally installed in a Corvette, it will also have a dual point distributor with a mechanical tach access on the side of the distributor).

The factory learned a bitter and costly lesson about solid tappet high RPM big inch motors with the 409. Namely any vehicle with a solid tappet cam could rev high enough to self destruct; or more frequently to take out all of the accessories on the front of the engine. So this also includes the solid tappet 350-360 horse 327 and the 283 horse 283 motor.

Are you aware that your stock riveted steel fan will shed it's blades above 4800 RPM?





Further air conditioning compressors will blow out every seal in the compressor at about the same engine speed. Even your water pump and alternator are nor equipped with bearings that can spin very high and will fail if pushed.

Chevrolet discovered these issues on all of their solid tappet cars and either restricted the availability of things like A/C (you can not get A/C on any engine equipped with a solid tappet); or to modify and reinforce the parts being stressed. Which is why the Corvette has it's own dual point distributor, short water pump, even after the long pumps were introduced in 1969, and a special high RPM alternator with special bearings and special alternator fan. (the Corvette short water pump also used a larger diameter shaft with sealed, greased for life roller bearings, instead of open ball bearings that need lubricant in the coolant to keep the bearings from burning up).

Because an Impala is a large, that is to say heavy car, combined with the fact that the 375 horse 396 had no bottom end torque to speak of, it wasn't installed in the Impala. The clacking of a solid lifter engine probably would also restrict a lot of buyers who would complain about the car's motor sounding like a sewing machine. Finally because the cam was so aggressive, it would require a manual transmission with the Impala to get the car rolling (this is because a loose converter had not been invented yet; which is why all the solid tappet 1967-'69 Z/28 302 motors where all bolted to a Muncie four speed and required set of 4.11 or 4.56 rear gears in a light Camaro body).

Check to see if your 375 horse 396 car has a single bump on the head to identify it as being a HiPerf rectangular port head (here is an example of the casting mark)



The difference in port size is hidden from view with the intake in place which is why you have to look for the that little casting identifier. But they are very different:



The intake difference between aluminum and cast iron is obvious, but the factory manifolds all have a Winters Foundry casting mark; not found on aftermarket castings with the name Edelbrock or Offenhauser ground off:



Same for the Holley carb; the 350 horse 396 used a Holley with square, single feed fuel bowls (a 4160 style Holley). The 375 horse 396 used the center hung dual feed Cathedral style fuel bowls (a 4150 style Holley). The 325 horse 396 used a Rochester QuadraJet.

The other difference is the 375 had chromed valve covers with spot welded drippers under the valve cover to oil the rocker balls (that were grooved on the 375 horse but smooth on the 325 or 350 horse 396). You should be able to see every spot weld mark in the chrome where the drippers are attached. After market valve covers are just chromed formerly painted 325/350 horse valve covers that did not have the drippers attached; and as such have no spot welding marks visible (just like the ones on the 450 horse 454 that some one claims is all original on the high performance head photo above). I can probably list ten or more differences between the motors but you have to be able to take it apart to see them.

Big Dave
Big Dave is online now  
post #3 of 10 (permalink) Old 05-26-2013, 03:35 PM
Senior Member
 
Join Date: May 2006
Posts: 1,055
Blog Entries: 1
 
396/375

You are correct, there was no 396/375 hp engine offered for the 1966 full size car, only a 396/325 hp motor.

Paul

Paul

1966 Impala SS

Please Visit our new site:
http://www.winvoices.com/
1959 through 1988* window stickers, car shippers, dealer invoices, retail sales orders and tank stickers, expertly reproduced, for most Chevrolet Models.





fsc66 is offline  
 
post #4 of 10 (permalink) Old 05-26-2013, 10:02 PM Thread Starter
BA.
Moderator
 
Join Date: Aug 2008
Location: Miamisburg, Oh.
Posts: 3,129
Blog Entries: 15
 
Thanks for the confirmation Paul.

HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
http://www.impalas.net/forums/blog.php?u=1432
BA. is offline  
post #5 of 10 (permalink) Old 05-27-2013, 09:59 AM
Moderator
 
Join Date: Jan 2007
Location: Lewisburg, Ohio
Posts: 2,909
 
I was at Springfield last weekend but I didn't see that car as it was probably gone when I toured the field every evening. Only 66 I saw was a primered one. As far as I know there was no 375 HP 396 engines in 66 Impala's. If you wanted more HP you had to buy the 427.
Hey Dave, I have a 67 Camaro SS hood that has those vents in it.
dadstoy is offline  
post #6 of 10 (permalink) Old 05-27-2013, 04:44 PM
Moderator
 
Join Date: Jan 2006
Posts: 12,361
 
Quote:
Originally Posted by dadstoy View Post
I was at Springfield last weekend but I didn't see that car as it was probably gone when I toured the field every evening. Only 66 I saw was a primered one. As far as I know there was no 375 HP 396 engines in 66 Impala's. If you wanted more HP you had to buy the 427.
Hey Dave, I have a 67 Camaro SS hood that has those vents in it.
Actually that is off another mod's car over on Team Nova. If you read the tech info on Flex-a-Lite fan's web site they discuss the fact that stock fans are for stock motors. If you plan on reving yours up without a viscus fluid clutch (that limits the fan's top RPM) be prepared to see holes like that in your hood as well. The Race fan that Flex-a-Lite sells is rated and tested to 10,000 RPM, and it looks and acts like the stock fan (just better made). I recommend replacing all stock fans.

In fact GM had a major recall on some of their stock aluminum bladed 18" fans that flattened out at higher RPM to save energy and cut down on noise. They were generally installed on all V-8 pick-up trucks to save the expense of a fan clutch.

Turns out a lot of good ole souther boys reved their trucks up in high school parking lots; or late on Friday nights when thumping their chests and other wise engaged in the mating rituals of the red-necked beer drinker. They often discovered that doing so would send enough fan blades through their hoods to justify a factory recall on all aluminum fan blades. I used to pull them out of the dumpster behind the dealership as they were light weight and popular enough so that even used they could be resold at the local sped shop.

Big Dave
Big Dave is online now  
post #7 of 10 (permalink) Old 05-29-2013, 10:28 PM
Senior Member
 
Join Date: Mar 2006
Location: Maine
Posts: 379
 
Send a message via AIM to TAR6569
The writing on the windshield says their is a build sheet. That would provide the original drivetrain combo.
TAR6569 is offline  
post #8 of 10 (permalink) Old 05-30-2013, 03:12 AM
Moderator
 
Join Date: Jan 2006
Posts: 12,361
 
Quote:
Originally Posted by TAR6569 View Post
The writing on the windshield says their is a build sheet. That would provide the original drivetrain combo.
I have seen adds on-line that offer to print you a window sticker, and a build sheet, and even to make you a brand new aluminum trim tag and sell you the star rivets to attach it to your fire wall; all on line. They claim that they offer this "service" so that your barn find can have any option, motor and trans combination that your little heart desires; and it will still "look" original (not that, that would be important to any one; they are just changing the documents to match the way they want their car to look, it is not an attempt to deceive any one). Admittedly these adds were directed at the Camaro community that covets the rare 460 horsepower 454 Z/28 with the RS-SS option on their 1968 Camaro with mono-leaf springs and a ten bolt rear; which probably explains why there are five times the number of Z/28 Camaros on the road than Chevrolet ever built. But it also applies to SS Novas and SS Chevelles that had the rare ZL-1 option years before or after it was ever offered (that makes it rare right?). Or in the case of the big block installed in a Camaro or a Nova that is sitting in the middle of the engine compartment; even though the factory moved the big block motor an inch to the passenger side of the car so that the exhaust would clear the steering box that everyone is complaining about hitting their headers (and asking why no one makes a set of headers to fit "their car").

My claim to fame was in building sleepers back in the day. I took a six cylinder Camaro or Nova and installed a 454 or bigger motor into it because the factory wouldn't do it. I changed everything over in the car using factory parts. I was in essence build a true "SS" using every part called out in the Assembly manual to make the car with me supplying the labor. I could afford to do this because I lived at the local Chevrolet dealership for a number of years and got all of my parts at the dealers actual cost; which was a considerable savings over the price they charged even a repair shop or body shop. Aside from the trim tag and the fact that there were no SS badges to be had, it was a SS on steroids. I sold them as fast as I could build them (three were sold to the Emir of Saudi Arabia, though how he found me I have no idea. His representitive paid cash up front, and included a "Call Tag" that had the cars shipped out of Miami bound for the Suez canal.). I know for a fact that I am responsible for no less than 27 of these rare factory exceptions that you read about. My point is I wasn't the only one doing this, I just did a better job than others in the area I lived converting the car over completely, using original GM parts that were still readily available because the cars were still brand new.


Big Dave

Last edited by Big Dave; 05-30-2013 at 03:35 AM.
Big Dave is online now  
post #9 of 10 (permalink) Old 06-09-2013, 09:42 AM
Senior Member
 
Join Date: Mar 2006
Location: Maine
Posts: 379
 
Send a message via AIM to TAR6569
If the build sheet for this 66 Impala showed 396/375, then it would be an obvious fake of course.
TAR6569 is offline  
post #10 of 10 (permalink) Old 06-09-2013, 06:30 PM
Moderator
 
Join Date: Jan 2007
Location: Lewisburg, Ohio
Posts: 2,909
 
The alternator is on the wrong side as are the brackets with the long water pump that indicates a later model engine installed. The chrome valve covers were never offered in 65 or 66. The air cleaner is wrong for 65 or 66 Impala. It very well may have been a 396 car when it left the factory. But most of whats under the hood isn't original. For dang near 30 thousand dollars I would want a original numbers matching car.
dadstoy is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Impala Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome