GM Protect-O-Plate

[ejw71]

Rec'd my GM Protect-O-Plate decode book today. With POP one can determine if a 1st Gen is a SS454 when motor is gone. Great stuff. The 454-ci V8 has these codes for '70s: CRN, CRQ, CRR, CRS CRT and CRV. The CRS code motor translates to aluminum heads. Is this Chevelle only? Haven't heard of an original SS454 with aluminum heads. Did LS-6 have aluminum heads? If so, this would answer my question. Sgt. Ed of the SS454 Police.

[Jim SS454]

I believe that the Aluminum head engine was actually called a LS-7. The LS-7 took the LS-6 engine and added aluminum heads (and possible a different cam but I am not sure of that). From what I heard, this was an over the counter option that could be added to the LS-6 engine. It was not released in any actual cars.

 

I am curious, where did you find the book to decode the protecto plates? That sounds like a slick tool to have.

[ejw71]

Jim, Not doubting your view. However, I suspect the 454 would be stamped with CRS on machined pad behind alternator. Which would mean aluminum heads were factory installed. Book can be purchased at Faxbook@faxonautolit.com, $17 plus 4.95 shipping. Got mine on eBay. Ed

[KLASSIK1]

the protect o plate was a way for gm service personnel to track service work completed on the vehicle during its warrenty period and was attached to the rear of the warrenty book , they ran the metal plate over the service form , it included the original owners id and vehicle id info such as motor trans rearend etc. these were first used in late 1965 as far as i know , they were usually not kept after the warrenty period and yes they are a great way to id a car when the original drivetrain is missing, they are a nice to have as most were disgarded .

 

 

Leo

[mjs-13]

Aluminum heads and the LS-6 depends on the year. In 1970, the LS-6 engine had "291" iron heads. They were unique in that they were closed chamber with small (5/8 inch) spark plugs. This was the only head to have "this" combination.

 

In 1971 the LS-6 engine did have aluminum heads on engines installed in the 188 Corvettes with this engine combination. There are no known as of now, applications (cars) besides Corvette where the LS-6 was factory installed in a production car.

 

So an LS-6 can go either way with aluminum heads depending upon production year of the engine. Most if not all over the counter "crate" LS-6 engines of any year manufacture were iron head motors.

[Guest]

Ejw the book sounds cool and a great knowledge base.Mjs I have to disagree on the LS-6 just being a Corvette install.They made their way into Chevelles also in '70-'71(although not sure of numbers offhand).The LS-7 wasn't an RPO(could have been a COPO)but was definitly sold over the counter.As stated the LS-7 was an LS-6w/aluminum heads much like the L89 option on the L78 396

[ejw71]

Have determined that the CRS (aluminum heads) engine code for 1970 transulates to only a '70 Chevelle 450 horse, 454ci, 11:1 cr, and only available with a TH 400 trans. The GM Protect-O-Plate decoder book has '70 Chevelle/Monte Carlo engine ID codes listed together. Makes sense as both are "A" bodies. Is this an LS-6 engine?

This book is like the Captain Marvel decoder ring (1950s mutant X type person) I got by sending in box tops from a Kellogg's cereal and some loose change from my Dad's pockets. Ed

[mjs-13]

Coolram,

 

I believe if you will check, there have been NO 1971 Chevelles found with a factory installed LS-6 yet. Lot's of rumors, but no cigar.

 

Kinda of like the 4 speed SS454's and LS-6 SS 454 Monte Carlo's, everyone remembers seeing but have yet to produce with any documentation.

 

As for the 1970 LS-6 production. Yes, there is a code for an aluminum head engine in 1970 however nobody has ever found one factory installed in a car with any paperwork. Remember, in my post I said factory installed. There were several different engine codes in numerous model years that made "the books" but were never installed in a production car. The only aluminum engine in a 1970 Chevelle was a 396/375 L-89. Of those, the production number is 18!!! There was also an iron head 396/375, the L-78. I have never seen 1970 Chevelle L-89 however I do have a friend who has one of these engines with a VIN from a 1970 Chevelle. He has had the engine for 20 years and still looking for the car. If he ever finds it, it will be the only one found so far. The nickname of the gentleman who has this engine is "COPO". That ought to tell you the type of cars he owns, buys and sells. Low mileage, no rust, original paint and paperwork. If one was out there, he would know of the car. These rare cars trade in a very limited group of "big bucks" people.

 

Have a great weekend!