Engine ID????

[Geert-Jan]

Hi Folks,

My 68 DeVille Convertible is slowly unfolding its (or should I say her) history mystery.

Because I suspect the car has a rebuilt engine (or a donor engine) I tried to retrieve the identity of it.

The block casting number next to the oil pressure sending unit is 1485200. From that number I can conclude that the engine is not matching to the body: from the last four digits (5200) I found out that its a 70-76 engine.... Oops! Then it could be a 472 ci or a 500 ci engine.

The number on the right (i.e. passenger side) exhaust manifold is 1486442. They fit on either a 472 ci or a 500 ci engine (right?).

On the other side (i.e. drivers side) of the block casting number side there is a shallow number stamped in the block: 6601920(. The 8 Im not sure because it could also be the roughness of the cast iron. To see that number I had to remove the air filter unit, unplug the oil pressure sending unit and after some cleaning I put white paint on it and whiped the surplus away. Even then I was not sure of the whole number sequence. Does anyone know what that number means?

What do I need to do to unfold the engine ID mystery completely and determine what engine it is (year, size; preferably without disassembling the whole engine)?

Thanks in advance for the advice!

Best regards,

Geert-Jan Ankoné


PS: had my tranny completely rebuilt last week. Garage did a very good job.

[Geert-Jan]

....obviously I dont have the cars history present (yet I have to admit because I wrote the previous owner in the States a letter with some questions).

Best regards,

GJ

[TJ H 20664]

You are correct that the 5200 block is a 70-74 472 or a 70-76 500.   The only change between the 472 and 500 is the crank and pistons.  Without removing the oil pan to see casting number in the crank the only way to tell is to measure the stroke which is not that easy with the head on.  I have never tried it but you may be able to use some sort of wire through a spark plug hole and turn the engine by hand to measure the stroke.  The 472 has a 4.060 inch stroke.  The 500 has a 4.304 inch stroke.  If the motor has not been apart you may get a clue by removing a valve cover and looking for the head casting number usually between the rocker pedestals in the center of the head.  68-73 had 76cc chamber heads with casting numbers ending in 250,902,& 950.   The 950 heads came on the 70 eldorados and did not have smog rails so there will be no hole in the front other than a vac temp sensor or a threaded plug.  The other numbers end in 250 or 902 and have the smog rail cast in but some may have not been drilled. The 68-70s were 10 or 10.5 :1 compression and had a peanut or bathtub shape dish in the pistons.   71-73 GM made them drop the compression to 8.5:1 so the pistons had a fairly large deep dish that had straight horizonial edges. 74 472  had flat top pistons. 74-76 500 had pistons with a normal looking small round dish.  74-76 heads were 120cc chambers and ended in 493 and 120 both cast with smog rails and there were a few 552s with out smog rails.

If the carb or intake is orignal to the motor the 74 and older had the choke coil in the manifold the 75 & 76 had electric choke so no well in the manifold.  Every manifold after 71 had EGR some pre 71s didnt. Pre 74s had mounting hole for the ignition coil  after 74 didnt because they used HEI.  The carbs numbers included a year so that may be a clue also if it had not been changed in the last 30+ some years.  First two digits should be 70 second two are year 28=68, 29=69, 40-45=70-75, 56=76.  Next digit is 2 for normal emissions 5 for ca & altitude.  Second to last should be 3 for cadillac and last should be and even number for auto transmission.

Hope I got it all right and I hope it helps.
Good Luck and have fun with the car.

TJ H
20664
StPaul/Mpls MN USA

[Geert-Jan]

Hi TJ,

Thanks for the extensive answer!

Two days ago I removed one valve cover and saw a cast number in the center of the head compartment: 1497902. From the information I found on the internet (i.e. http://forums.500cid.com TARGET=_blank>http://forums.500cid.com and Butlers A1 Motors: Cadillac long blocks) this info narrowed the possible options down from a 70-76 engine (because of the last 4 digits in the block casting number 5200) to a 70-74 472 cid engine with small 76 cc chambers.

I forgot to look at the carb number when I removed the air cleaner but I can do that this weekend. I have a spare one so I know where to look at on the one on the manifold. You are right that its also a good indicator of the construction year of the engine but since the engine is not original to the car it could also be the case for the carb.... Well see.

Ill keep posting my experiences.

Best regards,

Geert-Jan GJ Ankoné

[TJ H 20664]

The 902 heads were the earlier small chamber heads so they would not have come on a 74-76 car since those were the later 120cc chamber heads with differnt casting numbers.  I have 3 73 500s that all have 902s on them so I would assume they were the most common heads from 71-73.  71-73 also means that there were more 472s out there than 500s since the 500 only came in the eldos those years.  Good thing or bad depending on your view point is that its most likely low compression so you may not have to run it on high octane fuel.

Hard to tell this late in the game since so much could have been changed over the years.

Find anything else that gives you any clues to her past?

[Geert-Jan]

Yep.....

Checked this weekend the carb number 7029232, which means a Rochester carb for a 1969 49-State Caddy with auto transmission. So no more clues about her history than the knowledge that the carb is also a donor one.

From the Fisher tag under the hood I can see that its a 1968 Caddy DeVille Convertible (hahahaha!), assembled at the GM Auto Assembly Plant in Arlington (zone FWD: Fort Worth Dallas).

Maybe at the service and maintenance station they can find out (something about) the compression ratio. I have to take her anyhow for a ignition tune up because shes running bad now.

To be continued...

[Tim Pawl CLC#4383]

 FWD is the code for FleetWooD body plant in Detroit,Michigan not Fort Worth Dallas.

[Geert-Jan]

Okay, thanks for the info! From the shop manual I tried to decode the under hood tag and those were the only letters so thats why I came on Fort Worth Dallas.

What does it mean: Fleetwood body paint? Kind of layering? Color series?

Best regards,

GJ

[JIM CLC # 15000]

03-27-07
Geet-JAN, The GM compancy consisted of several seperate compancies. One being the FLEETWOOD Body compancy. Others were Fishers, body by. Delco Ramey (makers of elect. OEM components. to name just a few.
Good Luck,JIM

[Geert-Jan]

Hi Jim,

Thanks for the info. Is there some book I can find all this info in? Comparing to you all I feel kind of stupid, although I try very hard to get all the info posible.

This is what the under hood body tag says:

           Body by Fisher
      10A
ST    68-68367     FWD  2183         BODY
TR    366-              12-1         PAINT
GENERAL MOTORS CORPORATION CERTIFIES TO THE
DEALER THAT THIS VEHICLE CONFORMS TO ALL
FEDERAL MOTOR VEHICLE SAFETY STANDARDS
APPLICABLE AT TIME OF MANUFACTURE

According to the (factory) shop manual the assembly plant should be indicated by a 3-letter combination. Thats why I came on Fort Worth Dallas (the economical zone of Arlington).

Its very confusing. Am I right that the body is a Fisher design, made by the GM Fleetwood company?

Best regards,

GJ

PS: can you advice me some book titles I can find all this information in?

[JIM CLC # 15000]

03-29-07
Geert-JAN, I think it time for a WAG, If you will permitt me one. IM guessing that TR366 is the code for Fleetwood trim for a convertiable. 12-1 PAINT should mean 12 for the color of the body and 1 for top color. As for a list of books to read. I think your best bet is to go to your local library and get some Cadillac books to read. Also, the favorites list on your computer should have the following list of web-sites that you can go to for car infomation when you want to read: < thecarburetorshop>(makes for gooding reading. plus bein g very informing), (RPM is the mans initials, He is an engneer and makes modication to/for/on older Cadillacs)
(on line catilog) (on line catilog)You can put anything into your search-engine and it will come up.  TV Channel to watch: History ch, Discovery ch, and the Speed ch. Read all you can about cars.  HTH
Good Luck,JIM

[JIM CLC # 15000]

03-29-07
Geert-Jan, to continue with my suggestions contained in my post, dated 03-29-07. If you read all of todays posts. There are a couple of web-site mentioned that should be among your favorites.
HTH Good Luck,JIM