engine I.D.

Chumley · February 18th, 2007, 02:06 PM

Okay, my suspicions are confirmed. The motor in my '72 is not original. The number on the pad below the driver side head is 33M405642. Does not match VIN of car. I'm assuming this engine is '73 or newer, since it DOES have EGR . Is there any way to determine the actual year by the above number? I'm thinking a '73, since my parts book lists "M" as power plant code for '73 350 4bbl. Is that what the "M" in this number refers to? Also the block number above the timing cover is 395558 follwed by a larger size "2". Haven't got the number off the head yet. I'm also suspecting that the tranny was swapped as well. Need to get numbers there also. Also the valve covers say "OLDSMOBILE" in block letters. Have not seen this on any other '72s.

Chumley

texasred · February 19th, 2007, 08:18 AM

Chumley,

The 33M number indicates it is a Oldsmobile (3), 73 motor (3) and the car it came from was assembled in Lansing. The last numbers are the plant sequence code.

C.J.

2blu442 · February 19th, 2007, 09:37 AM

I've been told the valve covers with the name Oldsmobile pressed into the metal were only used in 1973 and maybe 1974. Sure the valve covers could have been changed but this agree's with what C.J. keyed out from your engine number. Those valve covers are in demand, so if you ever decide to change them don't throw them in the scrap metal pile! John

Chumley · February 19th, 2007, 11:54 AM

I thought that's probably how the numbers decoded. I'm not familiar with VIN code syntax after '72, but I guess it's pretty much the same as for '72. I had no idea about the valve covers. What I really want is a '72 motor in there. Can I swap heads and intake for a '72 with no problems? Is the rotating assembly for '73 much different from '72? Also what about engine wiring harness? I wanted to replace it with a '72(with HEI conversion) but want everything compatible. Right now there are wires cut and missing to accomodate the '73 when it was installed. Too many questions, I know, but I'm anxious to make a plan and pursue it. Thanks for all your help....Chumley

texasred · February 19th, 2007, 04:08 PM

It's all the same as far as heads and intake go, but it'll still be low compression. Not sure how low, but I know they killed performance in '73.

If you are near San Antonio, I will have a peppy street/strip '71 350 for sale soon. And there's a 72 motor in the for sale section.

C.J.

Chumley · February 19th, 2007, 05:56 PM

I thought in '73 they made the heads with smaller valves, but larger combustion chamber, hence lower compression. Actually, the car cruises fine with enough power. I'm not looking to hop it up, just want it to run smoothe when I go to sell it. I'm in CA., so no can do on the engine you have. There are sources out here, I'm just trying to save $$$$.
Chumley

redoldsman · February 19th, 2007, 06:17 PM

There really should not be much to a wiring harness for the 73 engine since there is no computer involved. It should be almost identical to the 72. From what I understand, the 73 actually had flat top pistons and the compression was lowered by using large combustion chambers in the heads. The 72 had dished pistons to lower the compression. Use some 72 heads (#7a) and it should work fine with probably a 9.5 CR. When you hook up the HEI, make sure you have a full 12 volts to it.

texasred · February 20th, 2007, 02:04 AM

You guys are right about the heads. 79cc versus 64 cc for the 68-72 heads!

From what I've read, they indeed use the pre-70 flat tops.

So...with some good heads, intake and rejetted carburetor, you should be able to pump up that engine quite nicely.

C.J.

70Wcars · February 20th, 2007, 07:05 PM

Have the number 8 heads ( that is what should be on the 73 ) rebuilt with a good valve job and mill them .030 . The # 8 heads used the larger 1.625 exhaust valves and had hardened valve seats for use with unleaded fuel. Use the .028 head gasket from Corteco and you should have a street friendly compression. Just my .02 worth.

texasred · February 20th, 2007, 07:41 PM

I KNEW Dan would have a solution!

C.J.

Chumley · February 23rd, 2007, 07:07 PM

Thanks for all the info, guys. I think I'll just keep the engine as is since it runs pretty decent(except at idle, need to look at carb issues). It already has HEI, somewhere I read that this was factory ignition for '73. Was it in the "tech" section on this site? What would the chamber volume be after milling .030? I need to run a compression test to see if rebuild is warranted.

Chumley

February 18th, 2007, 02:06 PM	#1 (permalink)
Chumley Registered User Join Date: Dec 2005 Posts: 217	engine I.D. Okay, my suspicions are confirmed. The motor in my '72 is not original. The number on the pad below the driver side head is 33M405642. Does not match VIN of car. I'm assuming this engine is '73 or newer, since it DOES have EGR . Is there any way to determine the actual year by the above number? I'm thinking a '73, since my parts book lists "M" as power plant code for '73 350 4bbl. Is that what the "M" in this number refers to? Also the block number above the timing cover is 395558 follwed by a larger size "2". Haven't got the number off the head yet. I'm also suspecting that the tranny was swapped as well. Need to get numbers there also. Also the valve covers say "OLDSMOBILE" in block letters. Have not seen this on any other '72s. Chumley

February 19th, 2007, 08:18 AM	#2 (permalink)
texasred Tom Servo's Stunt Double Join Date: Apr 2004 Location: San Antonio, Texas Posts: 824	Chumley, The 33M number indicates it is a Oldsmobile (3), 73 motor (3) and the car it came from was assembled in Lansing. The last numbers are the plant sequence code. C.J. __________________ Dad said, "Sometimes you read Job...sometimes you ARE Job!"

February 19th, 2007, 09:37 AM	#3 (permalink)
2blu442 Moderator Join Date: Sep 2006 Location: Medford, Oregon Posts: 2,257	I've been told the valve covers with the name Oldsmobile pressed into the metal were only used in 1973 and maybe 1974. Sure the valve covers could have been changed but this agree's with what C.J. keyed out from your engine number. Those valve covers are in demand, so if you ever decide to change them don't throw them in the scrap metal pile! John __________________ 1964 Cutlass Factory 4spd 1965 442 4spd 1967 442 Auto 1967 Cutlass Convertible 1967 Cutlass four door daily driver 1968 442 Auto 1969 442 W30 Auto 1970 442 4spd 1971 Cutlass Flat Top Wagon 1973 Che*vy 3/4 Ton 454/TH400 Tow Vehicle Only the tow vehicle is finished!

February 19th, 2007, 04:08 PM	#5 (permalink)
texasred Tom Servo's Stunt Double Join Date: Apr 2004 Location: San Antonio, Texas Posts: 824	It's all the same as far as heads and intake go, but it'll still be low compression. Not sure how low, but I know they killed performance in '73. If you are near San Antonio, I will have a peppy street/strip '71 350 for sale soon. And there's a 72 motor in the for sale section. C.J. __________________ Dad said, "Sometimes you read Job...sometimes you ARE Job!"

February 19th, 2007, 06:17 PM	#7 (permalink)
redoldsman Proud Viet Nam Veteran Join Date: Dec 2006 Location: Rowlett, TX Posts: 480	There really should not be much to a wiring harness for the 73 engine since there is no computer involved. It should be almost identical to the 72. From what I understand, the 73 actually had flat top pistons and the compression was lowered by using large combustion chambers in the heads. The 72 had dished pistons to lower the compression. Use some 72 heads (#7a) and it should work fine with probably a 9.5 CR. When you hook up the HEI, make sure you have a full 12 volts to it. __________________ redoldsman

February 19th, 2007, 11:54 AM	#4 (permalink)
Chumley Registered User Join Date: Dec 2005 Posts: 217	I thought that's probably how the numbers decoded. I'm not familiar with VIN code syntax after '72, but I guess it's pretty much the same as for '72. I had no idea about the valve covers. What I really want is a '72 motor in there. Can I swap heads and intake for a '72 with no problems? Is the rotating assembly for '73 much different from '72? Also what about engine wiring harness? I wanted to replace it with a '72(with HEI conversion) but want everything compatible. Right now there are wires cut and missing to accomodate the '73 when it was installed. Too many questions, I know, but I'm anxious to make a plan and pursue it. Thanks for all your help....Chumley

February 19th, 2007, 05:56 PM	#6 (permalink)
Chumley Registered User Join Date: Dec 2005 Posts: 217	I thought in '73 they made the heads with smaller valves, but larger combustion chamber, hence lower compression. Actually, the car cruises fine with enough power. I'm not looking to hop it up, just want it to run smoothe when I go to sell it. I'm in CA., so no can do on the engine you have. There are sources out here, I'm just trying to save $$$$. Chumley

February 20th, 2007, 02:04 AM	#8 (permalink)
texasred Tom Servo's Stunt Double Join Date: Apr 2004 Location: San Antonio, Texas Posts: 824	You guys are right about the heads. 79cc versus 64 cc for the 68-72 heads! From what I've read, they indeed use the pre-70 flat tops. So...with some good heads, intake and rejetted carburetor, you should be able to pump up that engine quite nicely. C.J. __________________ Dad said, "Sometimes you read Job...sometimes you ARE Job!"

February 20th, 2007, 07:05 PM	#9 (permalink)
70Wcars Registered User Join Date: Jan 2007 Location: Texas Posts: 64	Have the number 8 heads ( that is what should be on the 73 ) rebuilt with a good valve job and mill them .030 . The # 8 heads used the larger 1.625 exhaust valves and had hardened valve seats for use with unleaded fuel. Use the .028 head gasket from Corteco and you should have a street friendly compression. Just my .02 worth. __________________ Dan S 70 442 W-30 4-speed 70 442 W-30 Post Coupe Bracket Race car...10.66 @ 3650lbs.

February 20th, 2007, 07:41 PM	#10 (permalink)
texasred Tom Servo's Stunt Double Join Date: Apr 2004 Location: San Antonio, Texas Posts: 824	I KNEW Dan would have a solution! C.J. __________________ Dad said, "Sometimes you read Job...sometimes you ARE Job!"

February 23rd, 2007, 07:07 PM	#11 (permalink)
Chumley Registered User Join Date: Dec 2005 Posts: 217	Thanks for all the info, guys. I think I'll just keep the engine as is since it runs pretty decent(except at idle, need to look at carb issues). It already has HEI, somewhere I read that this was factory ignition for '73. Was it in the "tech" section on this site? What would the chamber volume be after milling .030? I need to run a compression test to see if rebuild is warranted. Chumley

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