1973 GT w/ a 1971 engine?

[HJ70600]

Hallo
I have a 1973 GT with a 1971 engine (1,9). Is it possible that this have been the original combination or have someone put in a "new" engine?

[baz]

it wil be a changed engine to get the high compression and better power of the earlyer engine

[hallgeir]

Baz, correct me if I`m wrong, but wasn`t all the european engines high comp no matter what year? Or is that GT imported from the US?

[HJ70600]

My GT is a US version and it is a low compression. The cylinder head says it is a 1971. Maybe it is only the cylinder head that is changed?

[hallgeir]

So, it seems that Baz knew something I didn`t. Better research I guess.

[69whitegt]

Can you find out the year of your car from the cylinder head? If so how do you decode it?

[yellaopelgt]

69 and early70's were solid lifters.Dont know how you could tell otherwise.
Joe

[GTJIM]

Originally Posted by 69whitegt Can you find out the year of your car from the cylinder head? If so how do you decode it?

When you take the rocker cover off there are two numbers cast beside the gasket rail ( er... the machined bit the rocker cover gasket sits on) which show when the head was cast - 68 or 69 or 70 or 71 etc ......
Once you find them it is easy to see.
Here is a 1968 head: LH # 68 = 1968 RH # is the engine size 1.9L and the Opel part Number.

Of course with the later head's liable to crack you can expect a few earlier heads to have been salvaged and put on later motors over the last 30 years ....

[hrcollinsjr]

I don't remember when they changed from solid lifters to hydraulics but somewhere around '70 or maybe '71.

I believe '72 was when they changed from the three bearing camshaft to the four bearing camshaft.

Harold

[kwilford]

Originally Posted by HJ70600 Hallo I have a 1973 GT with a 1971 engine (1,9). Is it possible that this have been the original combination or have someone put in a "new" engine?

What makes you believe it is a "71" engine"? Are there casting marks that indicate an earlier block or head (or both)?

U.S. spec engines were switched to the dished low compression pistons after a mid-'70 build date (from the '70 to the '71 model year), along with the switch from solid lifters and the three-bearing cam to hydraulic lifters and a four bearing cam. The '71 and '73 engine were essentially identical, EXCEPT (and this is BIG) the '73 (but this time after early 1973 build dates) had a 12 bolt head, as in two small extra bolts near the front, into the timing chain case. In North America, the 12 bolt heads were prone to cracking around the exhaust seat, due to a process called "flame hardening" used to make the seats less susceptible to recession caused by unleaded gas. I believe that the Euro engine didn't have that, due to leaded gas being used much later over there. But you very well may have a U.S. spec engine, or even a U.S. GT (quite common to have them re-repatriated to the Continent).

FWIW, the Euro 1.9 engines (as mentioned) were also ALL high compression (i.e. flat top pistons) right up to the end of production ('78 IIRC), again because they didn't have to meet the U.S. emission specifications.

HTH

[HJ70600]

Originally Posted by kwilford What makes you believe it is a "71" engine"? Are there casting marks that indicate an earlier block or head (or both)? U.S. spec engines were switched to the dished low compression pistons after a mid-'70 build date (from the '70 to the '71 model year), along with the switch from solid lifters and the three-bearing cam to hydraulic lifters and a four bearing cam. The '71 and '73 engine were essentially identical, EXCEPT (and this is BIG) the '73 (but this time after early 1973 build dates) had a 12 bolt head, as in two small extra bolts near the front, into the timing chain case. In North America, the 12 bolt heads were prone to cracking around the exhaust seat, due to a process called "flame hardening" used to make the seats less susceptible to recession caused by unleaded gas. I believe that the Euro engine didn't have that, due to leaded gas being used much later over there. But you very well may have a U.S. spec engine, or even a U.S. GT (quite common to have them re-repatriated to the Continent). FWIW, the Euro 1.9 engines (as mentioned) were also ALL high compression (i.e. flat top pistons) right up to the end of production ('78 IIRC), again because they didn't have to meet the U.S. emission specifications. HTH

I belived it was a 73 engine in the 73 GT until I opened the rocker cover. The head was marked with 71. Now I think it is a 73 block with a 71 head. It is a low compression according to the pistons, but if they produced low compression already in 71, - the complete engine can be a 71.
Thanks for a lot of answers.

[HJ70600]

Originally Posted by hrcollinsjr I don't remember when they changed from solid lifters to hydraulics but somewhere around '70 or maybe '71. I believe '72 was when they changed from the three bearing camshaft to the four bearing camshaft. Harold

My 71 head have hydralic lifters

[GTJIM]

If the block is a '71 it will have a "71" cast on it just like the head - can't remember just exactly where though ..........

[RallyBob]

Originally Posted by GTJIM If the block is a '71 it will have a "71" cast on it just like the head - can't remember just exactly where though ..........

Near the starter. Last two digits are the year.

[philcav]

Originally Posted by GTJIM When you take the rocker cover off there are two numbers cast beside the gasket rail ( er... the machined bit the rocker cover gasket sits on) which show when the head was cast - 68 or 69 or 70 or 71 etc ......

So is this head from 1933 or 1977?

[Bo Mows]

My '69 has a block with *19S-0311649* and 22C69 by the starter and unless th PO put Low Comp pistons back in (which i have not checked yet, looking through the spark plug hole the pistons are carboned up) By reading in this and other threads, I have a high comp engine. The Head is a 71. Is there any draw backs in putting the 71 head on a 69 block?

Bo

[GTJIM]

Originally Posted by philcav So is this head from 1933 or 1977?

Obviously 1933 !!

Nah! The "33" number is by the date/shift/batch indicator and probably is something to do with the pattern number or foundry number or some other production detail - you have a 1977 year of casting head........

Opel made heads in the hundreds of thousands and they neeeded to know when, where & who made them in case of faults showing up after casting.

[hallgeir]

Originally Posted by GTJIM If the block is a '71 it will have a "71" cast on it just like the head - can't remember just exactly where though ..........

Jim and Bob, or anyone, this is all I can find near the starter. Does this possible mean it is a -75? And what do the big H mean?

Was it maybe made for me? H as in Hallgeir? Nah! Don`t think so.

[Bo Mows]

The stamp is actually BEHIND the starter. If you lay under the car and use a mirror to see behind the starter, you can see it. It will be just below the 75 that you show in the picture HTH

Bo

[hallgeir]

Ok, Thanks Bo. I`ll have a look tomorrow morning.

[hallgeir]

BTW, any idea what that big H and 75 on the pic means? I don`t get a chance to look behind the starter until later.