This number is on the side off a motor I have: SI 12 004.101.102A 10 0 22H. Can I tell what motor it is with this number? I need to know if it is a 1.7 or a 1.8. also this number is on one head: 171158.

Show us a picture of the motor / heads.

We could only tell you what the motor started out as. So many opportunities to fuss with heads. bigger crank and cylinders fit any of the cases.
Pics as mentioned above would help to identify type of tin to put on head.

This is not the motor im having fixed. That motor is not at my location. I measured the cylinders on this motor and it is 93mm. I think that is 1.8 cylinders. we dont have the one we will be working on apart yet. I was told its a 1.8 also but i ordered the exhaust bolts that go into the head for it and they would not work. they had larger threads on one side and should have worked but I needed the bolts that is the same size on both ends so that would suggest its a 1.7. I was trying to get parts coming but i guess i may need to wait till i get it apart and measure it. I was just hoping these numbers would tell me somthing.

My mechanic did some pressure testing late on friday and thinks a head gasket is blown. So I was looking at maybe while we had the motor out go ahead and get some 96mm cylinders. I was reading that if you have a 1.7 some head work needed to be done to make them fit but would bolt up to a 1.8. so im trying to evaluate my cost

The engine serial number is on the top of the case in the middle near the case bolts.

The punched numbers you have in the photos above appear to be done by a shop, probably meant to keep all of the parts together during a rebuild. The numbers sticking out are casting numbers.

Neither have anything to do with the displacement of the engine.

You can find out the original displacement if you find the engine serial number on top of the engine. Many are on some of the webbing on top of the right case half (914 orientation) near the flywheel end. Some are in front of the oil filler tower. Serial numbers that start with "W", "EA", or "EB" are 1.7 engines. "EC" are 1.8 engines. "GA", "GB", and "GC" are 2.0 engines. All other codes were not originally installed in 914s.

The cylinders for the 1.7s were 90mm across. The 1.8s were 93mm, and the 2.0s were 94mm.

The register in the head where the top of the cylinder goes is 100mm across on the 1.7 heads. That same feature is 105mm across on the 1.8 and 2.0 heads. The 2.0s have spark plugs that tilt toward the outside of the engine, while the 1.7s and 1.8s (and all non-Porsche applications) have plugs that stand straight up. The 2.0 heads also have three studs holding the intake runner pipes onto the heads, the others all have four studs.

I do not believe that any of the engines had "step studs" (different sizes on each end) installed on the exhaust ports from the factory. They are a popular modification to make when a stud gets stripped or broken, and are available from many engine supply places.

--DD

The 1.8's came from the factory with M9-M8 step studs and so did the '76 2.0 heads on 914's and 912E's. Some '75 2.0 914's had the step studs, too.

1.7's were all straight M8, so if your step studs didn't fit and you have 4 intake studs then there's a good chance you have 1.7 heads.

wow, lots of great info. just what i needed. greatly appreciated

just a update. I took it apart and the cans do not match the heads. the outer lip on the cans are 100mm to the outside and the heads inner measurement is 105. So the head gasket was being pushed out to one side making the can so it hardly sat on one edge of the gasket. and so thats the side that blew out of course. it looks like the previous owner put on 1.7lt cans and had them board out for the 93 mm 1.8lt cylinders. The heads being 105 makes me think they are 1.8lt heads but the exhaust studs are 8mm on both sides like a 1.7. so im not sure what head it is. If they are 1.7 heads then why open them up to 105mm and make a mismatch with his 1.7 heads? it looks like there is a crack in the head by one of the valves so it trash anyway, right? What mess. I guess its time for new heads and pistons and cylinders. That sucks, I thought I was going to replace a gasket and be back on the road. Anyone have some used not cracked 1.8lt heads? I will by new big bore 96 p/c I think. I will try to post some pics.

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you can see by the last pic at the can was juuust catching the edge of the gasket. Good grief!

That the can not at the can. Sorry i should review before posting

Those are 1.8 chambers. They should have 105mm registers.

Odd that they did not come from the factory with M9xM8 step exhaust studs. Don't recall coming across that before on 1.8's, and I've seen an awful lot of them.