Guys, I really need your expertise on this. I had purchased a 1974 914 1.8L a while back. The former owner advised me that the engine was not matching. Looks like a previous owner had taken a 1.7 liter case and modified it to be a 1.8L and use a Bosch L-jetronic brain as well as all the air intake/manifold designed for a stock 1.8L. It ran well before I pulled the engine for a new clutch/flywheel etc. project. I had verified that the chassis number matches a 1974 914 and the engine number matches a 1973 1.7L (EA026464).

My real problem now is that I really do not know what exactly was done to the engine to make it a 1.8L. I want to keep the L-jetronic fuel injection system, but if I do want to do a stock engine rebuild, what parts would be for a 1.7L and what would be for a 1.8L. I have researched all over about 1.7L engine mods, but they all seem to be "how to modify a 1.7/1.8 to a 2.0L. Nothing what would have been done to make a 1.7 into a 1.8. an anyone please fill me in on the Possible Mods done to my engine? I have various service records that go back to the mid 80's, but it looks like the 1.7 to 1.8 mod was done prior to that. All those records seem to only mention the car being a 1.8L. I'm afraid to replace parts , not knowing how it became a 1.8L. Please advise, thanks.

The only thing different between a 73 1.7 & a 74 1.8L long block is Bore (P&C's).
Same 66mm crank.

also... the common upgrade for a 1.8 (or 1.7) when you put larger cylinders in... comes out to 1911

so not really a 1.8 technically.

you would put stock cylinders and pistons in to make it a 1.8 again
or you could keep the larger displacement as it is likely a more powerful engine

you would also want to see which heads are on yours when it is torn apart
if they are 1.7 heads then I believe they would have slightly smaller valves than a 1.8 stock motor would have.

the Air Fuel Ratio should be measured on a running engine to tell you whether your mixture is adjusted to handle a larger placement or whether you need to adjust the fuel injection system still

Would the heads have to be specific for a 1.8 in order to accept the L-Jetronic fuel injection?

I believe that engine number falls into the 71/72 manufacturing time frame and was used in a '72 911/4. I'd suggest checking the transmission s/n to see if they swapped the drivetrain or swapped out just the engine. Around that time the transmissions went from the 914/11 to the 914/12.

IMO the engine was not made into a 1.8, you probably have a 1.7 or 1.7 with larger cylinders. You can do a compression check to find out. If you are worried about replacing parts, wait for them to be replaced, pull it and see what you got. Seriously, don't overthink this. If it drives well, enjoy it. Once you start the idea of getting this to a stock 1.8 configuration, you'll start the process, realize you can make some improvements, add a little more power, and before you know it you'll drop $10K and still want more.

DaveB

You could pull a valve cover and rockers off and see what heads you have, you might have an 1.8 already.

I keep thinking that if the fuel injection is L-Jetronic (computer brain has L-jet serial numbers), would the heads not have to be 1.8 in order for a L-jet intake manifold to work with that type of Bosch EFI?

I actually have the rockers off due to replacing leaking push rod tubes. How do I find out what the heads are? I don't seem to see any part numbers on my heads.

nope.. heads don't care about induction
you can run any head... but the 1.7 head has the smallest valves.
but you can run L-jet on a 1.7/1.8/2.0 or 2056

bigger valves help move more air.. more HP
the 2.0 heads have the best flow and best design

injection fuel flow needs to match the displacement to get to the correct AFR
so many people will measure the AFR and adjust their injection system to accommodate their need on a particular engine....

Years back we turned our 1.7 into a 1.8 displacement engine. All you had to do was replace the 90mm p&c's with the 1.8 liter's 93mm and fly cut the heads to fit the bigger cylinders. There was a slip in 96mm option but the cylinder walls were very thin.

I've built a couple of Ljets with 2.0 engines, they run good.
Ljet was a more modern design than Djet.

Isn't the 76 912E L-jet?

Yes