1.7L Ljet advice Options

[timothy_nd28]

I just now realized this new engine that I have been piecing back together over the past few weeks isn’t the 1.8L that the PO said it was. The engine code on this engine is EA050723, which if I cross checked correctly is indeed a 1.7L

My issue is, I have been transplanting my old 1975 1.8L Ljet fuel injection parts on this 1.7 block. Can I run Ljet on this 1.7L engine? What obstacles am I up against? Is my 75 1.8L relay board interchangeable with the 1.7L setup?

[ape914]

I just now realized this new engine that I have been piecing back together over the past few weeks isn’t the 1.8L that the PO said it was. The engine code on this engine is EA050723, which if I cross checked correctly is indeed a 1.7L

My issue is, I have been transplanting my old 1975 1.8L Ljet fuel injection parts on this 1.7 block. Can I run Ljet on this 1.7L engine? What obstacles am I up against? Is my 75 1.8L relay board interchangeable with the 1.7L setup?

I think all the realy boards are the same, but they can be wired differently for the different year models. (ie the connectors are wired differently jumpers maybe used at the connector) My data only goes to 1973 (haynes book)

The L-jet is very vacuum signal sensitive, so cam and valve differences can make or break this. The difference in displacement is very small and is not so much an issue.

pay attention to cam and valves is the best advice i can give. If you do indeed have a D-jet cam and heads you might consider purschase or a D-jet system from someone parting out or doing a motor change.

Or make sure your cam grind and valve sizes are compatible with L-jet and run it on L-jet. Other folks maybe able to help with Cam shaft ID and valve sizes needed for L-jet

[Prospectfarms]

There is a thread that describes a 1.7 conversion, but I can't find it. Here's one a 'bout converting a 2L (to L-jet).root_werks 2.0 l-jet

[Katmanken]

Who knows what the DAPO did with the engine. The cases are universal, but swapping the 1.7 crank and rods and cylinders and heads for 1.8 parts can get you a 1.8. What cylinder size do you have? What heads? Pics?

You may be matched but it depends on the parts.

[SirAndy]

I ran a 1.7L DJet on a 1.8L engine. If you swap everything over, i see no reason why the reverse of what i did wouldn't work.

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[Valy]

You should be fine.
Cams are the same and ljet is much more stable and easy to work on.
You might need to adjust the AFM but not sure since the 1.8 were lean anyway for emissions reasons.

[Mike Bellis]

I have a pdf of the L Jat manual. email me and I'll send you a copy.

It's 6MB too big to post here

[Prospectfarms]

Here's a link to the Bosch, 28-page tech manual and trouble-shooting guide, with specs, courtesy of Jeff Bowlsby. Bosch L-jet technical brocure

[jcd914]

The best running L-jet 914 I ever worked on had a 1.7 transplanted into a 74 1.8 car.
The L-jet is very sensitive to vacuum leaks and with the low compression of the 1.8 engine there is no vacuum to spare. The higher compression of the 1.7 engie suits the L-jet system quite well.
Case, cranks, rods, cams are all the same 1.7L to 1.8L.
Heads and pistons/cylinders differ.

Of course you could have 2.0L internals inside the 1.7 case.
2.0L crank, rods, pistons/cylinders fit right into a 1.7/1.8 case (no machining).
1.8 heads fit the 2.0 cylinders, 1.7 heads need to be machined.

Jim

[Prospectfarms]

The higher compression of the 1.7 engie suits the L-jet system quite well.

The author of the earlier L-jet to 1.7 thread (that I still can't find) said the same.

[timothy_nd28]

I already installed this engine. I'm having difficulty getting the numbers off the heads.
At this point in the game, I will turn a blind eye to this 1.7 but rather pretend it's indeed a 1.8L. Everything is screaming 1.7L to me, with the head vents, and with the oil fill neck. However, the fan impellar only has 1 timing mark, and it's a bright red timing mark. Doesn't this indicate 1.8L? Maybe this is a hybrid engine, with the 1.7L case but a 1.8L rotating assembly as someone already posted earlier?




This pic shows the head vent

Oil filler, different set up than my old 1.8L

This is a bad pic, as the camera couldn't pic up the red timing mark.

[timothy_nd28]

I have a pdf of the L Jat manual. email me and I'll send you a copy.

It's 6MB too big to post here

Thanks so much! Sending PM now.

[Cap'n Krusty]

1.7 and 1.8 crank and rods are the same. Heads are different, but 1.7 heads can be opened up for the 93mm cylinders. If you do that, you'll have to calculate the increased compression and shim the barrels to compensate for it. Camshafts are the same. You MUST plug the head vents 100%. You MUST use everything that came from the 1.8 on top of the engine, including the oil breather/filler assembly, the intake plenum, and the distributor. There can be NO vacuum leaks whatsoever.

Have fun!

The Cap'n

[timothy_nd28]

Okay, this is all good news. One last thing, The head vents, can I just use vacuum rubber caps things on them? I was thinking about using them, and putting a hose clamp on it. Should I be worried about head temps melting them?



Also, was there a rubber seal/o-ring on the top of the dipstick? Seams like a good place for vacuum leaks.

[Prospectfarms]

Okay, this is all good news. One last thing, The head vents, can I just use vacuum rubber caps things on them? I was thinking about using them, and putting a hose clamp on it. Should I be worried about head temps melting them?



Also, was there a rubber seal/o-ring on the top of the dipstick? Seams like a good place for vacuum leaks.

Those rubber caps do seem kind of melty. You could stub short sections of hose over the vents and plug the hose with a bolt sized to match the hose.

I checked the PET diagrams for 1.8 dipstick the dipstick profile showed a bulge that might be grommet or flange on the dipstick located beneath the dipstick cover.