Lotus Elan

S4 No Fuel

PostPost by: SENC » Wed May 11, 2022 12:18 am

I can see your problem. I rechecked the book and found nothing similar - odd, clearly 1 thing stamped over the other, but the 3175 would give me some confidence I think. Is the rear also stamped 3175?

I'd double check your needles to see if they match. I doubt this is contributing to your problem unless there is a mismatch in needles with jets effectively shutting off the fuel flow. Looking at the jets, are they recessed from the bottom face of the chamber by roughly the right amount (thinking too high may restrict fuel flow as they'd be filled with the wider section of the needle).
Henry
69 Elan S4
65 Seven S2
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PostPost by: Temmck » Wed May 11, 2022 2:06 am

Yes, the other is clearly 3175R. You may have to zoom a bit to see it.

I check the needles tomorrow. i also reached out to Ken at DB to see if they have replacement needles and jets or preferably a conversion to adjustable pistons and needles.
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PostPost by: Temmck » Thu May 12, 2022 4:11 am

Needles are both B1G.
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PostPost by: Temmck » Thu May 12, 2022 4:27 am

Jet heights are both the same. 0.06" (1.59mm) to shoulder of jet and 0.086" (2.19mm) to center of jet.

Both needles seem to be recessed in the piston, not flush.

If I understand correctly, my jets may be a little too high (lean) but my needles are more recessed (rich) so, maybe about right overall.
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PostPost by: Temmck » Thu May 26, 2022 3:20 am

The engine is now running, not well but running.

There was no smoking gun! I remove the carburetors again, polished every stain off the needles, dragged a pipe cleaner through every passage (again), etc. I found the choke 180 deg out so put that right. Plugged all vacuum lines more securely and replaced all electrical components (plugs, wires, points, condenser). I didn't replace the rotor or cap - forgot to order.

The engine now starts pretty quickly with choke and I can hold an idle but there is a periodic backfire through the carbs and it sounds like its running on 3 cylinders when trying to rev the engine. I figure its a timing issue at this point. Will clean off the timing marks and get it timed this weekend.

Thanks all for your advice.
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PostPost by: HCA » Thu May 26, 2022 7:44 am

Not a helpful reply, for which I apologise, but now you are making an excellent advert for EDIS 8)

Hope the weekend goes well..!
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PostPost by: Temmck » Sat May 28, 2022 2:22 pm

One of the reasons I loves these old cars is the lack of electronics. You are right, this car would be much more powerful and reliable and easier to maintain if it had fuel injection, electronic ignition, variable valve timing, and a computer monitoring and managing every vital sign, but that's not the point. I already have a new Toyota and it's no where near as fun! I love the sound air sucking through the carburetors and the constant tinkering needed to keep it running and healthy. Restoring Lotus is my hobby and passion. For me the enjoyment is more about the work and the satisfaction of taking a car that has been rotting away for 30 years in a field and getting it back on the road than the driving - although that's pretty enjoyable too!
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