Lotus Elan

Fall/Winter/Spring Projects for 0248k

PostPost by: Craven » Thu Sep 28, 2023 7:07 pm

Just to put my mine to rest, will you with a cold engine use the choke and start the engine. This way as I tried to explain uses a completely different part of the carbs, it has its own jet and emulsion tubes air valves and air supply so all the main circuit is redundant at this point main jet size slow running jet size choke size emulsion tube pump jets etc. are irrelevant. Even level in float chamber is not important as the fuel supply is drawn from the very bottom of the chamber. Checking for wet plug needs to done with a cold engine as hot plugs won’t stay wet for long.
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PostPost by: steve lyle » Thu Sep 28, 2023 7:43 pm

Craven wrote:Just to put my mine to rest, will you with a cold engine use the choke and start the engine. This way as I tried to explain uses a completely different part of the carbs, it has its own jet and emulsion tubes air valves and air supply so all the main circuit is redundant at this point main jet size slow running jet size choke size emulsion tube pump jets etc. are irrelevant. Even level in float chamber is not important as the fuel supply is drawn from the very bottom of the chamber. Checking for wet plug needs to done with a cold engine as hot plugs won’t stay wet for long.
May help


When the engine's cold, I've always been using the "cold start device".
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PostPost by: Craven » Thu Sep 28, 2023 7:56 pm

OK I would rule out fuel then, you are only left with ignition timing, must be at the right Time and in the right Place. 0.025 is fine for gap.
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PostPost by: steve lyle » Thu Sep 28, 2023 9:09 pm

Craven wrote:OK I would rule out fuel then, you are only left with ignition timing, must be at the right Time and in the right Place. 0.025 is fine for gap.


Not so fast, my friend.

Your comment about the choke being an independent source of fuel made me think. I just did a cold start, used the "choke" (don't tell Randy I called it that), and pulled the #1 lead while the choke was on, at about 1500 RPM. Speed immediately dropped quite a bit. Tried the same on #3, not as much drop. So I opened up the mixture screws on 1 & 3 to 3 turns from seated, and got a drop on #1, again maybe a small one on 3 but hard to tell. I've currently got .45 idle jets on 1 & 3, will try the .55 jets that Randy wants me to use - won't that give me a richer idle mixture?

This is with new leads as well, tested for continuity. But after the "choke start", and before turning out the mixture screws, I did get the drop from both when pulling leads.

So now I'm thinking it's basically a matter of getting the idle jets and mixture set correctly. And if for some reason that can't be done, then dig deeper into the carbs. It is odd that 1 & 3 need the mixture screws about twice as far out as 2 & 4 do.

Re: timing - here's the current state of the valves, main pulley and distributor just before this last test. See anything grossly wrong?

Thoughts?

Screenshot 2023-09-28 at 4.00.36 PM.png and

IMG_0539 2.JPG and

IMG_0543.JPG and

IMG_0544.JPG and
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PostPost by: Craven » Thu Sep 28, 2023 10:18 pm

Seem to have moving goal posts here, golden rule in fault finding change one thing at a time.
It looks as if you have a vacuum retard on your distributor? may be correct on export cars!
Increasing to 55 will make a huge difference to big in my experience although the E10 fuels seem to need at least 50.
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PostPost by: pharriso » Thu Sep 28, 2023 11:15 pm

Craven wrote:It looks as if you have a vacuum retard on your distributor? may be correct on export cars!


That's unusual... my car doesn't have any vacuum activation on the dizzy.
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PostPost by: joe7 » Fri Sep 29, 2023 12:03 pm

Noticed in the above pictures, I think the rotor is chipped. Does it make a difference, don't know. Greg Z had an issue with a rotor being the "wrong size". A maybe?
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PostPost by: 2cams70 » Fri Sep 29, 2023 12:13 pm

You didn’t get your camshaft sprockets mixed up did you? Very easy to do because they are physically interchangeable but timing marks are in slightly different positions. If I were you I’d be measuring the valve timing with a dial guage and degree wheel to determine exactly whether it’s right or wrong.
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PostPost by: steve lyle » Fri Sep 29, 2023 2:08 pm

Craven wrote:Seem to have moving goal posts here, golden rule in fault finding change one thing at a time.
It looks as if you have a vacuum retard on your distributor? may be correct on export cars!
Increasing to 55 will make a huge difference to big in my experience although the E10 fuels seem to need at least 50.


It's a vacuum advance, not retard. Although I don't see a big, if any, difference when I plug the line.
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PostPost by: steve lyle » Fri Sep 29, 2023 2:15 pm

2cams70 wrote:You didn’t get your camshaft sprockets mixed up did you? Very easy to do because they are physically interchangeable but timing marks are in slightly different positions. If I were you I’d be measuring the valve timing with a dial guage and degree wheel to determine exactly whether it’s right or wrong.


They have "E" and "I" etchings on them, so I don't believe they're mixed.
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PostPost by: steve lyle » Fri Sep 29, 2023 2:17 pm

joe7 wrote:Noticed in the above pictures, I think the rotor is chipped. Does it make a difference, don't know. Greg Z had an issue with a rotor being the "wrong size". A maybe?


Don't see why it would matter electrically, or why the rotor would be an issue if 2 cylinders are good and 2 aren't. Honestly never noticed, but I'll take a closer look when I retime the dizzy to move 1/3 to the 2/4 dizzy posts. Hope to do that test today.
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PostPost by: mbell » Fri Sep 29, 2023 2:30 pm

Have you checked the carb balance airflow for each throat? How much fuel you need is dependent on air flow. So very different idle screw position might be needed for imbalanced carbs.
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PostPost by: Craven » Fri Sep 29, 2023 3:16 pm

As long as you are happy running non standard distributor. These devices are vacuum retard, as you don’t accept this talk to someone that knows how they work.
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PostPost by: steve lyle » Fri Sep 29, 2023 3:54 pm

Craven wrote:As long as you are happy running non standard distributor. These devices are vacuum retard, as you don’t accept this talk to someone that knows how they work.


Here's what I know.

The distributor was rebuilt by British Vacuum Unit, as recommended by Joe Curto when I had Joe convert my Strombergs to home market specs. BVU gave me an itemized bill which included charges for "Vacuum Advance". I had a conversation with Ken Gray about this earlier in this saga - he thought it was retardinig as well. I presume because Federal Elans had vacuum retard. So, I put the vacuum tube in my mouth and sucked on it with the cap off. And saw the distributor plate carrying the points rotate clockwise. Which I'm pretty sure is the direction of "advance".
Steve Lyle
1972 Elan Sprint 0248k @ https://www.mgexp.com/registry/1972-Lot ... 48K.30245/
1972 MGB Roadster @ https://www.mgexp.com/registry/1972-MG- ... 842G.4498/
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PostPost by: steve lyle » Fri Sep 29, 2023 4:00 pm

Bill36 wrote:Steve I’ve got a spare set Webber’s that I had on a 67.
I live up I-75, give me a call if you want to try them.
918-815-6995


Wow, Bill! Thanks for the offer. I assume I-75 is a typo? It looks like I'm making progress with these, but I certainly appreciate the offer and will keep it in mind.
Steve Lyle
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