Lotus Elan

Suggestions on initial mixture setting on '69 w/175 CD-2's

PostPost by: tdskip » Tue Jul 07, 2020 12:25 pm

Good morning - making progress on getting the engine ready to install and am nearly done rebuilding the Strombergs.

I wanted to ask to see if there was any coaching/tips on where to set the mixture for the first time I fire the car up. The engine has been recently rebuild and needs to be run in and I want to make sure I can do that right away rather than fumbling around before it starts and runs cleanly.

On my TR6s, and as suggested by the Buckeye Triumph tutorial, it is all the way screwed into the body and then one turn out. Not sure if that applies to our Elans as well.

Thank you for any responses and shared experiences.
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PostPost by: 69S4 » Tue Jul 07, 2020 2:24 pm

You're not talking about the 'idle mixture screw' are you - the one on the right hand side by the temp compensator. That's normally screwed all the way in and gently seated. It's not an idle mixture screw in the normal sense. The manual says fiddle with it a bit with a new engine that's being run in but after that it's not a normal adjustment. That should be done with the needle.

Starting position for that is with the shoulder flush with the bottom of the air valve. If (and I don't) you have the plastic washers on the bottom of your needles it's those that should be flush. You then move the needle up or down to play with the mixture. What I've tended to do is start with the needle flush and then move it in 10 thou increments depending on how the car runs. Because my needle jets are higher than they should be most of my adjustments have been to move the needle upwards but your mileage etc may vary.

Have you set the temp compensators? Getting those working makes a big difference (on my car anyway) to hot idle and particularly, hot starting.
Stuart Holding
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PostPost by: tdskip » Tue Jul 07, 2020 3:16 pm

Good morning Stuart, thanks for the thoughtful and detailed reply.

I was indeed asking about the needles that attach to the pistons, I will set them flush and see where that gets me.
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PostPost by: tdskip » Tue Jul 07, 2020 4:47 pm

69S4 wrote:Have you set the temp compensators? Getting those working makes a big difference (on my car anyway) to hot idle and particularly, hot starting.


Oops - missed this. Good tip, and on the list, but will give this extra attention.
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PostPost by: SENC » Tue Jul 07, 2020 6:07 pm

I agree with Stuart. Check your jet height - I posted recently at the end of my old Stromberg Rebuild thread a Lotus Service Bulletin that indicates the correct height. Last, as I recall you only have 3 or 3.5 functional turns on the adjusting screws - you might test that before putting the pistons/air valves in so you know how many turns are available to you either way from flush.
Henry
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PostPost by: tdskip » Wed Jul 08, 2020 2:26 pm

SENC wrote:I agree with Stuart. Check your jet height - I posted recently at the end of my old Stromberg Rebuild thread a Lotus Service Bulletin that indicates the correct height. Last, as I recall you only have 3 or 3.5 functional turns on the adjusting screws - you might test that before putting the pistons/air valves in so you know how many turns are available to you either way from flush.


Hello Henry - I have a bit over 3 turns.

Will check that thread.

Edit - found it: " Looks like the official is 0.120" recessed" for 1969 and 1970.

Thank you!
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