Lotus Elan

Weber DCOE 151 jetting for Sprint

PostPost by: zimzum » Fri Jun 02, 2017 10:01 am

Hello,

I have several issues with my carbs. They need adjustments as it feels too rich all the time.
I checked the carbs jetting and I have :
Main : 120 (OK)
Emulsion : F7 (!! should be F11)
Air : 155 (OK)
Idle : 50 F9 (instead of 50 F8)
Start : 85 F9 (instead of 100 F5)
Carbs are DCOE 151

Fact is I don't know what work has been carried out on the engine. I have found a bill stating there was an engine rebuild with new pistons and rebore. Is it an overhauling rebore or a capacity increasing rebore? That is the question. I don't know if my engine is still 1558cc.

Well, first I will sort out the carbs, and in order to do so, I need an advice for a place where to find the jets for my DCOE. What would you recommend? It seems in France, is't way too expensive (as most of the vintage car parts).

Thank you!
Caterham 1600K SS
Paris, France
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PostPost by: Craven » Fri Jun 02, 2017 10:25 am

From the Weber Manual, your setting do point toward a enrichment from standard.
Idle Jet F9 will give a slightly rich mix. Emulsion Tube F7 provides ? For Mixture Enrichment at Low RPM ?

May help you.
Ron.
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PostPost by: webbslinger » Fri Jun 02, 2017 10:58 pm

The Bean catalog lists the following jets for a Sprint with 33mm chokes:
Mains - 120
Air corr - 150 - 155
E tube - F 11
Idle - 50 F8
Pump - 35
An air/fuel gauge is extremely helpful to get it set up right.
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PostPost by: zimzum » Tue Jun 06, 2017 11:59 am

Do I need to buy the proper Starter jets? It seems most people remove the Starter on DCOEs.
In this case, I could leave the ones already fitted on my car and just not use the Starter lever. What do you think?
Caterham 1600K SS
Paris, France
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PostPost by: Craven » Tue Jun 06, 2017 4:12 pm

Hi,
F9/85 is the standard start jet for the 151 leave in place, starting in sub-zero temperatures may need adjustment!!
Ron.
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PostPost by: zimzum » Wed Jun 14, 2017 7:55 pm

I just fitted the usual Sprint jets for DCOE.
I have a better idle than before. But I need to set the richness screws at 2.5 turns. I usually hear about 1.5 turns. What do you think?

While driving, I still have misfires at very low pedal or very small acceleration under 3000rpm. Full throttle is fine. The misfires sometimes come with small explosions in the carbs. Do you think I'm too weak in transcients?
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PostPost by: mbell » Wed Jun 14, 2017 8:19 pm

Whats the ethanol content of the fuel you are using?

I have to use "up to 10% ethanol" fuel here. I am running hypo jets but had similar issues through the progression zone when I was running the equivalent to standard jet setup. I went up an idle jet size this seem to have address the stumble/misfire for me.

I am currently in process of fitting an air fuel ratio gauge so I can get better grip on the fueling.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: zimzum » Thu Jun 15, 2017 6:26 am

Here in France, the standard fuel contains officialy up to 5% ethanol. But it seems sometimes there can be more...
What are "hypo" jets?
Thanks for the information
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