Carbs the squirty bit.

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LotusMonkey
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Re: Carbs the squirty bit.

Post by LotusMonkey »

Thanks Dave and Peter. All great advice, and as said, in simple terms. I'll do a search for the butterfly setup posts.

Duncs
"A specialist job is just one I have not learnt to do yet...." :D

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DavidOliver
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Re: Carbs the squirty bit.

Post by DavidOliver »

Duncs, I have dug out a Dellorto document dated May 1969, in English and edited from Dellorto in Milano.

It has a section on Acceleration Pump Calibration.
Basically it explains how to measure the fuel flow produced by having the Carburettor off the engine, with a fuel reservoir 20 inches above the carb, the carb sloping slightly backwards, ensure the throttle butterfly is fully closed and the float chambers full with fuel, and by collecting the free fuel which the accelerator pump will push through the carburettor with 20 pump strokes you can calculate the fuel volume per stroke and compare with the specific setting for the engine the carb will feed.
The Elite/Eclat Workshop Manual does not give this value.
So perhaps you can compare volume between carbs, also make sure nothing squirts into your beer.
With the same volume you can then assemble on the engine and do road tests to get them where you fancy.

I have taken a photograph of the Dellorto description hope this copy works.
Image
Image

Dave the cog.

exceliom
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Re: Carbs the squirty bit.

Post by exceliom »

So after a real long time ordering new springs
I've possibly got it sussed now and got both carbs squirting at the same level. apparently, 40 openings should produce 17ml of fuel, ticked that box.
Now just waiting for Deamon Tweeks to supply the correct front disks again.Never again.

exceliom
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Re: Carbs the squirty bit.

Post by exceliom »

Thanks for that Dave , it really gave me pointers on where to start.

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Alan_M
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Re: Carbs the squirty bit.

Post by Alan_M »

This might also help. Info from Tim Engel.

Listed below are the Lotus OEM carb jetting specs for the 912 N/A engines.
Good luck,
Tim Engel

Lotus Spec 9
About right for a mildly warmed up 2.2 liter.
9.5:1 or 10:1 compression, up to 104 cams, headers.
Carb Type ....................... DHLA 45E
Choke .............................. 37 mm
Main Jet .......................... 160
Main Air Corrector Jet ... 230
Main Emulsion Tube ...... 7772-8
Idle Jet ............................. 55 (a little lean, try up to 58)
Idle Jet Holder ................. 7850-9
Float Weight .................... 8.5 gr
Float Setting Height ........ 14.5 - 15.0 mm
Float Needle Valve ......... 170
Pump Jet .......................... 50H
Starter Jet ......................... 95
Starter Emulsion Tube ..... 7482-3
Power Jet .......................... ---
Slow Running Speed ....... 900 - 1000 rpm
Idle CO Level (hot) ........... 0.7 - 1.5%

Lotus Spec 10
10.9:1 or 11:1 compression, 104 or DS2 cams, 2.2 liter.
Carb Type ....................... DHLA 45E
Choke .............................. 37 mm
Main Jet ........................... 135
Main Air Corrector Jet ... 150
Main Emulsion Tube ...... 7772-8
Idle Jet ............................. 56 (little lean, try up to 58)
Idle Jet Holder ................. 7850-9
Float Weight .................... 8.5 gr
Float Setting Height ........ 14.5 - 15.0 mm
Float Needle Valve ......... 170
Pump Jet .......................... 45H
Starter Jet ......................... 80
Starter Emulsion Tube ..... 7482-3
Power Jet .......................... 70
Slow Running Speed ....... 900 - 1000 rpm
Idle CO Level (hot) ........... 0.5 - 1.5%

Esprit NA, 1988 Onward
Tag Number
Front ................................ 5395A
Rear ................................ 5394P
Lotus Part Number
Front ............................. A912E2336F
Rear ............................. A912E2337F
Carb Type ....................... DHLA 45D
Choke .............................. 37 mm
Main Jet ........................... 135
Main Air Corrector Jet ... 150
Main Emulsion Tube ...... 7772-8
Idle Jet ............................. 56 (a little lean, try up to 58)
Idle Jet Holder ................. 7850-9
Float Weight .................... 8.5 gr
Float Setting Height ........ 14.5 - 15.0 mm
Float Needle Valve ......... 170
Pump Jet .......................... 45H
Starter Jet ......................... 80
Starter Emulsion Tube ..... 7482-3
Power Jet .......................... 70
Slow Running Speed ....... 900 - 1000 rpm
Idle CO Level (hot) ........... 0.5 - 1.5%
Pump Delivery .................. 8cc / 20 strokes
Pump Lever Clearance ..... 0.1 +/- 0.05 mm
Fuel Delivery Pressure ..... 4.0 +/- 0.25 psi

exceliom
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Re: Carbs the squirty bit.

Post by exceliom »

That was close regarding the pumps .
I found the info on an Alfa rebuild vid on youtube.
Thanks, everyone for all your help.

LotusMonkey
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Re: Carbs the squirty bit.

Post by LotusMonkey »

DavidOliver wrote:
Mon May 09, 2022 19:26
Duncs, I have dug out a Dellorto document dated May 1969, in English and edited from Dellorto in Milano.

It has a section on Acceleration Pump Calibration.
Basically it explains how to measure the fuel flow produced by having the Carburettor off the engine, with a fuel reservoir 20 inches above the carb, the carb sloping slightly backwards, ensure the throttle butterfly is fully closed and the float chambers full with fuel, and by collecting the free fuel which the accelerator pump will push through the carburettor with 20 pump strokes you can calculate the fuel volume per stroke and compare with the specific setting for the engine the carb will feed.
The Elite/Eclat Workshop Manual does not give this value.
So perhaps you can compare volume between carbs, also make sure nothing squirts into your beer.
With the same volume you can then assemble on the engine and do road tests to get them where you fancy.

Dave the cog.
Thanks for sharing this Dave and the other info on here everyone - definitely going to help on getting the pumps in the right ball park.
"A specialist job is just one I have not learnt to do yet...." :D

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