Dellorto Jetting Advice Please

[TeamBrian]

Engine: 1641, Engle100 cam (SSP's new engine).
Dellorto DLRA36 carbs with 115 main, 55 idles, 33p/j, 28mm chokes.
Right, my carbs are popping on deceleration, not badly, just now and again. Idle is good and steady, no flat spots on power, no air leaks, no exhaust leaks, timing set correctly, valves correctly set, fuel regulator set to 3.5psi. The spark plugs are brown in colour with a very, very faint hint of white on the tip. Fuel adjustment is wound out 4 turns. Engine doesn't appear to be running hot.
Should I wind the fuel adjustment out more or should I be looking at different jets?
How are you supposed to adjust the fuel, anyway?
Thanks.

 

[Paul Weeding]

Up you mains slightly... I've got a pair of dells in pieces on the bench off a 1600 and they've got 122 mains

 

[TeamBrian]

Thanks peter. What size of idles are in yours.

 

[TeamBrian]

....and Paul as well

 

[jonboylaw]

55 idles will be fine.


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[TeamBrian]

Cheers Jon. I've ordered 120 mains as the fellow at Eurocarb says it doesn't sound too far off the mark, and I still want to return a decent mpg.

 

[Paul Weeding]

:lol: my dad is Peter

The idle jets are between 45 & 55... But if they were too big, then you'd bog down when you go to pull away/accelerate, and if they were too small then you'd pop up through the carbs!!

 

[TeamBrian]

Thanks Paul.

 

[Paul Weeding]

Checked them again, and they're 57 idles...

 

[jonboylaw]

Also is it the zorst popping on over run? It could be a leaking exhaust manifold causing that.


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[Robbo1971]

Sorry, can someone explain “ mains and the idle readings”
I’m having the same issues with popping

 

[W1K1]

you would be best to invest in an O2 gauge weather a dash mount, or portable like an LM2 to see what your engine is doing and how it needs to be jetted. No two engines are alike, so it's a crap shoot asking for advice. my innovate LM2 has been used on numerous engine combinations to help jet them. You can download the info and chart your AFR, and see where you need to make changes there's running well with a proper AFR 12.5-13.3 https://www.thesamba.com/vw/gallery/pix/2204649.jpg or really rich 10-11 AFR, they both ran, one just runs much better and isn't dumping extra fuel

 

[Robbo1971]

you would be best to invest in an O2 gauge weather a dash mount, or portable like an LM2 to see what your engine is doing and how it needs to be jetted. No two engines are alike, so it's a crap shoot asking for advice. my innovate LM2 has been used on numerous engine combinations to help jet them. You can download the info and chart your AFR, and see where you need to make changes there's running well with a proper AFR 12.5-13.3 https://www.thesamba.com/vw/gallery/pix/2204649.jpg or really rich 10-11 AFR, they both ran, one just runs much better and isn't dumping extra fuel

Thank you