Dellorto DHLA knowledge

[stitebunny]

I am working on improving my carb tuning and while I have somewhat of an understanding i still have some questions.
1 being, is there a relationship to changing an idle jet holder to changing an idle jet?
Would going up or down one jet holder have the effect of 5 jet size changes for instance?
I have yet to get an af gauge as my exhaust needs some work. So I am trying to figure if I am rich or lean in the idle circuit to make some changes.
It feels rich to me but what i find online would indicate it’s lean.
I don’t have many holders or jets to choose from and while I don’t mind buying some, I’d like to be at least close to making the purchases.

[stitebunny]

Here is what I have in the 40’s.

IMG_3764.jpeg (732.56 KiB) Viewed 155 times

I have a set of 7850.1 holders.
And the jets that are crossed out above.
The 53 worked the best.
So wondering if I go lower on the jet or the holder to lean it out.
45 was too low. So maybe a 50?

[stitebunny]

Another issue I realized after checking float level and fuel level is that the level is much higher on the main circuit side than the idle side due to the engine tilt.
So obtaining the 27mm fuel bowl level is tricky. Split the difference between sides or?

[yenpit]

Your biggest issue here, is that the Dellorto's are kinda rare in the Japanese car market. They are true grit Italian, so maybe research on a classic Italian car forum ie Alfa Romeo and/or find an Italian car specialist in your area to work with etc. I did have a 510 BS race car with dual dcoe Dellorto's a couple years ago, but I sold the car back to the original owner, so I never got it running! I prefer Weber dcoe's, simply because I did not have the experience with Dellorto's, nor did anybody I knew! They are cool to have cuz they are rarer, but getting Weber's (or the more expensive Mikuni's) might be a much easier option, cuz at that point, you can easily find "base jetting" for whatever your engine combo is! Dellorto's, Weber's & Mikuni's can all be interchanged, so you should be able to use your existing intake manifold!

[510rob]

Also check with the early Lotus Esprit guys - those cars had Dellortos, including the early Lotus Esprit Turbo, which had a blow-through setup on twin sidedraft carbs.