robert kenney wrote:Might I ask what your initial timing is set at?
While you want 34-36 total with large cams initial will want to be 18*. Lazy low speed caused by big cams will induce large throttle openings that uncover all of the progression holes before you have enough air flow to pull fuel.
You mention increasing idle air bleed. You won't drill the emulsion holes in the 55 jet itself but the master bleeds in the main carburator body. This is common practice in high performance applications. With 55's i assume you have little idle screw opening. Adding air bleed will allow a larger screw opening and lean the cruise richness you are having with the 55's.
Hi robert:
Initial timing is 10 deg BTCD and maximum advance approx. 32 degrees BTDC. Im stuck with that because any more advance will produce detonation wery easily in situation that i describer earlier in this topic.
And cams are stock 2-litre cams, so no long-duration race cams here.
And you're right about the air bleeds. I got totally mixed up.
Brit01 wrote:DHLA pair was great. Even the mixture got little lean and jumped to lambda=1 range when accelerating lightly, it doesn't bog down like IDF's. It just goes.
With IDF's, when mixture goes even near lambda=1, it dies and stutters like mad and this lasts long.
I have another question.
I'm using DRLAs and would like to know what pump jet size you used and mains.
I have a box of idle jets, 52, 53 and 55.
Always used 142 mains.
52 idles is good in summer. I increase it to 53 in winter. 55 feels better but as you said my AFR is rich 10-11 and blackens the plugs in no time.
Even though I have an Alfa boxer I think we're along the same lines.
I have 33 pump jets and will increase these to 35's this week from a local mechanist who made them for me.
Had a little flat spot under acceleration after opening my air box a little more.
If you need 53,54 and in between sizes, I know a guy on an internet auction site who sells them in Italy.
If Guy doesn't mind me posting the seller or I can PM you.
I don't know exact specifications in my DRLA case bacause car wasn't mine. I remember that idles were 60 in size, but the engine was tuned 2-litre Fiat Twincam.
I can find 52 idles for IDF's easily. No need for DRLA jets. Thanks for offer.
I am interested which range your AFR's stay Brit01, while driving steady speeds, like 40, 60, 80 and 100 km/h. And how high the AFR jumps while you try to accelerate lightly/semihard?
I wonder, how these Alfa's perform in stock condition with DRLA carbs? Do they stutter while pressing accelerator pedal lightly or are they adjusted little rich side in the factory?
Haven't driven any car that have factory dual carbs...
My
DHLA case was, i believe with 5 progression holes, that might explain real good light/moderate acceleration AFR readings and good feeling.
Tommi