Previous owner had the car setup for autocross, so the idle was set to 1500rpm when I got the car. I'm trying to get the idle down to around 1K for street driving, but anything under 1200 isn't stable. What I mean is, I can adjust it to 1K and it holds idle after the adjustment. But when I go for a drive and come to a stop it'll hold 1K for a couple seconds, then a whistling noise starts and revs start to slowly decline to the point that it would die if I don't blip the throttle.

I'm still getting acquainted with the DRLA 40's, so I wanted to see if someone familiar with them might know what's going on.
Engine is a 2270. Idle jets on the DRLA are 75's. Is it possible I need to swap the idle jets out to a different size?

At 1500 I believe you are in the transition part of the fuel circuit. bringing it down to a normal level means you are now into the idle circuit so you may have to play with the jetting for the car to respond properly. How do the mixture screws respond?

Can u video it? What is your timing set at? 75 idles is massive for 40 dells. I'm running 58 idles on a vw ghia 1955 cc.and I'm running rich. It's also on ported and polished vw head. how many turns out is the idle/mixture screws. I'm only 1.5 turns out. Also best thing I did was convert the idles using the cb performance idle jet doctors. Worth every penny no clogged idle jets
http://www.cbperformance.com/ProductDetail...roductCode=7348

IIRC, DRLA-40s came with a 60 idle jet from the factory. I'm running 55 idle jets on mine (2L, Mahle euro PC set, elgin cam). The rest of the carb set-up on my car is:

Venturi = 30 (factory setting is 34)
Main jet = 135 (factory setting is 60)
Air correction jet = 180 (same as factory)
Emulsion tube = 9164.2 (same as factory)

I've got some old set-up articles too--PM me if you're interested.

Hope this helps,

Steve A-

I believe 135 gas 180 airs 60 idles stock setup

I just did 2 years worth of reading and am setting up a 2056 and Dellorto's, this is what I came up with as a good starting point. I upped the main jets, the rest is what came stock. I also have the 'anti whistle' carb gasket that plugs the two little holes in the bottom of the carb that causes the 'whistle'


Main Gas = 130
Main Air = 180
Emulsion = .2
Idle Jets = 60
Acc/Pump = 50

75 is way to big, go to aircoolednet or CB performance, they have what you need. Pull your plugs, bet they are sooty.

The whistle is the groove in the base of the carbs. Solution is to locate the gasket that plugs the groove or fill it in with epoxy. Don't know how thae groove effects performance. Delortos are great carbs. Buy the cb performance book and it'll answer all your questions.

Don't remove the dellorto whistle . That's the cool way to identify dells.

So here's the info on my Dells that the PO gave me:

Main jet: 150
Venturi size: 34
Idle jet: 75
Air jet: 180
Emulsion tube size: 9164.2
Pump jet: 50

Timing set to 27 degrees BTDC

I haven't messed with the mixture screws yet. My AFR gauge reads at around 12 with a warm idle at 1500.

So it sounds like I need a smaller idle jet then? You guys think 60 would be a good starting point to try?

BTW, I'd never remove the whistle. I love the angry bird scream they make at WOT!

Every engine is different but 40s on a 2270? Everyone I know including myself that has a 2270 are using 44 webers or 45 dels. Anyhow you have an afr gauge which is the best way to turn your carbs with.

Hey I didn't build the engine, Original Customs did.
Raby seems to think 40's are alright for a 2270 also: http://www.914world.com/bbs2/index.php?s=&...t&p=1267929

Anyway, it is what it is. I'm not changing carbs.
Any thoughts on where to start with the idle jets?

44 weber idf =40 dellortos. before you change the idles. I would be interested in the air fuel mixture. at 75 idles probably at 3/4 to 1 turn out . would love to see a video as you balance the carbs and start to lower the idle what the car does. if I had to start with idles and your keeping the carbs I would buy jet doctor for idles and place 60's then do air fuel mixture.

I'll see if I can get a video done. Might be a few days.
I'll order the jet doctors and 60's in the meantime.

What target AFR should I be looking for, and is it better measured at idle or WOT?

CB Performance is out of 60's at the moment, so I checked over at Aircooled.net. They've got them but at $10/jet compared to $2.95/jet at CB. I don't mind paying $10 if it's worth it, since Aircooled claims theirs to be authentic Italian made. I'm curious if there's any quality issues with the jets that CB sells. Anyone care to comment?

Aircooled.net has that price because I believe he (John) allows you to send them back if they aren't the right size. He calls it a "jet exchange" program since people don't often get it spot on the first try.

There is also a great vendor on Ebay that sells jets for a variety of carbs. Alfa1750 is the name of the store: http://stores.ebay.com/alfa1750scarburetorspartsstore/

why not give McMark a call, I had sold the previous owner dell 45's and McMark suggested he didn't need them. Mark had that car dialed in if memory serves.

Thanks for the tip on this guy. I picked up a set of 60's. I'll see how they work out when I get them.

George, the car is great except for the idle issue. I'm not sure why he'd put 75 idle jets in if, like everyone says, they're way too big. I'd venture a guess that that was the PO's doing, not McMark. If I can get the idle down to ~1K this car will be perfect. The high idle is just using excess fuel, and also makes it difficult to shift into 1st when fully stopped. Getting the idle down just to 1200 has helped the 1st gear issue quite a bit.

75 idles are too big, it's flooding out.

As others have pointed out, Dells just flat out flow better than Webers. I don't know the physics behind the two carbs, but it all relates back to Bernoulli's Principle and fluid dynamics in general. The design of each carb makes them flow differently and *act* differently. Hence, Dell 40s flow like the bigger Webers. In your case a set of Dell 40s with the proper venturis are indeed in the ball park for a 2270. And Mark makes fuching great motors, so if it was on there when he had it, it was probably right - the previous owner is the one who put the big ass idles in it.

Start with the 60s and see what happens. I betcha it'll idle much better and you'll have no problem getting it down to 850-900 rpm.

Just curious what fuel pressure you running. Has it been measured. When the car is idling use a mirror and see if fuel is spilling over. Your description also makes me wonder how the linkage it set up. Sounds like 1 arm may not be returning to the proper resting position. If it's off 1/16 of and inch the idle won't come down with whatever . I would like to see a picture of arms on both sides pushing against the set screw.

Hi,
what style linage are you using? The crossbar linkage is lots of headaches, not able to return to throttle stops, and unequal pulls can cause the problem you describe. My first step would be disconnect linage and sync carbs, then go from there.

I currently run 34 vents in my drla45's, much better drive-ability on the street. I beleve there are 65 idles.

Good luck

Carlos

I don't have a way at the moment to measure the fuel pressure. I think my FLAPS loans out fuel pressure gauges. I'll see if I can get a measurement. Where exactly would the fuel be spilling over?

I'll try to get some pics when I get a chance. I've got the push/pull linkage with the two separate arms the push outwards to open the throttle, and not the kind with the single big hex bar.