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Posted by: Ansbacher May 8 2017, 04:47 PM

I recently rebuilt my Dellorto DRLA-40 carbs. When remounting the carbs, I only had the cheapo type manifold base gaskets to use. Now I have a chirping type noise when under hard acceleration in mid gears. Am I hearing the proverbial "Dellorto Whistle"? Does the whistle sound like a one tone noise or does it chirp like when there is no grease where the points assembly meets the distributor shaft? That's what this sounds like but deeper and louder. Dellorto experts please chime in.

Thanks,

Ansbacher
'74 2.0L

Posted by: Jeff Hail May 8 2017, 07:41 PM

Usually sounds like a Type1 with a couple 1/4 inch holes drilled in the fan shroud. Dellorto's will chirp on throttle. Need to use the correct base gaskets that block the passage on the bottom center of the carb body. Double check everything is tight and not moving on hard acceleration including the linkage between the carbs.

Posted by: ConeDodger May 8 2017, 08:27 PM

That's what it sounds like.

I doubt you'll find the "correct" gasket as I bought what I'm told was the last one from CB Performance about 10 years ago. You can plug the notch with silicone I'm told...

Posted by: Whip618 May 8 2017, 10:10 PM

I don't think you will find those gaskets either but you can use the old stand by "JB WELD" and it works fine. I ran these 40 DRLA's for years with no problems. I was getting more of a chirping sound under acceleration>

36 DRLA on the left with no JB WELD and 40 DRLA on the right with JB WELD filler.



Phil

Posted by: bandjoey May 8 2017, 10:37 PM

JB to the rescue

Posted by: euro911 May 8 2017, 10:49 PM

Curious ... why hasn't the manufacturer changed the design to eliminate the issue? I'm sure they've known about it for some time, seems like everybody else does. My brother ran them on an 1835 in a '69 Ghia back in the 80's

Posted by: Krieger May 8 2017, 10:51 PM

https://www.youtube.com/watch?v=S_xFuWmdhLk

Posted by: Jeff Hail May 8 2017, 11:08 PM

Call em up and see if they still available.


https://vwparts.aircooled.net/Dellorto-DRLA-Anti-Whistle-Base-Gaskets-PAIR-p/dellorto-whistle-gasket.htm





Attached image(s)

Posted by: ljubodraz May 9 2017, 06:01 AM

My DRLA 40 DELLS did not require the special gaskets to eliminate the chirp/whistle.

When I replaced my gaskets to thin gaskets, they began to whistle. I then ordered thicker rubber gaskets (without the special tabs) and the noise went away. My theory is that it's not the cavity itself that creates the whistle, instead its the thin gaskets within the open cavity. The thin gaskets act like a reed instrument that vibrates creating the sound. Like when you blow on the edge of a piece of paper as a kid and you get a whistle sound.

Because of this, I am sooooo happy I didn't try filling the voids with any type of filling material like JB Weld.

Posted by: Ansbacher May 9 2017, 09:22 AM

I believe I've read somewhere that Dellorto put those notches in the base to satisfy a particular Alfa Romeo, which used DRLAs extensively. Thanks for all the great info and pics. I will search for the proper gaskets.

Ansbacher

Posted by: barefoot May 9 2017, 12:47 PM

Yes, after seeing this post, I also wonder why these slots were designed in, must have been some reason that eludes me, did it set up some sonic disturbance to help atomize fuel ???, can't believe it produced higher air flows.
Barefoot

Posted by: ljubodraz May 9 2017, 02:39 PM

I also read somewhere (probably on the Samba) that those voids are used for a circuit on certain applications and has a hole drilled into them. Just be sure you rule out any intake vacuum leaks which might also chirp or whistle. Depends on what changes you made before the sound started. Good luck.

Posted by: McMark May 10 2017, 06:58 AM

Those cavities are were the extra fuel from the choke enters the airstream. Most of the Dells you see were never drilled for the choke.

So really, the cavities are vestigial.

Posted by: ConeDodger May 10 2017, 09:50 PM

Mark's got the word vestigial trending on Google.