Dellorto accelerator pump hell

It's been a while since I last pulled my Dell 40s apart, but IIRC there are two seals on the accelerator pump jet - An O-ring on the far end of the jet itself, inside, then the jet, then a small filter screen, then a fiber sealing washer for the cap screw.  That's it.

I never re-use gaskets or seals on carburetors and will go as far as buying a full rebuild kit just to get one small thing that I need.  That's left me with several partial kits over the years, but at least I cured the problem of the moment.

I hope your vintage car guy fixes it easily.  They can be a bear to cure, sometimes.

Thanks Gordon. This one has seriously messed with my mojo. At least now I know how to take the carbs on and off quickly.

Hi folks, I thought I’d give an update on this.

The mechanic I took it to did what I think is the right thing. Ordered rebuild kits and went through both carbs. He arrived at the conclusion the offending pump jet wasn’t seating fully, so he ordered a tap and tapped the thread.

After all this it still leaked fuel from the outside of the jet. So he put an extra gasket in and that has stopped the leak.

I got the transmission mounts changed while it was in. I could have done it myself but it’s way quicker and easier with a hoist and transmission jack. Now the shifting is poor into first and third. I know how to adjust that myself.

What have I learned?

- maybe I didn’t do such a bad job myself. I could have put an extra gasket in from day 1, but I wanted to do it right.
- the professionals with general classic car experience aren’t worth as much as the years of specific experience on this forum. To everyone who takes time to reply to people’s technical questions, some of them easy, some of them tough I salute you.
- I wish I’d just sent the single carb to a specialist.

I’ll keep doing my own work in future. I am nowhere near as experienced as a professional mechanic, but sometimes passion and a care for what you do combined with great advice trumps experience.

For what it’s worth, I put up with a pair of Dellorto 40mm carbs for years that were just running OK - Not great, but ok.

Then I finally sent them to the guys at Blackline Racing and asked them to set them up on a carburetor flow bench given my engine specs.  They found that my venturiis were too big for everything else and once those were the right size for my engine flow, everything else sort of fell into place and they’ve been fantastic ever since.

The moral of the story is those guys (Dave Hoagland, really) had the experience to know what was going on and how to make it right.  There is no substitute for experience.

It’s been a few years, now, but IIRC it cost me around $150 each for the diagnosis and rebuild to spec.  In the long run, that’s pretty cheap.

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I have two left thumbs.

And two more on the other hand.

My dad was not a car guy, and growing up in the city, no one on my block worked on their own cars. So, as car guys go, you could say I was culturally deprived.

Over the years, I've taught myself a few skills, have learned to do some simple jobs, but have also botched up a couple things beyond repair. This has all taught me that the most valuable skill is knowing when you are in over your head or when you are about to be.

Putting the wrench down in a timely manner is often the most cost effective thing you can do.

Your car will thank you. Your fire marshall will thank you.

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