Dellorto DHLA40 on Shovelhead - First Timer

[bpeak]

Yeah brother I own a few of them. That specific one is a dhla 40-H. I know they make a few different models because I also have a 40 without any letter after it and a 40-c. I would buy them on eBay whenever I found cheap ones because I thought they were cool and people ask crazy amounts at swap meets for them. If anyone has some information about the differences between the carbs by the letters at the end I would love to learn more about them!

Awesome! So as far as I can tell, the added letters have to do with the progression holes in the barrels? So the letters may have different flow curves depending on the use and demand and application. As I read (somewhere), the no-letters were original, and when the carbs started to be added to more and more car engines they needed alternate flow curves and did so with progression holes rather than going to different bodies or jetting assemblies or mm diameters. Found some really interesting tuning info (for cars but still the math is fun):

http://www.dvandrews.co.uk/

I used this, and info from another forum dude who was running a 40(C) and asking questions about the right Venturi size, choke size, and jetting. Based on Dave Andrews... I did some interpolation and came up with what MIGHT be a baseline for a 1340cc shovelhead:



Again, this would be for the no-letter model. When I compare this to the other dudes (C), and what he runs, and the tuning problems he was seeing, it makes sense based on his advanced progression (I guess).

SO HERE'S MY QUESTION TO YOU - Have you run any of the no-letter models? If not, with your 40 (H) on the shovel, can you confirm what jetting you ran? Also then, what year, model, engine cc and estimated peak HP? If I can get that data, I can plug it into my database I'm building to see how it shakes out.

Thanks dude!

[bpeak]

Also - update on the cleaning process.

Some pics below. Where we're at:

CARB BODY
- 120 grit abrasive wheel
- stainless wire brush down in the tight spots

CARB LID
- 120 grit abrasive wheel
- stainless wire brush down in the tight spots
- 180 grit abrasive wheel

Still got 320 grit and 400 grit abrasive wheels to go... then polishing wheels and compound.

Starting to actually look like a carburetor again!





Hoping to be able to spend some time with it thru the rest of the week and into the weekend... then do some engraving on it.

Also gotta do some cleanup on the manifold. That part wasnt as bad, and doesnt have the tight nook and cranny areas so that should be pretty straight forward.

In the meantime, I'm going to start matching up the new parts and pieces of the rebuild kit... discarding the old junk that they replace... and making another shopping list of any OTHER parts I'll need to order along with whatever venturis/chokes/jets I'm going to run. Still researching math on that part.

Much more to come!

[james69]

Thanks for posting this sort of content bpeak. So cool to watch whatever you touch!

[bpeak]

Thanks for posting this sort of content bpeak. So cool to watch whatever you touch!

Thanks man! Truth is... I have no idea what I'm doing. Scrounging as much info online as possible... and didn't want my thread to be like the others on the web where there's no proof of what is being tried. So as I learn... you guys get to watch (and laugh). Haha. Fingers crossed that when its all said and done it will actually run!

[bpeak]

Ok so I am totally sick of this process. Polishing is not my happy place. Big props to you cats who make a living polishing. For real.

I finished up the abrasive wheels to 400. Was going to hit the bigger spots by hand with 800 paper or 1200... but got impatient and went straight for the polishing wheels and compound. Started off with the black rouge which, as I understand, is more for cutting and getting any deep marks out. It worked. Granted - this carb has some pretty serious cavities in the aluminum. But the black did help. I want to pause there and just say how many fabric wheels I burned thru, and how much effort it was to get into all those tight spots of both the body and lid. I hated it. I don't want to snowball you like the TV shows where they cut the scene and POOF it's done. 2 hours. 2 hours of polishing just with the black stuff. Granted - it really paid off. But sheesh.

Went to bed happy. Woke up feeling a lil frisky. Decided to do it all over again but this time with the red rouge polishing compound. Back at it again for another 2 hours.

End result can be seen below. Again - this carb will never be spotless clean like brand new. It's seen too much "life" for that. But maybe that's what makes it cool. I dunno. Does for me.



It's kinda funny. I flip flop emotions on this carb so much. When I look at this video, I get bummed because all that work and the surface still looks wavy, worn, and pock marked. But then I look back at the very FIRST post in this thread to see what I started with... and I get pumped again.

Ugh. Oh well. Time for some rebuild parts organization and some engraving!

[bpeak]

Oh yea... so I wrap all that up... thinking life is grand... I go to put the carb on the shelf in a towel and I see the aluminum intake manifold sitting there staring at me like "hey buuuuuuddy". Son... of... a... gun... more stuff to polish.

[bpeak]

Got the manifold as far as I'm going to take it.







Next up... engraving.

In the meantime, trying to figure out the tuning charts to figure out what jets and internals I need to order.

Wondering if... once I estimate a baseline that I think will math out... if I order that kit -- and also order 1 up and 1 down of everything. So, for venturis, chokes, main jets, emulsion tubes, air correctors, idle jets, etc - I'd basically get three. That way if I want to test either direction I can. And if that still doesnt work I should be able to test tune farther at least knowing which direction to go.

Make sense?

Unless I can chat with someone that has a 1340cc shovel running a DHLA40 (no letter) in a hot humid climate region - to show me what setup they are running, I think I'm going to have to try to do it this way. Hate to spend that loot but with shipping from odd places around the world, might make sense to get it all at one shot?

I dunno.

[bpeak]

So for the future of the internet... got talking with a fella named Scott over Facebook and Instagram who is running a 1971 shovelhead stroker with a Dellorto DHLA40 (no call letters)... and it runs. He sent me this is good info from Rivera Engineering from way back when they sold the Dellorto Kits. Stuff is priceless for a clueless guy like me. Check it out:









From what Scott is running, and how he ended up re-tuning his bike, it seems as though the proper baseline setup that I should run is:

Venturi / Choke: 30mm
Main Jet: 130 (but also buy a leaner 128 and a richer 132 just in case)
Main Air Corrector: 180
Main Emulsion Tube: 7772.5
Idle Jet: 50 (but also buy a leaner 45 and a richer 55)
Idle Emulsion Tube: 7850.2

Seems like this will be a decent starting point. Currently assembling a shopping list of everything I'll need. I'll be ordering parts mainly from two sources.

First source - CB Performance (https://www.cbperformance.com/) out of Farmersville, CA
(but they don't carry every part and piece, just the primary components)
(what they don't carry - I'll go to the treasure trove overseas...)
Second source - Eurocarb UK (https://www.dellorto.co.uk) out of Pangbourne, UK

I talked with a local VW repair shop that has access to Dellorto repair - and their method for sourcing parts is the same exact method that I described above. Obviously if I can stay state-side that would be better. When I bought that rebuild kit from Italy and it took forever to arrive. Plus the CB Performance prices for the jets is cheaper (let alone shipping) so... we'll see.

Once I have the full shopping list, which is essentially every nut and bolt needed for the internals, I'll post it here so future searchers can see where I sourced each part from and what to do. More to come.

Cheers!

[JBinNC]

Treat any air bleeds like jets, and get a variety.
You need to go in larger steps with air bleeds than with fuel jets.
I think you should get a larger variety of jets than just three.

Jim

[bpeak]

Treat any air bleeds like jets, and get a variety.
You need to go in larger steps with air bleeds than with fuel jets.
I think you should get a larger variety of jets than just three.

Jim

Gotcha gotcha. So when you say air bleeds, is that the emulsion tubes? (sorry - I'm still learning these carbs). So maybe pick up one up and one down on those too?

Perhaps the baseline jet, then two up and two down for a total of 5 on each?

[JBinNC]

The main air corrector is an air bleed. Get a variety.
I don't know if you will be able to differentiate between the available emulsion tubes without a dyno.
Yes, a range of five rather than three is more like it. Your pipes and cam combo will have a lot to do with the jetting, so someone else's set-up may not help you much

Jim

[bpeak]

The main air corrector is an air bleed. Get a variety.
I don't know if you will be able to differentiate between the available emulsion tubes without a dyno.
Yes, a range of five rather than three is more like it. Your pipes and cam combo will have a lot to do with the jetting, so someone else's set-up may not help you much

Jim

Awesome thanks man. Much appreciated!

[bpeak]

I'll likely pick up a few more jets than what is listed below... but I didn't get a chance to update yet. So far this is based on the baseline plus 1 each direction. Have a look at this damage...





OUCH! For those keeping track of the math... that's $462.69 all in to rebuild this sucker... on top of the $84.52 I spent for the basic rebuild kit I showed in the previous pics.

That would be a total of $547.21... on top of what I paid to buy the pile of junk in the first place (which wasn't much thankfully) and the supplies to clean and polish the body to how it is today. Granted, that came with the intake too so that does carry value. But my word.

What have I got myself into.

I'm seriously second guessing this process. I think I can buy a complete DHLA40 for a lot less than that, even with rejetting and new venturis/chokes. I think. Do I go that route if I want to maintain the dual throat? Do I toss away this carb? I get the romance of "saving old nostalgic parts", and I love the look of these setups. But shoot. This is a bit nuts.

Not sure what to do. Gotta think on it a little bit before I go dropping 400+ on parts.

[Tattooo]

What have I got myself into. Not sure what to do.

I tried telling you to stop and think about it weeks ago.......

Now's not the time to start rethinking things............ You've gone to far to back up now............. Spend the money.......

[farmall]

Fuck saving old junk when you can buy new. It's a mass produced consumer good, like a toaster. If no one bought new carbs there would be no new carbs! The only real reason to run one vs. a CV or whatever is appearance so why not go for new?

Throwing money at a mistake just amplifies the mistake.