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Wed Jun 04, 2025 9:26 am

I am looking for help with a starting point for setup/jetting on some DRLA 36s for my son's Baja.

The engine is this:

1956cc - 76x90.5
Engle FK-42 Cam
1.4:1 Rockers
CB Panchito Heads (40x35.5, CNC Chamber, dual valve springs)
Magnaspark Distributor and coil
1 1/2" Baja header with resonator/muffler (straight through)
Dual Dellorto 36s

Wed Jun 04, 2025 12:00 pm

36s are on the small side for that size engine. Mostly used on 1600-1776 engines but maybe they’ll be ok.
I’ll take a look at my Dellorto book and see what it says about venturi size etc and report back

Wed Jun 04, 2025 12:19 pm

jeffrey8164 wrote: 36s are on the small side for that size engine. Mostly used on 1600-1776 engines but maybe they’ll be ok.
I’ll take a look at my Dellorto book and see what it says about venturi size etc and report back

Thank You!

Wed Jun 04, 2025 1:33 pm

Ok so having a look at the book and some parts suppliers here’s what I’ve found.
For your 1956 you’re looking at 36mm venturis which should be good to around 5500 rpm.
Dellorto Parts UK only lists 32mm as the largest available for 36s but CB lists a 36mm vent but I haven’t called them to find out if that’s actually true or available.

If your current 36s still have factory stuff you should have:
30 Vents
180 Air
122 Main
60 Idle
50 ACC pump

If the 36mm vents are true and available, you should start with 150 mains and 65 idles. Leave the Airs and the pumps the same.
These are all just theoretical numbers based on math so I’d get some extra extra idles, one step down and maybe 2 steps up and a step above on the mains.

If you find that the largest vent is only a 32mm then you’re in the market for larger carbs as 32s will suffer above 4500 rpm no matter the jetting.

If I’m wrong I’m sure someone else will chime in.

Hope this helps.

Thu Jun 05, 2025 10:41 am

jeffrey8164 wrote: Ok so...Hope this helps.

You are the MAN!

I Greatly appreciate your efforts. I will pull them apart and report back on the findings.

That said, this is in my son's car, unless there is some reliability concern...I am completely okay with her running out of breath at 5000 RPMs.

Thu Jun 05, 2025 12:03 pm

36mm vent in a 36mm carb????

Thu Jun 05, 2025 2:14 pm

mcmscott wrote: 36mm vent in a 36mm carb????

Doesn’t seem possible to me either.
That’s why I said “true and available”
I think it’s a miss on CB’s website but I’ve never had any 36 Dells in my hand so maybe the bore is large enough? Can’t say.

Thu Jun 05, 2025 2:54 pm

jeffrey8164 wrote: mcmscott wrote: 36mm vent in a 36mm carb????

Doesn’t seem possible to me either.
That’s why I said “true and available”
I think it’s a miss on CB’s website but I’ve never had any 36 Dells in my hand so maybe the bore is large enough? Can’t say.

I used to work for CB, still do work with them. I have probably built 500 drla carbs. Trust me there is no 36 vent for a 36 carb, The 36 and 40 share the same size bore above the throttle plate.

Fri Jun 06, 2025 6:46 am

You're 36 Dells you have now will work just fine with your engine size I ran many healthy 2 L engines on 36 dells, although I generally swapped out the smaller 30 mm Venturi for a 34mm, so if you are equipped with a 30 mm that would be a standard size for that carburetor when it was new and you may just have all the stock jetting, and there is absolutely nothing wrong with the stock setup in those carburetors to run on your engine you would just want to up the main jet depending on the elevation that you're at, but your engine size would most likely benefit from a bigger Venturi and on my suggestion maybe a 32mm.
Sounds like you're running this son of Baja, if so I don't think you're probably looking for top end speed but most likely bottom in and mid-range, so if that's the case a 30 to a 32 might be where you want to be, but you're starting off with a great set of carburetors.

I make venturies for the Dells, also CB does.

"Rick Hunt Industries "

Thu Jun 19, 2025 8:58 am

You mean very nice venturi!
When are these going to be retailed in the UK?!