Thoughts on pre-start jetting 2110 single 48IDF

[RCP Phx]

Pretty much says it all, currently there are 34mm Venturi's installed (it came with 38's and I tried some 36's) on a CB manifold with a fairly small crossover between the runners.

[Dan Ruddock]

Do you mean a balance tube between the runners? If yes, why have you added it?

[Dan Ruddock]

[RCP Phx]

[Witnin01340]

I had the same intake and carb on a similar engine 1.70 should be around the main jet size,it should have better torque with the 34mm vents but for all around power 36mm worked better in mine,the lower the compression the bigger main jet it will take or at least it should and harder to tune,.10.1 not bad to tune 7.1 is harder to tune. with a centermount.

[RCP Phx]

Here's where I left off in November with the 1955 motor. 34mm venturis, 65 idle jet, I don't recall the pump spray bar, 165 airs, F11 ET, 150 mains.

This all started back in July '20 when I decided to change up the 32/36 carb and from a std bobcat to a super-trapp set-up, plus going from Pertronix ignitor I to a ignitor 3. All of this at the same time plus the exhaust tuning.

I did just order up some F7 ET's that might help also. I just need a good baseline to get started with on the new motor.

If I don't get any input here I will just start by the book!

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[modok]

I don't know.
I don't see how you would need a carburetor larger than a 44idf but I could be wrong.
I'd try main jet 4.5 times venturi with the 8mm emulsion tube.

[RCP Phx]

I bought it for the larger throttle plates knowing that I could choke it down for the actual jetting! After 50yrs and FI I still believe the Weber to be the most tunable carb out there.

[Witnin01340]

Sorry, i said mine had same carb but it was a 44 but i ran alot of centermounts over the decades and can not see where a centermount 48 would benifit over a 44,for this 1 reason even with a 44 (being tuned properly )it wont run over a 36mm vent umless its a huge engine with hi compression, i had a single 44 on a 10.1 compression 2.2liter type1 engine and 36mm vents was max on it anything bigger couldnot tune it properly, so for the people that truly knows correct me if im wrong, a 48mm centermount is a waste because it will only accept 36mm vents if properly tuned,unless the engine is huge with serious compression .

[jimmyhoffa]

The only charts I have seen where a 48IDF makes sense is when there are either aftermarket end castings (CB, old Deano stuff and some others, Bugpack Trick Ends, Wensing's ends, etc.) or cut-in-half, ported, and welded back together stock end castings.

With stock end castings that have not been ported all the way through, usually a 40 or at most a 44 will be all you can take advantage of. Going bigger will just kill bottom end/fine throttle control resolution.

My single 44 is jetted as:

36mm vents
F-11 emulsions
160air
150main
55 idles
Float at 11.5mm

CB low profile manifold
Guido Wensing high flow end castings

I daily drive this car and have a wideband- I think it's pretty close. I tweak airs and mains a few points seasonally back and forth. I think I have about 10k miles on this setup.
_________________
1974 Chenowth 2RL #1244 Street Legal
My other car isn't ridiculous.

[RCP Phx]

[jimmyhoffa]

It's a 1915cc, 8.7:1 CR, Web 218/119 cam, ported MOFOCO 042 heads.

I probably wouldn't go bigger than 1.5 OD (1.375 ID) tubing like the CB manifold has. I have a 1-5/8 OD manifold too but throttle response really falls off a cliff with runner tubes that big. Gotta keep airspeed up in the runners either by keeping tubing size small or having better end castings so it's justified to upsize the center tubing.
_________________
1974 Chenowth 2RL #1244 Street Legal
My other car isn't ridiculous.

[Witnin01340]

4inch stacks helps on a centermount they help keep the velocity up and helps with fuel puddeling in the intake,a 1915 with that compression id swap the 48 out and put a 44 on with 32 vents because i feel you will end up in that area with 32 vents and about a 150-160 main jet to get it tuned properly,on a centermount one has to give and take because when no1,3cyl is running rite 2,4cyl will be a little rich,the only way to change that is run individual runners to all cylinders or go dual carbs with dual throats,if one can get a centermount 44 etc tuned properly then dual carbs will be a breeze to tune.

Centermounts are not easy to tune and the lower the compression the bigger main jet it will take and harder to tune.

[modok]

I agree with all that.

jimmyhoffa got it tuned in very close.
But still found the float setting and cruise mixture to be very touchy.
Going to a 48 throttle body would make that worse.
Not yet close to matching the performance of my dellorto, MAYBE you can get closer with a custom emulsion tube but only maybe.

AND opening up a cross-port between the sides will end up needing a smaller venturi.
So if you do that as planned, you may actually have to go down to a 40mm carb body. I don't recommend it, but it can work. Maybe I just don't know how to work it. hasn't worked for me but maybe my engine is just too small

Or also if you prefer the performance of plenum type intake then the more classic choice is the deano/racetrim manifold that fits a DCNF carb. Isolated manifold is fine up to 4k, maybe 4500, but need more above that you need to go with a plenum.

[Witnin01340]

Modok i agree, infact thats why i come back on,if it takes any less then a 34 vent in a 44carb i myself would go down to a 40 carb,iv seen this alot of times where guys put way to big of carb on including myself when i first got into the vw some 45yrs ago ,then the engine wont idle right so they put bigger idle jets etc in to cure the symtom when the problem is to big of carb with to big of vents,it takes velocity to get a centermount tuned properly.

Sorry ,i thought it is a 1915 but if its a smaller engine then definetly go down in carb size,vent size etc.

[RCP Phx]

The set-up I'm going to start with is 34mm venturi's, I will also start with the F7 emulsion tubes(which are not anything new or custom). I will also start with a isolated manifold and if I need to add a balance port I will do so later.

[Witnin01340]

The older i get the more i forget,2110 with a 48idf yeah id put 34 chokes in to,i didnt see the compresion ratio it plays a big part but if it was mine id go 44 with 34chokes and a 1.70 main to start with,but if i had a 48 and thats only carb i had ,id do same as you.

[RCP Phx]

My CR is 9.4 and I was thinking about starting with 175 air and 160 mains.