carb tuning VanGuard 23

sanddragbronco

Having problems getting cart running good. new vanny 23hp rev kit, timing key ect. Plugs are black/ dry and white tips Lean? stumbles alot at low rpm but seems pretty good after 2500k. Very ruff idle at 1400 and below. I seem to have NO external adjustment on carb except for idle screw. I have the Performance vtwin k&N. Seen post on adjustments (external) But where??? Motor also starts pretty hard and has since day one. Maybe has 10-15 hrs on motor.

Also what have any of you done on the rear breather line into the air box when you switch to the k&n. I have a small air breather but I have gotten pretty good oil blowout through it at higher rpm (5800- 6000). Oil pressure is at about 50psi when at rpm.

BGW

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CC-John

That new non-adjustable carburetor is a POS... The timing advance and cam change the airflow and destroy idle quality.. Your only hope is to change to the early style with adjustable idle mixture jets.. I had to do this on my dad's cart, the 23 Vanny kit I installed had the non-adjustable carb.. I never could get it to act right compared to mine with the early style carburetor.. I ordered the early style carb and put on it, and all the idle and hard starting issues went away.. Once warmed up, it will fire and run before you can let off of the key, and settle down to a nice 750 RPM idle..

I ordered the carb from Jack's Small Engines.. The Briggs part# for the early style carburetor is: 808626

Flintrock

Yep CC. You can get larger jets, but I don't know if that will solve your idle problems. Those carbs just aren't designed for a full range response. I will say that your problems sound worse than most though. There are places (EC Carbs) that will tune those for you and claim good results, and is probably cheaper than a new carb. I'm still working on a totally different set up with a 38mm TM Mikuni that I think will take care those problems

BLACK DEATH

Do the 18 vannys have this issue also?

CC-John

Flint,

My Vanny never had any problems, it came with the early style carb with adjustable idle mixture.. The Vanny I put in my dad's cart had the later "smog" carb on it, NO idle mixture needles or adjustment.. Installing the cam & rev kit, screwed with the airflow at idle so bad the engine ran like chit.. After pitching the EPA required POS, and installing the early model carb with idle mixture needles, his engine starts and idles the same as mine does..

The 23's with a cam will really idle down low with a shallow "balance" port ground between the ports on the carburetor mounting elbow, right behind the throttle plates.. This eliminated the "flat spot" when punching the throttle from a dead stop..

Flintrock

Good tip. I'll try that. Thanks.....

CC-John

Not sure if the 1 bbl carburetor on the 18's still have adjustable idle mixture jets or not.. The 2 bbl on the newer 23's is completely sealed, the only adjustment is for idle speed..

CC-John

Don't grind the groove too deep, you'll end up with a vacuum leak at the center mounting bolt hole.. If I get a chance today, I'll pull the carb on my Vanny and post some pics of the mod..

smallblock450sl

Great info CC Would like to see those pic's.

CC-John

Here's the pics of the "balance" port I cut in the carburetor mounting face of the intake elbow.. It's approx. 1/4" wide and approx. 1/16" deep (kinda hard to see in pic).. I used a Dremel tool with a metal cut-off wheel to mill out the material, also lightly chamfered the corners at each end to smooth airflow.. In the last pic you'll see the mounting bolt hole that passes between the bores, mill too deep and you'll have a vacuum leak..

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