Vanguard Vtwin Info: 16hp and 18hp differences

[slonomo]

Reviving one of my old threads because I'm trying to find out the differences in the carbs on the 16 vs 18. I've done a little research and am finding that the two engines definitely have different carbs. What I'm curious about is the actual venturi size.

I've found that the opening on the #350447 Briggs single carb Vanguard intake manifold is 26mm. I measured it as slightly over 1" (1"=25mm) so that looks correct.

[slonomo]

My 16 engine is Model 303447-1147-A1. The carb for that is #809011.

I looked up an 18 Model 356447-0069-F1. The carb for that is #845023.

So, what I'm wondering, if they look identical, hook up identical, what's the difference? I'm betting venturi size and jet size. Can anyone confirm this?

I have found that some say the 16hp carbs have a 17mm venturi and the 18hp carbs has a 19mm. Does that sound correct?

What would be the difference in 2mm when all other things are equal on a 16hp engine? I know that small jetting changes can make a pretty huge difference in idle quality and acceleration, deceleration, air/fuel ratio, etc. HP wise, probably not much difference. Right?

[BIKERMIKEYBLACK]

Idk wat the difference is but I have both carbs I’ll try and have a look at them later

[slonomo]

Originally Posted by BIKERMIKEYBLACK

Idk wat the difference is but I have both carbs I’ll try and have a look at them later

Wanna sell them? I have a bad one on my engine now.

[BIKERMIKEYBLACK]

Sure

[slonomo]

Originally Posted by BIKERMIKEYBLACK

Sure

Sending you a PM

[sho305]

Smaller venturi is going to cut high rpm power, too big will start to cut low rpm as the flow will not be enough to keep stable mixture. I'd say if you have a different cam in it you will certainly need a larger carb to get the most out of it.

[slonomo]

Thank you to BIKERMIKEYBLACK for the carbs!

As I inspected the two carbs, one from a 16hp and one from a 18hp Vanguard, I could see for sure the 18 carb was larger. How much larger you ask? I'm glad you asked....

According to my caliper, the following photo shows the results. 18 hp carb venturi measures 21.8 mm, and the 16 measures 17.3 mm. The pilot jet fit the same micro drill bit, a 0.6 bit. The main in the 18 fit a size 1.0 micro bit, the 16 fit a 0.9 bit (thinking thats in millimeters).

Now, I know the measurements I've taken are NOT perfect and scientific, so don't call me out on that ok? But what this physically shows is the 18 carb is in fact larger in Venturi and main jet. Now who knows if the main jets have been monkeyed with?

I'll be using the 18 hp carb!

[slonomo]

I also noticed the floats are different. The 18 had a plastic one, the 16 had a brass one. Not sure which is better.

The throttle valves are noticeably different when side by side, but that's not surprising.

[slonomo]

Another thing I found is the 16 hp carb base spacer has a little bar across the bottom of the spacer opening. What is that? See photo.

And lastly, the 18hp carb has a little spout in throat on the topside. The 16 carb does not have that. What is that? See photo.