His car runs great the engine sounds good and is been recently tuned and the advance is 22° I believe. I just can’t believe I’m getting 10 miles to a gallon I had to Weber carburetors 40 mm


Is this what I should expect 

Original Post


@JPC , is this the new car you just got two months ago from Vintage Motorcars in Phoenix?

If so, I'd take it back to them, tell them you're getting only 10 mpg, and let them take another crack at tuning it.

Your mileage should improve as the engine gets broken in, but, unless you're spending all your time at the drag strip, it should be a lot better than 10 mpg. I think most of us with dual carbs are averaging at least 18-20. And some of us are in the 20-25 range. If I try real hard on a steady highway run, I can eek out 26-27, but it's more usually 20-22.

Another thing to check is how you're measuring your mileage. The trip odometers in a lot of the Chinese replica speedometers don't work or record only intermittently. So, what may read as 80 miles since you last filled up may actually be 160. I think I'd check that first before messing with the carbs if the engine seems to be running OK otherwise.


Now we’re getting somewhere.

If they are Kadrons, they’re probably leaking by the needle and seat internally, and flooding over the top of the bowl and down the throats.

Will it idle for a minute straight, without blipping the throttle? Or do you need to “clear it out”?

I’ll leave the technical stuff to those who know more than me but, make sure you are actually measuring your mileage at the pump and not the fuel gauge. These gauges are notoriously inaccurate and when it reads full it probably is. However, after you start driving the gauge can quickly show you don’t have any fuel. So fill it up, reset the trip odometer, drive it, fill it up again, and divide the mileage by the gallons and get your mpg. 

If you did all that, see the technical stuff. 

JPC posted:
Please call me 414 7944301

Justin is still working on several unfinished details that you might have
in common

I’ve got 1000 miles in my engine it will have to be rebuilt by leading edge


Sun City West

Do I understand this correctly, your engine needs to be rebuilt with only 1,000 miles on it?

Also, what did you mean by this "We only deal with the best Brazilian speedometers"?


I have a 1915cc with Kadrons. Built by VS in Hawaiian Gardens in 2013. Bought the car with 3,000mi in March 2017, have 9,000mi on it now. Average between 22mpg-25mpg. 

MPG’s get bumped up if it’s solely highway driving to around 30mpg at 3200-3800RPMs with the 3:88 Freeway Flyer. Given the cheapo gauges, I refuse to believe I’m cruising the highway at 88mph at 3800RPM. 

Stan Galat posted:

Now we’re getting somewhere.

If they are Kadrons, they’re probably leaking by the needle and seat internally, and flooding over the top of the bowl and down the throats.

Will it idle for a minute straight, without blipping the throttle? Or do you need to “clear it out”?

I encourage following Stan first on this one.

In my "broad" observations involving a total of 1 speedster (a VS with with 1915, dual carbs), a carb was replaced on two separate occasions over a couple of years.  Once when only a few months old, and another time a couple of years later.

Reason:  Float bowl problems.  The needle valve wasn't closing fuel delivery to the float bowl and raw gas was overflowing directly down the intake manifold.  Mileage would naturally be affected as if pouring gas down the drain.

Early symptom:  Idle problems, because one side of the engine was in a constant state of "flooding".

Worse, (in the case of my observations) when parked long enough, gas continues to trickle from the tank thru the carb and overflow down the the intake, ultimately filling the intake as well as filling the carb all the way to the top.  If an intake valve were open, then the cylinder would fill up before gas backed up through the intake and overflowed to the top of the carb.  (Of course the gas in the cylinder would leak past the piston rings and now gas is in the crankcase contaminating the oil.  And, this is compounded by nothing good is about to happen if trying to start the engine with a cylinder full of gas on the compression stroke.)

Not good if gas is leaking past pistons into crank case - is that why the comment on engine needs to be rebuilt with 1k miles?  That will surely destroy the engine fast - if it doesn't catch fire and destroy the car first.  Can you smell gas in oil?  Is the oil over filled and diluted?  I'd also check for gas leaks ... and buy several fire extinguishers for safety.

The needles and seats on Kadron carbs aren't very good (to be kind). There is no rubber on the needle valve, so the seal is just brass on brass, which is why you're only supposed to run 1-1/2 psi of fuel pressure with them. Maybe they’ll seal, mabe not  

Regardless, 1-1/2 psi is really, really low pressure, since a stock VW fuel pump will develop about 4 psi. The "solution" (such as it is) is to keep stacking up gaskets under the fuel pump, so that the arm of the fuel pump makes progressively less contact in the case. It's a really cheesy way to go about adjusting fuel pressure, but it's the commonly accepted manner.

The problem could be as simple as too much fuel pressure. But lots of times Kadrons' needle valves will only be able to hold gravity pressure (from the tank sitting higher), and won't seat while the car is running, even if they have almost no pressure on them.

Knowing if the car idles for more than 30 seconds to a minute, without feathering the throttle to clear it out is really is the first step to diagnosing this problem.

We can keep guessing all week, and won't get any closer until we know the answer.

This: 3 posts ^^^^^^^  above!

Stan is 150% on the money here. Fuel pressure is crucial for Webers and Dells but ESPECIALLY so for Solexes and Kadrons. 1.5 psi may be too high. The only way to get it right is to run the engine with a gauge T'd into it. If mechanical, stack up the gaskets. It's hokey, but it works. I had eight gaskets on one I did to get it low enough, and it was still 1.75 psi.

If the pump is electric, an aftermarket regulator needs to be used. Same procedure, but adjust the regulator until you get the right reading. The regulator "settings" are known to be VERY inaccurate to actual pressure. 

Needle seats are notorius for leaking on the single throat carbs.

Great post Stan!

P.S.    I get 32 mpg on Carlisle trips ripping along at 65 to 110, but usually sitting at 75-80. I have 180 hp and Weber 44 IDF. The car is tuned, synched and jetted properly.

10 mpg is PIG rich and is emptying your wallet and filling your crankcase with gasoline-washed oil. BAD!

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