Can't get the idle right

[Mitch//pa]

thats interesting as i find using 2 red gaskets works perfect for me on my carbs. i never had trouble with the viton valves as thats all i use now////hmmmm
also when i do get any play in the throttle shaft i use an oversize

[jmeckel]

On the vitron tip valve, if you pushed it shut with much more force than tbe float uses you can harm it. Also a very good way to clean all the passageways is to use a glass bead blaster, then chase every passage way with a small wire tip cleaner. You would be amazed at the amount of rust, old lead from the old gas, and general dirt I have removed from a carb that was chemical boiled and cleaned before it was sent to me.

[Purdy Swoft]

If the float is set too high it will cause stalling when coming to a stop. If the level of the fuel in the carburetor is too high , like higher than the top of the main and cap jets, fuel will continue to drip out the tops of the jets and out the choke end of the carburetor. Most usually think that the float is set correctly , when it is usually set too high and allowing too much gas to collect in the bowl of the carburetor. When this happens, you get stalling when coming to a stop and leaks. The only problem that I ever had with viton tipped needle valves was that that they could stick closed, this is clearly not the problem.

[Tom Endy]

I never had much luck with those little gadgets that hook into the drain port for setting the float level, so I built a float level test stand. I mount just the top casting to it and flow fuel into it with a glass container positioned below. When the valve shuts off the float level is indicated on the side of the glass. It can be measured and accurately adjusted. It also shows if the valve is holding over a period of time and not creeping.

My experience has been that many float settings that do not hold repeatedly is because someone in the past molested the float trying to adjust the level. This causes the float to not come up straight and off-sets the valve. Unmolested new floats from Bratton's work very good and only require one fiber washer.

I also set the bottom casting into a wooden holding fixture and pour fuel into the casting just above the comp jet and let it sit awhile to see if fuel is leaking around the main jet, cap jet, and GAV assembly.

I have had very good luck with the Viton tip float valves. The first ones I bought would not shut off at all. I took one apart and found it full of brass shavings with brass shavings stuck into the rubber tip. I called and spoke to Walt Bratton about it and he complained to his supplier and the situation improved... somewhat.

However, though there was a vast improvement in later shipments it is not perfect. Walt, like everyone else is at the mercy of his supplier. I usually buy several at a time and very carefully take them apart and inspect and clean any brass debris I find in them.

Tom Endy

[Growley bear]

Originally Posted by Tom Endy

One thing you might want to check is the gap between the tip of the rotor and each of the contact points in the distributor upper half. Many of the repos are notorious for not being even. Each gap should be the same. I have seen a number of gap values stated, however, I think it is more important that they all be the same. Find the one that is the furthest away and file the contact point down on the others to match. Somewhere around .025 is nominal.

Tom Endy

This is very good information from Tom. Many times carburetor problems are ignition related. There is an amazing difference in idle quality with even rotor gap vs uneven gap.

Chet

[JOES31]

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Tom
Thank you. I put the other zenith on that I rebuilt and the idle was better. Then I checked the rotor gap and yes they were not even. I set the largest gap to the correct gap and had to file the other contacts to match. It idles much better but somehow the timing has changed as now the full retard position doesn't lope the engine. I'll re time her tomorrow and see how she runs.

Thanks everyone for the great advice.

[Tom Endy]

Originally Posted by JOES31

Tom
Thank you. I put the other zenith on that I rebuilt and the idle was better. Then I checked the rotor gap and yes they were not even. I set the largest gap to the correct gap and had to file the other contacts to match. It idles much better but somehow the timing has changed as now the full retard position doesn't lope the engine. I'll re time her tomorrow and see how she runs.

Thanks everyone for the great advice.

Check that your points haven't closed up. New points tend to close up more during the first few hundred miles. During the first hundred miles they can close up to half what you set them at. Set your points fist, then the timing. I set mine at .020. When the points close up it will change the timing and the car will run poorly. When you reset the points to what you previously had them at when you set the timing, the timing will return to the previous setting.

Tom Endy

[rocket1]

I would say if it is a fresh rebuild with very little miles like my A it won't idle well,try putting your 2 fingers across the carb air intake,if the idle smoothes out it's a mixture problem,air to fuel ratio found this out playing around with my carb.I found no intake leaks at block or carb shafts.