Float level

[Doug&Deb]

I’ve seen many references to lowering the float in the carb to compensate for ethanol. My question is how much lower?

[Plymouthy Adams]

I would suggest about 1/8 an inch...the fuel reserve is the typically the call for the float level to ensure you do not run out of fuel at WOT sustained runs....with the normal working fuel pump be it upgrade electric or even stock mechanical can easily keep your fuel bowl filled and I am willing to bet you do not race about at WOT all the time.  Anyway, it is a place to start and do not overlook the fact that your float can be damaged by PO's in there before you or even contain a bit of fuel if its integrity is breached.  

Edited June 12, 2020 by Plymouthy Adams

[Doug&Deb]

Thanks. I rebuilt the carb last year with an ethanol resistant kit. I have had either vapor lock or percolation on occasion. I’ll try dropping the float and see what happens.

[Plymouthy Adams]

percolation is so easy to identify and in my opinion is all to often the culprit in hard restarts but I never rule out the degrading heated coil especially if the car will start quickly once cooled about 30 minutes....do check both.....if not but for reassurance 

[Sam Buchanan]

24 minutes ago, Plymouthy Adams said:

percolation is so easy to identify and in my opinion is all to often the culprit in hard restarts but I never rule out the degrading heated coil especially if the car will start quickly once cooled about 30 minutes....do check both.....if not but for reassurance 

 

The reason I'm convinced my car suffers from carb percolation is if I attempt a restart shortly after the hot engine is shut down it will fire immediately. But let the hot engine sit for 15 minutes and it will need to crank for several seconds before it starts. It seems to me a weak coil would make any hot restart difficult.

 

Are you suggesting dropping the float a total of 1/8" or 1/8" lower than spec? I made a float gauge for the standard spec and lowered the float a little more than that but not nearly an 1/8". Maybe I need to lower it some more?

Edited June 12, 2020 by Sam Buchanan

[Plymouthy Adams]

the lowering of the float can be done to the extent that in truth you  have fuel to operate under your normal driving conditions without running out of fuel during periods of acceleration.  Percolation was a problem with normal fuels of the past and is greater with the modern blends.   Heat shields and insulation plates between intake and carb help also.  Another side effect of high float level depending on carb used as some retrofit but still seldom seen here due to the fact not many corner hard in these puppies or do nose dive braking....this splash over also can trigger a flood condition that results in sputtering or shut down.  The test of restart hot for coil on sustained after immediate shutdown is good...but sometimes heat saturation can attribute...depend on coil mount but if mounted factory should be reliable test.  Percolation due to saturation is however a cooking process as the engine block will increase in temperature when shut down....restart will see the fall of the temp rise when circulation resumes.  

[Sam Buchanan]

Another variable in my case is the installation of an aftermarket float. The brass float sprang a leak so it was replaced with the only float I could find, a composite float from Mike's Carburetors. I don't know if the new float has the same buoyancy as the brass float so the spec measurement of 5/64" may not be optimum. I'll probably try lowering the float some more, the electric fuel pump shouldn't have any problems keeping the bowl full.

[Plymouthy Adams]

the brass fuel float is an easy repair....you can often find the pin hole by drying the outside with the fluid inside and look for the wet spot....little applied heat..(no flames, say hair drier) to evaporate the inner liquid and just solder the hole...you back in business, have done this a number of time over the course of many decades of tinkering about carbs.  The composite should very well do the same job as original but they are often susceptible to saturation by absorption adding some weight.   Be careful not to scratch them.  They more prone to failure in many cases.....but...plastics and composites are here to stay.  We work around them, I feel to some certainty that a tad lower and you be golden.   Any pump functioning close to spec will keep you fueled up.....Set your fuel level not by the top of float but by a scribed line noting the fuel level on the fuel bowl...lower the level by actual fuel and not float body measurement.  

[Sam Buchanan]

I still have the brass float, intend to repair it...one of these days. It has a substantial flaw, the repair will add weight. The new float is not solid, it is some sort of plastic and hollow.

 

Here is the link in case anyone needs a new B&B float:

 

https://www.carburetor-parts.com/Carter-Float_p_2998.html

 

Edited June 12, 2020 by Sam Buchanan

[Plymouthy Adams]

the small portion of solder will not add to the weight in a fashion it should affect the float unless you just flat out glob it on without any flow technique applied....that float above appears ABS and not the phenolic resins I am accustomed in replacement/modern floats.  

[Sniper]

One thing I have pondered regarding hot restart issues.  The first time I went to put gas in my tank it shot gas out when I opened the cap.  So I bought a new cap because I figured the old cap wasn't venting.  New cap did the same and I could hear the tank oil canning as it heated up during the day, again not venting.  So I took the new cap apart and it has two spring loaded vents, one for pressure and one for vacuum, the original cap appeared to have just had some open vents with no spring loaded anything to restrict flow in either direction.

 

Now I don't know if this is a case of the law requiring the new style or some engineer who doesn't know a wrench from a crowbar did this (regardless of brand they all appear to be from the same manufacturer), but they do not work properly.  I almost wonder if the increased pressure I observed in the tank is causing others issues by forcing gas past the float and into the intake?

 

In any case, I cut the spring in the pressure relief side down to about half height and no more oil canning or gas shooting out the neck when I open it up.