Flooding flathead carb's

R

RICK SHERMAN

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Most flathead owners have experienced the flooding carb problem. I have tried every method under the sun to fix this issue-with mixed results. Yes-the float is at the proper adjustment-and this is not happening as a result of an overheated engine. After shut-off--and after a few minutes-the carb will dribble fuel out the rh side-throttle-end of the throttle shaft-running down onto the intake manifold. This is of course flooding the engine-and washing fuel into the cylinders-and thinning the oil-as well as making it a hard starter. This is on a 59 carb-atop a 46 59ab V8. Does anyone have an answer to this problem-? I've lowered the float-more than spec-and used gross-jets-and you name it in an attempt to solve this. I say again-I've had the same problem on various flatheads-of all years and engines. It seems universal. Anyone have a good solution to this--?? Thanks
 
Try opening the hood when it's not going to be too unsightly, like in the garage at the end of the day. That's the only thing that's worked for me. It's the heat build up under the hood after shutting down that causes mine to do just what yours is doing.
 
Thanks Old Henry-it's heat related for sure. I've heard that the gas actually percolates in the bowl-and spills over. I can't believe these cars could have had this consistent problem when new. My 54 merc has a half-inch bakelite spacer-base under it's holly 4 barrel. I think some kind of insulator where the carb bolts to the manifold may be the ultimate fix. Of course you're raising the carb somewhat-meaning the fuel pump to carb line would have to be changed. As I'm sure you know-hot exhaust passes under the carb-inside the manifold-and this area is what I think stays hot-and maybe gets a little hotter when sitting a few minutes. Thanks for your input--
 
if you havent done so already remove intake manifold and plug the two exhaust cross over holes in the block, they are there to apply heat to carb and the ford v/8 doesnt need any more heat applied any where on motor, install a fiber, not plastic phenolic block under carb, usually about an inch thick, another problem is an aluminum manifold transfers more heat and faster to the carb than a cast iron one does
 
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Ford changed some of the parts in the later carbs to help aleiveate this ,how good it works I dint know but. Use the HiLift nozzle bars and the necessary diff top section from a later carb.Might help.Ive had customers do this and have had no complaints about the change.Might work. Hi lift bars and idle tubes and a correct top and gaskets would go around $68 . ken ct.
 
Rick : Are you positive that the fuel is coming from the bowl. My guess is that the power valve may be the culprit, either the actual valve leaking or the wrong gasket being used. Check the gasket mounting surface of the power valve as the valves intended for use in later Ford carbs have a radius that prevents the original type gaskets from sealing (although the valves will seemingly fit the hole properly). I had a 59A with a Holley 59 carb and had a similar problem that I initially tried to solve with a phenolic spacer (insulator), but found the P.V gasket was the real problem. Also if you use the "new" vitron tip needle, it too can cause problems with todays gasoline. Stick with the solid steel type. BTW, almost every 94 I've rebuilt has had warped surfaces at the bottom of the main body and top of the throttle plate body allowing a vacuum leak to the power valve chamber. Unless these surfaces are milled (or filed) smooth, the power valve will never close. Ironically , I also have a '54 Mercury. Good luck : Bruce
 
ken ct said:
Ford changed some of the parts in the later carbs to help aleiveate this ,how good it works I dint know but. Use the HiLift nozzle bars and the necessary diff top section from a later carb.Might help.Ive had customers do this and have had no complaints about the change.Might work. Hi lift bars and idle tubes and a correct top and gaskets would go around $68 . ken ct.
Click to expand...
Ken is right about this.
These carbs did in fact "boil over" when they were new.
I learned the "trick" Ken refers to back in the early 70's. It helps a lot.
The parts required are from '49 - '53 carbs.
 
A note about the fuel boiling after shut down on the 94 carburetors. The venturis were changed to a round venturis with the Holley 2110 carburetors (I am using the three bolt ecg6's) the round booster venturis can be installed into the 94's by using the jets and etc that come with the venturis. Below is what the Holley 2110 manual says why the change was made. The ECG6 bodies and tops are a little different but the nozzles, venturis and etc will fit into the 94's
.
The booster venturi nozzle bars minimize
percolation effects by providing a larger main
well with a long vertical rise. Percolation occurs
on hot days after the engine has been shut down.
The fuel in the bottom of the main well is heated,
forming vapor bubbles which trap raw fuel between
them as they rise. This action drains the fuel
from the carburetor and deposits raw fuel in the
intake manifold, making it difficult to start the
engine. By incorporating larger main wells and
longer passages, the bubbles break as they rise.
No liquid fuel, therefore, is carried into the hori
zontal passage leading to the main discharge
nozzle.

picture.php



Vergil
 
Thanks to all for the input-I have a couple 8BA carbs with the taller style nozzle bars-I'll try that first--although I have to say-I've had the same problem with 8BA carb on an 8BA engine in the past-especially in summer heat. Rick
 
You must use the top with the bump in the casting to allow the left hi-lift bar to clear the top. Supposedly the Booster type bars are even better on this problem. ken ct.
 
Verg,
Many thanks for that post....it is most appreciated.
Although I cannot explain why, it has been my experience that excessive clearance between the throttle shaft and the base will also prompt this weeping.
Charlie ny
 
47Merc said:
How about one of these to stop heat sink.

http://www.hotrodcarbs.com/parts.php?spacers
Click to expand...

Tried one of those. Didn't help the post-shut down percolating because the heat that causes such doesn't just come from the intake manifold, it comes from everything hot under the hood that builds up the heat under the hood and heats everything under the hood to the temperature of the engine. That's why lifting the hood works to prevent my percolation when nothing else I've tried has. I started a previous thread discussing this problem and proposing a novel idea I had for a solution in response to which I received a myriad of suggestions that is worth reading if one has this post-shut down percolation problem. Here: http://www.fordbarn.com/forum/showthread.php?t=116273
 
VERGIL,me too thanks you,now guys will know what to use when changing nozzle bars around. Not sure if needed with the Booster type,will have to try tomorrow,never did that before. ken ct.
 
ken ct said:
Ford changed some of the parts in the later carbs to help aleiveate this ,how good it works I dint know but. Use the HiLift nozzle bars and the necessary diff top section from a later carb.Might help.Ive had customers do this and have had no complaints about the change.Might work. Hi lift bars and idle tubes and a correct top and gaskets would go around $68 . ken ct.
Click to expand...

I put the later high nozzles in along with a phenolic plate and problem solved.
 
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