Fuel leak in odd circumstances
Discussion
Well, here's my latest little problem (ah, the joys of owning a 12 year old kit car, eh ? 
)
I have an "odd" fuel leak from my front 45DCOE.
If the engine is ticking over, or revving hard when at standstill, no leak. If I drive the car "normally", then no leak, either when running or when I turn the engine off.
If I take the car out for a damn good spanking, when I pull up and let the engine idle, there's no leak either. However as soon as I turn the engine off, after driving the car hard, the front carb positively puthers fuel out of what appears to be it's underside somewhere. Difficult to tell exactly where's it's coming from, it actually dribbles off the carb at the point where the carb bolts to the manifold, but that might just be coz it's the lowest point on the carb. It will drop about an eggcupfull of fuel, give or take.
Anyone any ideas ?!?
) I have an "odd" fuel leak from my front 45DCOE.
If the engine is ticking over, or revving hard when at standstill, no leak. If I drive the car "normally", then no leak, either when running or when I turn the engine off.
If I take the car out for a damn good spanking, when I pull up and let the engine idle, there's no leak either. However as soon as I turn the engine off, after driving the car hard, the front carb positively puthers fuel out of what appears to be it's underside somewhere. Difficult to tell exactly where's it's coming from, it actually dribbles off the carb at the point where the carb bolts to the manifold, but that might just be coz it's the lowest point on the carb. It will drop about an eggcupfull of fuel, give or take.
Anyone any ideas ?!?
A tuner told me recently that totally polished is actually bad .... what you are after is a slightly rough surface, akin to fine sandpaper. Apparently this helps create a tiny bit of turbulance as the fuel/air/gas travels down the ports, which is a good thing (apparently).
As mentioned above, the big thing is to get the rough edges off .... however as I understand it, this is a bit of a black art in itself, and really can't be done without a flow bench, as even small apparently innocuous modifications can ADVERSELY affect power ! (especially on cylinder head mods, rather than manifold mods)
Didn't get time to check my O rings last night, will probably look tonight.
As mentioned above, the big thing is to get the rough edges off .... however as I understand it, this is a bit of a black art in itself, and really can't be done without a flow bench, as even small apparently innocuous modifications can ADVERSELY affect power ! (especially on cylinder head mods, rather than manifold mods)
Didn't get time to check my O rings last night, will probably look tonight.
Graham - mirrors, the cheeky things ! Thanks for the tip, coz I was going to order them too ...
Well, I whipped of my problem carb last night ... my O rings are perfect. BTW, how do you know how hard to tighten the carbs back up again ? (I dont want to squash the rubber)
So .... what else could it be I wonder ?
Well, I whipped of my problem carb last night ... my O rings are perfect. BTW, how do you know how hard to tighten the carbs back up again ? (I dont want to squash the rubber)
So .... what else could it be I wonder ?
Gassing Station | Kit Cars | Top of Page | What's New | My Stuff