In dire straits, #4 fuel leak

[Diederick/DVK]

To all willing to drop in their 2 cents:

Due to circumstances I had to rebuild my engine again over the winter with all new bearings. The car is still suspended and I can't drive yet but I've just got round to firing her up again last week. And today after some tweaking, my problems remain!

The engine revs fine and all seems good. The engine ran before so there shouldn't be a reason that won't work. But, to cut to the chase, I have fuel dripping from under the #4 combustion chamber. When I rev the engine up I get a bit of splatter on the ground and on the header. There's also a small drop of fuel that came from the header and muffler gasket and some initial splatter from the exhaust. Soon enough I shut the engine off, cause this just isn't right and moreover potentially dangerous.

What I have checked so far is that the #4 plug, which is new, has a slightly black liquid electrode already.
The #4 chamber appears to be full. Yet, the engine doesn't appear to leak when it's shut off.
The IDAs are good, fuel pressure is a steady 3 psi and jetting is in the ballpark.
Also, the ignition appears to be working. The Magneto is at 28 degrees and the engine revs like a fierce barking dog.

I am in dire straits since one of my good friends is to use my '67 for his wedding in 19 days time.
Since he asked I put a lot of money into the car and I'd be heartbroken if I'd have to pull out!

[nicolas]

i would look at the carbs, seems to me one is spilling fuel. the fuel can't be burned completely and therefore goes in the header and the exhaust.

[Diederick/DVK]

Thanks Nicolas. I get what you mean but there's no fuel leaking from the carbs or intake as far as I can see. The fuel drip is only visible underneath the car.
It also seems it comes from the ribs of the head somewhere, so that's a bit more inward...

[Diederick/DVK]

Hard to shoot a sharp pic but what you see are the #4 pushrod tubes and the leak above it.

[TexasTom]

I know you said the #4 plug is new ... what is the gap? Remember, mags like small gaps, like say .018 to .020"!
Also, have you checked that there is good spark at the plug on #4? If there's fuel unburned and no leaks, no spark? or POOR spark ... ?
Let's get this thing FIXED, Diederick!

TxT

[Diederick/DVK]

Tom, I replaced all plugs with new BP7ES that I gapped at .018" and that solved the faulty ignition issue of last weekend.
Ignition seems good now listening to the engine. How should I best check whether I have good spark?
I can't imagine I have a combustion leak, but I suppose I could hook up a compression meter and quickly compare #4 and #2?!

Thanks again, Tom!

[Type1/DVK]

I've done some brainstorming about and to me it seems to be a leaking #4 intake on the ida or somewhat spilling/bleeding on that channel. After that when the combustion chamber is full of liquid/gasoline it will hydropress those liquids out of the chamber (around the barrel) and onto your tubes.. but that is just a brainstorm  

Compression numbers on that #4 are good? what about leaving the plug out and cranking the engine, if it spitting liquids you know your chamber is if somewhat full of gasoline. Plug gap also good?

[TexasTom]

Let us know what you find on the compression and/or spark tests, Diederick!

[Zach Gomulka]

Swap the carbs from side to side. No need to hook up linkage, just fire it up and rev it a bit with your hands. If the problem moves from 4 to 1, you know the problem is in the carb. If it doesn't move, then you've at least eliminated one factor.

Float level too high?

[jaqo]

Had a similar problem caused by - well known problem for ida- fuel squirter (acc. pump) leaking fuel.

[Fastbrit]

Float level too high
Main jet loose (or the whole jet stack – happened to me on the rolling road, and wiped out the rings on one cylinder inside 20 minutes due to excess fuel)
Leaking accelerator pump
Poor head/barrel seal

[Zach Gomulka]

Faulty needle/seat?

Swap the carbs, it's easy!

[Jim Ratto]

Is your fuel line TEE anywhere near the fan opening on front of fan housing?

[Diederick/DVK]

Thanks for the replies. The TEE is the Holley regulator underneath the deck lid spring.
I'll check the carburettor suggestions this Friday. But how do I find out if the accelerator pump is faulty?

[danny gabbard]

Whats your fuel presure ?

[Jim Ratto]

turn fuel pump on (don't start car) and let it run 20-30 seconds, and leave it on. Get a mirror and look down #3/4 throats, see if you see fuel spilling over onto butterflies. If your fuel pressure is 3.0 it's not too high. You either have a defective float, a defective or loose needle valve or your float level is off. I just had a needle valve go haywire in my 1/2 carb and flooded engine over badly. Luckily I was in my garage.

[Lanny Hussey]

I had an IDA float with a pinhole in it. It only held a few tablespoons of fuel but really caused mayhem.

[Zach Gomulka]

turn fuel pump on (don't start car) and let it run 20-30 seconds, and leave it on. Get a mirror and look down #3/4 throats, see if you see fuel spilling over onto butterflies. If your fuel pressure is 3.0 it's not too high. You either have a defective float, a defective or loose needle valve or your float level is off.

X2!!!

[jaqo]

Thanks for the replies. The TEE is the Holley regulator underneath the deck lid spring.
I'll check the carburettor suggestions this Friday. But how do I find out if the accelerator pump is faulty?

In my case I just looked inside at the carb barrel while the engine was running and I could see the fuel dripping.

[wolfswest]

Thanks for the replies. The TEE is the Holley regulator underneath the deck lid spring.
I'll check the carburettor suggestions this Friday. But how do I find out if the accelerator pump is faulty?

In my case I just looked inside at the carb barrel while the engine was running and I could see the fuel dripping.

X2: I also had this once, took the carb apart, cleaned and greased some parts and everything was A okay after firing up the engine again.

[Type1/DVK]

any news? 

[Diederick/DVK]

I got to spend a little time on it today. Took the carbs apart and set the floats, which were way off, replaced and set the needle valves, checked the jet stacks.
Then, once I put everything back I turned the fuel pump on and all seemed well as far as the absence of fuel spillage. Fired up the engine and after a few seconds the leak started again.

Ran out of time, so that's it for today again...

[Jesse/DVK]

You need to close your butterflies more. This is normal (got is also a bit with a cold engine) the pulses of the engine make te butterflies vibrate what triggers the accel pump.

[jaqo]

Disable the acc. pump and check again.

[Diederick/DVK]

Just when I thought I had it sorted. Now I'm really lost at it.

What I recently did is:
- Replace the floats, needle valves, gaskets and a few jets and set everything within factory weber specs.
- I replaced my Facet fuel pump with a self-regulating lower output rotary pump.

I finally had time to install everything today. And what I have now is an overflowing carburetor with the fuel pump on and engine off. Fuel is gushing from the jet screen in between the velocity stacks, pouring into the venturies through the pump jets and there's a pool of fuel underneath the #3-#4 side. It has always been the same IDA, new everything did not help. Now I don't even want to think what this is doing to the engine in terms of bore wash and my sump gaskets that have already started to leak oil.

I'm open to suggestions, please.

[Zach Gomulka]

You have swapped the carburetors side to side and the problem followed?

Try swapping the carb tops and see what happens. It's a process of elimination, dude

[Taylor]

What needle and seat do you have?? 

[gizago]

Float bowl damaged or cracked and leaking into carb body/ Venturi?

[Lids]

run it with some 48 DRLA's, and then send the IDAs to someone to look at

[peejke]

NO sollution, but as far as the ignition part goes, dump the BP7ES plugs. They can't stand a rich mixture. Probably gone allready.