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Fuel Leaking from Carb in, and Carb to Carb


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Right, so fixed all of the Ignition problems (previous post) now I can get it running but after a few seconds it develops a leak from the Float Bowl connections.

Original Fuel Pump was shot, so replaced with equivalent to OE part 208493. from Classic Parts Trader from Ebay.

Not sure if this is where I have made my mistake - but part looks exactly as the one from Rimmer Bros.

Ive got all Fuel Clips as tight as they will go but still leaking - i've checked all of the spigots, and no gouges or anything, and have been cleaned of all rubbish.

Anybody any ideas?

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I'm assuming you're talking about leaks from the point where the rubber hoses attach to the top of the float chambers?

On the top of the float bowls, in the same boss that holds the stub connections for the feed pipes, there are small vent drillings - which also serve as overflows.  Could it be coming from there?

If so, it means that the needle valves are leaking.  This could be because
- they have dirt in them
- they are old and tired (wear ridge on the cone section of the moving part)
- Floats don't float any more
- Fuel pressure too high.  SUs only like about 1 - 2psi and some of the pumps sold today produce a fair bit more, forcing the valves open.



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stopped leaking from pipes, now leaking from the vent holes! improvement in my eyes!

replaced spring in Lift-pump to reduce pressure - seems to have worked.
replaced needle valves and made sure of 3.175mm gap

still getting a leak thou - is that 3.175 critical? or if it was lower does that make a difference?

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I had an issue with my CD175's constantly dribbling. They were freshly rebuilt so I knew it wasn't them. I've fitted an electronic German copy of the old SU fuel pump and it's rated at around 3-5psi. I fitted a fuel pressure regulator set at 3psi and no more dribbles!

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Fuel Pump defo over-rated for the application!!! why do they do that!!

Quick fix, volume of pump chamber is more or less exactly the same as original, so just need to replace spring!  and would you believe it, the new springs are twice as long as the originals.  Quick swap and hey presto regulated the flow back to 2-3 psi!

New floats arrived today-fitted to Carbs, and wow! no more fuel leak!!

Now for the fun stuff!  Got her running for a good 5 minutes and then checked the oil level, omg! full of bubbles!! now to me that screams water in the oil - checked the radiator and the water level has gone down - c**p now the head gasket has gone?

Is there anything else I can do to check if  need to replace the gasket?  compression of cyls 1,2,4 all look good, round 140-160 PSI. although 2,4 spark plugs were wet.  (couldn't get to 3 with the distributor on, and didn't have time to drop it.)

Any help please!


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oo forgot to add, while running had noticed some steam? / exhaust coming off the engine, I initially thought it was just the dust burning from the manifolds.

So after a quick clean up and spray from the Jizer what can I see..... a crack that has been welded (badly) and has cracked again, and another crack.

Dam, new manifold as well now! woo!

Can anybody recommend a decent place to get a new one?

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