The 'E' Type Forum

Chaps,

Since fitting a new Filter King regulator, carb no.1 (nearest bulkhead) is leaking fuel out of the trumpet when the engine's switched off.

The pressure is set correct on the regulator, so i assume the valve in the float chamber is not closing properly?

What should the float level be set at? and what damper oil do people use for the dashpot - mine seems empty.

Any advice would be greatly appreciated

The Service Manual recommends SAE20 oil for the dampers but you can use engine oil, SU damper oil or a thinner oil like 3in1 to adjust the throttle response to your liking.

I had dead floats. They were original, brass, BUT had LOTS of cracks all- round.

I tested them by dropping them in almost boiling water- and zillions of bubbles came out, and an oily stuff.

Solution was to re-new them. If it would have only been one or two holes, okay, but not 50.....

They are not that cheap I remember. IIRC Joe Curto had them + was cheapest. And he?s a great guy.

Carsten

Finally got around to ordering 3 new needle valve assemblies and fitted them today. Yet to fire her up yet though.

The new needle valves were different to what i replaced though? The one's replaced were a one piece item with what looks like a ball bearing at the end and lots of holes around it, and the new one's were two piece? Fitted fine though and i checked the float fork levels and this was all ok.

Any idea's as to why the car had this "different type" previously fitted, or was it just a "race mod"?

It sounds like someone installed Grose jets in your car at some time. These have been a popular modification for many years, to replace the occasionally leak-prone needle valves that were often found in aftermarket SU carb rebuild kits. I installed them in both of my E-Types, as well as my Healey 3000, after getting tired of the leaks and flooding associated with the needle valves. Fortunately, I never experienced a fire. I've always had good experience with Grose jets, but I've also heard that the quality of the newer units isn't what it once was.

Interesting that the problem only occurred after fitting the pressure regulator. What is the pressure set at? The correct range is in the 2.5 - 2.7 lbs/sq.inch range ( about 0.2 bar if you are metric )

Christopher raises a good point. If you're running the stock SU fuel pump, flooding problems should be a rare occurrence, but if you have an aftermarket pump installed you may just have your regulator set high. I ran a Facet pump for a time in the early '80s, when running my '65 FHC as a daily driver, and the regulator was an absolute necessity. I also found that with the Facet pump, parking the car facing downhill with a full tank would allow fuel to leak past the needles, flood the bowls, and pee it on the ground overnight.

christopher storey wrote:Interesting that the problem only occurred after fitting the pressure regulator. What is the pressure set at? The correct range is in the 2.5 - 2.7 lbs/sq.inch range ( about 0.2 bar if you are metric )

Chris, fuel pressure is set correct at 0.2 bar.

New needle valve assemblies fitted, float level forks set correctly - and the problem remains :(

No problem when running, but after engine shut off, fuel accumulates and drips out of NO 1 carb

Any further idea's? Float gone porous?

The car has a red top Facet pump with a Holley regulator that was recently replaced with the Filter King combined filter and regulator.

The problem has only surfaced since fitting the Filter King

Dump the Facet and fit an electronic SU pump. There was a Facet fitted to my FHC but I could not stand the ridiculous noise it made - I threw it away in disgust. My OTS has an electronic SU with a Filter King set to 2.5psi and it works superbly.

I can rule the pump out as the problem has only recently surfaced.

I can also rule out the Filter King as carbs 2 & 3 are fine so, there has to be an issue with the carb.

The problem only presents itself after the engine has been shut down. No fuel comes out of the float bowl overflow, just fuel trickles out of the jet at the base of the carb after the engine has been shut down.

I suppose the first port of call is to swap the floats from Number 1 and Number 2 carb and see if the problem migrates to carb 2?

After having given this some thought last night - i think i know what's wrong. When removing the old needle valve assembly from NO1 i noticed that there were 3 small fibre washers between the needle valve and the float lid - hinting at a previous problem? I think the needle valve assembly isn't sealing correctly into the float lid and fuel is trickling in with the residue fuel pressure when the engine is off, causing the float chamber to fill and flood. Plausible?

This has obviously come to light since fitting the Filter King as it's obviously maintaining a degree of pressure to the carbs after engine shut down (unlike the 20 year old Holley regulator that was probably worn out. I'll order a new float lid and see if this resolves it

FWIIW, I remember cutting my teeth 20+ years ago on an Aston Martin that had a similar problem ; I think if the correct fibre-washer with 3 or 4 cut-aways is not fitted to the lower face of the breather/overflow pipe banjo on the float-bowl lid, then the air displaced by the ingress of petrol cannot get out of the float-bowl, and ends up forcing petrol to flood everywhere else except out of the overflow/breather pipe.

This may be shooting from the hip so please don't castigate my memory too dismissively, but this is obviously today's pressing problem for you and I thought it might be worth a look.

Ah, now I think we are getting nearer . If the rubber diaphragm to which the jet is attached perforates, you will probably get a leak of this type. These rubbers do go hard over a period and then tear with choke operation. Also, even if the diaphragm is good, the 4 screws which hold the base of the carburetter to the main body can loosen and a leak will then occur. Also, Rory's point about the perforated washer on the chamber lid holding down bolt is another good one to check ( although this more commonly results in flooding via the top of the jet, rather than leakage from the base

christopher storey wrote: commonly results in flooding via the top of the jet, rather than leakage from the base

Chris

This is exactly what is happening. There is leakage from the top of the jet which then trickles out of the air intake / trumpet after the engine is shut down. The base isn't leaking - this is fine. When i replaced the float bowl needle valves, i noticed that on Carb 1 (the affected item) that there was 3 fibre washers between the old needle valve and the float bowl lid :? I suspect that this has been a problem here before as the other two carbs have just one fibre washer fitted. What i suspect is happening is that the new regulator is holding better pressure to the carbs after engine shut down and fuel is leaking into the float bowl from a bad seal between the needle valve assembly and the float bowl lid - hence filling the float bowl and trickling out of the main jet.

Hi......When i rebuilt my SU,s a well known carb restorer recomended a tiny smear of sealer when fitting the needle valve......Steve

Someone has been playing silly beggars with your carbs ! I have just been and checked my SU manual ( the official one available from Burlen ) and there is no SU float lid that I can find which has a gasket between the needle seating assembly and the lid. This accords with my recollection although it is a few weeks since I changed a needle valve - the brass housing screws directly into the float chamber lid with no washers at all. As Steve has said, someone uses some sealant ( possibly David Lonsdale although I think he would regards that with suspicion ! ) but I would not advise this since ethanol fuels tend to dissolve most sealants, and I have never yet in nearly 55 years of playing with SUs had a leak from the quite deep thread of the valve seat assembly

Thanks for that Chris - most interesting. Perhaps i should just remove this washer & see how we get on - and if it resolves the issue? If not, i guess a new float chamber lid is required

It is likely that whoever put multiple washers in to lower the valve was trying to prevent a flooding condition. Removal may worsen it but the conventional float height adjustment ought to bring it back into spec. Don't throw new parts at the problem until there is no other option. If you do eventually buy a new rear float bowl cover you can sell me the old one!

Pete

It's all a bit of a mystery Pete. The Grose needle valves that were fitted have a longer thread so maybe the 3 washers were to pack this out? Incidentally, Grose jets come with a sealing ring (nylon i think) between the float bowl lid and the valve. I've taken it back apart this afternoon, removed the sealing washer and screwed the needle valve straight in. I've yet to start her yet, so will report back in due course

Jason

What was the float height measurement after you had the carb top in bits?