Lotus Elan

Stromberg floats stuck?

PostPost by: bulfin » Sun Apr 08, 2018 8:28 pm

Hi,

My 69 S4 sat for a while due to redoing the suspension and a move to a different city. When I put new gas in the drained tank it would not start. It had spark and the gas was flowing to the carbs. I took the tops off the carbs and turned on the electric fuel pump and worked the throttle by hand. No gas came up through the little hole. Both holes are clear - I pushed a very small wire through them. I am certainly no expert on carbs but I thought gas should have flowed. Are the floats stuck at the top and preventing fuel entering the float bowl? All help appreciated.

Thanks,

Bob
Bob Bulfin
1969 Elan S4 DHC
Mobile, AL USA
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PostPost by: Chancer » Sun Apr 08, 2018 10:04 pm

If you were expecting fuel to come out by just actioning the throttle then no, fuel would not flow in that instance as Stromberg carbs have no accelerator pump.

If you were cranking the engine at the time then no again as having removed (presumably) the diaphragms and needles then there will be no depression over the jet and no fuel would flow.

It is however probable that the floats/float valves are stuck, removing the float chambers will tell you more than removing the top covers.
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PostPost by: 69S4 » Mon Apr 09, 2018 6:41 am

In my experience Stromberg floats are more likely to stick open than closed but dried fuel deposits could have glued the needle valve shut. From memory a wire pushed down the jet hole won't hit the float and that hole is large enough to be almost clog proof.

If you can hear the electric pump running (mine makes a series of clicks) you can tell whether the float bowl has filled by the click rate. If fuel is getting in it clicks rapidly to start with for 5 seconds or so and then slows down as the needle valve shuts the flow off. If it doesn't click rapidly occasionally you can get lucky by tapping the side of the float bowl with something like a wooden hammer handle (not the metal end) while the pump's running to jar the valve open.

With modern fuel (never seemed to happen years ago) I can get an idea of what's going on inside the float bowl by looking at the main needle after a lay-up. If there's a kind of dried green deposit all over it then its probably best to strip the carbs down and clean them. If its bright metal then the inside of the float bowl is probably ok.

When my carbs have been left to dry out for a while sometimes the drillings in the choke mechanism - particularly the smaller ones - clog up so the engine won't cold start. One of my carbs seems to be more prone to that than the other. Again, if the needles are covered in gunge then the choke drillings are probably on the suspect list.
Stuart Holding
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PostPost by: bulfin » Tue Apr 10, 2018 8:23 pm

Thanks for the advice and info. I'll have another go at it when i am there Friday.
Bob Bulfin
1969 Elan S4 DHC
Mobile, AL USA
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PostPost by: bulfin » Sat May 05, 2018 8:20 pm

Hi All,

I was back in Auburn this week and tried to take the carbs off. (69 S4 Strombergs LHD) I could not even get a wrench on the rear lower bolt. Searching here, I only found one post that mentioned it, and it said it is hard to get to. Is there a trick or do I need to raise the engine to get to it? Guess I will trailer it to its new home, but will have to address this eventually.

Thanks,

Bob
Bob Bulfin
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Mobile, AL USA
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PostPost by: 69S4 » Sat May 05, 2018 9:37 pm

Yes the bottom nut on the rear carb is a bitch to get to. And if getting it off is hard just wait till you try putting it back on.

I have one spanner that - just - gets on there and undoes it one flat at a time. It's a cranked ring spanner about four inches long, 1/2'' at the business end and 7/16 at the other. Take off the throttle cable and the fuel line from the T piece. The spanner goes in through the gap in the middle using your right hand. Your left hand fingers go in from the other side of the carb to guide the ring onto the nut.

It's slightly easier if you take off the front carb by undoing the linkage but you can bend the W clamps if you're not careful so I tend not to bother unless I'm getting desperate.

I won't ruin your day even further by detailing the contortions need to get the nut back on the stud but it can take me anywhere from 5 seconds to 2 hrs to get it started depending on how my luck is running. The other 5 nuts are no problem at all.

Jacking the engine up to get a bit of extra space does seem like a sledgehammer on a walnut and only something I ever did once.

One further tip - get some spare O rings before you take the carbs off. They swell up in use and don't fit the recess for a couple of days till they shrink back. Getting a good seal here is really important for smooth running so don't be tempted to leave the awkward nut off.
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PostPost by: david.g.chapman » Sun May 06, 2018 10:42 am

For my Strombergs, to get the lower rear mounting nut on and off I use a cut down open ended spanner. It's only about 2 inches long. I also ground down the jaws to make then slimmer.

Dave Chapman.
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