Leaking Carby - Series II HS1

Post by **David53** » Mon Jun 15, 2009 11:48 pm

Hi there from Australia.

I have just finished restoring my 1953 Series II which I have kept totally original. She is now registered and on the road.

One small problem is that I have a leak from the jet assembly of the carb. It is the original HS1 carb and was rebuilt prior to getting the car on the road. There is a drip about every 20 seconds with the engine running. A couple of questions:

1: How dangerous is it to have this petrol dripping near a hot exhaust? Assuming petrol requires a naked flame or spark to iginte am I in danger of a fire?

2: Talking to folks here in the Aussie clubs they tell me the HS1 carb always leaked and there's not a lot you can do. Apparently the cork seals around the jet quickly wear with the choke action and allow petrol to seep. Apparently they fixed it on the HS2. I have ordered a rebuild kit and plan to spend a pleasant afternoon rebuilding the carb but is it true that the HS1 will always leak?

3: If this is the case, what suggestions for a carb to upgrade to? The engine is original 803cc, original oil bath type air cleaner.

Here is a pic of the car

Many thanks.

Post by **PSL184** » Mon Jun 15, 2009 11:53 pm

Nice car David - Fuel leaks are bad and yes you defo risk a fire. The spark could come from anywhere and the flash point of petrol is probably near to manifold temp in a hot climate so it could go off without a spark anyways.... I'd get it fixed asap. I'm not an expert on the HS1's but I do know the HS2's leak from the jet if the seal is damaged or missing so I guess the design is similar.

Post by **bmcecosse** » Mon Jun 15, 2009 11:57 pm

You should be able to tighten up the jet nut slightly - to make the washers petrol-tight. Just not so tight the jet can't move ! You would need to uprate the manifold to take a larger carb - and lose the originality of your car.

Post by **David53** » Tue Jun 16, 2009 9:56 am

Thanks bmceossse. When you say the jet nut I presume you mean the main one, not the mixture adjusting nut..??

I have ordered a kit from ESM and will replace all seals and washers but will try tightening it this weekend as a short term measure.

Post by **bmcecosse** » Tue Jun 16, 2009 11:33 am

Yes - the main one !

Post by **damian1978** » Tue Jun 16, 2009 11:37 am

Hi David, I had exactly this problem with my HS1 carb on my 803cc before I started my rebuild. It's a relatively easy problem to fix though.

In the kit you'll get a replacement jet, two small cork seals, a large cork seal and a couple of brass washers which are bevelled. It's these parts that will fix the problem. When you take it apart you will more than likely find that the cork seals are shot. If you've never dismantled a carb before (as was the case with me) just go about it slowly and follow the workshop manual and the leaflet that comes with the kit, for guidance.

Remember to soak the cork seals in light oil for 24 hours prior to use.

I used my orginal 1950's BMC workshop manual - if you don't have one I'd be happy to scan the relevant pages and email them to you.

Good luck with the job. Once done you should have no more leaks. This cured the problem for me anyway.

Damian

Post by **jaekl** » Tue Jun 16, 2009 12:53 pm

The soaking in oil must be the trick. The original ones looked like leather. The replacements looked so much different. The oil must help it reshape itself to seal better. I used O-rings with success for some years, but the leak did come back so I updated to HS2.

Post by **David53** » Tue Jun 16, 2009 1:31 pm

Thanks for the tips - I am waiting on the kit from ESM so will do as you suggest when it arrives and report back! In the meantime will tighten that main nut and see what happens

Post by **mike.perry** » Tue Jun 16, 2009 6:09 pm

Just being picky but the Series II was fitted with an H1 carb not an HS1. The smallest HS carb is an HS2 which was fitted to 948 and 1098 Minors.
The jet designs are different so you are likely to be supplied with incorrect spares. The cork seal does tend to drip, especially if the car is not used and seal dries out. When fitting a new seal it should be soaked in petrol to swell it before fitting.

Post by **David53** » Mon Jun 22, 2009 11:41 am

Well, I rebuilt the carb using all new seals and washers and......it leaked worse than ever!

After much frustration and pulling the carb to pieces again I found that the jet casing was loose inside the housing. The jet itself was nice and snug, but the jet casing was loose. The only washer is a single brass washer on top. I replaced this with a rubber O Ring style waher and....bingo! Nice snug fit and no leaks.

Then she wouldn't start....Given that all I had touched was the carby I naturally assumed fuel.....so spent another hour fiddling. Then it occurred to me that it was very much like no spark....and guess what? Corroded connection on the HT lead into the coil...Cleaned it up and away she went.

Don't you just love Morries?

Post by **bmcecosse** » Wed Jun 24, 2009 9:37 pm

Well done - they will certainly keep you on your toes!