Starting The Engine

ian Howell · Post by **ian Howell** » Fri Jun 01, 2007 1:05 pm

The petrol pipe on my 1930 Long Four has a nut on the end and this screws onto a double-ended brass fitting that in turn is screwed into the carb body.

I have cleared the leaky float valve by VERY GENTLY 'skimming' (only a couple of thou') off the seat with a VERY SHARP drill.

The needle now seats and seals perfectly.
I have also made new cork sleeves for the petrol tap as the (very) old ones leaked badly.

Not difficult, but quite time consuming.

The devil is in the detail.

Tony Fearn · Post by **Tony Fearn** » Fri Jun 01, 2007 2:06 pm

Hello Ian,

Thanks for entering the discussion about the older type of carb.

It might be of use to mention the size of drill you used to skim the needle valve seat on your bronze carburettor as there are probably quite a few that will need doing in the future.

I also have a CO2 extinguisher as well as a powder, a foam and a water one. You can't be too careful. It's no good "going to buy one" if you haven't done so before the the balloon goes up.

By the way, George Garside (or was it David Fox) always had a flat cap in the car as I remember. This fits perfectly around a blazing 'elephant's ear choke, and was said to be rather effective if you didn't burn your hand.

Tony.

Tony Fearn · Post by **Tony Fearn** » Fri Jun 01, 2007 5:18 pm

Alan

I've photocopied a couple of pages of the Pitman's "Book of the Jowett" for you this afternoon which relate to valve timing.

They are in the post which leaves at 5pm so you should get them soon.

I like the Avatar picture. What did the DNA search throw up?

Tony.

AlanBartlett · Post by **AlanBartlett** » Fri Jun 01, 2007 6:41 pm

I've got that book tony, which page?, and what do you mean by dna search. Glad you like the avitar hee hee, just another random day at college, I think that was the day i tried the fruit salad, from the look on my face I don't think I liked it.

Tony Fearn · Post by **Tony Fearn** » Fri Jun 01, 2007 7:28 pm

Hello Alan.

Pages 27, 28 and 29 detail valve and ignition timing.

The reference to De-oxyribose Nucleic Acid (DNA) and your avatar was another "hee hee".

The technique for DNA profiling can sometimes use a buccal scrape of the non-keratinising squamous epithelium lining the inner cheek. That's got a a layer of nucleated cells which contain amongst other things DNA.

Tony.

AlanBartlett · Post by **AlanBartlett** » Fri Jun 01, 2007 7:31 pm

Oh I get you now, it looked like a DNA swab ha ha

AlanBartlett · Post by **AlanBartlett** » Sat Jun 02, 2007 12:42 pm

Hi Tony,

Thanks for the photocopies, thats straigtend it out a bit i know what I'm looking for to set up the gears again, center punched notches, also one thing I dont get is thou- i know its for thousand but its a bit far back from metric for me.... imperial mesurement inch confusing, no doubt ill work it out.

AlanBartlett · Post by **AlanBartlett** » Sat Jun 02, 2007 8:12 pm

Back to top dead center, I setup the timings again today referencing to tonys photocopies, but the only trouble is that the cog that had been put on there I think had been turned round at one stage so the tdc notch was on the reverse side, so after some umming and arring I found the other cog off the other engine and found the tdc mark on the oposite side to the facing side on the engine. Which in my mind when they were made they were all machined near enough identical I guess? So I lined it up with the one on the engine, taking note of the little engrving numbers and hole alignment, I was able to locate it to the nearest of two teeth. So I may be one tooth out but now when cranking the engine over by hand I can only describe of hering a popping coming from one of the cylinder heads? Is this normal? Am I anycloser to my timing setting.

ian Howell · Post by **ian Howell** » Sat Jun 02, 2007 9:05 pm

Tony, Alan (et al)

The drill I used was a 3.5mm. This was in spite it being JUST a bit bigger than the existing main hole but it was a brand new, very sharp, titanium tipped drill that I knew would cut 'clean'.

Incidentally, I applied the same technique years ago to the float valves in the 30VM5s? on my Javelin, but they had to be unsoldered first - not too difficult.

The angle is not too critical it seems, as long as it is different to that of the needle, so that the needle and the re-cut seat touch on a fine line.

The problem I now have is that the main jet appears to flood, but I will strip the carb again and have a closer look at the height of the jet tube in the venturi.

Are there any instruction sheets for these Zeniths on the club website anywhere? I don't seem to have a lot of luck getting to the Gallery - probably my ignorance of matters IT.

Tony Fearn · Post by **Tony Fearn** » Sat Jun 02, 2007 11:52 pm

Alan,

Somewhere in your dad's tool box there should have been a set of feeler gauges. These will probably be Imperial rather than metric.

In the past, you could set the plug gap by using a torn off piece of a Players cigarette packet. It was about 25 thou thick!!

If you haven't got an Imperial feeler gauge set, and you can't source one, and there are a few car boot sales around your area it might be useful to visit a few.

If all else fails, let me know, there's probably a spare set in the garage.

I can't comment on the"popping sound" but others might do so.

Tony.

Ian,

I've a notion that the Jowett Shop may have a leaflet on setting up the Zenith carburettor. Give Robert a ring.

Tony.

Keith Andrews · Post by **Keith Andrews** » Sun Jun 03, 2007 2:00 am

A nice little free unit converter for your computer
http://prdownloads.sourceforge.net/unit ... e?download

AlanBartlett · Post by **AlanBartlett** » Sun Jun 03, 2007 7:57 am

I can only describe to popping sound as positive note I hope, because its now sucking in the petrol fumes and there is no carberttor leak I can only assume its combusting, like sucking in the fumes, compressing it and pop combusting it or something? or making that sort of motion but minus the spark from the plugs?

Bryan Walker · Post by **Bryan Walker** » Sun Jun 03, 2007 11:27 am

Hi Alan,
is the popping back out the Carb? If so it suggests the mixture is to lean or float level to low.

Bryan

AlanBartlett · Post by **AlanBartlett** » Sun Jun 03, 2007 4:34 pm

No, It appears to be coming from the cylinder heads or like the pistons area, head cylinder area,

Tony Fearn · Post by **Tony Fearn** » Sun Jun 03, 2007 7:37 pm

Alan.

Have you actually seen with your own eyes :-

1. That there is a spark at the distributor points when the ignition is on and the distributor cap is removed and you turn the engine over by hand? (a darkened garage helps here)

2. That there is a spark jumping the gap at the spark plug? This one's a bit tricky and can be painful, and if no-one local can show you how, give me a ring.

Also, now you think you've got the valve timing correct, if I remember correctly, Ian Priestley told me that if you set an inlet tappet to 6 thou clearance (when the opposite inlet valve is at the top of its lift) and put the 6 thou feeler gauge in the gap, if the valve timing is set up correctly, the feeler gauge should become trapped as the flywheel mark shows top dead centre. - i.e. the inlet valve is on the point of opening on that cylinder. Please can someone corroborate that. Then of course the tappet clearance will have to be reset to 2 thou. the same as the other valves, (again when the opposite inlet valve is at the top of its lift).

Then from the book, when one inlet valve is just about to open, the dizzy should be set so that it is about to fire the opposite cylinder plug just as the points open.

You could, as an afterthought, have one of the monthly Section noggin and natter meetings at your house if your mum doesn't mind, and she can feed everyone that turns up! Make sure they come prepared to get dirty in the garage, and have copious hand cleaner on tap.

Tony.

JowettTalk

Starting The Engine

Carburettor needle valve seat

Thousands.