Gaskets

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Graham Smith

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Hi all

I recently bought a Vincent rotavator from eBay, which Josh and I have managed to get running, although we haven't used it to churn the garden up yet!

Unfortunately, the carburettor leaks fuel all over the place, because the previous owner at one time or another had made a gasket out of what looks like a cornflakes packet, and this has now failed.

We have some sheets of proper gasket material, and wondered if anyone had any hints and tips on cutting intricate shapes and punching holes etc.

I was thinking of using a scalpel?

Any suggestions?
 

Bazlerker

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I used to stick a sheet of gasket paper onto one surface, then trim away the excess using an x-acto knife with a new, pointed blade in it..slow and steady, trim the inside first, then remove the excess on the outside -after the pieces are bolted in place- after all, excess on the outside is only cosmetic whereas excess on the inside can be quite serious if the excess dissolves into the oil/gas..
 

Nulli Secundus

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You will probably need a proper hole punch for any holes.

You might be able to hold one part of the carb against the gasket material and with a slightly oily finger press and rub the gasket material like you were doing a brass rubbing in church. Just don't let the gasket material slip.

You will then have a profile to cut with sharp nail scissors.
 

Magnetoman

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Unfortunately, the carburettor leaks fuel all over the place,
If the carburetor is a pre-Monobloc, and if the fuel is coming from just above the ring at the bottom of the carburetor, the problem (or one of the problems, since there could be more than one...) is the float needle isn't seating. If that's the case, burnishing it into the seat using very fine grinding past will fix that problem.

You will probably need a proper hole punch for any holes.
It's not commonly known, but hole punches come in a variety of sizes. Small shops will carry only the "standard" ones that makes holes 1/4"-dia. (at least in the U.S.), but they also are available in smaller sizes that are more suited for the gaskets you need.
 

ossie

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lay the gasket paper on the carb manifold or its mating surface. then holding it still over it gently tap round it with a small hammer ,this will cut the outside and inside shape then get a ball bearing bigger than the securing holes and tap it into the gasket over the hole. this will cut the holes out. my dad an raf airplane repairer in tubrok? tiger moths etc showed me how to do this years ago. he also welded up the aluminium parts with an acetaline torch no mig welders in 1938.
 

ossie

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lay the gasket paper on the carb manifold or its mating surface. then holding it still over it gently tap round it with a small hammer ,this will cut the outside and inside shape then get a ball bearing bigger than the securing holes and tap it into the gasket over the hole. this will cut the holes out. my dad an raf airplane repairer in tubrok? tiger moths etc showed me how to do this years ago. he also welded up the aluminium parts with an acetaline torch no mig welders in 1938.
or if you do the holes first you can put a bolt through them to hold the gasket in place ,try a practice run on a piece of thin card.
OSSIE
 

Nulli Secundus

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Ossie, my Dad also showed be the same method and I use it myself, but with a delicate carb I probably would not use it.

The trick is to tap hard enough to almost cut through the gasket material, or just a tad more, but if you tap a little too hard you may bruise the corners of the casting.
 

Bazlerker

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You can use the "tapping" method to make a gasket with an iron or steel casting...carburetors are made from either brass or a lead/zinc alloy..far too soft, too easily damaged to use that method.
 

greg brillus

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I make small hole punches out of a short piece of tube and linish a sharp edge on one end, whilst chucked in a hand cordless drill. The problem with cutting holes in thin gasket paper is that unless the paper is new a still soft, the hole punch tends to split near the edge of your gasket, as advised, it pays to cut the holes first. The taping with a ball peen hammer works well in most cases, but on fine and more delicate items it can be very risky.
 
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