Javelin Carbs

[craig ainge]

After reading Paul Wilks' request for rebuilt kits I am minded to report a problem I had with the VM5. The car wouldn't idle nor run correctly and slowly got worse despite frequent adjustment. The problem was that one of the floats had become perforated causing flooding in that carb and fuel starvation in the other. The perforation was not visible until submerged in a bowl of water, when a stream of very tiny bubbles appeared from the side wall. It was not the soldered seam or any of the joins but the side wall of the brass float. It could be caused by constant movement against the strakes in the float chamber or possibly the damage caused by modern fuels, although I have been using 'counter- ethanol' products for a while.

[Keith Clements]

A common problem. Usually found by shaking the float to listen for ingested fluid. I have also seen bowls being distorted and the float not properly floating. Check by pushing down when full of petrol and making sure it floats up again easily. Note also the requisite thickness of washers under the float valve.

The rebuild kits do not contain new sleeves for worn throttle shaft holes which is the usual problem in the carbs. These require expert fitting and reaming/lapping in. TOPIC See this webpage.

[CyrilWhite]

I noticed service kits are available from JCS , what does this kit consist of?
I have a flat spot when gntly accelerating , so need to accelerate mor strongly .
Ok otherwise .

[Forumadmin]

JCS Kits contain the gaskets, needle valve and washers but exclude the spindle and butterfly (but Paul says these can also be sourced) so email him.

[paul wilks]

Hello Cyril

Here's the link provided by Keith.

http://zenithcarb.co.uk/carburettor-kit ... -kits.html

Paul

[CyrilWhite]

Thanks., hope it will cure the flat spot and make driving a bit smoother. Will get on with it it when I have solved my water pump problem , (damaged key way ).
As other people have reported I am sure it was damaged due to insufficient tightening of the pulley retaining nut .
Might try a bit of epoxy metal to build up the worn edges of keyway until I can get a spindle or find someone to re cut.

[Forumadmin]

I cleaned up the shaft and pulley boss then fitted key with plastic metal. This worked fine but later I recut the keyway on the opposite side of the shaft and fitted a new pulley with a new tight fitting key. Worth checking occasionally the tightness to make sure the pulley cannot move.

[CyrilWhite]

Have obtained a new spindle frim Bill Lock . Will fix it temporarily as you did and get new bits ready to fix later.

[David Morris]

Hi Paul,

Good to hear from you again! If you are having problems with worn carbs, my advice is to bite the bullet and get a pair reconditioned. There are several companies doing reconditioning and it saves a lot of experimentation at home with spindles and probably the need for bushing on the castings, which is where most of the wear occurs. Do make sure you are actually getting a pair of Javelin ones reconditioned! There is a Zenith model number stamped on the float chamber body and if you are speaking to a reputable reconditioner, he should be able to tell you exactly which model you should have.

Once you get them back, all nice and shiny, my advice is to invest in a super tool for balancing them that really does seem to work well on Javelin engines. It almost seems to be designed for our engines and is called a Synchrometer. This can be plugged into the top of the carb intake pipes ( on a Javelin ) as there is a good squishy rubber seal on the end of the meter without seeming to affect things too much and you can read the vacuum easily on the well-damped gauge. The carb linking rod is very, very sensitive in length to getting an even balance, with only about 1mm really throwing the balance out. I find a reading of about 5 on the scale of the meter is about right, with the engine beating over nice and slowly. On my car, someone in the past has manufactured a really nice 'click' adjuster in solid brass and this is fitted in the carb connecting rod that allows you to make really small adjustments. Just one 'click' on the adjustment throws out the balance! Doing it by hand must be a nightmare, especially with the fan inches away! ( Perhaps JCS should start selling them? ) The Synchronmeter can now be purchased from Amazon, search for STE BK Synchrometer ITCBK1-30/1. It's not cheap at £35, but really does seem to live up to its promises. [ PS I have no connection at all with the product! ] Hope all this helps - good luck! David.

[Forumadmin]

Used one a couple of weeks ago and can only endorse what David says.
David, I would be interested in pictures and an engineering drawing of the adjuster. Obviously a great idea, perhaps I could manufacture a few.

[paul wilks]

Thanks for advice (as ever David) Nice to hear from you too!

All the very best

Paul