Cold Start Fuel Jet

[Chug-A-Lug]

Hi All,

I just thought I would share this for anyone who might want to clean their cold start fuel jet in future, as although I found mention of disassembling one, it wasn't clear and I couldn't find any photos myself;

Here is the fuel jet when I first got it apart. As you can see, the collar has an internal screw thread so an appropriately sized screw can be used to pull the collar, the ball and spring then followed.


I was then puzzled because I still couldn't see through the jet and couldn't seem the clean/clear it. After a week of soaking the jet in various solvents a further piece fell out! There is a final copper bung with a helical groove around it's edge which must be intended to 'swirl' the fuel before it is forced through the eye of the jet. Everything was so gummed up with carbon that this was jammed solid on mine, no surprise that fuel couldn't pass. Now that it is all cleaned up and reassembled I can blow through the jet without any troubles.

L-R:- Jet Body, Helical Bung, Spring, Ball, Threaded Collar


I'll refit it at the weekend and finally be able to use the proper cold start procedure!

Hope this helps someone

[Johnmcm]

Thanks for taking the time to post the pictures. I'm sure it will help many of us when we can't get her started in the cold.

[ianpdexta]

I echo Johnmcm's thanks.

This jet is very different from mine which is integral with the tap and is an aftermarket type. I wonder about the ball and spring, does anyone know, was it meant to 'buzz' on the seat to aid atomisation or be a positive cut off against gravity? as a for runner to the tap.

I have taken one of pattern tap/ jets apart and modified another in an attempt to make it spray fuel on to the hot coil, I have some pictures to show but will wait until this weekend when I hope to try it out, it will be in my Dexta resoration thread.

Regards

Ian

[Chug-A-Lug]

Absolutely not a problem. Like I said, the real puzzle was that helical plug until it finally came free and all became clear.

I believe what I've shown is an original fitment, but I might be wrong. Others on here might be able to confirm. If it is original then it is likely quite an early version (before the integrated tap was used) as I have an early engine mated to a '64 back end.

I think the ball and spring is more of a non-return valve than to hold back the fuel against gravity. My aftermarket tap/plunger at the fuel tank seems to close the pre-heat fuel line anyway so this isn't an issue for me.

It wasn't too cold at the weekend but I did use the full cold start procedure as per the manual just to see. There was a satisfying 'pop' after about 20 seconds as the coil came up to temperature, igniting the first spray of fuel. The tractor has never been a hard starter but it positively leapt into life with the addition of the restored fuel jet!

I am slowly getting 'Henry' back in shape With each little bit of maintenance I'm gradually putting things back as they should be.

[blackbob]

Was the photo taken after the funeral of some enormously huge bloke, who needed a Dexta as coffin-bearer?