Drilling 2nd stage question

[Flarty]

When drilling the 2nd stage what's the best way to flush out any swarf from inside the jet without just blowing in further into the carb body?

[GTphil]

Be very careful with the drill bit and try as much as possible to not get any swarf inside it. Then once done give it a real good blast with carb cleaner. Other than that I don't think their Is a lot more you can do. :agree:

[Matt Cole]

Drill with the carb jet facing the floor. Allow the swarf to drop out. Any inside and it will end up in the ports and the carb scrap.

[Flarty]

Drill with the carb jet facing the floor. Allow the swarf to drop out. Any inside and it will end up in the ports and the carb scrap.

This makes me reconsider drilling it at all, can the drill not push the swarf into the carb even if you have the port facing the floor?

Tempted to do it the old school way and change the main jet instead.

[Flarty]

How much difference in MPG is there between drilling the 2nd stage and doing it the old school way of changing the main and ac jet? I really don't like the idea of taking a drill to my carb and potentially rendering it scrap if any swarf gets inside :mad:.

The car isn't used daily anyway, it spends most of its life tucked up in the garage so mpg isn't a huge issue plus i can easily return it to standard fitting the t2 and putting the original jets back in.

I will be running 18-20psi, from what i have read people used to run 135/140 mains and .9 air correctors for this pressure, is that right?

[Trevhib]

I don't think it's a choice between one or the other, where doing the main jet is simply the less fuel efficient option. I had thought that drilling the 2nd stage was about getting the fuelling right throughout the rev range?

[tubbyG]

When I did mine I never did it with the bush facing down - I would find that a bit harder to drill straight and true.

I had the body in a vice with the bush facing up as best I could, bit of grease on the drill bit and drilled slowly.

If you can get acces to an air line to blow through the carb once done that would be great, but a tin of carb cleaner will do you just fine......... but in saying that, no matter how good you are at removing the swarf some will go through :laugh: it wont do any damage though so dont worry.

[James5]

I don't think it's a choice between one or the other, where doing the main jet is simply the less fuel efficient option. I had thought that drilling the 2nd stage was about getting the fuelling right throughout the rev range?


Sticking a larger main jet will yes allow more fuel for on boost driving but will give you crap fueling on normal / off boost driving.
Doing the 2nd stage only will not effect off boost / normal driving and allow's for decent fueling off boost yet correct fueling on boost. You could always smear some vaseling on the drill bit so the swarf sticks to it and just drill the 2nd stage very very slow, you are bound to not stop all the swarf but just clean the carb through a couple of times with carb cleaner and clean the idle jet (Brass screw on side of carb a few times).

[Flarty]

Thank's guy's

I am definitely going to drill the second stage now, Seems silly not to given all the advantages! :agree:

[Ian S]

You can also drill out the end of the enrichments ball plug and turn the screw to change the spring pressure. I forget which way and more details, it's been about 10 years.

Edit...I think the idea was to turn it in a bit so the enrichment start later and doesn't over fuel with the larger hole in the jet.

[Trevhib]

There is an article/thread with pics on that somewhere Ian :agree: