Drilling Carb Jets

[PULSE]

I'm just looking for anyone whos had success drilling carb jets.

I don't want to fork out for a whole heap of jets, and I've heard that you can re drill them to the size you want, or solder them up then re drill a smaller hole.

I searched the forums and google and all I could come up with was this http://www.xs11.com/tips/maintenance/maint30.shtml
It lists all the size drill bits corresponding to the jet sizes. Now my problem is I can't find drill bits measured this way they're all either in imperial or metric but these seem to just be numbrered? Where would I be able to find these drill bits?

Also when they say that you can full the jets with solder and then re drill them, is it just regular electronics type solder?

Cheers, Matt

[Duk]

I have heard of drill bits specifically for jets or other calibreated orifices but they wouldn't be cheep and I've never seen any from the usual automotive or industrial tool supplyers.
Apparently Weber jets are drilled, the flow mesured, and then marked with the size that a perfectly drilled hole would flow. Or something like that
Standard drill bits that you and I buy wouldn't/don't give a decent enough quallity finish, especially if you're drilling out a hole to a bigger size. They also tend to leave an oval shaped hole.

[M.J.H]

http://bobmay.astronomy.net/misc/drillchart.htm

Try that chart for the cross over for the sizes.


yes you can drill them out as the dyno shop I use does this.
Not sure if it is normal solder that you would use but why not get an old piece of crap carb from somewhere for next to nothing and experiment on that one first.

[oldcorollas]

for short term testing, there is no reason not to use normal solder.
that guide has imperial sizes.. next to useless for the metric world

jet sizes are in mm, ie 120 = 1.20mm, 155 is 1.55mm

http://www.micro-tools.com/Merchant2/e_drill.htm
here is a list of metric and imperial from someones old catalog
http://209.85.173.104/search?q=cache...nk&cd=10&gl=au

when i did it, i drilled a couple of jets to abotu 2mm, and then filled and drilled a couple at a time.. then, when i gto close, i bought jets above and below the drill size i used.. (cos the hole will always be a bit bigger than the drill, but the rough surface may make it effectively smaller.. or some such crap)

[PULSE]

thanks for all the help guys, + rep for all!

The jet sizes being in mm makes things so much easier! I'm just hoping I'll be able to find a set of drill bits with such a small marginal change between bits if that makes sense.

Oldcorollas you mentioned "for short term testing" - will solder deteriorate or is there any reason other than its just not the best option? I havent had much luck searching on the net to buy jets, but I think I'll go down to a carb tuning shop to buy the proper jets after.

Plonka - I was about to buy a jetting drill set off ebay for $30 odd until I did a little research and realised that #60 to #80 range of bits isnt quite guna cut it.

Cheers, Matt

[jeffro ra28]

You can buy down to .010"(.25mm) drills from gasweld. They are intended to be drilled with a small handheld chuck.

[oldcorollas]

you can also get them from sayy.. blackwood$, or from electronics stores (jaycar?)
if you are drilling solder than they don7t need to be excellent quality.

you can easily get webber jets, and others should be not sooo hard to find.. not so common anymore tho.
you could always buy small jets and dril to whatever size works after the testing

what size jets do you have now? what carb?

for a single webber on a 4K, i needed a range of about 1.0 to 1.7 for testing.
you can always "wiggle" bits or "push pull" to make the hole in the solder bigger..

edit: i am not sure about longevity of solder. while i think it would be ok as long as you fluxed it properly and the jets were brass.. and cleaned all the flux off after... i would still feel better with proper jet..

then again.. it probably really doesn't make that much difference if the solder and brass have good connection

[PULSE]

Cool I'll check out those places and see what I can get my hands on.

What I've just put on is a 32/36 DFEV/DFAV im not sure which - its off a fiat I think. And I havent had a look at the jets yet so I can't tell you what size they are.

[oldcorollas]

ahh k.. what sizes are the chokes?
my 34/34DMS had maybe 120 and 150 jets..

weber jets are easy to get hold of and cost me about $5-8 each for different sizes...
was from carby place on paramatta road, shidoney...

[allencr]

Keep the solder off of the jet's seat. Even though it's softer then the aluminum, it's still hard enough to score up the seat cut into the carb body.
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Any decently stocked automotive parts house should have 4 different standards of bits.
I think the numeric sizes will be less expensive & closer to what you want then getting a whole set of jet drills.
Imperial/British - inches 1/64 ->
Alphabetic - letters A thru Z .234 -> .413in
Numeric - numbered 1 thru 97 .228 -> .0059in
Metric - milimeters .2 ->

There must be lots of tables out there somewhere.

[PULSE]

I've had a search on both the jaycar site and the gasweld site and can't find those kinda size drillbits. gasweld has sets with intervals of .5 which is too big obviously. and jaycar doesnt really have anything either.

EDIT: I just checked blackwood too and I had a bit of a look but there are a thousand options(as in different types of drill bits) though I'm pretty sure they don't have them.

[jeffro ra28]

Just go in and see them. My local gasweld store in Tamworth has heaps of them!

[gazza53]

Dunno where you would get them now, when i was jetting my ta22 celica / turbo / weber setup i purchased a full set of carbi jet drills ( there is about 40 in a set). I got them from Lynx along parramatta road and i think they got them in from england, they cost a small fortune then, probably thirty years ago now.

[Rodger]

Just been following your links and nice find oldcorollas.

I have been looking for small drill bits for drilling jets but try the US Micro Tools site as the one in Europe will not sell outside Europe.

I have a set of metric from P&N 1.00 to 5.00 in 0.1mm steps and get good results by sneaking up to the final size.

Micro Tools, believe it or not have sets of metric drills. 15pcs 1.05 -- 2.0mm

https://www.micro-tools.com/store/it...emCode=82616MD

and 15pcs 0.30 -- 1.00 in 0.05 steps

https://www.micro-tools.com/store/it...emCode=82615MD

at $3.00 USD each set I could not resist and bought some.

Regards

Rodger

[rms]

Try engineer's supply places for tapered jet reamer sets.

I have what is left of a set that are probably 50 years old. Went from (converted from imperial) .25mm to 3mm.