Ivan
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| posted on 25/1/12 at 04:29 PM |
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Technique for drilling out a carb Jet?
I think I need to increase the jet size of my Holly accelerator pump jets from .025" to .032" (or possibly bigger) because of a massive
bog and 2 X backfires before the engine accelerates like hell when you floor the accelerator when cruising at lowish speed.
Any technique I should be aware of before drilling to make sure the hole is good and round - I guess the highest speed and ultra slow feed rate with
lubrication is the secret but am I right.
The reason I am drilling and not buying a bigger jet is that although standard jets are available in RSA larger ones are not so if drilling
doesn't work I can always go back to standard for about 2 Pounds a jet.
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tegwin
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| posted on 25/1/12 at 04:40 PM |
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Do you have a lathe?
With a drill that small it would be the easiest option.... But yes, high RMPS slow feed and a suitable lube for the material
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www.verticalhorizonsmedia.tv
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britishtrident
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| posted on 25/1/12 at 05:13 PM |
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I drill out LPG nozzles from 1.2mm upwards.
A simple Jewellers Spiral "Push Drill" (sometimes called an Archimedes drill) will do the job with sufficient accuracy but it will
take about 30 minutes for each jet to drill through. A Dremmel type tool will also do the job but will require and patience to produce an
accurate hole.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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Fred W B
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| posted on 25/1/12 at 06:09 PM |
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To do jet drilling at the track we always just used to hold a loose chuck with the drill bit in it in the hand and turn the jet onto the drill with
the other hand. We may have held the jet in a tap holder. The brass (at least with the jets we used) was soft enough.
It's not like the hole needs to be a precision fit.
Cheers
Fred W B
[Edited on 25/1/12 by Fred W B]
You can do it quickly. You can do it cheap. You can do it right. – Pick any two.
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jacko
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| posted on 25/1/12 at 07:04 PM |
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Put the drill bit in a vice and twist the jet by hand
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MikeRJ
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| posted on 25/1/12 at 07:04 PM |
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A pin vice and a steady hand works perfectly.
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JoelP
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| posted on 25/1/12 at 07:43 PM |
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i just used a normal drill bit, a cordless drill, and did them by hand. Took a few seconds on each.
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Ivan
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| posted on 26/1/12 at 03:16 AM |
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Thanks all for advice - seems like slow feed is the answer otherwise any speed from dead slow to fast works. Now to decide what size to drill them. I
think I will go up in 10% increments - i.e. approximately 20% increases in flow.
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Fred W B
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| posted on 26/1/12 at 06:02 AM |
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If you go too big you can close them up again with solder and redrill
Cheers
Fred W B
You can do it quickly. You can do it cheap. You can do it right. – Pick any two.
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jossey
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| posted on 26/1/12 at 07:59 AM |
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Really simple
Take carbs apart. Take to a bike shop.... Give them £20-25 and let them do it. Pick up later all done :-)
Thanks
David Johnson
Building my tiger avon slowly but surely.
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sprouts-car
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| posted on 26/1/12 at 09:38 AM |
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quote:
Originally posted by jossey
Take carbs apart. Take to a bike shop.... Give them £20-25 and let them do it. Pick up later all done :-)
Thats not the locost way! 
Build blog
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Peteff
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| posted on 26/1/12 at 09:56 AM |
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quote:
Originally posted by JoelP
i just used a normal drill bit, a cordless drill, and did them by hand. Took a few seconds on each.
I did the same but with an Aldi Dremel type tool. If I run a drill that small at a slow speed it will just snap off guaranteed.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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