john_p_b
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 posted on 13/5/07 at 10:23 AM |
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weber experts - rejetting my 40's
posted up last week regarding spitting back on my freshly set up 40's.
well i rang the place up that did the work and set them up etc. the chap now reckons they need bigger pump jets and smaller main jets (said from when
i picked it up in needed smaller mains cos it chokes up at low revs). can't say i'm overly impressed really after spending 200 quid first
time round and now he's quoting £90+ vat to change the jets again.
so basically can i do it myself or is it all going to need balancing up etc? i know what mains i need because when i picked it up he said i could drop
from 130 to 120 mains but it's the pump jets i'm not sure on and is there any way i can identify them? found a place on ebay that do jets
and what appears to be decent prices but without knowing what i've already got i don't know what to drop down to.
any help much appreciated!
cheers
john
built a car, built a home, had a family. lost the family, lost the home, still got the car.
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flak monkey
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| posted on 13/5/07 at 12:03 PM |
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The pump jets are marked. You need to pull them out (they are under the brass bungs with a screwdriver slot in either side of the main float
chamber).
Did you try just richening the idle mixture up on the barrels that were spitting back? This can also cure flat spots, as mixture is still flowing
through the idle jets during the progression phase.
What size engine have you got??
David
Sera
http://www.motosera.com
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john_p_b
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| posted on 13/5/07 at 12:51 PM |
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it's a 2.1 pinto. richening things up only made it run worse! it's running way too rich anyway, the guy that set it up said better to be
rich at bottom end than lean at top end but when do you ever need to be using full revs on a 7?!
built a car, built a home, had a family. lost the family, lost the home, still got the car.
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flak monkey
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| posted on 13/5/07 at 12:57 PM |
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OK, my pinto with 40's is currently running:
Chokes - 34mm
Main Jets - 140
Emulsion Tubes - F16
Air Correctors - 180
Idle Jets - 50F9
Pump Jets - 40
Aux Venturis - 4.5
It runs quite sweet at that, with no flat spots etc, but its not been on the rolling road yet so dont know what the power is like.
I know the emmissions are good at idle though.
It is better to run a bit 'fat' than too lean.
[Edited on 13/5/07 by flak monkey]
Sera
http://www.motosera.com
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britishtrident
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| posted on 13/5/07 at 02:17 PM |
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Frankly I would take anything this guy says with a pince of salt.
120 mains are much too small for a 2.1 litre engine, 120 would be more suited to a 1600 engine, 140 would be nearer the mark.
Idle jets control the mixture up to about 1800 rpm from 2000 rpm upwards it is down to the main jets.
The main jet size depends mainly on the peak BHP of the engine.
Pump jets and the pump stroke only have effect in the second or two it takes to floor the throttle.
First thing to do is clean ie blow through the jets and check the accelerator pump jets are actually squirting, its not unknown for them not to work
either because the plungers get stuck, or the jets block or because the little roll pin that transmits the movement from the throttle spindle drops
out.
All the jets have numbers on them, check what the guy has actually fitted.
[Edited on 13/5/07 by britishtrident]
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britishtrident
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| posted on 13/5/07 at 02:20 PM |
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quote:
Originally posted by flak monkey
OK, my pinto with 40's is currently running:
Chokes - 34mm
Main Jets - 140
Emulsion Tubes - F16
Air Correctors - 180
Idle Jets - 50F9
Pump Jets - 40
Aux Venturis - 4.5
It runs quite sweet at that, with no flat spots etc, but its not been on the rolling road yet so dont know what the power is like.
I know the emmissions are good at idle though.
It is better to run a bit 'fat' than too lean.
[Edited on 13/5/07 by flak monkey]
Sounds right to me
[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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britishtrident
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| posted on 13/5/07 at 02:43 PM |
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Most of the info you need for a 2.1 Pinto is here
Dave Andrew site
http://members.aol.com/dvandrews/webers.htm
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cadebytiger
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| posted on 13/5/07 at 04:54 PM |
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agree that 120s sound too small. i am running 155s! set up by aldon
what size chokes you got in?
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john_p_b
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| posted on 13/5/07 at 07:12 PM |
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without ripping them apart i really can't be 100% sure but i'm 90% sure the guy said they are 34mm.
so really even 130 jets are too small then. feeling a bit pi$$ed off to be honest, i left the car with them for 2 days and my only instructions were,
i want it running right, if parts need changing then change them. paid out the best part of 200 quid and now i'm feeling i'm best off just
starting again!
built a car, built a home, had a family. lost the family, lost the home, still got the car.
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flak monkey
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| posted on 13/5/07 at 07:20 PM |
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It sounds like the people who set it up might not have had a clue what they are doing. 
120 mains are far, far too small for a 2.1 pinto, your engine will either melt a piston as it will be too lean, or will just peter out at high
revs.
I would expect you to need at least 140's maybe even 150's.
But with 34mm chokes in 40s your base setting should be what I posted earlier. Any adjustment from that will be pretty minor, as in no more than 10
either way on the jets. 34mm chokes will give you max power at about 5500rpm, they are a bit small for a 2.1 (you really want 36 or 38mm chokes, but
they wont fit in 40s).
I dont proclaim to be an expert (a long way from it!) but I can say from my experience that configuration of jets works well on my engine. And that is
a series of settings I came to from reading several books, and i think you will end up with the same settings if you follow through the stuff on dave
andrews website.
David
Sera
http://www.motosera.com
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cadebytiger
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| posted on 13/5/07 at 09:55 PM |
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i would go back to them and say you are not happy! Sounds like they don't know what they are doing!
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