Board logo

Pinto weber dcoe jetting
flak monkey - 9/8/07 at 11:20 AM

OK, mines not far out, but I am curious to see what jetting other people are using, in the hope that I might be able to sort mine out and get it a bit closer.

I know I am running rich, but not sure by how much. Its not belching out black smoke but the plugs are sooting up.

Mines currently got:
55F2 idles - went from 50F9 being too rich by a mile and 50F2 being way too lean, and these ones seem a touch on the lean side, with a slight miss under load at certain revs.
145 mains
180 air correctors
F16 emulsion tubes
36mm chokes
45 pump jets

Any help appreciated

Cheers,
David

cadebytiger - 9/8/07 at 01:35 PM

mine was set up on a RR before i had the car but everything i have ever read has said it should be too rich!

To be quite honest. when i go the car one webber pair has 36mm venturis and one had 38s. I have changed them all to 36mm now


Starter Jets F985

Air corrector 180
Emulsion tube F16
Main jet 155

Idle jet 55F9
pump jets 45

Main venturi 36mm
aux venturi 4.5

flak monkey - 9/8/07 at 07:37 PM

Cheers

I have bad misfire/stumble at about 2-2.5k rpm. Not sure if its main jets or idles/progression jets to blame? Some books seem to suggest idles but they are already way too rich ticking over... My mains do seem a bit low compared to some, I have some 145s which I could try in the morning

David

mookaloid - 9/8/07 at 09:03 PM

Hi David

I had a quick look and found:

Chokes 36mm

Mains 140
Tubes F16
Idles 55F8

As I say it was a quick look - not a million miles from yours though

Cheers

Mark

cadebytiger - 9/8/07 at 09:58 PM

Flak - are you simply going on plu colour at idle to know if you are running rich or lean? I have heard that this can be very misleading. maybe you could get it checked out with a lambda or something.

Do you get much spiting back? This, as you probably told me, is associated with it being too lean.

Do you get stumble at 2kish under load and no load?

As far as i understand the main jets only start to come in at around this point so it is more likely to be the idle jets which are causing the problem. The main jets agree with everything i have read about this spec of pinto

flak monkey - 10/8/07 at 06:15 AM

quote:
Originally posted by cadebytiger
Flak - are you simply going on plu colour at idle to know if you are running rich or lean? I have heard that this can be very misleading. maybe you could get it checked out with a lambda or something.

Do you get much spiting back? This, as you probably told me, is associated with it being too lean.

Do you get stumble at 2kish under load and no load?

As far as i understand the main jets only start to come in at around this point so it is more likely to be the idle jets which are causing the problem. The main jets agree with everything i have read about this spec of pinto


Only get the misfire under load, perfectly ok with no load, which tends to indicate its not too far out.

I have a CO meter and was simply going by the fact its saying about 5-6%CO at idle unless the idle screws are screwed in to about 1/3 turn out with the 55F2's. I understand that the fuel component of the idle jet has a bigger effect at low revs, and the air component at higher revs during the progression phase. You both have slightly richer idle jets on the air hole, so maybe this is my problem.

Thanks for the help so far gents, very much appreciated.

cadebytiger - 10/8/07 at 11:09 AM

my other thought is that.. now let me try and explain this so everyone including myself understands. lol

if your idle jet is too small (lean) then maybe your butterfly is too far open or closed at idle (cannot work out in my head which it would be).

if it were too far closed off the progression drillings you would get a miss or hesitation.

maybe worth checking where you butterfly is in relation to your drillings. This can be done as i am sure you know but shining a torch down the chock and taking the progression drilling cover off. you should be able to see the butterfly movement through the drillings.

cadebytiger - 10/8/07 at 11:11 AM

like this Rescued attachment Photo 42.jpg
Rescued attachment Photo 42.jpg

cadebytiger - 10/8/07 at 12:22 PM

i have a nice article here.

just trying to find a way of getting it digitalish

cadebytiger - 10/8/07 at 04:46 PM

sorry i have not been able to upload the document but the gist is that if the car stumbles under progression it can be because the idle jets are too small.

Hope this helps and good luck

westf27 - 10/8/07 at 08:46 PM

try some plug cuts to identify the area where the mixture may be wrong.a stumble around the rpm you mention may well be the transition from idle jets to mains

cadebytiger - 10/8/07 at 11:37 PM

your mains don't look as it they are undersized. i know mine are larger but going by every thing i have read you should be very close. i think it is more likely to be the idles

Angel Acevedo - 7/9/07 at 02:21 AM

Flak,
See post:

http://www.locostbuilders.co.uk/viewthread.php?tid=73557
I`ve just posted....
Hope it helps..
Maybe too late.....

LOL I`ve just used search,
you posted this very same info quite some time ago...


[Edited on 9/7/2007 by Angel Acevedo]