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PV, 120 (Amazon), 1800 General Forum for the Volvo PV, 120 and 1800 cars |
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Setting up Hs6 carbs - jet bearing seating, jet and bridgeViews : 423 Replies : 2Users Viewing This Thread : |
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Mar 20th, 2019, 20:15 | #1 |
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Setting up Hs6 carbs - jet bearing seating, jet and bridge
Hi all
I serviced my 1968 1800S last week and when changing the plugs it was clear the carbs were running rich. I reset the mixture using two Gunson Colourtunes and ended up leaning each carb by three flats. Today I thought I would measure the depth of the jet below the bridge on each carb using a vernier caliper, as I am told (Des Hammill book among others) that both carbs should be set to the same depth (using a average to the two readings). On the rear car the jet was 44 thou below the bridge and on the front car it was 66 thou! A bit odd I thought. On closer examination I could see that the jet bearing was not flush with the bridge on either carb (the bearing was 13 thou below the bridge on the rear carb and 34 thou on the front carb). I rebuilt both carbs a few years ago and I think I would have screwed the jet bearing as high up (and close to the bridge) as it would go. I did set the floats up at the time. My questions are:- 1) Should I worry that the jet bearings are not at the same height and therefore the jets are at different heights relative to the bridge? 2) Should I reset the jet bearing depths to the same measurement for each car and then reset up the carbs with the Colourtune? Having done that I can then average the two jet depth below the bridge (of course they may end up with the same depths using this approach). or 3) Ignore the fact the jet bearings and jets are set differently and just rely on the observation that Colourtunes are saying the two carbs have a good mixture setting (plugs have a nice milky coffee colour) and therefore must be balanced. Thanks Phil |
Mar 20th, 2019, 23:05 | #2 |
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Last Online: Apr 22nd, 2024 19:39
Join Date: Jan 2006
Location: Falmouth
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Those bearing differences are minimal, and typical I imagine. I know mine are different for example.
1:As long as your jets are the same height below the bridge, you're fine. It is easy to do. 2:I would not reset the bearing depths for the sake of 20 thou. You might not even be able to. 3:Set the jets as per 1, I bet the colortune does not change.
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Falmouth, Cornwall. 1970 California white 131. |
Mar 21st, 2019, 00:13 | #3 |
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Last Online: Today 13:32
Join Date: Jul 2007
Location: Connecticut, USA
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Phil;
In general, "equalness" of position of the Jet Bearing to housing is less critical IMO than Jet within the Bearing, because the later obviously determines mixture, and we want those to be as close as possible to equal. If Colortune is indicating a good mixture, that is a good start, but as I always try to point out, unless the Colortune is employed while on a dyne, with the engine under load, these results are strictly a starting point which is subject to adjustment and further optimization after dynamic road/load tests. Cheers See also: http://www.sw-em.com/SU%20Jet%20Bear...be%20Notes.htm |
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