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Vacuum lines

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Marksg1 Avatar
Marksg1 Mark Greenbaum
Evanston, IL, USA   USA
1976 Triumph TR6 "Nigel"
Ah, should have caught that.



I love the smell of hydrocarbons in the morning.

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Joe in CA Joe W
St Helena, California, USA   USA
Hi Gary,

That is an open nipple on that line crossing the manifold, that line is only connected to the front and rear fuel bowls. when running if I plug that nipple the rims increase and then the engine dies.

Good question about the vacuum line off the distributor and I could try switching that line over to see what happens.

Joe in CA Joe W
St Helena, California, USA   USA
Hi Paul,

Thank you for asking. Fortunately we were not impacted except leaving the valley for some time with the fires approaching and because the air quality being what it was. We are back and finally getting back to normal routines

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Joe in CA Joe W
St Helena, California, USA   USA
Hi Dave,

I just notice another difference between your picture and mine. Do you have a choke cable going to each carb? Mine only has the choke cable going to the front carb.

Joe in CA Joe W
St Helena, California, USA   USA
Thanks Gary. Please let me know if you see anything out of place with the vacuum lines.

poolboy Avatar
poolboy Ken D
Sandy Hook, Mississippi, USA   USA
Yes, you have to keep the float bowl vents open to atmosphere or as you found, the carbs will be starved of fuel...Dave's method is a little more subtle and doesn't attract the attention that your open nipple on that "T" fitting, but the result is the same.
As far as activating the vacuum timing...if you detect at least 15 in-Hg WHEN THE ENGINE IS IDLING on that front carb nipple you can connect a distributor's vacuum Retard module to it as a Vacuum source...but if the vacuum is less or only detectable at a high but steady rpm, it is not going to be suitable for retarding the ignition timing...
However,, if your distributor has been modified with a Vacuum Advance module that replaced the Vacuum Retard module, you can probably use that nipple to supply vacuum to it..depending on when the vacuum in that location 'kicks in".
You will want to connect a Vacuum Gauge to that nipple to actually see what's what.
If it were a ZS carb, I could tell you.



Edited 1 time(s). Last edit at 2017-10-21 11:30 AM by poolboy.

yycdave Avatar
yycdave Dave More
Calgary, AB, Canada   CAN
1976 Triumph TR6 "Miles"
In reply to # 1492997 by Joe in CA Hi Dave,

I just notice another difference between your picture and mine. Do you have a choke cable going to each carb? Mine only has the choke cable going to the front carb.

Mine too has just the front choke cable connected. The rear activates on a shaft connection from the front. The rear is still there but unused.



Cheers,
Dave

76 CF58310UO

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barry s Avatar
barry s Silver Member Barry Stoll
Alexandria, VA, USA   USA
1972 MG MGB GT
1974 MG MGB
1976 Triumph TR6
1980 MG MGB
'76 TR6 has 2 choke cables for 2 connections, not just one.

poolboy Avatar
poolboy Ken D
Sandy Hook, Mississippi, USA   USA
But on the SU carbs, one cable can operate both carbs' choke, Barry.
And when I had my 74, one of the 2 cables broke loose from the knob...I cut it off and just used the choke on one carb to get the engine started...I don't remember that ever being a problem...but that's Mississippi "winters" for you.
Also for the longest time those of us who had triple ZS carbs had to use the regular double cable, until Richard Good 'invented' the triple cable set.

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yycdave Avatar
yycdave Dave More
Calgary, AB, Canada   CAN
1976 Triumph TR6 "Miles"
Just following up on a bit of research on the vacuum advance which I had previously done. It appears that the small capped nipple on the rear carb shown here is in fact the one to use for vacuum advance. I found a failrly comprehensive site about SU rebuilding (light reading if you're interested) for the Volvo SU's I have.

http://thosbryant.wordpress.com/2014/01/02/su-carburetor-rebuilding-hs-6/

In the article the author makes the statement

"The rear carb is pretty much like the front one, except for some that have a hose nipple for use with a vacuum advance distributor. If you can get your hands on one of those distributors, and a proper rear carb to use with it, I highly recommend it. But… make sure it’s a vacuum advance distributor, from an early B18, and not one of those vacuum retard distributors that were used on some later models with B20 engines."

Whether this will work with an advance module on the TR6 distributor remains to be seen.





Cheers,
Dave

76 CF58310UO

barry s Avatar
barry s Silver Member Barry Stoll
Alexandria, VA, USA   USA
1972 MG MGB GT
1974 MG MGB
1976 Triumph TR6
1980 MG MGB
Ken Now that's the 2nd time in this thread that I've overlooked the SUs instead of the Strombergs. Will I never learn???

Tote Tony M
Kingston, Ontario, Canada   CAN
Isn't the distributor a vacuum retard on TR6's? Or, was it changed at some time during the TR6's production run?

yycdave Avatar
yycdave Dave More
Calgary, AB, Canada   CAN
1976 Triumph TR6 "Miles"
Sorry, I should have clarified. It IS retard however there are third party advance modules available for the stock distributor. The reference in my previous post from the article’s author was with respect to vacuum advance, so I can’t comment on its effectiveness for retard.

Sorry for any confusion.



Cheers,
Dave

76 CF58310UO



Edited 1 time(s). Last edit at 2017-10-21 06:50 PM by yycdave.

poolboy Avatar
poolboy Ken D
Sandy Hook, Mississippi, USA   USA
It is a retard only beginning in 72. Prior to that the distributor's had both.
But some of us have replaced the retard module with an advance module and used a different vacuum source to make it work.
Moss, TRF as well as the BVU (the manufacturer direct) are selling this. Scroll to the bottom 1/3 of this page:
https://www.britishvacuumunit.com/special-advance-units.html
Here it is installed on my distributor..


Attachments:
ADVANCE 2 and 3 002.JPG    58.7 KB
ADVANCE 2 and 3 002.JPG

DerekM Avatar
DerekM Silver Member Derek McAllister
Toronto, ON, Canada   CAN
I have also installed the advance "conversion" that Moss sells. It appears to be working well with my ZSs with the top nipple on the rear carb.



Derek McAllister
Toronto, Ontario
1974 TR6 Sapphire Blue/Shadow Blue


Attachments:
IMG_4335.JPG    43.6 KB
IMG_4335.JPG

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