-
Hey Guest!
British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!**Upgrade Now**
(PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Hey - did you know if you click on the title of a thread it will take you to the first unread post since you last visited that thread?
but were afraid to ask: 
STOP!! Never post your email address in open forums. Bots can "harvest" your email! If you must share your email use a Private Message or use the 
smilie in place of the real @
Pretty Please - add it to our Events forum(s) and add to the calendar! >> 
TR6 carbon canister
- Thread starter sundown
- Start date
Share this page
poolboy
Yoda
Offline
No affect on peformance.
If you have a 73-76 TR6, the anti run-on valve worked in conjunction with certain plumbing from the carb to the CC.
https://www.mv.com/ipusers/last/emissions/page_18.html
If you have a 73-76 TR6, the anti run-on valve worked in conjunction with certain plumbing from the carb to the CC.
https://www.mv.com/ipusers/last/emissions/page_18.html
poolboy
Yoda
Offline
I don't know which year your carbs are but if they are 73-76 they would have nipples on the left side like the one in this picture that I colored red. They should not be capped off if you remove the CC. They are vents for the carbs' float chamber and must remain open to the atmosphere.
On the right side of the carbs pointing up at a slight angle are similar size nipples that originally not only were connected to the CC, but also the valve cover.
You can eliminate the connection to the CC but at least one of the carbs needs to remain connected to the Valve Cover in order to relieve crankcase pressure... Also ...NOTE the Banjo fitting on the intake manifold.
Like so:
OR like so:
Basically any nipple EXCEPT the "red" ones need to be capped off if not in use.
On the right side of the carbs pointing up at a slight angle are similar size nipples that originally not only were connected to the CC, but also the valve cover.
You can eliminate the connection to the CC but at least one of the carbs needs to remain connected to the Valve Cover in order to relieve crankcase pressure... Also ...NOTE the Banjo fitting on the intake manifold.
Like so:
OR like so:
Basically any nipple EXCEPT the "red" ones need to be capped off if not in use.
TR3driver
Great Pumpkin - R.I.P
Offline
FWIW, I've had good luck with capping both vacuum taps, and just running an open hose from the rocker cover fitting down to somewhere near the ground. This was an engine that was kind of "tired" and would generate more blowby than the carbs could handle, resulting in various oil leaks. Leaving the vent open like that stopped the oil coming out past the rocker cover gasket, and cut way down on the oil coming out the front & rear main seals.
TR6BobNF
Jedi Hopeful
Offline
A timely post for my purposes as the start up of the new engine has been delayed once again due to work issues. Retired in June and been busier with my so-called part-time retirement gig than my old full-time job. Anyway, I have a replacement '75 engine in my '76 with no EGR (removed and plugged), no air pump, etc, which leaves me with the carbon canister and the anti run-on valve (which has a busted electrical connection anyway) so I'd like to leave the canister and valve off the new setup. Is this going to be a problem? I plan on following Ken's (poolboy's) advice on the nipple issues :wink-new: and simply leave off the canister and anti run-on valve. Apparently, one of the wires on the anti run-on valve was busted before I ever took the car apart and I experienced no issues so it seems like a non-issue to me at this point. If the carbon canister is deleted, what happens to the hose(s) coming from the rear of the car? Cap off?
Thanks,
Thanks,
poolboy
Yoda
Offline
NO..NO..don't cap that hose, Bob.
It's the vent for the gas tank and if plugged a vacuum will build in the gas tank as the fuel level drops..then the gas stops gravity flowing into the fuel pump and then the carbs run dry and the engine stops.
If you remove the CC there are a coupls of options..
On my 74, I ran that hose to the front carb, to the nipple that would have ordinarily been conjoined with the rear carb to the valve cover. Rear carb to the valve cover..front carb to the gas tank vent.
On my 73, the hose was simply cut and left dangling straight down slightly above the nearest part of the frame...
I thought I was smelling the odor of gas, so I extended the vent hose to a small motorcycle Carbon Canister bought off ebay that I strapped to the frame under the boot.
I continued to smell that gas, btw, and by removing the 'gas tank board' behind the seats, I discovered a loose hose clamp around the vent line and some dampness
Once tightened the odor left.
I know a couple of guys who just left the vent line unattached once the CC was removed.
It's the vent for the gas tank and if plugged a vacuum will build in the gas tank as the fuel level drops..then the gas stops gravity flowing into the fuel pump and then the carbs run dry and the engine stops.
If you remove the CC there are a coupls of options..
On my 74, I ran that hose to the front carb, to the nipple that would have ordinarily been conjoined with the rear carb to the valve cover. Rear carb to the valve cover..front carb to the gas tank vent.
On my 73, the hose was simply cut and left dangling straight down slightly above the nearest part of the frame...
I thought I was smelling the odor of gas, so I extended the vent hose to a small motorcycle Carbon Canister bought off ebay that I strapped to the frame under the boot.
I continued to smell that gas, btw, and by removing the 'gas tank board' behind the seats, I discovered a loose hose clamp around the vent line and some dampness
Once tightened the odor left.
I know a couple of guys who just left the vent line unattached once the CC was removed.
TR3driver
Great Pumpkin - R.I.P
Offline
Yes.
Since the cap is not vented, the crankcase eventually fills with blowby gases; but that is as original. Having the largish hose open to the atmosphere (ISTR we used 1/2" heater hose, but line rated for PCV use would be better) allows the excess gases to escape rather than build up pressure against the smaller ports (and restrictors) on the carbs.
poolboy
Yoda
Offline
Ok, just curious since I had the opposite experience. When I bought the 74 the PO attempted to make a 'road draft' tube from the valve cover vent with a long piece of red heater hose.
The engine was a grimy mess. I cleaned it up and connected the valve cover to the evacuation ports on the carbs with good results.
The engine was a grimy mess. I cleaned it up and connected the valve cover to the evacuation ports on the carbs with good results.
poolboy
Yoda
Offline
73's..
Then you may trace the problem you are having back to this.
1973 was the year that the Anti Run-on Valve (ARV) was initiated and the arrangement that you see in this picture was conceived to accomodate it...however it must not have worked as well as hoped from the very beginning, because the next year in 1974, the arrangement was changed to a more sturdy, reliable arrangement which remained that way until the end of the TR6 run in 1976.
I've lost count of the number of people with 73 carbs that have had idle problems that were traced back to a malfunction of THAT vent valve. Rebuilding the carbs does not solve this particular problem..
Since there are no new replacement parts for this valve, I usually end up gutting the valve, which restores normal operatiion of the carbs and makes them function like the pre 73 carbs.
Then you may trace the problem you are having back to this.
1973 was the year that the Anti Run-on Valve (ARV) was initiated and the arrangement that you see in this picture was conceived to accomodate it...however it must not have worked as well as hoped from the very beginning, because the next year in 1974, the arrangement was changed to a more sturdy, reliable arrangement which remained that way until the end of the TR6 run in 1976.
I've lost count of the number of people with 73 carbs that have had idle problems that were traced back to a malfunction of THAT vent valve. Rebuilding the carbs does not solve this particular problem..
Since there are no new replacement parts for this valve, I usually end up gutting the valve, which restores normal operatiion of the carbs and makes them function like the pre 73 carbs.
Last edited: