View Full Version : TR6 73 TR6 Emissions Removal

11-17-2006, 05:15 PM
Has anyone that owns a 73 TR6 removed all their emissions stuff. If so could could please provide the details on what you did and what kind of results you noticed after the removal.if you noticed better performance, gas mileage, etc.
Thanks /ubbthreads/images/graemlins/cheers.gif

11-17-2006, 06:59 PM
Jerry, my 73 has zero pollution stuff. I have no cannister. My dizzy is set up to run centrifugal advance 8* BTDC, I pull a vacuum on my valve cover through my carbs (though an oil separator) As you know my engine is not stock, but even when it was, I had no devices on the engine. It ran well then (sometimes) and runs well now. I think you will see a modest improvement on a stock engine with the removal of this stuff, but that is debatable.

I guess what I am saying is there is not a whole lot of "pollution" stuff on a 73. The late-model TR6 has a lot more. (74-76)

If everything is working well, leave it on for originality, If you are modifying your engine, take it off. Make sense?

The late-model TR6 engines are horrible to look at, what with air pump and pipes and hoses coming out of manifolds. Your 73 doesn't really have that much.


11-17-2006, 07:19 PM
I don't know the diff between '74 and '73 but my 74 has the EGR removed and a brass plug is in the head as well as a brass plug in the intake manifold. There is no appreciable pwr diff but the idle is smoother and low RPM (<2000 RPM) seems smoother. My 74 does not have the dual diaphragms on the distributor; it has just one. If it had the two gadgets, I would get a one vacuum diaphragm distributor and plumb it to work as the '74's do. I also have a temp sensitive vacuum switch that does not allow the vacuum advance to work until the engine reaches operating temp. I think this is a good device because it speeds the warm up of the motor and then allows the advantage of the vacuum advance system to work. My opinion is that you will not get appreciable power increases with the removal of the anti pollution devices but the motor will be easier to maintain and operate smoother at low RPM's.

11-17-2006, 07:59 PM
The 73 TR6 has three emission systems.

The most obvious is the oil vapor recovery systems from the valve cover to the intake manifold. You need to retain this.

The second is the gas vapor recovery system, that oft mentioned canister with big tubes. If disabled, you need to provide proper venting for the gas tank and decide whether to retain the anti-run-on valve (below the canister) that breaks the vacuum when the engine is turned off.

The third system is the vacuum retard which is designed to reduce emissions at idle. There is a thermostatic switch found in the top radiator hose that connects the vacuum retard diagram on the distributor to manifold vacuum via the rear carb and is designed to break the should the engine start to over heat. In all likelihood the switch no longer works.

Your only real option that may affect performance is, as TRbill mentioned, whether to retain the vacuum retard on the distributor. If you opt not to have the vacuum retard, then timing needs to be advanced 8-12 degrees BTDC. Removing the retard may cause difficulty getting the idle speed down. To see if this option works for you, I suggest temporarily disconnecting the vacuum line to the distributor, plug it off, re-tune your engine and see how you like it. Otherwise leave it all connected.

11-17-2006, 08:09 PM
Thanks guys. As usual this place holds a wealth of good info. /ubbthreads/images/graemlins/cheers.gif

11-17-2006, 09:08 PM
Dead on the money for what I did to my 74 TR6. My anti-run on was sticking and causing a massive drain on the battery, so I disconnected it. The car ran all summer without it and I had no problems. I did get another on ebay and I'll install it as soon as I get ambitious again.

I did take my timing up to 16 degrees BTDC and it runs super on high test gas.

I removed the upper rad hose temp switch and replaced the hose with a one piece long ago, along with the gas traps, EGR and plugged the vacuum retard. I did try putting vacuum back to it from the bottom of the front carb and it made no difference in performance, so I left it hooked up.

Very important to leave vapor vent system hooked up so fumes do not enter car, especially in hot weather, while in congested traffic.

11-17-2006, 09:51 PM
FWIW... The charcoal canister also helps reduce 'offgassing' of the car. My TR6 sits in a pretty insulated garage. Not airtight but not drafty either. When all the items were not hooked up to the charcoal canister there was a very bad gas smell. When I redid the vapor lines... no more smell. Quite nice in the garage now.