Welcome to our resource for MG Car Information.



TR parts and Triumph parts, TR bits, Triumph Car Spares and accessories are available for TR2, TR3, TR3A, TR4, TR4A, TR5, TR6, TR7, TR8, Spitfire and Stag and other TR models are available from British car spares and parts company LBCarCo.

Triumph TR6 - Failed Emissions

Hi All,
I recently purchased a 76 TR6. It's in fair shape,as it sat in a CO. barn for a couple of yrs. While I'm still evaluating everything, I took it in for testing - failed idle emissions for HC & CO. The car is stripped of the air pump & I don't think the vac. retard works either. How do I check the EGR valve & can it be taken apart on the later models? Also I noticed the after market cruise control vac line leaks. Will be removing that! Mixture on plugs looks good [brownish]. Any suggestions I can use to meet Wis. emissions will be much appreciated. Thanks in advance, enjoy your comments & friendly banter?
ED Edward Dorsch

What is there test criteria for a 76 TR6?
Did they have actual specs. or was it tested by general 1980? And how did they know it ever had a pump? If it was tuned and oil changed. Not smoking like a bandit with all kinds of lines hanging off. After a good hour run on the highway a reasonable TR should pass. Based on 76 standards.

I don't think a 76 TR was ever subjected to actual emissions testing?? So no original data at least not by present day standards exists! Most often they followed idea's. OH look cool a responsable company. It has an EGR or an A.I.R pump just like the GM/Ford. Reality let them sell in CA.

If your car has an EGR it did not have an A.I.R pump or vise versa. Both serve the same purpose letting air into exhaust to improve final burn and can't work together?

See what you can find out.

Bill Brayford


Have you checked with the VTR Club in your area ?

Vintage Triumphs of Wisconsin, LTD
Mary Jo Ploetz, President, 262-392-2559
Kent Howard, Newsletter Editor
W330 S3435 Bryn Mawr Road, Dousman, WI 53118-9719

Do you know Bob Dempsey at "Wunderwerks" ? He used to be down the slope - down in the basement at 212E North Street in Waukesha but I believe he has moved. He repairs TR's. His number used to be (414) 547-0052.

Don Elliott, 1958 TR3A
Don Elliott

Not to be contrary, but the EGR (exhaust gas recirculation) and the AIR pump do not serve exactly the same funtion.
The EGR valve, under certain conditions "recirculates" a small portion of the exhaust gases back into the intake manifold. Where the AIR pump, forces fresh air into the exhaust stream in order to aid burning off any unburned hydrocarbons that remain.
As I do not own a 76, your observation as to both EGR and AIR pump not being in place, is probably the case. But the functions are slightly different.

I really enjoy all of the experience on this list!

PS as I usually look at this list from my work, It is harder to join up.

Mark Riddle

Now this is an interesting antique car that failed an emissions test. Unheard of. Not subject to emissions testing???? At least not in Canada.
Right on Bill and Don.
I gotta hear the end of this story Ed.
Rick C
Rick Crawford

Have you run the car to get all the old gas out? Gas that sits for years ends up looking like turpentine. Maybe all you need to do is drain the tank and get fresh gas.
R.C. Blair


I've heard the way to pass the CO & HC emission tests is to really lean the carbs out - such as turn that needle in 3 rounds past your normal setting - and retard the timing 4 deg. The car won't run well, and you won't want to push it hard anyway when too lean. Of course, you reset things after the test....

'73 TR6
Brent B

Hi Ed Mark and all

Lots of good suggestions. Most everyone on the sight has had some problem with EPA testing of some sort so more will follow I'm sure.

Doug and Jim of course have more problems with the S.P.C.A. .... :)

Mark Geese are contrary good points are not..:)

I kind of rounded that out and Mark is correct. I stress though. Both do the same job but go about it differently so to my knowledge they are never found together?

A.I.R. pump does add some restricted air to the exhaust flow. EGR adds some recirculated restricted exhaust flow to the air at high RPM high air flow in the intake manifold. The EGR also reduces head temp. if carbs are set lean etc. etc. The sights below will give more on that plus Eds original question.

Ed I don't have a 76 and don't know anyone that has to look. But from your description/manuals/partsbook there is a diverter/relief valve for A.I.R. pump back of distributor that kind of looks like an EGR? If you had an air pump the exhaust manifold will have ports at top of each but if there blocked and you have an EGR that only means a change by Leyland at some point. Not an after market mod that the EPA types will gripe about.

EGR systems were and still are 5 times cheaper than A.I.R. so changing to them in midsteam was common for all Mans.. CA liked the A.I.R so there may have been some either or thinking when shipping from Leyland?

Now for a rant!

FYI in Ontario the test for "Emissions standards site operators" was taken from CA.. Around 80% of writers mostly A class mechanics failed. So they re-wrote the test. "The Government not the applicants"?
Seems few in Ontario knew much about the effect of CO2 on CA. Redwoods?

We also have the roadside Smog Police spot checking. All are highly paid environment grads. No Mechanics. "Looks like you have something missing there sir". Heres a $380.00 fine and you will have to prove otherwise to the courts with full documentation. Not one has a bloody clue how an engine works!!!

The EPA and all like groups would serve better if they fired all the dreamers and lobbiests that demonstrate and lobby for more tax money so they can hire more dreamers etc. Most feel the 18th century pre-industrial environment was ideal except for a few sewer plagues and mass starvations of course? Give the funding to Engineers and plumbers. Both know that S**t flows downhill and paydays Friday if the bloody "Jobs done"!!!!

Rant finished!

The EGR is in the head on Carb side just back of oil filler. Haynes test is blip the throttle while watching to see if diaphram goes up and down. Will give more extensive info if you determine thats what you have.

Sorry for such a long honk got my eider up:)
Bill Brayford

Thanks again for your comments. The EGR valve on the 76 is different than my old Haynes manual [up to 73] There is a screw slot on the top, but it's kind of rusty so don't want to force things if it dosn't come apart! Will try to get at it this weekend.
ED Edward Dorsch

I don't recall EGR on 1973, but do on 74 up. Air pumps and associated hardware are 75 & 76 on 50 state cars, may or may not have been present on 74 CA cars, just don't remember, we were in Texas and didn't see many CA cars. EGR's purpose is to dilute the inlet mixture with a small amount of exhaust for the purpose of reducing NOx levels. If they don't check that (often the case on the older cars), then nothing much to worry about there.

The air injection is indeed to reduce unburnt hydrocarbons by oxidizing them in the exhaust port. Some cars such as the TR6 use a port in the manifold and short pipe to dump the injected air into the exhaust port, others such as the Spitfire and MGB are set up so that the air injection manifold is afixed to the cylinder head and injects directly to the exhaust port. As for leaning it out, that can lead to failure also. There is a trough in the CO curve and the HC curve intersects along the stoichiometric mixture line. Too rich and CO goes down, HC goes up, too lean and CO goes up, HC goes down (most of the time). I have seen in odd circumstances cars that were lean enough to exhibit lean misfire show high HC. There wasn't enough fuel to burn efficiently, but there was plenty of it left over for the sniffer to detect. Bottom line is you need to be in that "happy zone" along the stoichimetric line

All that being said, unless WI has extremely stringent rules for cars of this era, I would expect that a well tuned car should pass the test even if the emission equipment was not present. The guy who does the testing for us offers the following:

1) Change the oil so it has nice fresh oil in it.
2) Make sure it is tuned up.
3) Make sure that it is good and warm before taking the test.

He was adamant on that third point, claims to have seen way too many cars tested when they weren't thoroughly warmed up fail the test, then pass after being warmed up. Best of luck with your car.

Hi Ed
That screw slot is a factory adjustment and its an EGR. Its staked or welded so don't try to move! Do the checks for diaphram lift first. There's a ball type valve in the stem that is the only service part cleaning the carbon deposits. Loosen off the locknut and then twist out. Sparkplug sandblasters suggested for cleaning base ball? Anyone with a spot sandblaster will do.

Hi SteveP you have seen a TR with both systems used? Don't know what was sold in the states especialy CA but would like to know more?

And yeh, I know you use your engineering skills to make jets stuff go supersonic for a living but please try to watch your language around this dumb old guy. Stoichiometric curve whawazat? :)

Ed follow the 123 part. Puts it all in a nutshell. Likely all you need.
Bill Brayford

Bill - There are some Canadians who say "Quebec is distinct" and I have to agree. Here in Quebec, we must still all be in the pre-industial revolution era because we still don't have emission testing. No-one ever mentioned it. What does "emission" mean ? Is it something that comes from geese ?

Don Elliott, 1958 TR3A
Don Elliott

Hi Don

Yeh Quebec folks tend to be a lot more aware and vocal with there politicians.

But be carefull in Ontario. Any modification to a car changing carbs even will net you a $385.00 fine. Not original. Last summer in Hamilton at a Mopar car show 34 American cars were fined as they were spot checked leaving. Most for having after market airfilters. Politicians say they are targetting grossly polluting vehicles? OH sure next time I head down to the states to enter a car show I will dust off a junker blowing smoke??? So if you have a Chrome breather cover even? beware.

One other thing of interest. If your accused of something by anyone including police. If you decide to go to court to fight it the accuser must attend? Not these guys they passed another neat little law that there work was to important to waste time going to court? Politicians don't want to touch the hot issue of the day so they let them. For the greater good????

Heres one URL

Bill Brayford

After reading the attached url it seems as though you have a group of very well practiced revenue enhancement officers at work up there. Do they test tailpipe emissions on a yearly basis in your province?Sounds as though the roadside spotters are just eyeballing and penalizing.
Currently here in the peoples republic of Massachusetts my 72 gets a yearly safety item check no tailpipe. I think this varies from state to state. A $385 tag would sure pop my cork.
Keith Dixon

I agree Keith.

We have the safety only when vehicle changes hands.
Emissions are done on any vehicle under 20 years old every 2 years.
Vehicles over 20 years are exempt?
Unless they get pulled over by the Smog police which is likely???

So as Sally Q. Public no mechanical skills you buy a car take it in have it safetied/licenced and insured no emissions test because its over 20 years old cool. Drive down the road and get Tagged for $385 because some DPOs mechanic bypassed an emissions hose or replaced the ailing Rochester Carb. with a HOLLY 10 years ago. And that will be the only time Sally gets any indication her dream car is a pollution menace?

Main thing here as I just mentioned to DonE in e-mail. It does not matter were the car is registered and the border is a target I hear. They will nail you.

Bill Brayford

How blessed we are - no emisions testing whatsoever, no limitations on anything you want to do to your car.
Peter Gooch

This thread was discussed between 30/10/2003 and 01/11/2003

Triumph TR6 index