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Triumph TR6 - Engine power drops off at 3000 rpm

I have a 73 TR6 stock engine that runs great but power drops off at 3000 rpm. The engine pulls strong untill 3000 rpm then power drops off, It will continue to accelerate to 4500 rpm but will do so at a slow rate. It almost seems like a rev limiter is installed. I can free rev the engine to 4500 rpm and it is strong. The carbs are rebuilt, ignition parts new. Havn't had the distributor checked but seemd good. Plugs pulled after a run to 3000 rpm and shut off indicates slightly rich. The engine has good compression across all the cylinders, leak down is very good, cam lift at the rockers is all the same and measures to factory height. The car has 40,000 mi but the engine has been apart at the front, no signs that the cylinder head has been removed. The previous owner had given me receipts that indicate the timing chain & gears were replaced. Is there the possibility that the timing gears or chain are off?
Any ideas will be appreciated.
Jeffrey Palya

My first guess is that advnace curve is off. Seems you've checked all the other stuff. Mark distributor, then advance a hair, and see what changes.Let us know. Peter
Peter Gooch

I had the same problem with my 1975. Up to 4000rpm the engine was responsive but I could never rev it up higher than that and if I tried it was laboured and seemed to run out of breath. It was like hitting a wall. and like you said it was as if there was a rev limiter on the engine (hey Lucas can even get the small stuff to work right, a rev limiter would be out of their grasp!!!)

I solved my problem by eliminating my EGR valve and assembly. The engine is now super flexible and revs up and past the redline until you get valve float. Then engine is a joy to drive and now can run up and down all the gears without feeling that I am driving an asthmatic. Unless you drive in California where your car has to pass tough pollution standards then it is a modification that is well worth it. Done right (with the right plugs) you can't tell that the stuff is missing. Also disconnect the vacuum retard (only there for emission stuff). I suspect that your EGR valve is stuck open and it is pumping in lots of exhaust gases back into the combustion process and the faster you go the stronger the force and the volume of this stuff is affecting your mixture above 4000

Valve timimg can cause the problem.

Egrs sprayed and cleaned with decarbonizer and TLC will usually work Ok. EGR should only function off idle and cut off at WOT. WOT vac may be your problem? Due to timing?

Steven: We now have the Ontario SMOG Patrol based on California's.

They are targeting vehicles out of the emissions loop. $380.00 fine for any emissions equip. removed or disabled. They don't care how old. Spot checks are roadside run like Breathalyser and seat belts. Backed by OPP. Seem to be targeting any vehicle without an emissions sticker in windshield.

Although there legislated mandate is supposed to be smoking vehicles. Most seem to think there after anything that looks hot and may be modified with loud exhausts?

Gotta love 6 week trained bi-law Cops on a mission! I can't seem to get any info but I think there are about 60 of them in fancy teams. Guess who's paying the bill? Yep your right not the guy with the beater smoking K-car that can't pay his parking tickets.

Running in the 401 corridor south to the boarder. In Guelph for a week about 6 weeks ago in Kitchener 2 weeks ago.

Keep your eyes open.

Bill Brayford

The only emission equipment my 75 car had was an EGR, PCV, vacuum retard and charcol canister. How did the car get by without a cataytic converter as most cars that day had them. Was the carb set up clean enough? I remember my dads 76 SAAB did not have one b/c it had fuel injection and it was much cleaner burning than carb cars

Hi Steven

Cars are visually inspected for removed or disabled devices by Smog Patrol. Canister was on late 60s cars. Egrs came in around 72. Pcv early 60s. GM first to put cats on in 74. Imports had to comply by 76 I think in California which was the demise of the TR6. One funny thing I read though is GM did not fit cats on any car for export to Europe till 88?

Some Brit engineer at the time was handed a cat and told he had to fit a couple under a TR6. I think his answer was. Would you like 4 wheel drive as well? Bloody Idiots:)


Bill Brayford

Thanks for the response. My 73 does not have an EGR. I have checked my dynamic timing and it does give me an advance mechanically. I have disconnected the vacuum retard. I suspect the timing gears are off.
Jeffrey Palya

Hey, Jeff. You never did say where you had the timing set. Have you checked if the weights in the distributor under the breaker plate are free and lubricated? If the weights hang up, the timing advance will stop, which could cause the problem.
Brent B

This thread was discussed between 11/05/2003 and 15/05/2003

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