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Triumph TR6 - Revs on stock engine

I am a new owner of a 1975 TR-6 (carb and emmision). I owned a couple of MGB GT's back in the early 80s and managed to squeeze more out of them through simple breathing modifications. Of course I want more power and am pretty familiar on how to get there. My question to you is what are the top end revs on a bone stock engine. I find that 4k (on tach) is a push. Should I hook up another (coil fired) to check the acuracy of the mechanical or is this all this 6 has to offer in it's present configuration.

Alas, the good old pushrod six cylinder will not rev as high as a Honda 600 will be at idle!

With a bone stock engine, you'll probably find yourself out of the torque band and acceleration will start to diminish.

It will rev higher, but it won't go any faster.
Bob Blair

Bob- No cracks @Honda 600s. I owned a cute yellow sedan.

You should be able to run it up past 5000 with no problem, but expect power to start falling around 5500. The redline on the tach is fairly realistic on these cars. With the long stroke they generate rather high piston speeds (~3500 ft/min @ 5600 rpm) at fairly low revs.

So the next question would be to determine if the tach is reading accurately or if your car has a problem. Hook up that coil fired tach, running the wires into the interior. Grab an assistant and go for a quick drive. Have the assitant compare the revs from the vehicle tach to temporary tach. If they match, then you need to start some diagnosis work on the car.

Thanks for the input. I will hook up a shop tach and compare. It may be a case of a little lube in the cable or something simple like that. Engine pulls well enough and sounds right although it does feel a little anemic. Oh well...which way to the slippery slope?
S.M. Stephano

Don - I was actually refering to the Honda 600 motorcycle - those things scream.

Bob - original owner of a Harley-Davidson 1977 XLCR cafe racer (1715 miles) - which does not rev very high
Bob Blair

I sorted out the tack. A spider web....
Second owner Since 1977 of a Harley Davidson 1970 FX which does not rev very high but sounds great doing it..
101,783 miles
S.M. Stephano

thanks for the flash back,i know it a bit off topic
but back around 1977/78,i was at Mosport raceway
racing my yamaha rd 350 in the production class,
and in between races they had a 77 harley and a
vintage honda 4 srtoke if memory serves correct
redlined at 15k,doing a couple of laps during
which time they manage to slide into each other
but boy did that honda sceam.
M Macdonald

I agree with SteveP about the power drop off - on the dyno, my output flattens out to level starting at 5500 and by 5800 is flat. It starts to drop slightly at 6000. My exhaust was built to be efficient at mid-range (for torque) and is noticeably better than stock between 3500 and 5000. I think the drop-off point at 5500 could be raised to 6000 (or more) with a set of tuned 6/1 headers and specialised flow work on the head, which is more of a true race setup.
A few guys here (apparently) run to 7000+ but these are not your average street engines.
At the risk of stating the obvious, the better balanced you are, the higher you can rev!!! particularly with our long strokers.

PS - I am a little more timid after recent events, but glad to say she still appears comfortable to 5750.

Footnote: I have also detected a noticeable improvement in my hearing!

Roger H

I have spent quite a bit of time this weekend reading some of the related archives. It looks like I will start off stripping the emmisions equipment. I have a head on its way that I will modify and from what I have read....for the time being will keep the strombergs possibly rejetting them for the new head and and exhaust if needed. I am not looking for a dragster here. Just a little more performance as the car was intended. The car was performing to its capacity and the hung up tach was a bit decieving. I could here the engine working...Torque seems to drop of just after 4500 and the rest after that is noise.

S.M. Stephano

Another thing, is with old Strombergs, the jets could be getting gummed up. If you remember, the mid-70's were the height of lack of performance due to emission restrictions, which usually meant that the engine was jetter real lean to begin with. If your six has been setting for long, gas residue could be leaning out your jets even more. Just a thought.

Re: Old bikes (and old cars) - of all the vehicles I own, only two are overhead cam - the Porsche and the Benz (oh yeah, and the new Mustang GT I gave my son). Everything else, is pushrod. I personally get concerned everytime I let an engine rev very far (like letting my pickup (Cummins turbo diesel) get above 2200 RPM!). I rarely take the Corvette past 4500 RPM, and that's usually for very brief accelerations (2nd gear is good for 60+ - now, what do I now do with the other four gears!)
I must say, I'm not a racer, but I do enjoy going to Summit Point to watch others. And I like all cars, old and new. The new technology is amazing. It's great to see clean burning engines that have 300 to 400 horsepower, and IDLE smoothly.

Bob Blair

Summit Point!!- Spent many a weekend there in the 70's Some I don't even remember! The best part was the winding approach road to the track. Don't know if it is still like that now.

This thread was discussed between 25/03/2005 and 28/03/2005

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