Safe - for the car - top speed

[Acollin]

Hello all

I have a series v with a non-overdrive 4 speed synchro gearbox.
I was running an errand yesterday and jumped onto a faster speed roadway. While I always knew that there is a “too fast” for my car without OD, as my speedometer was reading about 55mph, I was wondering how long my car could safely ( safe for the car) maintain this blistering airspeed.
Questions:
1) what is a comfortable top speed for a near stock series v with a non synchro gearbox?
2) without risking damage, how long can I expect my car to maintain that top speed?

I was able to pass someone on horseback and was about to shut down a teenager on a bicycle.

✔️oil pressure was good
✔️no overheating
Be well all
Andrew

 

[sunalp]

So long as you're not running at the red line, oil pressure and temps are good you should be able to maintain
that almost indefinitely. I used to run my old SIV with a 1725 and no O/D on the run back from Watkins Glen
with the engine running about 4K, good oil press and temps. Ran it the whole trip home (about 2.5 hrs)
without a hitch for years. Rootes engines are pretty robust. By the way, my speed ( from a not too accurate
speedo) was between 60 and 65 mph. I passed actual cars!

 

[Shannon Boal]

I think that 4000 RPM is pretty well proven as sustainable cruising engine speed. Ralph Selfridge and I cruised his series V at 4000 RPM for 1800 miles on I-75 twenty years ago. I dissasembled and inspected that motor since. The valve spring installed heights were too long because the exhaust seats were recessed. This meant the spring pressures were too low, lowering the speed at which the valves would float. Even so, there was no trace of over-rev damage in the valve train i.e.; no burrs on the valve stem grooves or keeper grooves no spalling (pitting) on tappet faces.

 

[mikephillips]

You might also want to find a deserted or low use road where you can test stopping from speed too. For example, if you have original wire wheels instead of disc wheels, overstressing the splines can be an issue. I had an emergency stop years ago where the rear wheels grabbed for a moment, then the splines folded up from wear over the years and I went from 4 to 2 wheel brakes. Fortunately off on to the berm so no damage but age can play a part. Plus look at the condition of the bushings in the steering linkage, are they loose or tight and just overall condition of the brakes from master to wheels.

Speed, I ran around 70 from California to Ohio when I moved back in the 80s with no running issues.

 

[Tim R]

Coincidentally we were on the motorway this morning in my son's pretty standard 1725 Series V. In overdrive top it will sit at around 70mph doing about 4,800-5,000 revs all day long. It passes plenty of modern cars every time it is out and about! My own car has a 3.7 diff and will sit at a genuine 70mph (from the sat nav) with 2,850 revs which is really relaxing, I think the top speed would be somewhere around 110mph but I've never tried for that. Where permitted it sits at a genuine 80mph with no problem. This was a clip we took this morning in the 'standard' car. . Rootes made high quality cars, don't be afraid to use them how they were meant to be used!
Tim R

 

[alpine_64]

Hello all

I have a series v with a non-overdrive 4 speed synchro gearbox.
I was running an errand yesterday and jumped onto a faster speed roadway. While I always knew that there is a “too fast” for my car without OD, as my speedometer was reading about 55mph, I was wondering how long my car could safely ( safe for the car) maintain this blistering airspeed.
Questions:
1) what is a comfortable top speed for a near stock series v with a non synchro gearbox?
2) without risking damage, how long can I expect my car to maintain that top speed?

I was able to pass someone on horseback and was about to shut down a teenager on a bicycle.

✔️oil pressure was good
✔️no overheating
Be well all
Andrew

If a USA market SV check to see if it still has the 4.22 rear.. they spin the car up a fair bit... If you can swap a 3.89 in it will make life easier on the car and your ears....

Before my OD conversion I had a 3.89 and stock wheels.. I used to sit at 60mph at around 3700rpm... This was ok for the car and enough for my ears ( 62mph).... The funny thing was the car was sitting around max torque...so at 62 mph you could put your foot down and it had decent acceleration

 

[Paul A]

with my W58 Toyota 5 speed, 13" wheels, 175/70/R13 tires I get 22mph for every 1000 rpm. I have driven cross country on both interstate and secondary roads and had no difficulties keeping up with traffic. Years ago my bride and I traveled over 4800 miles from South Dakota to the Atlantic Ocean, down the coast to Richmond, VA and back home through St. Louis and Kansas City. Over 4800 miles on the trip. The 1725 engine worked just fine! The V6 now in the car works equally well.