Constant Engine Running RPM.

[vette]

Hello Folks, I was just wondering, what RPM do you feel the Healey 6 cylinder engine can sustain constant running for long periods of time. Such as on a long trip on the USA's interstate system. Just wondering?

 

[HealeyRick]

If the 6 could do six hours at 150 mph at Bonneville before the head gasket blew (https://www.healeysix.net/Records.htm) you could probably make it from PA to CA and back at highway speeds without a problem.

 

[red57]

I'd think that depends more on driver comfort than what the engine will tolerate.
I have spent a lot of hours in the 5-6000rpm range on tracks without any known failures due to revs. but I wouldn't want to drive across the country at 5000.
I remember when I started racing someone told me that even stock they will run all day at 6000 but blow at 6200 - probably an old wives tale but I have always used 6 as my redline (with stock internals but well balanced) and only occasionally 65 (heat of the moment thing....).
I really think well balanced but with stock internals these motors can run 6 all day and then some, I just don't think it would be a very fun way to cruise.
I would think 3-4000 could be fine though for driver comfort if you have the right mindset
Curious what others think.
Dave

 

[vette]

Thanks Guys, I'm also curious what others think.
Rick, what do you interpret highway speeds to be? Well to get down to where the bull meets the road.... I am disappointed in the lack of smoothness my Healey does at "Highway Speeds". I interpret that to be around 65 to 70 mph. I know I have talked about this before and the only thing that I have done about it is a good rebalance of all 4 wheels and tires, and making sure everything is tight in the front end. I don't know if my tach might be off a little but I have checked my speedometer with the GPS and the speedo is right on.
I have 3:54 gears in the rear, OD and 650/15 tires and I am running about 2700 rpms at 60 mph. At 65 I am just a tick under 3000rpms. I would have thought that I would be closer to 70 mph at 3000rpms.
I can run all day long at 60 mph and it's a pleasure to drive, when you push it up to 65 it just starts to get uncomfortable. Plenty of cowl shake, engine vibration and noise. (i believe the muffler is about hollow by now, it is well over 20 years old). The MG guys are putting me to shame. Their 'B's will run all day at 70 smooth as silk and I'm wanting to keep it under 65. Overall, my concerns are (1) my bodily functions, (2) the cowl shake is just unpleasant, (3) can the engine run above 3000 rpms for hours on end with no appreciable wear? thanks for your thoughts. Dave.

 

[Michael Oritt]

I agree with Red and while (given a sound engine) you could certainly drive all day long at 4000 rpm's I think you'd get tired fairly soon of "pushing against the wall".

It's been a while since I switched over to a 5 speed and taller diff but my recollection is that with the stock gearbox and 3.9 differential 3500 RPM's in 3rd OD correlated to a bit under 70 which was about as fast as felt comfortable. With my present setup--Toyota five speed, 3.5 diff and 180 XAS's--3000 rpm's yields around 73 mph.

 

[bdcvg]

Have You had the rear drums balanced?

Thanks Guys, I'm also curious what others think.
Rick, what do you interpret highway speeds to be? Well to get down to where the bull meets the road.... I am disappointed in the lack of smoothness my Healey does at "Highway Speeds". I interpret that to be around 65 to 70 mph. I know I have talked about this before and the only thing that I have done about it is a good rebalance of all 4 wheels and tires, and making sure everything is tight in the front end. I don't know if my tach might be off a little but I have checked my speedometer with the GPS and the speedo is right on.
I have 3:54 gears in the rear, OD and 650/15 tires and I am running about 2700 rpms at 60 mph. At 65 I am just a tick under 3000rpms. I would have thought that I would be closer to 70 mph at 3000rpms.
I can run all day long at 60 mph and it's a pleasure to drive, when you push it up to 65 it just starts to get uncomfortable. Plenty of cowl shake, engine vibration and noise. (i believe the muffler is about hollow by now, it is well over 20 years old). The MG guys are putting me to shame. Their 'B's will run all day at 70 smooth as silk and I'm wanting to keep it under 65. Overall, my concerns are (1) my bodily functions, (2) the cowl shake is just unpleasant, (3) can the engine run above 3000 rpms for hours on end with no appreciable wear? thanks for your thoughts. Dave.

 

[HealeyRick]

Dave,

I'd say 65-70 sounds like reasonable highway speeds. Maybe your engine isn't the cause of your discomfort. Cowl shake can really make driving at speed miserable. At the risk of beating this horse to death, have you balanced your brake drums yet? It really can make a huge difference in cowl shake. I shouldn't think you'd get a lot of engine vibration at 3,000 rpm unless you have a bad motor mount but wind noise with the top down and a bad muffler could be making driving tiring as well. When I redid my car for the V8 install, I did what I could to rid it of the cowl shake it had previously. That involved Dayton 72 spokes and Michelin XZX that were mounted, balanced and shaved by Hendrix Wire Wheels as well as having the drums balanced. I also did the cowl reinforcement https://www.britishcarweek.org/scuttle.html as long as I had the motor and tranny out and was doing sheet metal mods in the tunnel area. I don't know whether it was one or all of those changes but my car is extremely smooth riding and will happily run at 80 in the left lane. With a 5 spd and 3.54 rear, I'm only turning 2,600 rpm at that speed. Noise through the mufflers is pretty quiet then and wind buffeting is the major issue and makes radio listening impossible. I really think if you tackle the scuttle shake you'll be much happier. I don't see any reason why your six couldn't easily run at 3,000 rpm without any appreciable wear.

 

[Bob_Spidell]

If you're going to do a lot of highway cruising the taller--for OD cars--3.54 rearend is the way to go. The 11% reduction in revs makes a significant difference--less driver/passenger fatigue--after a couple hours. I even think if your engine has a lot of grunt having the 3.54 and 28% OD would be fabulous on the freeway. Gary Anderson--of Anderson-Moment Resto Guide--claimed that might be the best combo for a touring car; the taller rearend actually makes first gear sorta useful as well.

 

[Bob McElwee]

When I was working we use to take 2-lanes to the regional shows and boogy, boogy home on the interstates. We have put about 50K miles on both a 67 BJ8 and 62 BT7. (100K+ in Healeys)
On the interstate we'd run 70 - 75 mph with 3.9 and 3.54 rear ends and standard Healey tranny in the BJ8 and a 5 speed added later to the BT7. RPM ranged from around 3500 at 75 mph with the 3.54 and 4th OD to just under 3K for 75 with the 5 speed.
Longest non-stop run was 1,093 miles from the VA Conlave to Poteau, OK for a grand nieces wedding. Left about 6:00 am ET and arrive about 10:30 pm CT.
Loved every mile!!

 

[glemon]

I have had many British cars that for whatever reason have a vibration period of some kind at certain highway speeds. While checking to make sure everything is in balance and nothing is worn out is certainly a good idea, I have also found that many time you can drive out of the vibration period by slowing down or speeding up 5 mph or so. If 65 feels bad don't give up, try 70 (as long as things don't seem to be getting dangerously worse at speed).

 

[bob hughes]

My recent trip at around 700 miles - there and back plus a bit around the lanes etc. was carried out at speeds between 30 - 40 around the villages but when it came to the motorways 65 - 70 with occasional bursts of 80 plus sat there all day with no problems I guess that over 60% of the journey was on roads that had 60 or 70 mph limits. The engine has been rebuilt and balanced in 2013 and the cowl shake eliminated last year thank goodness. It was joy to drive.



Bob

 

[mgtf328]

Interesting thread. I have a 3.54 diff, Michelin 180x15 tires and a fast road engine. Only bought it last May. It can do nearly 70 at 2700 rpm in OD with short burst up to 80 for hours on end. I toured Europe and did over 1000mls in June with no problems at all. The previous owner assured me it will run at 80 all day. I'm sure it'll do more than 80. It's the wife and I that are the weak link. The wind turbulence and exhaust noise gets tiring on long journeys, I'm looking for a rear wind deflector that fits behind the seats, maybe I can rig something up using the tonneau support frame. Haven't noticed vibration to be a problem but steering can feel a bit vague at speed. The steering wheel moves nearly an inch at the rim before the wheels respond (I'm told this is not unusual) so driving at 80 can be tiring after a while. I find 60 much more relaxing.

AJ

 

[EV2239]

3,750 max cruise IMO, we used to cruise them at over 4000 way back in the sixties and the oil pressure would start to fall till you backed off a bit.

C Series were dynamically balanced from new, so if yours vibrates, get the box out, and have the flywheel and clutch balanced together. It makes a huge difference, especially as many new clutches are quite a way out.

The racers take them over 7,000rpm these days with special cranks, but I think they're straining a bit much over 4,000, especially on a freeway.

 

[vette]

Thank you all for your sincere responses. Firstly, about my engine, I believe it is in pretty good shape. It was rebuilt by Healey Surgeons about 20 years ago and that was just before I bought the car. It doesn't use hardly any oil, no sign of blue smoke and just a few small leaks under the engine. I have put about 30k miles on it since I have bought it. I put the 3.54 rear gears in it about 3 years ago and I was disappointed in that I expected a smoother ride and lower rpms than I am getting. But from your remarks I am more confident that I am experiencing something of the norm unless I take other steps. When I restored the body I didn't know about the schuttle shake situation so I didn't do anything at that time. I have not had the rear drums balanced, which I know I should, but I usually don't run much on the interstates. This car is alot of fun on the 2 lane roads.
I would say that my vibration period is between 62 and 65 mph. Right about where you want to drive most of the time. That why on the 2 lanes I am usually running around 60 mph. Since the car is appreciably more unconfortable from 65 on up I was starting to wonder what the experiences have been with the engine running at 3000 rpms and up. I can drive out of the vibration period but then the rpms are at or above 3000 rpms and I was just wondering is the Healey engine balanced and robust enough to take it. I don't want to have to do an engine rebuild just because I decide to push it to much. I believe Healey Surgeons did a good job when they did it. I believe my next two moves will be to get the rear drums balanced and to go to bigger tires. Thank you all for your input. Dave.

 

[Bob McElwee]

Dave, suggest you also give Bruce a call at Healey Surgeons. They've always been very helpful whenever I called.
I ran 195/70 X 15 on both cars until I couldn't find them any more. Minor rubbing issues but nothing serious.
I got rid of the dreaded 55 - 60 shimmy when I put 72 spoke Daytonas on the BJ8 and replica minilites on the BT7.
I agree the best road for a Healey is a 2-lane twisty that you can run 60 mph on. Actually we enjoy any 2-lane road anywhere in America. We have a beautiful country with mostly very friendly people.

 

[HealeyRick]

Dave,

I'd definitely do the drums next. You may be able to find someone local to do it, but I just put them in a heavy-duty rubbermaid storage box and shipped them off to Hendrix. EZ-PZ.

 

[EV2239]

If it's not clutch/flywheel issues, is the torsional vibration damper in bad shape.

 

[vette]

Thanks Everyone, I'll check that damper too.

 

[bob hughes]

I'm with Bob McElwee, I was set to get the drums balanced but never got around to it, I replaced the wheels with some decent second hand chrome jobs, new hubs and new tyres and that did it for me. Smooth as silk now - well almost!

My old tyres were made in 1989, one might say a tad too old. The splines on the old hubs were shot, not sure about the wheels but the splines in them were probably as bad as the hubs. I did discuss the possibility of checking the balance in the hubs on a static wheel balancer but so far that has yet to happen.




Bob

 

[mgtf328]

Bob,

I have no interest in this company but I did find this when I had the same problem with my MG. New wheels and hubs sorted it for me too.
https://vibrationfree.co.uk/our-services/wheel-balancing/
AJ