Joined: Aug 2017 Posts: 2,748 Threads: 31
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Location: Auckland, NZ
16-10-2018, 08:05 PM
(This post was last modified: 16-10-2018, 08:24 PM by Bob Culver.)
If there is no intention of using the revs or close to, extra valve springs contribute nothing but friction, wear and stress.
Cranks which fail have generally been cracked for thousands or tens of thousands of miles prior. What triggers the final failure of the sliver of remaining metal is barely relevant. ( Somewhat over a million cycles just above the fatigue limit stress lead to failure. The typical old crank even if at only 100,000 miles will have clocked possibly 600 million revs. The mystery is just which 1/2 % or so start the cracks. Revs at closed throttle are not good; best to coast down 60 mph gradients!)
I found on various old cars years ago on a surprising numbe the throttle did not open fully.
In the gears the car should accelerate continuously albeit sedately. With seriously retarded spark may accelerate in surges and die off.
I found that with an engine using oil and the earlier head a decoke transformed performance for a while. Some claim that a long run will rejuvenate oil using engines used only for short runs.
Joined: Aug 2017 Posts: 202 Threads: 11
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I have a GPS speedo in my Mk I Ruby, so the mph is much more accurate than the speedometer, on my car, the speedo under-reads slightly as speed progresses, at about 40mph it is about right, then above this it over-reads (I have a magmo speedo).
On a level "A" road, 45mph cruising is relaxing, I have gone over 50mph (it creeps up) and the fastest was just a tad over 55mph, I did this speed for just a few seconds (on several occasions), I was not confident at going faster, even though the pedal still had travel. I have hydraulic brakes and the twin front damper set-up, so I am confident that the car will stop.
On hills, particularly in 30mph & 40mph speed limits, the slowing speeds from the climb (South Downs) dictates changing down from top into third (then back up, then realising it is going to happen, back down again) I seem to be doing about 30mph in third, engine is revving hard, but changing into top, the revs drop back and the engine starts to labour, so back into third, there is not a happy medium between third & top on some hills if decent progress is to be maintained.
On level surfaces, I change up from third at around 24mph, I can leave the gear lever in top when easing off the throttle to around 18mph, I can increase the gas, or change down into third depending on what the road is doing (this happens in city traffic).
Third gear is quite flexible, but hill climbing at speed it is really too low. I rarely use first gear, but it does have a lovely whine!
My car has a fully-rebuilt two-bearing engine (John Barlow crank), with a late Ruby HC head, 1" SU OM-type carburettor and flatter tappet blocks (this made a noticeable difference in performance going up hills), standard gearbox & axle. Engine still running in, I have been using the car as a daily driver over the past couple of months and have done a number of return journeys of 60 to 80 miles as well as shorter return journeys of 15 to 30 miles, I prefer to walk or ride my bike for local trips.
Joined: May 2018 Posts: 331 Threads: 51
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Location: East Sussex Coast
(17-10-2018, 06:45 PM)GK5268 Wrote: I have a GPS speedo in my Mk I Ruby, so the mph is much more accurate than the speedometer, on my car, the speedo under-reads slightly as speed progresses, at about 40mph it is about right, then above this it over-reads (I have a magmo speedo).
On a level "A" road, 45mph cruising is relaxing, I have gone over 50mph (it creeps up) and the fastest was just a tad over 55mph, I did this speed for just a few seconds (on several occasions), I was not confident at going faster, even though the pedal still had travel. I have hydraulic brakes and the twin front damper set-up, so I am confident that the car will stop.
On hills, particularly in 30mph & 40mph speed limits, the slowing speeds from the climb (South Downs) dictates changing down from top into third (then back up, then realising it is going to happen, back down again) I seem to be doing about 30mph in third, engine is revving hard, but changing into top, the revs drop back and the engine starts to labour, so back into third, there is not a happy medium between third & top on some hills if decent progress is to be maintained.
On level surfaces, I change up from third at around 24mph, I can leave the gear lever in top when easing off the throttle to around 18mph, I can increase the gas, or change down into third depending on what the road is doing (this happens in city traffic).
Third gear is quite flexible, but hill climbing at speed it is really too low. I rarely use first gear, but it does have a lovely whine!
My car has a fully-rebuilt two-bearing engine (John Barlow crank), with a late Ruby HC head, 1" SU OM-type carburettor and flatter tappet blocks (this made a noticeable difference in performance going up hills), standard gearbox & axle. Engine still running in, I have been using the car as a daily driver over the past couple of months and have done a number of return journeys of 60 to 80 miles as well as shorter return journeys of 15 to 30 miles, I prefer to walk or ride my bike for local trips. Just saw you going up the hill on the A259 in Newhaven, looked good to me, only a little queue behind you. 
Joined: Aug 2017 Posts: 2,400 Threads: 33
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Location: Deepest Frogland 30960
Car type: 1933 RP Standard Saloon
18-10-2018, 04:47 PM
(This post was last modified: 18-10-2018, 07:56 PM by Reckless Rat.
Edit Reason: seems to have got posted twice
)
In relation to hill climbing, the gear ratios in the 4 speed synchro box are more favourable as 3rd is closer to top than in the 4 speed crash. When hill climbing in my RP, once I've gone down to 3rd there is no point trying to get back into top gear until I've cleared the crest because due to the time it takes to get a double-declutch change in (without mashing the contents of the box), you've lost quite a bit of momentum and the then car bogs down because of the large gap between the ratios. Same applies on a steep hairpin where second is needed. It's really hard to get back up to third unless the gradient eases off. I don't really push the car beyond 25mph in 3rd when climbing, but it will rev away happily at this speed all day long. I think the secret is just to let it run at a speed it's happy at without thrashing the nuts off it (or losing your fillings) and enjoy the view.
Here's a link to a short video of my RP making its way to the top of the Col du Pré de la Dame on Mont Lozere in January 2017. There's a glimpse of the speedo at around 2m26secs.
Joined: Jun 2018 Posts: 65 Threads: 14
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Location: Kenilworth, Warwickshire
Gents, to close the loop on my initial question regarding what engine speed I should be able to achieve because it didn't seem like the engine was running correctly at high load/higher engine speed - symptoms were stumbling then surging under these conditions. Issue was found to be fixed by swapping the 80year old coil to a new part - and I now have a lovely free revving engine.....Its certainly not now a performance car, but it's as good as it can be!
Ray
Joined: Aug 2017 Posts: 2,400 Threads: 33
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Location: Deepest Frogland 30960
Car type: 1933 RP Standard Saloon
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Location: Darkest Bedfordshire
Joined: Aug 2017 Posts: 1,346 Threads: 240
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Location: North Herts
Browsing the shelves of a local secondhand bookshop yesterday I found different editions of two of Sammy Davis' 'Casque's Sketch Books' that were published by Iliffe & Sons in the early 1930s. Utterly delightful cartoons with pithy comments on every page. This one is perhaps applicable to what is max speed for any engine...
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