Best Answer Cooperman , 11 October 2020 - 11:26 PM
Is the engine already bored to 1380? If not, you might not want to go to that size because it is the practical limit for re-boring, it needs offset boring and once that size needs another re-bore the block is either scrap or expensive special sleeves are needed. On my engines I will never go beyond 1330 and after that I have standard sleeves fitted tpo get back to 1275. That is a bit of an aside to your question, but I thought I should mention it.
With a very high diff ratio like a 2.95:1, you need a cam giving a wide torque band at mid-range revs. This enables you to keep the engine nicely 'on the cam' through the wide-spaced gears. A close ratio gear set won't help because that would make 1st gear so high that you would be slipping the clutch to get it away from a start and frequent clutch changes would be necessary.
The Mini Spares Evo001 cam is excellent, as is the Kent 266 a MG Metro (which are virtually identical) and should work with the high FDR, although the other engine mods indicate that you are more interested in performance than in long distance constant-sped cruising. A 2.95:1 FDR is a bit high for good acceleration on twisty roads and some of us prefer the 3.44:1 for nice general driving. That ratio is great for twisty B-roads and good acceleration. With that a lighter flywheel would be good, ideally a pre-Verto type with a Cooper 'S' clutch set-up.
The 12" wheels have virtually no effect on the overall gearing as 10", 12" and 13" have almost identical rolling radii when fitted with the correct tyres for those size rims. Thus wheel size can be ignored in cam/gearing considerations. What is important is where the best torque happens, especially with very high geared cars. There are cam charts on the web and for your engine you need a strong torque band from about 2700 rpm to 5000 rpm. Forget about maximum bhp, as it is torque which determines how driveable on normal roads the car will be.
For better overall performance you could go to a 3.44:1 FDR, an original Cooper/Cooper 'S' gear set and a Kent 276 or equivalent cam. Now that would really go very well on both twisty roads and motorways.
I hope this helps.
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Learner Driver
Posted 11 October 2020 - 05:55 PM
When I stripped the engine of my new project I found this camshaft fitted. Could someone enlighten me as to what/whose cam this is so I can set it up properly when I rebuild the engine. Many thanks
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Camshaft & Stage Two Head
Posted 11 October 2020 - 05:59 PM
Uncle Cooperman, Voted Mr TMF 2011
Posted 11 October 2020 - 07:10 PM
That is a very 'lumpy' cam and not really suitable as a road cam.
I have one in my historic rally 'S'. The peak power is at 6400 rpm and it needs to be kept between about 4500 and 7000 rpm.
Engine wear rate is high due to the need to use high revs and a low final drive ratio with close ratio gears is necessary.
If your car is for rallying or some other motorsport use, then it will be fine, although it needs a very careful and accurate build.
For a road car, though, it is far from ideal. I won't even use one in my road-rally 1990 Cooper 1330. In fact, in that I use an MG Metro cam although a Kent 266 would be just as good and virtually identical.
Learner Driver
Posted 11 October 2020 - 07:19 PM
That is a very 'lumpy' cam and not really suitable as a road cam.
I have one in my historic rally 'S'. The peak power is at 6400 rpm and it needs to be kept between about 4500 and 7000 rpm.
Engine wear rate is high due to the need to use high revs and a low final drive ratio with close ratio gears is necessary.
If your car is for rallying or some other motorsport use, then it will be fine, although it needs a very careful and accurate build.
For a road car, though, it is far from ideal. I won't even use one in my road-rally 1990 Cooper 1330. In fact, in that I use an MG Metro cam although a Kent 266 would be just as good and virtually identical.
Thanks for the replies, any recommendations for a road friendly replacement. The engine is 1380cc with a "stage3" head, twin hif 4 carbs and a med. bore lcb with a 17/8" system and a 2.95:1 final drive on 12" wheels.
Edited by Ollie1953, 11 October 2020 - 09:05 PM.
Uncle Cooperman, Voted Mr TMF 2011
Posted 11 October 2020 - 11:26 PM Best Answer
Is the engine already bored to 1380? If not, you might not want to go to that size because it is the practical limit for re-boring, it needs offset boring and once that size needs another re-bore the block is either scrap or expensive special sleeves are needed. On my engines I will never go beyond 1330 and after that I have standard sleeves fitted tpo get back to 1275. That is a bit of an aside to your question, but I thought I should mention it.
With a very high diff ratio like a 2.95:1, you need a cam giving a wide torque band at mid-range revs. This enables you to keep the engine nicely 'on the cam' through the wide-spaced gears. A close ratio gear set won't help because that would make 1st gear so high that you would be slipping the clutch to get it away from a start and frequent clutch changes would be necessary.
The Mini Spares Evo001 cam is excellent, as is the Kent 266 a MG Metro (which are virtually identical) and should work with the high FDR, although the other engine mods indicate that you are more interested in performance than in long distance constant-sped cruising. A 2.95:1 FDR is a bit high for good acceleration on twisty roads and some of us prefer the 3.44:1 for nice general driving. That ratio is great for twisty B-roads and good acceleration. With that a lighter flywheel would be good, ideally a pre-Verto type with a Cooper 'S' clutch set-up.
The 12" wheels have virtually no effect on the overall gearing as 10", 12" and 13" have almost identical rolling radii when fitted with the correct tyres for those size rims. Thus wheel size can be ignored in cam/gearing considerations. What is important is where the best torque happens, especially with very high geared cars. There are cam charts on the web and for your engine you need a strong torque band from about 2700 rpm to 5000 rpm. Forget about maximum bhp, as it is torque which determines how driveable on normal roads the car will be.
For better overall performance you could go to a 3.44:1 FDR, an original Cooper/Cooper 'S' gear set and a Kent 276 or equivalent cam. Now that would really go very well on both twisty roads and motorways.
I hope this helps.
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