Discussion
There is a lot of muddled thinking about cam choice.
The tendency is to go for a cam which gives maximum power.
However, the cam can only enable a well-built and properly gas-flowed engine to produce its potential power.
Then the use to which the car is to be put becomes very important.
If it's a road car then the requirements are very different from a rally car and, in turn, from a race car.
So once the use is defined the power band needed can be chosen. For a road car it is unlikely that you'll want to be driving around at 6000 to 7000 rpm, so if you choose a cam which has peak power at 6500 rpm you will either be screaming it's head off all the time, or be losing out on what would be possible with a more gentle cam.
There are cam power graphs available, so just get a set and decide where you want to be driving in terms of rev range.
A 286 cam gives max power in a 1275 at around 6400 rpm, so a 286 equipped engine needs to be revving at between 5200 and 7000 rpm to give best power. If outside this rev range a 276 or, maybe better a 266 will give better performance.
Then there is the question of gearing. With a 286 or hotter a close ratio straight cut gearbox is needed to keep the engine 'on the cam'. This, in turn, means a very high first gear which then dictates a low ratio final drive which means lower cruising speed at any given rpm in top.
It is not possible to simply 'up-cam' an engine and just get gains. There is always a down side. A hot cam, like a 286 or hotter, means very high revs, expensive transmission, high fuel consumption and regular engine re-builds. If it's a competition engine, then all that is acceptable to give better special stage or lap times. For the public roads it's a different matter.
The tendency is to go for a cam which gives maximum power.
However, the cam can only enable a well-built and properly gas-flowed engine to produce its potential power.
Then the use to which the car is to be put becomes very important.
If it's a road car then the requirements are very different from a rally car and, in turn, from a race car.
So once the use is defined the power band needed can be chosen. For a road car it is unlikely that you'll want to be driving around at 6000 to 7000 rpm, so if you choose a cam which has peak power at 6500 rpm you will either be screaming it's head off all the time, or be losing out on what would be possible with a more gentle cam.
There are cam power graphs available, so just get a set and decide where you want to be driving in terms of rev range.
A 286 cam gives max power in a 1275 at around 6400 rpm, so a 286 equipped engine needs to be revving at between 5200 and 7000 rpm to give best power. If outside this rev range a 276 or, maybe better a 266 will give better performance.
Then there is the question of gearing. With a 286 or hotter a close ratio straight cut gearbox is needed to keep the engine 'on the cam'. This, in turn, means a very high first gear which then dictates a low ratio final drive which means lower cruising speed at any given rpm in top.
It is not possible to simply 'up-cam' an engine and just get gains. There is always a down side. A hot cam, like a 286 or hotter, means very high revs, expensive transmission, high fuel consumption and regular engine re-builds. If it's a competition engine, then all that is acceptable to give better special stage or lap times. For the public roads it's a different matter.
Strange,I've built several engines using the SW10 with no problems and they have all gone like stink.....
So questions!!
What is the cam timed in at?
What final drive is in the car?
What size wheels are you running?
What carburetor?
What air filter?
Has the car been set up on a rolling road,if so where?
So questions!!
What is the cam timed in at?
What final drive is in the car?
What size wheels are you running?
What carburetor?
What air filter?
Has the car been set up on a rolling road,if so where?
I drove to work everyday for 2 years with a 1293 and 286, at least 95% of the time it was annoying. I'd go for a 266 for road use but I'd expect you could go for something a bit hotter for occasional use without getting annoyed. In my opinion the 286 is a very good cam, it's just not practical to drive everywhere above 4000rpm.
Crosswise said:
I drove to work everyday for 2 years with a 1293 and 286, at least 95% of the time it was annoying. I'd go for a 266 for road use but I'd expect you could go for something a bit hotter for occasional use without getting annoyed. In my opinion the 286 is a very good cam, it's just not practical to drive everywhere above 4000rpm.
Never had a problem with a 286 in my car, I only find it flat below 2.5k. 10" wheels, 3.7fd, 1380, big valve head fed with a webber.nick1275 said:
Crosswise said:
I drove to work everyday for 2 years with a 1293 and 286, at least 95% of the time it was annoying. I'd go for a 266 for road use but I'd expect you could go for something a bit hotter for occasional use without getting annoyed. In my opinion the 286 is a very good cam, it's just not practical to drive everywhere above 4000rpm.
Never had a problem with a 286 in my car, I only find it flat below 2.5k. 10" wheels, 3.7fd, 1380, big valve head fed with a webber.Personally driving around on the roads at 5000 to 7000 rpm is not ideal and not really practical. If you are not going to be doing that, then don't fit a 286.
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