14 replies to this topic

[johnR]

Has anyone tried a Minisport ST cam for fast road? ST 948 or 731 - the price seems reasonable.

[Anthony30]

I would rather fit a kent 266.

[Chris.Williams]

Or a Minispares evolution 1, now that's a great road cam at a great price......almost sounds like I was paid to say that hahaha.
What cam have you got now, in what size engine?

[Northernpower]

Has anyone tried a Minisport ST cam for fast road? ST 948 or 731 - the price seems reasonable.

Whats made you consider these over everything else on the market and are you open to alternative suggestions?

[Dusky]

I can vouch for the evo1 as well.

[AlexMozza]

What about the swiftune SW5. Probably the best fast Road cam.

[Cooperman]

I would recommend a 266 as a 'not quite so slow' road cam.

[Carlos W]

What about the AC Dodd RS?

[johnR]

the engine is a 1275 with a big valve head - l only wondered because they're cheaper and l wondered what you get for the extra money with the more pricey ones

[Cooperman]

Unless it is for out-and-out competition there is little to choose between them, despite what the different vendors will tell you.
Of greater importance is the quality of the gas-flowing and porting of the head and the accuracy of the engine builder.
For a road engine you need good mid-range torque combined with nice driveability.
Any of the camshafts mentioned will give this so long as the head is modified and improved with a CR of around 9.8 to 10 to 1. Accurate cam timing, good manifold matching, etc, are what is needed.
But don't buy a cam because it is cheap. Many of us have experience of inaccurate lobe timing and poor case hardening.
Unless the head, induction and exhaust systems are right a different cam may not give much of an improvement.
It's the entire engine spec which gives an improvement.

Edited by Cooperman, 19 March 2017 - 11:31 PM.

[johnR]

I'm looking for a compromise between performance (on the road mostly) and driveability and plan to have the head mildly worked on for maximum efficiency. At the moment I'm just looking at various parts and assessing their suitability. Obviously cost is an issue as well so I'm looking for value for money (or more accurately, my wife is looking for value for money!) I won't buy something solely because it's cheap, but conversely I don't want to pay more for a brand name if another product will be just as good. 

[Cooperman]

First of all get the head done well. With the ancient A-series engine it is the head which is the key to making the classic Mini not quite so slow.
Then get an HIF44 carb on a good alloy manifold and a good, like Maniflow, exhaust system. If you do that an MG Metro or Kent 266 cam will be ideal.
But the build accuracy is so very important. Things like machining the block deck to bring the pistons right to the top, port matching, cam timing and correct comp ratio are what makes an engine perform well.

[hhhh]

I'm surprised port matching was included in the list of important factors. As long as the receiving port is larger with no step from the source port, matching offers no benefit, and may even prevent a beneficial anti-reversion effect.

[Cooperman]

Port matching is vital. It is necessary to ensure that the receiving port is either identical to or slightly larger than the delivering port, so any step must be 'downstream'.

 

I have been surprised in the past when re-building engines how often an inlet manifold has been opened out to beyond the diameter of the head port, or even a simply non-compatible inlet manifold used.

 

Checking the port matching is a vital part of engine building,as is everything else really.

 

It is always interesting to see the improvement when an otherwise standard engine is 'blueprinted'. This is done mainly for competition when the regulations require that there are no engine modifications beyond what is allowed for normal service and repair. I once blueprinted a 1275 engine from a 1990 Cooper. It was bored to 1330, the max normal over-bore, the head was skimmed to the maximum of 25 thou allowed in the workshop manual. The ports were matched and casting 'flash' was removed from the alloy inlet manifold and the combustion chambers and ports. The cam timing was corrected using offset keys and a few other simple 'tweaks' were done. It gave 84 bhp at the flywheel at 5700 rpm. An MG Metro cam was used and, although not strictly allowed, a pre-Verto flywheel, slightly lightened, was used and the inlet valves were 35.6mm. Now these were not standard in the 1990 Cooper to my knowledge, but the Haynes manual gives that as the correct size, so I had documented evidence if challenged. I also fitted a 3.44 :1 FDR. The HIF44 was gas-flowed and a K & N filter fitted.

[hhhh]

Port-matching to me means making the shapes identical with no step either way. This used to be considered essential by the conventional wisdom, but has been disproven by dyno testing. Oddly, there's an old story available on the net about BSA carb testing for racing in the 50s where a step formed by too large a carb on a smaller port actually increased horsepower over the "correctly" sized carb. So there are sometimes surprises that contradict conventional wisdom. Another example is adding mass to a valve train can sometimes be beneficial due to particular resonances being tamed.

Edited by hhhh, 20 March 2017 - 05:17 PM.