30 replies to this topic

[Screwdriver]

My goal has always been to improve N105UHO's road drivability further, while preserving as much of the car's originality as possible. This rules out swapping the fuel injection system.

 

All roads led to changing the head as a next step. When I approached AC Dodd to procure one of his famed heads, he argued that an injection Mini didn't need one to improve road drivability. "Fit a lightened flywheel/ clutch combo, a set of 1.3 roller rockers and a good road head from anywhere...you don't need one of mine" was his advice. 

 

But where to buy the best reputed road head from? Here are my options as I understand them. If you know of another option from a reputed seller, please do share. 

 

1) MED - New castings, now sold without exchange

2) Minispares Aluminium - Couldn't find these on their website but I understand that these were sold. Main advantage is the reduction in weight.

3) Keith Calver - Recommended by AC Dodd

 

Many thanks in advance!

Edited by Screwdriver, 05 April 2020 - 11:32 AM.

[cal844]

Dont discount Turbo Phil either

[DeadSquare]

If Mr. Dodd recommended Keith Calver, you would be foolish to waste time and effort looking elsewhere.

[Ethel]

The fact it's injection makes no difference, though perhaps you could run a bit higher compression by virtue of the more accurately controlled fuelling?

[ACDodd]

Turbo Phil is another recommendation.

Ac

[blacktulip]

Somerford do Longman heads. They must be among the best too?

[DeadSquare]

Mr. Dodd's wisdom can be judged by the fact that he foresaw Covid 19 well in advance of many of us, and took the precaution of facial protection.

[Screwdriver]

The fact it's injection makes no difference, though perhaps you could run a bit higher compression by virtue of the more accurately controlled fuelling?

 

AC, you were quite bullish on the head swap. When I asked how much power it would net if I also changed the CAM, I got  "don't touch the injection Camshaft" back, and that the head with the roller tip rockers will yield a notable increase when combined with my stage 1 setup. The lightened flywheel/ clutch setup from MED would make it much more pleasurable to drive in London. 

One more question: Any preventative maintenance while swapping out the head/ clutch/ roller rockers?

Edited by Screwdriver, 05 April 2020 - 11:44 AM.

[dyshipfakta]

I think the logic being the cam is quite mild and responds well to just the rockers without having to bugger about liftin the motor

[DeadSquare]

When Sir Stirling drove that special bodied MG on the salt in the 60s, it probably had a rally cam, because reading between the lines at the time, the fuel consumption was under 10MPG.

 

To get a full clean charge in the cylinder, a lot was probably overblown straight through and out of the exhaust., so either stick to the existing cam, or tow a fuel bowser.

 

Out of interest, with a normally aspirated 850, I could get quite an improvement, just by making a larger than needed, sloping cut-out in the block down to the top ring level, below the inlet valve, ( especially good with angled larger valves which were not mentioned in the racing regs ), but there is not enough metal to do this on 1300s.

[ACDodd]

The spi injection can be made to.go very well with the stock cam by increasing the rocker ratio and fitting a ported head, well into the 90hp territory. However emissions become a problem and so does the driveability. Changing the he cam does little expect narrow the powerband. As I said before you don't need an expensive head porting job, just a decent chamber cleanup and a multiangle. valve job and some mild valve pocket porting, thats pretty much it for a road spi. In my mind spi drive nice with around 75hp and no more.

Ac

[Screwdriver]

The spi injection can be made to.go very well with the stock cam by increasing the rocker ratio and fitting a ported head, well into the 90hp territory. However emissions become a problem and so does the driveability. Changing the he cam does little expect narrow the powerband. As I said before you don't need an expensive head porting job, just a decent chamber cleanup and a multiangle. valve job and some mild valve pocket porting, thats pretty much it for a road spi. In my mind spi drive nice with around 75hp and no more.

Ac

 

Cheers AC. When you say increasing the rocker ratio, do you mean to 1.3 or 1.5? I'm assuming you're still recommending this paired with the head? Cooper Car Company (Minisport) claim over 82 bhp for their "kit".

 

Finally, it would appear that MED put alot less into porting their road heads vs. their racing heads. I'm assuming this is what you mean. 

 

Edited by Screwdriver, 06 April 2020 - 12:26 PM.

[ACDodd]

No I am not recommended a rocker ratio increase at except may be up to 1.3:1.
This is a prime cause of the just off.ie flatspot which can be most annoying. Just fit a mildly reworked head and a compression ratio of 10:1 maximum. Valves bigger than 35.7 X 29.4mm will promote cracking in road use. Don't do it.

Ac

[Spider]

Can I suggest here, to zero in on one supplier who you're comfortable to go with and run with their recommendations / packages.

 

I suggest this as they will have tired certain combinations that produced results that they are happy to market and likely, would have a car that you could try and see for yourself what the results are and if they meet your expectations.

[Screwdriver]

Very wise advice. Sadly, I'm unable to find a single SPi with a road head to try from any supplier...let alone from multiple suppliers. Even MED don't have them.

 

If you have any suggestions, I'm very open to them. Till then, I'm left with word of mouth, reputation and AC's very long waiting list :)