11 replies to this topic

[The_Doctor]

Hi everyone,

 

First off, I know questions like this often open up a massive can of worms and go on with a lot of conflicting opinions but I'll try my luck!

 

I'm wanting to get more power out of the engine in my mini. It is a 1275 from a 1976 Austin Allegro with about 45,000ish miles on it and runs beautifully. At the moment the engine is completely standard except for a minispares stage 1 kit and a professionally reconditioned HIF44 carb.

 

I had planned to improve a cylinder head I had already but that was found to be cracked. Instead of buying and testing multiple heads risking the same result I'm considering buying this cylinder head casting brand new:

 

http://www.minispare...ck to catalogue

 

Although the link is to minispares, I will be buying it locally (New Zealand) since I've found one at a very good price. This means I'd much prefer not to buy any other cylinder head from Britain since the price will be much higher with shipping and tax unless I find this one isn't appropriate for what I want to use it for.

 

I understand these are new old stock from MPi mini's, so my first question is of course will this work on a 1976 1275 engine?

 

Secondly, does anyone know what hardware I need to build the head up? I'm planning on manganese-bronze valve guides, larger inlet valves (35.6mm), standard exhaust valves, springs and all other bits and pieces for now.

 

What parts would I be able to buy to match that list on the head casting from the link?

 

I will be having a local engine building shop build up the cylinder head when I acquire all the parts, and once that's complete I will have it ported and polished.

 

Thanks for taking the time to read through this, I understand it's a fairly involved question. Any help at all would be massively appreciated.

 

Cheers, James

 

 

 

 

[cal844]

That head will work if you drill the head for the heater hose nearest to valve #8

[whistler]

Have a look at this from David Vizard.

[nicklouse]

to be honest I would not bother spending any money on a standard head that you are then going to work on.

 

I would find a person in NZ who have been working on Mini heads for years and tell them what you want and what you have and they will provide what works.

 

if you want to have a go and learn use the cracked head to see how it is done. at least you are not potentially trashing a good head.

 

an over worked head on a mild spec engine will not be good.

 

remember you will need the guides pressing out so you can work in that area. then new guides and seats recut so some work will need to be shopped out.

 

Vizards book is a great place to start with some infos.

[Turbo Phil]

If you're using the MPI casting you'll need to use the MPI thermostat housing, or machine the head to accept a standard thermostat. There's also no hole for the temperature sensor in the head, as this is fitted into the thermostat to.
You can drill the heater take off at the end of the head easily enough like standard.
These castings can be modified in the same way as any of the other big bore heads.
What's your intended use, cam and rocker combination ? This will dictate what valve and guide type is suitable.

Phil.

[The_Doctor]

Hi Turbo Phil,

 

The end goal at the moment is a fast road sort of build. The end goal would be to have a SW5 or similar with a properly matched distributor and cylinder head. From what I've been able to understand, the sort of set up I've come up with above would match that reasonably well (open to correction of course!). I'm not after massive power but would like to be putting out enough to enjoy the handling capabilities that I have even more and to keep up with at least a Corolla at a track day1 I don't know what rockers I would go for after I replace the camshaft. I've read that the standard rockers would work well enough but if the consensus is to upgrade then I will. The reason I'm quite keen on the brand new cast head is that I can get one for about 250 pounds including tax and shipping which to me seems worth it since I know i won't be dealing with a worn out or cracked head.

To Nicklouse, thanks for your input too, I think I'll go into my local mini parts store and see what the owner has to say about what I'm planning. He's quite intimidating from what I've heard and that has stopped me from going in the past but I guess I should just suck it up considering how much I could save and how much better the build could come out!

 

Thanks to everyone else as well, every bit of info i've been able to take in has been massively appreciated!

 

Cheers,

James

[Turbo Phil]

Ok, if you're looking at a fairly conservative fast road kind of build save yourself some money and fit the iron guides (1/2 the price of the bronze ones) and use the road spec valves. They will be more than up to the job for your proposed application.
With a 30degree back cut on the inlets they flow almost as well as the race valves until higher lifts.

Phil.

Edited by Turbo Phil, 23 March 2017 - 03:42 PM.

[Spider]

I bought a small swag of these heads a few years back and I 'modify' them to use on much earlier 1275 engines.

 

Machining the Heater Outlet and Temp Sender Pockets present little problems, just be sure if doing it yourself that the seat for the Temp Sends is left 'clean' or it will leak.

 

They are a great head, in regards to what Phil's mentioned regarding the Thermostat, I have on some heads machined a seat to take the thermostat, as Phil has suggested, and on others, simply cut the plate of the thermostat back to the first pressing rib and they end up a very snug fit. I now actually prefer to do this as it retains a greater gasket surface area between the edge of the cut out and the studs.

 

Two words of caution though is that these head castings do have a thinner deck on them from the earlier heads. This doesn't normally present an issue, unless you need to skim a big chunk from the head to get the CR up, typically, if your engine has the low CR type pistons already fitted and running a longer duration Cam (as you as suggesting), then you could run in to issues. Don't be turned off by these 'thinner deck' heads, they are not 'weaker' in any way and I gotta say, I like them as I find the cars run slightly cooler with them.

 

The other word of caution and not usually a problem, but one that should be checked in any case. These heads have small pressed 'freeze' plugs pressed in to the decks, where as the earlier heads had either Brass (YUK) or cast iron plugs in them. I'd suggest laying the gasket that you will be using over the head to be sure that the firing rings don't cross these plugs. Not the end of the world if they do, just have the plugs removed and replaced with a solid plug, hover be aware that unlike the earlier heads these have a shoulder in the head behind them.

 

I would also suggest sticking with Iron Guides. The Bronze ones (in their various versions) are good, but they do not take 'abuse' at all, eg, if you overheat the car, expect the guides to grab the Valve Stems. If you do use a new casting, it will have the guides fitted (and also has hard seats in the exhausts for unleaded)

 

If you are looking for a commercial shop nearer to you to 'do' a head on your behalf, I can recommend Competition Heads in Melbourne, they are about the only shop left in Aust who actually know what they are doing, at least with Mini heads.

[Spider]

As another option I can also recommend as being good 'off the shelf' already modified heads are those from Mini Spares, I don't think you'd be too disappointed with one of these, the only thing - which you'd check in any event - is to CC the head. They are stamped with their CC, but I've found them to usually have more than as stated.

 

Or of course, have a chat to Turbo Phil - his heads look the goods!

 

<Edit: While these at first blush may appear more costly, do the maths, they don't work out too bad, especially with current exchange rates. >

Edited by Moke Spider, 23 March 2017 - 08:06 PM.

[The_Doctor]

Thanks again TurboPhil and thank you MokeSpider. Very glad to hear about the pitfalls of the bronze guides, definitely will stick to the regular ones. What's in this thread has clarified what I was confused about perfectly. Thanks so much to everyone for that! I'll have a chat with my local mini guy and price up my options.

Cheers,
James

[Petes.one]

If you want good advice from an engine builder here in NZ, contacting Alan Harris at Harris Performance (formerly Lynn Rogers Automotive) in Auckland would be a good place to start.  Very experienced with Minis and occasionally have heads available.  He would be very helpful in matching a head to the rest of your build.

[Chris.Williams]

Contact Kevin at horsepower heads, does awesome work. Call Swift Automotive, they may have a head.