21 replies to this topic

[MRA]

Unless you are going to thrash it long and hard - don't bother with unleaded (or additives) - set inlets to 12 thou gap and exhausts to 15 thou. But do measure the head thickness - if you have flat top pistons it needs to be ~ 2.710" inches, if dished pistons then go for ~ 2.670".

 Of course the information for dished pistons is dependant on the size of the dish and the bore size and what CR you require.

[MRA]

Hi sorry to jump on this thread I am new to the forum. I want a little more out of my mini and have been told that changing the cylinder head is probably the best thing to do on a standard 998. I am pretty good at using a spanner and have done plenty of work on my mini before but have never ventured that far just need a bit of advice as i'd pretty much like to do a straight swap. and only really have to readjust the carb. so just wondering which head i could use to just do a straight swap, rough price and how much power it would give? I do not want loads of power but just a bit more that the normal mini has. Ive recently fitted a stage 1 kit so that should also improve it.

any advice would be much apreciated. 

thanks Josh

 

A decent modified 998 head casting will give you benefits in both torque and power if done correctly, there are a few companies about that modify cylinder heads,

 

Keith at Calver Special Tuning, http://www.calverst.com

Swiftune, http://www.swiftune.com

Phil at Turbo-Mini, http://www.turbo-mini.com.html

 

to name a few of good ones.

[Joshua.w]

 

Hi sorry to jump on this thread I am new to the forum. I want a little more out of my mini and have been told that changing the cylinder head is probably the best thing to do on a standard 998. I am pretty good at using a spanner and have done plenty of work on my mini before but have never ventured that far just need a bit of advice as i'd pretty much like to do a straight swap. and only really have to readjust the carb. so just wondering which head i could use to just do a straight swap, rough price and how much power it would give? I do not want loads of power but just a bit more that the normal mini has. Ive recently fitted a stage 1 kit so that should also improve it.

any advice would be much apreciated. 

thanks Josh

 

A decent modified 998 head casting will give you benefits in both torque and power if done correctly, there are a few companies about that modify cylinder heads,

 

Keith at Calver Special Tuning, http://www.calverst.com

Swiftune, http://www.swiftune.com

Phil at Turbo-Mini, http://www.turbo-mini.com.html

 

to name a few of good ones.

 

Hi thankyou for the links any idea how much they would cost? 

Josh

[blacktulip]

You need to work out your intended camshaft that you are going to use first. If standard you will need to atleast run a higher compression ratio to get anything from the head. If you have got dished 998 pistons I would advise against using the 12g295 head as you will need to skim too much off the head in order to get a good compression ratio. The problem with taking too much off the head means you risk going into the oil gallery in the head. There is a lot more to look at first before just changing a head otherwise you will end up disappointed with the results.

[Ethel]

A 295 is certainly doable with dished pistons. I also wouldn't make any assumptions about any 295 you find, they've been out of production for decades and a top choice for modifying.

[MRA]

Josh the cost is dependant on the spec you choose, any of the companies I mentioned above will advise you on a best choice for your engine specif you know it ?.

[limby2000]

I had 80 thou machined off my standard 12g295, and when we burretted it, it was only reduced to 24.5 cc , it still had potential for another skim but did,nt want to risk it.