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MG Midget and Sprite Technical - Modifieing a 12g295 cylinder head for race - 2

For some reason I'm not able to get into my otheer thread by the same name - could someone please copy the answers over in this thread.


thanks
Ole Aaen

I've now tried another computer, and it is impossible for me to see the old thread.

What I was asking for was a person who could do modifications on a 12G295 head for an midget 1098 race engine.

Any suggestions?

Ole
Ole Aaen

Peter Burgess is a good man with head modifications

I will ask him to modify my Metro head when / if I get some spare cash

Porting and a compression ratio hike should help me keep Gary's car not too far in front of me on his new engine
Bill

Here were the answers from your original thread. The names given are IMO all very good modifiers except that I am personally not a big fan of Avonbar. That said the diffence between one modified head and another is abut 1 BHP not worth worrying about. what amused me about your original post was your statement about eing a racer and not having enough power, does any racer have nough power?? NO!



B Richards, Grampian, United Kingdom
MED, Avonbar, Peter May or Slark to name a few all have good reputations.



Posted 28 July 2008 at 11:23:11 UK time
Nick, Durham , United Kingdom
Keith Calver is 'the' man for the '295 heads I believe: http://www.calverst.com/


Bob (robert) Midget Turbo

Hi Ole

I posted this on your first thread.

The 295 has throats too wide to get good flow. Are you allowed the 206 casting which ( Vizard is wrong in his book before you all respond) has smaller inlet valves that the 295. The chambers are the same shape as 295. If the head is modified to accept 295 inlets the flow is really good.
If you are allowed larger valves the usual route is to use 1275 standard inlet valves and exhaust valve (not the 1.402" MG Metro Cooper S size) The valves are approz 3 mm longer so you would need to space the rockershaft.



Peter
peter burgess

BLASPHAMIE!!!!


Pure Blashamie!!!.....Vizard Wrong???? There is no way!!!....Vizard is the 2nd comming of lucas


I am truly appalled at the notion....that someone can actully question Vizard, let alone make the mistake of SAYING HE IS WRONG.....lol


ALL ways got to be an athiest in every crowd.

prop
Prop

Thanks for the answers.

We are allowed to use the 206. The 295 is just the last we are allowed to use, and as I've read the "Vizard" I thought it would be the best starting point.

The sizes of valves is ofcause also restrictet - I do not have the sizes right here (I'm on vacation in Italy) but as soon as I return later this week I'll be back
ole aaen

And thanks Bob for copying - you are quite right they newer get enough - in this actual case I have a race friend with more power, and that is bad.
Ole aaen

please do look at the 12G202 head

in standart form it is the least of the heads but it has better potential than all others
with less chance of cracking (you 12G295 will crack eventualy)

there is more material in het head so it can be shaped better and it has less chamber volume so it is possible to get a better cr without going into the oil/water chanels
so it will take more work but the result will be more reliable and better flowing
o Könemann

The 202 hasn't got the potential of the 206, the chambers will not rework as well and the porting is better. The 206 is ideal to increase the inlet valve to 295 size. The 206 runs the same sizes as the 202 head. We haven't had many 295s cracked over the years, mainly 1275 heads.

Peter
peter burgess

Keith Calver had some real good flow dat on a 202 he had worked on (close to his 12G940 he said)
that is why he advised my "head guy" to take that for my old hot 998 mini

with the camber volume of the 295/206 and the aditional work can you get the cr to a good level without dome pistons?

but the 202 is much more common than the 206/295 and that is a fact
And in holland it is a b*tch to get a decent 206/295 for a good price
o Könemann

Ole.

I wouldn't doubt Peter's words of wisdom, but I do have to agree with o Könemann, the 206 is a hard head to find. I have used the 'Calver' 202 on a few occasions with very good results.
Peter, I would happily try one of your 206 heads to back to back test each one and report on the difference if you like.....

Mark.

PS. Peter, it'd be good to catch up again, must be 15 years now....?
Mark T. Boldry

Hi All

I have slowly accumulated a few 295s and 206s, a few years ago I tried to sell a couple on ebay and had little or no response.202 heads seem rare too these days.
Mini Spares till 10 years ago supplied O/S inlet valves to overcome the throat problem in the 295.Lack of demand means they are NLA.
We frequently fit inlet seat inserts to reclaim the valve throat.
Maybe you would need special pistons to get the CR correct, it is a shame to trade bhp to save some money on pistons.
Miss one race at £200 in the UK and you have saved enough to pay for the difference between run of the mill off the shelf pistons and made to measure specials.
What was that American saying...bhp costs money how much did you want to spend..or something along those lines.
Thanks for the offer to test my heads Mark. I do not need to prove my credentials at the moment :)
You will have to come down with that T-type for a dyno session.

Peter
peter burgess

Peter

I know one of my keen competitors is reading this - so I send you a mail!!

Don't need to reveal everything

Ole
Ole Aaen

This thread was discussed between 28/07/2008 and 31/07/2008

MG Midget and Sprite Technical index

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