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Posted: Wed Dec 02, 2009 6:53 pm
by bmcecosse
Only if you use the useless 'concertina' hose -which will burst shortly after. Better to use nice thick-wall straight rubber tube.
As for the gasket blowing - check it's all clean - and torque the head down to 44 ft lbf, and then re-torque it after the first run! I do this with HOT engine - but other do it cold. It probably doesn't matter. I assume you will take the chance to grind in the valves while the head is off ? And don't bother with 'unleaded' conversion - it's not necessary unless doing LOTS of miles at high speed!
Posted: Wed Dec 02, 2009 11:14 pm
by bmcecosse
No need to take the cables off the carb - in fact - if leaving the manifold on the exhaust just leave the carb (and cables) on it and push it out of the way. Otherwise - take the carb off complete with cables and just lay it aside. Old head gasket acts as 'keeper' for the push-rods, and be sure to 'shake' them well before lifting them out of the block. Also always take care to slacken off the 4 small nuts securing the rocker pillars before undoing the headnuts. Similarly - tighten all the head nuts before finally tightening these 4 smaller nuts - and note they DO NOT get the same torque as the head nuts.
Posted: Thu Dec 03, 2009 8:13 am
by stuart_k
Never thought of using the gasket for the pushrods
I prefer the cables out of the way just because it makes lifting the head off less fiddley and in this case I am further dismantling anyway. Carb will be serviced, manifold cleaned up, new (secondhand) spruced up airfilter housing, engine painted, bay cleaned up and a few other bits of housekeeping. I'm also thinking of having the head ported and flowed so if doing that an unleaded conversion seems the way to go. I was going to do all this in the Spring but the headgasket forced the issue and there seems little point in putting it all back together again if I'm going to disassemble in the Spring. I doubt I'll get much motoring in before then now the weather has finally broken.
Posted: Thu Dec 03, 2009 8:14 am
by kennatt
not scotland then

Posted: Thu Dec 03, 2009 11:24 am
by bmcecosse
Don't waste time/money 'porting' or 'unleading' that head! Just get a better head - 12G 295 comes all ready ported and flowed with larger inlet valves - skim by 60/80 thou and bolt it on. 12G 940 head has even larger inlets and larger exhausts - just sink the exhuast valves by 40 thou and bolt it on - no skimming required.
Unleaded conversion only required is doing large mileages at high speed. Otherwise - don't worry about it - just set the exhaust gaps at 15 thou and keep an eye on them.
Posted: Thu Dec 03, 2009 12:33 pm
by stuart_k
Come to think of it, I don't even know what casting the existing head is. This is the first time I've had occasion to get the spanners out since I bought the car. I must remember to have a check and see what is already on there. Looking at my pics on the photo essay it looks like a 12G202. Isn't the 12G295 rather difficult to come by these days?
Posted: Thu Dec 03, 2009 1:20 pm
by stuart_k
Found one on ebay at the moment

Posted: Thu Dec 03, 2009 1:24 pm
by PSL184
Still plenty of 295's around but be careful not to get carried away and overbid on ebay. 940 heads are potentially better and are the standard 1275 head.
Posted: Thu Dec 03, 2009 1:27 pm
by stuart_k
Don't tell me about getting carried away on ebay, that's how I ended up with the Midget!

Posted: Thu Dec 03, 2009 1:49 pm
by PSL184
It looks nice though

Posted: Thu Dec 03, 2009 3:16 pm
by stuart_k
It is! But I was lucky.
Posted: Thu Dec 03, 2009 4:02 pm
by bmcecosse
The 202 head is a fine head - excellent upgrade for a 948 engine. But it's just not worth going to all the hassle of 'porting' it - when much better heads are available off the shelf for relatively low cost. My 940 heads usually cost me £10/15 - never more than £20 - and then only for the 'big valve' version.
However - it does appear - perhaps due to constant publicity (

) on Mini and Minor forums - that prices have crept up slightly recently.