57 replies to this topic

[twrminisport]

As above. We can all helP you when you have the measurements.

Interesting to note is if your 12g295 has been skimmed to a sensible CR it will not just bolt on. The engine will not turn over because the thermostat housing pushes down on the top pulley. Take the pulley off and file off about 1-2mm from the pulley and make sure it's smooth so it doesn't srhed you fan belt. The. You can bolt on. Check the clearance. I have about 12 thou :L

Aswell if the head has been skimmed you may need rocker post shims due to the relative height of the con rods. I could not fit 1.3.1 roller rockers because of this until I had shims.

On a different note. The 12g295 gas flowed and ported with 33mm inlets is optimal. You CAN get 35's in there however you will need to pocket the block to do this. It's so close with the 33's. And you lose a small amount of performance because in short words. It's all to big and no pressure Flows.

[charliedurrant]

Okay, thanks for the details.

I'm back with the 'head' on Wednesday evening so will take the measurements then and report back!

Charlie

p.s.

I have about 12 thou :L

that is very close indeed!

[charliedurrant]

Right,

I have the measurements and some photos to assist those who are as unsure about these things as I.

Measuring the total 'head' height

uploads/monthly_10_2011/post-52659-0-53004900-1319113693.jpg

Measuring the depth of the oil hole

uploads/monthly_10_2011/post-52659-0-95657600-1319113701.jpg

uploads/monthly_10_2011/post-52659-0-23924800-1319113700.jpg

uploads/monthly_10_2011/post-52659-0-84133400-1319113696.jpg

uploads/monthly_10_2011/post-52659-0-47293500-1319113698.jpg


So in conclusion

(A) Total head depth = 2.750''
(B) Oil hole depth = 2.530''

(A) - (B) = 0.220''

So my oil hole is not as deep as it should be - is this wrong or within a margin? Also I have a very wobbly themostat stud, is that fixible with a helicoil?

uploads/monthly_10_2011/post-52659-0-55123500-1319113695.jpg


Charlie

Attached Files

•  total-head-height.jpg   55.04K   29 downloads
•  wobbly-themostat-stud.jpg   50.34K   26 downloads
•  vernier-depth-in-hole.jpg   23.8K   26 downloads
•  depth-of-oil-hole.jpg   37.05K   17 downloads
•  vernier-depth.jpg   41.37K   24 downloads
•  oil-hole-to-measure-depth.jpg   41.53K   20 downloads

Edited by charliedurrant, 20 October 2011 - 12:52 PM.

[lapider]

if you have the original engine and the pistons are in good condition hold on to those as they are d top pistons only used with the 295 head thus making a brilliant base for the engine if used with the head as you would not have to skim it to get the correct compression ratio only to clean it up.

as far as fitting a 240 cylinder head bmcecossie is giving his opinion from his experience that he prefers 240 heads. the problem is that to get a 240 head to fit you need to pocket the block. this combined with the fact that most a series engine tuners including david vizard swear by the 295. generally people go for 240 heads because they can get one in good condition for a 3rd of the price of a similar condition 295. that and they dont mind pocketing the block.

i personally am using a 12g295 because i don't have to take the engine out to pocket the block to fit the head and if i ever want to put the car back to standard it is possible as once you have pocketed the block only 240 heads can be used.

when i say 240 i actually mean 940 my bad

Edited by lapider, 20 October 2011 - 01:43 PM.

[charliedurrant]

bump

[Cooperman]

0.22" between bottom of hole and faceof head is just fine.
At 2.75" total head casting thickness it looks as though it's never been skimmed, so you have a really good head there capable of being skimmed to get the comp. ratio exactly as you want it.
In all, a result!

[liirge]

or left for a turbo application!!

[charliedurrant]

Cooperman,

Thanks for confirming. What about my lovely wobbly stud?

Charlie

[jaydee]

Try to treat the rust on the threaded hole in the head, and change the studs.
Hope it cures it, i had the same problem with mine.

Alternatively, you can replace the studs with bolts, some later cars are fitted with bolts.

Edited by jaydee, 21 October 2011 - 03:26 PM.

[charliedurrant]

Jaydee,

I guess yours ended up okay? If I was betting, I would say mine had been dropped / left on the stud as the thread only seems to have worn on the top half.

Charlie

[Brookesy]

Blimey was looking at doing this on me mini but seems like it would be a tad hard on a daily driver without a week off to get it all sorted :S

Good luck with it and ill be watching the thread

[jaydee]

Jaydee,

I guess yours ended up okay? If I was betting, I would say mine had been dropped / left on the stud as the thread only seems to have worn on the top half.

Charlie

I replaced the studs, the one which replaced the wobbly stud didnt like to tighten up fully.
To be honest thats the only thing which didnt cause any real trouble lol, i had problems with the bypass and the cylinder head being skimmed to much for fitting aftermarket rollers (needs shimming).

[coopdog]

ive just got the same head and seems to be pretty similar to this one,
dont think it skimmed,
dont have any calipers so i roughly measured it with a tape :L
will have to get my hands on a set of calipers from my old school, im sure they wont mind haha






what do you think?
needs a good clean..
and is ther another way of increasing cr without messing with the head??

Edited by coopdog, 25 October 2011 - 08:45 PM.

[charliedurrant]

Coopdog,

I think your cylinder head looks much better than mine. Mine is much more rusted - notably around the area of the thermostat. I think D-top pistons are the way to go without skimming the head or even more raised ones than d-top ones (ready to receive corrections on that assumption)

All,

Right well, I'm ready to start my rebuild of a 998. I should probably post this in a new thread but in some ways it seems sensible to continue in this thread. I have:

1) 1980s A+ 1998
2) 1968 Cooper 998 engine with all parts apart from the damn D-top pistons

I want to rebuild an engine as a challenge and essentially want to get the most out of a 998. I'm not that interested in max power ( I have another car for that ) but I want to:

1) Build a solid road engine
2) Extract as much efficiency and power as I can without sacrificing driveability.

I don't want to do the head work myself as if I mess it up then I'll kick myself so what recommendations do people have? I'm driving with a piper 270 fast road cam in a 1275 with a mildly ported head. I don't expect the same performace out of a 998 but I want to challenge myself and get a useable but good performing 998. I have read to use a MG metro cam and an HS4 carb but over and above that I'm at a loss. Note I have a maniflow LCB with an RC40 backbox and a minispares alloy inlet manifold. I also have a 59D4 electronic dizzy.

Charlie

[coopdog]

ive been told a mg metro cam will be lumpy on idle in a 998, any truth in this?