What is the standard thickness of a 12G295 head

[Pandora]

Having acquired my 'Mini for life' I'm clearing the garage of surplus spares to both make space, and raise a bit of funds.

I've found a 295 head which I think is completely standard, but does anyone know the depth between the rocker cover gasket face and the head combustion chamber face on an un-skimmed head so i can check?

mine measures 68.3mm

Ta,

Al

[JohnA]

2.750"

[rich@minispares.com]

You know the saying al


'A dog is for life, not just for Christmas! '

[Pandora]

Rich, it's not like I change projects more often than you change your socks.

So mine has had about 50 thou skimmed. I have a memory that it was perhaps done to suit a 998 with flat top pistons at around 10:1 CR. Would that sound about right? (obviously I can't find the burette in the garage to just check the CC of the head, that would be too easy!)

Al

[carbon]

Al, 50 thou off a standard 295 head will leave you with about 25cc in the chamber

[Peter Laidler]

'A dog is for life, not just for Christmas! ' reminds me of the old banger I saw in Oxford last weekend. Same sticker, dogs trust logo's etc but the wording was '....a dog is for life, not just Friday nights.....' No..., wifey didn't see the funny side either

[winabbey]

Having acquired my 'Mini for life' I'm clearing the garage of surplus spares to both make space, and raise a bit of funds.

I've found a 295 head which I think is completely standard, but does anyone know the depth between the rocker cover gasket face and the head combustion chamber face on an un-skimmed head so i can check?

mine measures 68.3mm

Ta,

Al

You can see on the BMC Engineering drawing for the 12G295 head that the depth specified is 2.718" to 2.750".

12G294 Cylinder Head depth wm.jpg

[CooperTune]

I'm currently building two A+ 998 s using the late press fit rods, flat top pistons and a pair of 295 cyl. heads. It appears these are uncut heads. With O/S lead free triple groove valves the valves set nice and high in the chamber. I have pre assembled the blocks and measured piston to deck machining for zero deck. I have ask around to see if someone knows how many .001 per CC when surfacing a 295 head. I was told place head upside down level place the amount you want in chamber and measure down to the fluid. There is a setup and surface .010 to .015 and a charge per .001 after that. Would like to hit close first set up. For some reason I'm thinking .015 per CC. Doing two I will find out.

Also what are the over bore sizes for a 998? I know 1275, 1293, 1310, 1330. Thanks Steve (CTR)

[Dr S]

1010, 1030, 1050 @ plus 60.

1080 about the max, not sure what pistons presumably a shade over +80

[CooperTune]

I'm working on the thought that 25 CC s will give me the CR I'm looking for. As mentioned heads have guides, seats and new O/S valves. Due to a shipping error one head is done and one back to machine shop to have seats cut. I have measured both heads at 2.750 and figured I'd be looking at 29 CC s. I set up the head I have to measure down to the 25 CC s ( this does not work for me ) so I dumped that and CC ed the head to find as is uncut it's 27.2 now. I'll drop this head for surface and pick up the other to CC before returning it to cut. Due to fuel I'm aiming at 10.2 as highest CR for these. I'm going to take .050 off the first one and see what that does. I can always reshape the chambers if I go over and one block has yet to be zero decked. Steve (CTR)

[CooperTune]

I'm working on a pair of 295 cyl heads. I have been told the one with scalloped manifold side is an earlier one. After having hard seats installed and new O/S valves cut in I have CC ed each and found the flat manifold side one is 27.2 CC s and the scalloped one is 28.2 CC s. I have ask around about how many thousandths per CC with these heads. Both of mine are 2.750 and neither is the 29 CC s I was expecting. I have one on the shelf that has std valves a valve job and is 2.743. I will CC it and see what I can figure out. Having the 28.2 one cut .060 and will see what that does. I can always open the chambers a little if I need to. Steve (CTR)

[CooperTune]

OK, both heads are done as for guides, seats and new O/S valves. Since I have two I decided to cut the larger chamber head .060. The result was from 28.2 CC s down to 23.2 CC s which leads me to believe each CC is .012. With flat top pistons at zero deck I'm thinking I missed my 10.2 and ended up closer to 10.5 to 1. This head has a very high oil galley drilling and could be safely surfaced much more. I'll check location of drilling on second head before surfacing. One engine is already sold and the second is for speculation. Steve (CTR)

[Exminiman]

Sort of following on on this theme, did they make this head in different thicknesses or chamber sizes ?

Back in the day we used to get these heads off the 1100’s, MG etc…., but as far as I can remember they didn’t have the raised D shape pistons the Coopers had ?

But both the 1100 and Cooper had similar CRs of 9/1, didn,t they?

[CooperTune]

I'm not and never been a math guy. Seems simple at 1100 CCs that should add 25 CCs to each cyl. to figure in total volume. Steve (CTR)

[Exminiman]

Umm yes I might of overlooked the bleeding obvious….

Quick look at MG 1100 production dates, shows 1100 MG might possibly of had the head first, which could explain the d shape Cooper pistons ?

[timmy201]

Yep, the 295 works perfectly on an 1100 with the same type pistons BMC used on every other engine

Only the 998 cooper used the raised dish pistons to get a decent compression ratio

[Tim]

I have a 295 head that came off a Morris 1100 Automatic. I think they used the 295 to try to make up for the performance lost in the auto box. I had it planed 50 thou to get the compression up enough to use on an 1100 block in my Moke.

Tim