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checking a second hand head.
https://www.ausmini.com/forums/viewtopic.php?f=2&t=32213		 Page 1 of 1
Author:  matt850 [ Mon May 28, 2007 5:09 pm ]
Post subject:  checking a second hand head.
Is pressure testing a second hand head good enough or should I go the whole 9 yards and have it properly checked for cracks, dye etc etc
Author:  sports850 [ Mon May 28, 2007 5:17 pm ]
Post subject: 
Depends on what the head is , Mk1 cooper s definitely check as they crack , any others maybe . Do you know any of the heads history , is it off your previous car or did you buy it sight unseen ? did you pull it off the motor or was it sitting by itself ?
Author:  Mike_Byron [ Mon May 28, 2007 5:33 pm ]
Post subject: 
With any old head its always a good idea to take it to your local reconditioner to chemical clean it, strip and check (and they will crack test it if you ask). Most mini heads warp over time, so skimming it flat is necessary and they will check and replace the valve guides for you as well as refacing the valves and the valve seats.

You might as well get the exhaust valve seat replaced with hardened ones for unleaded petrol at the same time. Cost all up is in the <$200 range.
Author:  drmini in aust [ Mon May 28, 2007 7:17 pm ]
Post subject: 
I had a 1275 head I accidentally ported out thru the water jacket (as Vizard says happens) :shock: . After bronze welding it I bolted it to another head with a gasket, sealed the thermostat, heater and bypass connections, and hooked the garden hose to it. That is about 1,000KpA around here (142psi)- no leaks, she's a good-un again.
You could do this trick with heads suspected of being cracked- 142psi won't hurt the head, but should sure show if any cracks go into the water jacket.
If cracked the water will run out the ports. :wink:
Author:  matt850 [ Mon May 28, 2007 8:16 pm ]
Post subject: 
Doc,
as you know, we are talking about a 295 head. I have a choice of 2. Niether have been used for many many years.
One is still attached to the block. My tendancy is for this one as I guess it would be lees likely to be warped.
Obviously both would require a lot of work and we have already talked about that.
Which one would you think would be better given they are both $300.00.
Author:  drmini in aust [ Mon May 28, 2007 8:33 pm ]
Post subject: 
Measure thickness with a vernier caliper- they were 2.750" when new.
If one is much thinner buy the thicker one. Even if warped (unlikely) there is plenty of metal to deck it clean.
If the exhaust valves have sunk into the head, best solution is get unleaded seats fitted.
Author:  matt850 [ Mon May 28, 2007 8:56 pm ]
Post subject: 
thanks Kev, I'll take some verniers with me.
Cheers
Author:  simon k [ Mon May 28, 2007 9:02 pm ]
Post subject: 
matt850 wrote:
thanks Kev, I'll take some verniers with me.
Cheers


if you can pop the valves out, a good idea might be to douse them in petrol and let it evaporate, if there are cracks the petrol will stay in them and show them up.... good idea anyone?
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