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Old 01-13-2016, 09:10 AM   #220
Chris Wilson
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Join Date: Dec 2007
Location: Shropshire, England, UK
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There's no way at all water pressure will blow core plugs, anything like the sort of pressure needed would blow the rad apart, or blow a hose. To me it smacks of block squirm. Even the Motorsport Cossie Sierra blocks would pee oil out of the rear main seal if they were true 500 BHP plus motors used on a circuit with a LOT of boost for sustained periods. Block movement could be sufficient to allow core plugs to move, for sure, on weak blocks used well over their design limits. The Sierra blocks always seemed to have tiny cap heads and washers in either opposing pairs or even tripled around the periphery of each core plug, as well as using Loctite hydraulic seal on them. Whether there had been an issue with plugs coming out, or it was just good belt and braces engineering practice I don't know, I ran N/A converted ones with nothing like the same cylinder pressures or torque capability.The few serious turbo Sierra engines used in circuit work here in the UK were always wet at the back end, and I was always told that block squirm, even on the Motorsport heavy duty castings, was the cause.

In the early days of the Cossie Sierra in competition they had head gasket issues and used to pre pressurise the cooling system to try and help them through a race. They ran special rads and hoses to withstand this coolant system pressure, but I never heard of them popping core plugs. I think they may have gone to Reinz gas filled rings later.

Has anyone any photos of a red block band sawed open, width wise and longitudinally? It would be interesting to see where the material was, and was not!

I do this to heads that are new to me, to see where one might hit fresh air or water before porting a good or new casting. For years people in the UK used to say you must not remove the hump in the exhaust ports on Nissan RB26DETT heads, as you'd be into water. I got a scrap head and band sawed it up. The talk was rubbish, the water was miles away. No one had done this before in the UK and people seemed amazed anyone would want to do this. The head was scrap value with a dropped valve.... Go figure!
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