A friend just completed a modified head. He put in large valves and removed the boss in the intake ports. Also done the porting of the chambers both intake and exhaust. Nothing radical on the porting,just a good clean up job with matching ports. Problem- when the head was torqued on the block the head had a leak around the #6 exhaust valve. This was discovered when new valve springs was being installed. Various gaskets have been used but still the same thing. In fact the last time it leaked even worse and around other exhaust valves. Have came to the conclusion the head is flexing in that area. Has anyone else had a problem of this kind with a modified head? Any feed back would be appreciated.
Dear Hud;
Hard to say what went wrong, so I would have the head 'Magna-Fluxed' & see what that tells ya.
May have been cracked before, or ground into a water jacket.
Good luck, John M., #3370
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For a quick fix try MOROSO Ceramic Seal - about $12 a bottle.
Do you mean to say that the leak is inside the valve cover, and that is why it was discovered when changing valve springs? Or is the leak between the head and block, and which side of the block is it on? There is a VERY good possibility that the head is tweaked because of removing the bosses.
Your friend may be looking at taking the block down and having the deck flat milled, and at the same time having the reworked head flat milled too. Just a couple of thousandths off of each is all it takes. And use head studs when reassembling.
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David
newbie #4153
Thanks guys for the feedback. The leak is at the valve seat. We were putting air in the cyl. to hold the valve up while we changed the springs. When the torque on the head bolt next to #6 exhaust port goes over 50 lb. it will start to leak. The block and head have both been milled. The head should definately be mag. checked to make sure. We have even bolted it to another block-same. He had another head with only the bosses removed and nothing else done to it. We bolted it to two different blocks and got the same results-leaks at valve seat. Thanks again guys.