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L head modifications


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Found this over at the realm.... http://performanceforums.com/forums/showthread.php?67302027-Doing-some-stupid-shit-to-an-old-datsun-head geez those Australians are nuts.





Note above the top coolant passages were also welded and below the head bolt holes oval-ed so the head could be shifted sideways over the cylinder. 





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There are other guys over here That work these even more than this example.

They not only weld up the chambers but move the valves over. And raise the exhaust ports by putting a insert on the bottom of the port floor.

Completely welding up (or maybe it was filling with epoxy) the inlet port and boring a brand new strait down inlet port from just under the rocker cover was also tried by some until it was found that there were no gains doing this. And the stock inlet port can be made to work well enough with porting and it's the exhaust ports on the heads that just don't keep up.


Because of the underperforming exhaust ports, cams are ground to suit, I think they have more duration but less lift on the exhaust than the inlet.?

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Rebello welds the combustion chambers on some of the race motors. It's a tough job with the porous aluminum and proper cooling is crucial.


We also used to fix warped heads by heating them with a rosebud torch and overbending them the opposite direction by clamping them to the welding table with spacers on the ends and big c-clamps in the middle. I came into the shop one morning to find a head broken in two. It broke during the night. I wonder what that sounded like.

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