88 Dominator Rocker Shaft won't fit

Fritzer_108

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Sep 27, 2022
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I'm rebuilding a 1952 88 Dominator cylinder head for my project. I replaced the rocker shafts on the lefthand intake, exhaust, and right hand exhaust valves with no issue. I froze the rocker shafts and heated the head with my torch. They fell into place smoothly, so I was shocked to find that the rocker shaft for the right hand intake wouldn't fit in the head, even with the heating and cooling treatments. I measured the rocker shaft to be .4975" in diameter. I don't think that the aluminum is concentric as I measured it to be 0.498" in one orientation, and 0.4965 in another. Any tips on how to proceed? Thanks in advance,
 
Fritzer_108 said:
I'm rebuilding a 1952 88 Dominator cylinder head for my project. I replaced the rocker shafts on the lefthand intake, exhaust, and right hand exhaust valves with no issue. I froze the rocker shafts and heated the head with my torch. They fell into place smoothly, so I was shocked to find that the rocker shaft for the right hand intake wouldn't fit in the head, even with the heating and cooling treatments. I measured the rocker shaft to be .4975" in diameter. I don't think that the aluminum is concentric as I measured it to be 0.498" in one orientation, and 0.4965 in another. Any tips on how to proceed? Thanks in advance,
Click to expand...
How deep in the hole can you measure?

Is it just near the end?
Or all the way down that is mis-shapen?
 
I can only measure the first half inch or so with my calipers. It looks like it is mis-shapen the the entire hole, but I don't know about the internal seat for the rocker shaft. Really strange
 
If your calipers are anything but starrat or mitutoyo , get new bearing with a ½ bore this will help you calibrate the internal side of your calipers, typically cheaper verniers are out by .15 mm or about .006" .i:e zero on the bearing then measure the hole , you can calculate a more accurate size .
 
Just an idea because your mostly assembled, I'm sure reaming lightly could ease the high spots but maybe just get some silver steel or bright ½ and machine or polish a thou or thou and half off , or tad smaller than your shaft I should have said , make sure it's a good surface finish , 600 + round the end smooth make it long enough to hold well in vice jaws , add some say wd40 and mount head to it work it back and forth . This should help ease the problem . Years ago doing, conrod bushes on a sunnen hone, we would always finish off with the little end pin and honing oil fines to help remove the high spots . Cheers .
 
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