223 Oversize intake valves--Safest Max

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Anonymous

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Stock 223 intake is 1.78. Any suggestions on taking these to 1.95 or 2.0. Realize
will have to grind out CC wall .080-.090. What about any seat caveats or problems.
Have some 1.95 available but OAL is .235 shorter than stock. Does not seem to be enough lash adjustment left in adjuster to compensate. Am milling head .060. Any advice out there??
 
It could be one of those problems best solved by sectioning a spare head, if at all possible. The wall thickness (as cast) in the valve bowls awas probably around 3/16". Corrosion will have taken some of this, and also added porosity. 76 thou - odd radially is a bit but as the chamber roof will be thicker than the bowls, it's fair to assume seat insert cuts will be safe. If you're careful on the blend of new to old in the bowls, you might just wing it!

On the valve length, you'll either have to lower the rocker arm shaft (tough one!) and use shorter pushrods, or get longer valves. Sure can't add ¼" with lash caps.

Adam.
 
ADAM, THANKS. 'SECTIONING THE HEAD' ?? NO SAVVY. ANY FURTHER ENLIGHTENMENT/ EXPANSION ON SUBJECT. (TWO OF MY WIFE'S SISTERS AND FAMILIES LIVE IN ADELAIDE. COMING STATESIDE IN MAY)
 
:D Adelaide's nowhere near close! I'm 900 miles away! :wink:

By sectioning, I meant cutting a spare head into slices, across the areas you are curious about. Look for the thinnest area in the casting, and assume that all your "actual" head is that thin, around the same area. It's a nice trick if you have the spare (a cracked one?), the means to cut cleanly, and time to study it.

Regards, Adam.
 
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