|
I got my 'race' cylinder head (bought on eBay - http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=2471020578 ) in the mail a couple of days ago.
Looking it over I see lots of good news. Ample evidence of porting and polishing in the intakes and exhaust ports. Double valve springs. Oversized valves. I popped out the valves (and a pair on my stock head) to compare and was really struck by how small the exhaust opening was in my F head, the ported head is dramatically wider. It still takes a sharp bend off the valve, but there is no way around that. I'd guesstimate there is about 1/3rd more room in the exhaust port in the tightest spot.
Not so good - it's very noticably thinned down, especially compared to the F head I had on the car. I cc'ed one of the combustion chambers and got 38 cc's, which on top of my big bore (92 mm) bottom end would end up roughly 12:1. Not good at all for pump gas. I got a set of carbide burrs and used a router, tried it briefly and it carves the cast head like butter.
Next step is to (carefully, obviously) extend the ends of the oval out to the 92mm bore size (have to double check, because it already looks very, very close, perhaps it was already done to fit a big bore engine). Then to extend the combustion chamber outward around the intake valve until I hit 47 cc's - which should result in a CR in the mid 10's. Then some polishing to remove any roughness left behind by the carbide burrs (although they seemed to leave a very smooth finish where I tested it).
|
