Gettin a-head - The 1947 - Present Chevrolet & GMC Truck Message Board Network

petemonster · 10-25-2006, 05:21 PM

Hey kids,
I' new here. I have a question about a 250 inline six.
A friend of mine wants to hop up the 250 in his truck.Does anyone know of a good site on building these engines?
I heard something about using Olds rods and pistons.
Most importantly however,I would like to know about the cylinder head.
My question on that is,what is the wall thickness in the ports?The head uses chevy 1 3/4 small intake valves ,and I was wondering if there is enough meat there to straightbore the valve pockets to accept 1 15/16 large valves...........I do this all the time on small valve 624 and 882 V8 castings and use 3/8 stem 1 1/2 exhaust valves.
Or would it be better to do maybe say a 70 degree taperbore and install new valve seats?

10-25-2006, 05:21 PM	#1
petemonster Registered User Join Date: Oct 2006 Location: minnesota Posts: 5	Gettin a-head Hey kids, I' new here. I have a question about a 250 inline six. A friend of mine wants to hop up the 250 in his truck.Does anyone know of a good site on building these engines? I heard something about using Olds rods and pistons. Most importantly however,I would like to know about the cylinder head. My question on that is,what is the wall thickness in the ports?The head uses chevy 1 3/4 small intake valves ,and I was wondering if there is enough meat there to straightbore the valve pockets to accept 1 15/16 large valves...........I do this all the time on small valve 624 and 882 V8 castings and use 3/8 stem 1 1/2 exhaust valves. Or would it be better to do maybe say a 70 degree taperbore and install new valve seats?



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