Valve size question????
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Junior User
Joined: Dec 2003
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Valve size question????
i have a set of early 351c 2v heads. what is the largest valve i can put in them so they flow better than their 4v counterparts. Or if thats not possible then i just want them to flow way better than stock 2v heads.
Elder User
Joined: Jun 2003
Posts: 886
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From: Houston/Hope BC
2.19/1.71 but from what I've read here (danlee) this is not the optimal. Search here and read.
Flow data: http://www.jason.fletcher.net/tech/f.../cleveland.htm
Google the guys making the aftermarket heads (CHI 3v?), they have flow data on there site and the valve sizes they chose.
Read up on the castings, the early heads may not like the big valves. (I recall reading something somewhere (here?) about the later heads getting more metal around the exhaust ports to aid in heat flow.) My later castings took em fine. Set me back about $800 as I recall to do the deal, not bad all in all, you get about 90+% of the ultra trick head flow for about 45% of the price. Of course, you don't get the weight saving of going to aluminum, but it's a P/U not a race car, right?
Also, this is a job for a head specialty shop that deals with racing work, there are particular radius cutters they will employ in the bowl area that a typical slam bam back to stock rebuilder typically won't have. GL
Flow data: http://www.jason.fletcher.net/tech/f.../cleveland.htm
Google the guys making the aftermarket heads (CHI 3v?), they have flow data on there site and the valve sizes they chose.
Read up on the castings, the early heads may not like the big valves. (I recall reading something somewhere (here?) about the later heads getting more metal around the exhaust ports to aid in heat flow.) My later castings took em fine. Set me back about $800 as I recall to do the deal, not bad all in all, you get about 90+% of the ultra trick head flow for about 45% of the price. Of course, you don't get the weight saving of going to aluminum, but it's a P/U not a race car, right?
Also, this is a job for a head specialty shop that deals with racing work, there are particular radius cutters they will employ in the bowl area that a typical slam bam back to stock rebuilder typically won't have. GL
