Just starting to build the new motor to replace the detonated one. Can't decide what valve size to use. The new motor will be 313ci still blown like the old one. What do you reckon will be best. Been stratching my head so long think ive now got a bold patch.
1.6 untake and exhaust is what most folks say. Barney Navarro has a motor with about 1.8 valves intake and exhaust that looked mighty impressive. Overkill! I have been thinking 1.7 intake and 1.5 exhaust lately. I think that with flatty exhaust being what it is, there isn't much point going over that for most motors but the larger intake might air things out a little. I dunno... 1.6 would work just fine.
what is involved in running the chevy valves?...can you use the same adjustable lifters?...how about the seats?
Used the chevy valves in the old block worked good thought i might try something different but cant decide. They work with the adjustable lifters just need to get the seats re cut. You also needed to put a shim on the valve spring to get the correct spring rate. They do work good. Was thinking about flathead jacks pro-flow valves which are under cut on the valve stem for better flow. But havent heard if they are any good.
Jim, Talk to Joe Abbin - he's flowed it & the 1.72 doesn't gain much over the 1.6 intakes, but I assume you'll be running the blower again, so double-check with him. My personal guess is 1.6/1.6, but with the size engine yer runnin, ya never know!
Jim ,I running with !.6 intakes 1.5 ex.My 313 cracked very early in it life 30 mim. unless you have a aftermarket block 3 3/8 not the way to go for me .I like 3 5/16.Went 12.91 sunday 3200lb