Has anyone ever taken a ported head that has been flowed and simply changed it from 11/32 valves to 5/16 valves. Then reflowed the same port. Same type of valve job, same valve manufacturer
.031 smaller stem in the most important area of the head. I bet it is worth something since you're adding CSA
I have looked at that stuff too, since there's more LS valve sizes available build my Dakota r/t heads with those. Magnum ports could use a tapered stemI would think so too. Taking examples from newer technology magnum heads and LS type head’s running 5/16 (8 mm) sized valves.
Has anyone ever taken a ported head that has been flowed and simply changed it from 11/32 valves to 5/16 valves. Then reflowed the same port. Same type of valve job, same valve manufacturer
I can post weights today of the 2 different stem valves, all other dimensions sameI have. The flow increase was small. I think it was 5 CFM or something.
I didn’t care about the flow. The valve weight was what I cared about. I forget what the weight savings was, but at that point using 5/16 stems was cheaper than Ti valves, which I eventually went to.
Im not sure I can prove it, but any time you put a round section in an air column it makes turbulence and IMO that’s never good, but what we get to live with.
I have. The flow increase was small. I think it was 5 CFM or something.
I didn’t care about the flow. The valve weight was what I cared about. I forget what the weight savings was, but at that point using 5/16 stems was cheaper than Ti valves, which I eventually went to.
Im not sure I can prove it, but any time you put a round section in an air column it makes turbulence and IMO that’s never good, but what we get to live with.
And the LS folks are going to 7mm stem stuff on the really hot stuff, the guy I'm doing the MGB unit on was a little nervous about the idea at 1st, lol!! I told him, uhh if a 2nd Gen Hemi can crank 8K on 5/16 stems w/a 2.30" head hangin on the end, poppin' at the will of a solid roller,......your little MG will be fine.I would think so too. Taking examples from newer technology magnum heads and LS type head’s running 5/16 (8 mm) sized valves.
I once flow tested an 11/32 valve in a 3/8 guide iron head by carefully cutting and wrapping 0.010"-0.012" plastic shim stock around the stem. It was a little crude, but it worked good enough for a flow test. I have the flow results, but they are meaningless because it was not a true A to B comparison test.
The set of Edelbrock heads I’m working on now are on standby for PAK springs. They have him going with a way smaller diameter spring on his .700
Cam combo. Again for weight.
If he's comparing a nail head to a tulip... it is not a good comparison. The stem will not be the reason for this massive increase you see as much as that tulip valve Under head eating up bowl volumeI’d be curious to see your results.
Here's the results of the valve stem diameter test. Tests were run back to back on a ported SBM steel 587 head from a 1973 360 motor. Valve diameter is 2.02. Single 45 degree angle on both valves. No backcut. First valve was a Hughes 3/8 valve with an 11/32 reduced stem. Second valve was an Edelbrock 11/32 with a 5/16 reduced stem. Both valves are nail head and appear to be similarly shaped.
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Most 2.02 11/32 are around 120 grams