Nail head valves

[1MeanA]

It isn't talked about much...not sure why. Perhaps its just a small gain? I put nail head valves in my 340 to decrease the chamber volume. I did this instead of massively cutting the heads. I believe it was nearly 3 cc. The valves need replacing anyway and I believe they used Chevy valves and guides.

 

[abdywgn]

I'm sure there were articles about that in the dark ages when quality replacement or updated parts were not as readily available.
The 11/32" valve guide diameter would help flow. Would be interested in learning if it helps performance or not. Watching.

 

[Locomotion]

This book has some charts and discussions (Bob Mullen) about slight flow increases when going from OEM "tulip" style intake valves to "nailhead". Not sure if it was the same source but somewhere I read that the exhaust preferred the opposite but wasn't as critical. Aftermarket stainless valves tend to be more "nailhead".

Using the smaller stem Chevy valves also help flow in the bowls. Undercut stems in the bowl on any valves can also be a benefit.

Always best to confirm results for your particular application on a flow bench because there are many other variables involved.

 

[RustyRatRod]

@MOPAROFFICIAL actually talks about it a good bit on here. He's right, too. It can make a substantial difference changing from tulip style valves.

 

[273]

It's interesting how much different valves can effect flow even valves of similar shape and specs, there's a few valve shootouts out there, it's surprising the amount of change you can get and valves you think would do better like the under cut stems don't always.

 

[MOPAROFFICIAL]

It's interesting how much different valves can effect flow even valves of similar shape and specs, there's a few valve shootouts out there, it's surprising the amount of change you can get and valves you think would do better like the under cut stems don't always.

People talk about turbulence in some bowl/guide shapes being a turbulence influencer.
I use them and don't worry about it.lol

 

[RustyRatRod]

People talk about turbulence in some bowl/guide shapes being a turbulence influencer.
I use them and don't worry about it.lol

I think there are some terms and subjects people just use to make themselves sound smart. Valve shrouding is one example. I know it "CAN" exist, but IMO in reality it makes very little difference in most cases.

 

[273]

I think there are some terms and subjects people just use to make themselves sound smart. Valve shrouding is one example. I know it "CAN" exist, but IMO in reality it makes very little difference in most cases.

Velocity and compression are the one's that get's me some people seem to grab on some phenomena and it's negative consequences and not consider the full picture.

 

[MOPAROFFICIAL]

I think there are some terms and subjects people just use to make themselves sound smart. Valve shrouding is one example. I know it "CAN" exist, but IMO in reality it makes very little difference in most cases.

There are positions around the valve in the chamber that if you deshroud too much can disrupt and yank everything with it...while if you don't have the proper amount of deshroud near the chamber... you have poor low n mid lift flow or fps balance issues between dogleg and chamber sides.