valve seat cutting

65ShelbyClone

Well-Known Member
#23
Now for some trivia :) Years ago when our shop had a SERDI demo, the sales rep showed me a seat cutter for the SERDI with a 9 angle cut that one of the NASCAR engine builders used at the time. "9 angles" - I thought that was cool!!!
There are also radius cutters that, from a mathematical standpoint, have infinitely many angles.

It's probably hard to measure a flow difference between nine angles and a radius.
 
#25
There are also radius cutters that, from a mathematical standpoint, have infinitely many angles.

It's probably hard to measure a flow difference between nine angles and a radius.
I asked the "rep" why they cut 9 angles. He said "cause it works for them". I couldn't argue with that. LOL And I agree with 65ShelbyClone about "a flow difference between nine angles and a radius" because, wouldn't science tell us that air running over a smooth radius would flow better than over the angles with their sharp edges? I won't go into anymore detail here, because I could spend way too much time discussing flow in internal combustion engines.
 
#26
I asked the "rep" why they cut 9 angles. He said "cause it works for them". I couldn't argue with that. LOL And I agree with 65ShelbyClone about "a flow difference between nine angles and a radius" because, wouldn't science tell us that air running over a smooth radius would flow better than over the angles with their sharp edges? I won't go into anymore detail here, because I could spend way too much time discussing flow in internal combustion engines.
i like to see more flow testing with a large 32 mm valve and reshape the bowl like a vortex port. see if that would increase the flow/performance like it does on the chevy heads. i'm sure some of the big clone engine builders are all ready doing this and if it's working they ain't going to tell the littles guys like us....lol
ole4...winter project testing next fall for you.....lol
 
#27
i like to see more flow testing with a large 32 mm valve and reshape the bowl like a vortex port. see if that would increase the flow/performance like it does on the chevy heads. i'm sure some of the big clone engine builders are all ready doing this and if it's working they ain't going to tell the littles guys like us....lol
ole4...winter project testing next fall for you.....lol
To me, "Flow" is the most interesting part of engines and engine building. I haven't done as much practical application as I'd like. When I worked on automotive heads for a living, I was too busy doing basic stuff to get to experiment very much. Way more stock builds and not nearly enuf performance/racing work to suit me. I love to fabricate and have thought about building a basic flow bench. Over the years, I've read every article that I could find on the subject. It would not have all the bells and whistles as a store bought unit, which would be fine with me. Just using it as a comparator would accomplish all I needed. I don't need legitimate numbers, just need to know if I'm headed in the right direction of backing up. I took a small engine course back in my Army days in the 1970s when I was stationed at Ft. Bragg. IIRC, I rebuilt an 8HP Briggs. It was for my family's riding mower and I cleaned up the ports on it when I built it. It seemed to have a more noticeable amount of power - but that could have just been me being so proud of what I did and not a real world improvement. LOL
 
#28
Be happy to. Been sidetracked with other equipment breakdowns. My bobcat sprung a leak in a hard-line going to the spool valves and I am trying to get to it without removing a bunch of other hoses.
 
#29
reclayed and ole4, I know on my Tecumseh ohh head has a off set intake into the bowl area. without flow testing that it may have a slight vortex affect. if you look at the running. the most of the air flows down the outside and without flow testing the air movement i am only assuming the air wraps around the outerside and then exits the valve into the center of the chamber. keeping the fuel and air more optimized. now maybe this is something else to think about without flow testing? would this head work even better with a larger valve and then create vortex ramp in the bowl area and also with the deflective wall on the other side of the runner right before the air enters the bowl. allowing the air and fuel to ramp up the bowl area better and into the chamber.

this may take a little more work on a clone head,but not impossible. here is couple pictures of a stock tilly clone head27/25
not the best pic's but you can basically see the air and fuel enters the bowl area from the left and right and then around the valve stem and against the flat bowl wall. assuming only at this point the air and fuel tends to crash into each other then tries to exit into the chamber.



something I am going to try on my little greyhound motor with only 25/24 narrow stem ss valves. this is only being use as a circle track head where I need it to come at 4000-7000+ rpm's and will be only a back engine this year. so it may never see the track this year and was very quick off the corners last year with out this mod i am doing now.
i filled in the back side of the bowl area's to allow the air and fuel to ramp up evenly and the way i did this was filled in the back side and then set it up on my mill and made a cutting tool that would reshape a radius bowl on he back side so the air and fuel is now redirected to flow towards the seat area. it should have a less affect of the air and fuel crashing into each other like a stock bowl would. thats where i think a vortex might be something to look into and i would think a larger valve would give you a better ramp affect and air and fuel flow. going to need more area for all this to move correct or i would think by using a small valve and building a ramp up you would lose a lot of air space and then things would just bottle neck up. yep really need a flow bench...for sure...lol
here is a picture. still need to do little more finally touch ups and polish out the exit side, it's terrible with my cell phone.
 
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65ShelbyClone

Well-Known Member
#30
On a mini bike, probably not.
I meant even on a good flow bench. Probably have to a be a NASCAR shop to see the difference (if there is one).

I asked the "rep" why they cut 9 angles. He said "cause it works for them". I couldn't argue with that. LOL And I agree with 65ShelbyClone about "a flow difference between nine angles and a radius" because, wouldn't science tell us that air running over a smooth radius would flow better than over the angles with their sharp edges? I won't go into anymore detail here, because I could spend way too much time discussing flow in internal combustion engines.
Something something turbulent flow something something laminar flow something something wet flow....Fun thing about cylinder heads is they're not at all intuitive.

And also, I recommend to anyone that when a current racer/team/etc. gives away seemingly "secret" info, take it with a big grain of salt. It's something that they aren't afraid of their competitors knowing which means it either isn't secret, isn't current, or isn't true. ;)
 
#31
I meant even on a good flow bench. Probably have to a be a NASCAR shop to see the difference (if there is one).



Something something turbulent flow something something laminar flow something something wet flow....Fun thing about cylinder heads is they're not at all intuitive.

And also, I recommend to anyone that when a current racer/team/etc. gives away seemingly "secret" info, take it with a big grain of salt. It's something that they aren't afraid of their competitors knowing which means it either isn't secret, isn't current, or isn't true. ;)
when comes to nascar racing it's about keeping it a secret or i should say cheating until you get caught...lol
smokey yunick is a good old classic....hey doesn't that 66 Chevelle look little smaller...;)
 
#32
when comes to nascar racing it's about keeping it a secret or i should say cheating until you get caught...lol
smokey yunick is a good old classic....hey doesn't that 66 Chevelle look little smaller...;)
Would you be referring to the same Smokey Yunick that would shoot compressed air in his fuel tank after tech inspection - which would expand the tank so it would hold a little extra fuel? Or the same Smokey Yunick that would knock the ring gear off of his flywheel and drill radial holes in it to lighten it, then replace the ring gear and nobody could tell what he did? Are we possibly talking about the same "think out of the box" geneus? BTW It's only cheating if you get caught. LOL
 
#33
I meant even on a good flow bench. Probably have to a be a NASCAR shop to see the difference (if there is one).



Something something turbulent flow something something laminar flow something something wet flow....Fun thing about cylinder heads is they're not at all intuitive.

And also, I recommend to anyone that when a current racer/team/etc. gives away seemingly "secret" info, take it with a big grain of salt. It's something that they aren't afraid of their competitors knowing which means it either isn't secret, isn't current, or isn't true. ;)
I'm guessing it wasn't much of a secret. The SERDI rep knew it because he worked closely with his NASCAR customers. But, it was probably the "trick of the week" or "season". Science and science principles are "science". All of those sneaky "work arounds" are the secrets that they try to conceal. Unless we're seriously involved, we can only imagine the experimentation and R/D that goes into being competitive at that level.
 
#34
Would you be referring to the same Smokey Yunick that would shoot compressed air in his fuel tank after tech inspection - which would expand the tank so it would hold a little extra fuel? Or the same Smokey Yunick that would knock the ring gear off of his flywheel and drill radial holes in it to lighten it, then replace the ring gear and nobody could tell what he did? Are we possibly talking about the same "think out of the box" geneus? BTW It's only cheating if you get caught. LOL
I heard, or was told he had a gas cap (this was before fuel cells) he drilled out for a tire valve stem to be inserted, and after tech inspection he would install the special cap and shoot compressed air into the tank, belling it out, thereby increasing the volume by a few gallons. The advantages to doing this are obvious. If they placed in the money, the car would retire to the pit area, where a waiting crew member would roll a floor jack under the car and smush the fuel tank back in. Smokey wrote a book callled "Power Secrets".......very good read. He had probably forgot more information than most of us will ever know.
 
#35
I heard, or was told he had a gas cap (this was before fuel cells) he drilled out for a tire valve stem to be inserted, and after tech inspection he would install the special cap and shoot compressed air into the tank, belling it out, thereby increasing the volume by a few gallons. The advantages to doing this are obvious. If they placed in the money, the car would retire to the pit area, where a waiting crew member would roll a floor jack under the car and smush the fuel tank back in. Smokey wrote a book callled "Power Secrets".......very good read. He had probably forgot more information than most of us will ever know.
Yep. I didn't know or didn't remember about the gas cap, just knew he pressurized and swelled the tank. LOL Those were the good ol' days of racing.
 
#36
Those were the good ol' days of racing.
and just think when i was a kid i got to watch dick trickle ever friday night at capital super speedway... thumb1.PNG
dave marcus,alan kulwicki,mark martin,matt the bratt kenseth,rich bickle...so many of them.
what was this thread about again? heads or something. oh yeah the guy in the video using a drill to spin a neway cutting tool at high speeds...:rolleyes:
 
#37
and just think when i was a kid i got to watch dick trickle ever friday night at capital super speedway... View attachment 263224
dave marcus,alan kulwicki,mark martin,matt the bratt kenseth,rich bickle...so many of them.
what was this thread about again? heads or something. oh yeah the guy in the video using a drill to spin a neway cutting tool at high speeds...:rolleyes:
Let me be the first to apologize for my part in steering this thread off track. Everybody can feel free to hijack any of my posts - I don't mind. Dave Marcus? How about them "wingtips"? LOL
 

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