Engine builder offered to Deck the head

Arepeeam

Member
I inquired on some services and had an email back about decking the head and running the thinnest gasket. I was told that gasket surfaces are a non-tech option. That didn't sound right so I declined.

Is this a standard practice?
 
I inquired on some services and had an email back about decking the head and running the thinnest gasket. I was told that gasket surfaces are a non-tech option. That didn't sound right so I declined.

Is this a standard practice?
No, it is NOT a "standard" practice and very little can be gained. It still goes on though.
The gasket surface is not a tech item, that much is correct.
On some heads, there is .002" to be gained -- is it worth it? Maybe to someone, but it's not worth 1/10 CHP on our dyno so we don't even offer it on new engines. Now, if you've got a head that's pulled down near the exhaust port, it can be straightened and take a skim cut on it to save it. We do that, sure.
Just out of curiosity, how much was this particular builder charging for "decking" the head?
.


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🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
www.youtube.com
34 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 
Same here. We don't do it. The only time we will touch that surface is as Brian mentioned. Trying to save a head and save a customer some money is way different than offering it as a "performance" advantage.

FWIW, We get a few engines for rebuild every year with "suspicious activity" done to them. Its always the same builder(s) stickers. Stick with a well-known, respected builder and you will be fine.

Brian, Steve, Gary, and Jimbo all support and help folks on here. Start with them. Rob at Kart City is another person who is 100% legit and super helpful. Stick with one of these folks and you will be fine.
 
Same as the two guys above. I have also suspected block decking in a couple I have seen. Since Briggs changed to .0035 on pop-up I don't see it at all. Most engines I see now are at .000. In addition you can only get about two uses out of a head gasket before the thickness is questionable providing it's not torn up on removal. FWIW I always use a new stock Briggs gasket. Performance claims on some of those "modifications " to the head and carb are virtually nonexistent and are merely justification to charge a premium price.
 
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Local track a few years back did a post race tear down in the 206 class and found a head/block had been milled down, immediate dq suspension and fine...this is after the track had put their own seal on the engine at the start of the season....🤔
 
The more qualified experts have spoken already, their advice is excellent!

For those of you who are better than math than I. Here is some fact.
By all means please do verify.

A 2.6875" bore diameter at 0.0020" height.
The equation for volume of a cylinder being Pi (3.1415) times the bore radius squared times height...

<sounds of pencil scratching, erasing, more scratching, mumbling, counting on fingers, removes one sock to access toes>

Equal to 0.0113 Cubic inches or 0.1852 Cubic Centimeters.

Ask yourself if potential DQ is worth that gain.

As mother would say - "That's a BB in a box car difference"

Look for speed in your chassis set-up and driving style.

Edit: My very good friend Walter Myers pointed out my intentional typo in the value of Pi. Wally is a true rocket scientist and numeric sensei.

Did anyone else catch that error?

 
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No, it is NOT a "standard" practice and very little can be gained. It still goes on though.
The gasket surface is not a tech item, that much is correct.
On some heads, there is .002" to be gained -- is it worth it? Maybe to someone, but it's not worth 1/10 CHP on our dyno so we don't even offer it on new engines. Now, if you've got a head that's pulled down near the exhaust port, it can be straightened and take a skim cut on it to save it. We do that, sure.
Just out of curiosity, how much was this particular builder charging for "decking" the head?
.


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
www.youtube.com
34 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
Taking a "skim cut" on the head??? isn't that machining the head surface? I thought that wasn't allowed? I would think you being a tech instructor and tech man, you would know that.
 
The more qualified experts have spoken already, their advice is excellent!

For those of you who are better than math than I. Here is some fact.
By all means please do verify.

A 2.6875" bore diameter at 0.0020" height.
The equation for volume of a cylinder being Pi (3.1415) times the bore radius squared times height...

<sounds of pencil scratching, erasing, more scratching, mumbling, counting on fingers, removes one sock to access toes>

Equal to 0.0113 Cubic inches or 0.1852 Cubic Centimeters.

Ask yourself if potential DQ is worth that gain.

As mother would say - "That's a BB in a box car difference"

Look for speed in your chassis set-up and driving style.

Edit: My very good friend Walter Myers pointed out my intentional typo in the value of Pi. Wally is a true rocket scientist and numeric sensei.

Did anyone else catch that error?

Yes, you should have rounded up to 3.1416. I always use 3.14159. I didn't mention it because I thought it would be a bit anal. Most are just fine with 3.14.
 
The more qualified experts have spoken already, their advice is excellent!

For those of you who are better than math than I. Here is some fact.
By all means please do verify.

A 2.6875" bore diameter at 0.0020" height.
The equation for volume of a cylinder being Pi (3.1415) times the bore radius squared times height...

<sounds of pencil scratching, erasing, more scratching, mumbling, counting on fingers, removes one sock to access toes>

Equal to 0.0113 Cubic inches or 0.1852 Cubic Centimeters.

Ask yourself if potential DQ is worth that gain.

As mother would say - "That's a BB in a box car difference"

Look for speed in your chassis set-up and driving style.

Edit: My very good friend Walter Myers pointed out my intentional typo in the value of Pi. Wally is a true rocket scientist and numeric sensei.

Did anyone else catch that error?

Your logic Is flawed. It leaves out a very important factor.
 
Taking a "skim cut" on the head??? isn't that machining the head surface? I thought that wasn't allowed? I would think you being a tech instructor and tech man, you would know that.
While we're not supposed to "blueprint" or machine the gasket surface, you've got to realize the reason the visual was taken off of that surface. This was something that I pointed out to Dave Klauss at the Tennessee show when new engines were coming from the factory with two passes cut on the gasket surface. At that point, the tech man could no longer tell if the factory had made that second cut, or an engine builder had done it. I had suggested stamping or laser etching the gasket surface, but at that point it would have rendered 1000s of cylinder heads illegal that were already in service. Couple that with racers "scraping" their old gaskets off with everything from razor blades to screwdrivers, Roloc to flapwheels, and you've got a surface that is very much "not" from the factory.
By taking a skim cut, often times you can save the racer from having to purchase a new head when the #1 head bolt has pulled that corner or the head down as well. Repairing a cylinder head is still cheaper than replacing them.
Again, the rules clearly spell out that there is no visual on the gasket surface. That's why you have builders offering to mill the heads. (see my first response to this thread) I know exactly why the visual was removed and a good idea how many cylinder heads it has saved, not only the factory, but individual racers.
 
While we're not supposed to "blueprint" or machine the gasket surface, you've got to realize the reason the visual was taken off of that surface. This was something that I pointed out to Dave Klauss at the Tennessee show when new engines were coming from the factory with two passes cut on the gasket surface. At that point, the tech man could no longer tell if the factory had made that second cut, or an engine builder had done it. I had suggested stamping or laser etching the gasket surface, but at that point it would have rendered 1000s of cylinder heads illegal that were already in service. Couple that with racers "scraping" their old gaskets off with everything from razor blades to screwdrivers, Roloc to flapwheels, and you've got a surface that is very much "not" from the factory.
By taking a skim cut, often times you can save the racer from having to purchase a new head when the #1 head bolt has pulled that corner or the head down as well. Repairing a cylinder head is still cheaper than replacing them.
Again, the rules clearly spell out that there is no visual on the gasket surface. That's why you have builders offering to mill the heads. (see my first response to this thread) I know exactly why the visual was removed and a good idea how many cylinder heads it has saved, not only the factory, but individual racers.
Awhile back I made a post about repairing header mounting holes, and you really gave me down the road and criticized me for doing so by welding the bolt hole up and re-drilling and tapping the hole and putting studs in it. I did this for the same reason that you just stated....to save the racer from having to buy a new cylinder head. The rules say, no welding or machining. My procedure caused no performance gain, but your procedure cut the head. There is a measurement on the thickness of the head. What do you call a skim cut....how many thousands is that?
206 head.JPG
 
It's not thousandths removed from the head, it's pulling that corner of the head back that typically pulls down due to it's location near the exhaust port. All I am seeing being done is pulling that corner back and touching up that corner to make it flat with the rest of the head gasket surface. There's not enough room to take a full pass across the entire gasket surface and still be legal. That's why we have the measurements to go by. It still has to be legal. Which is why someone offering to mill a brand new head is NOT the norm.
I remember our conversation on welding the head to repair. It's not what I would do (or recommend) BUT if you think it's not detectable by the tech man, you're welcome to try to get away with it. Personally, we use heli-coils, then over-sized Keen inserts if it's very bad. There's certainly a lot more nefarious things going on with these heads than repairing stripped exhaust threads. I guess the issue I have with welding is any change to the port or combustion chamber caused by localized heat that is induced. I'm sure you are a much better welder than most and can do a nice job without distorting the combustion chamber, EX port, or needing to remachine the gasket surface enough to change performance. I can't say the same for most welding repair jobs.
 
My engines have been teched by some of the best tech men in the sport. They have no problem with them.....none have been DQ'd for anything. Experienced welders can do this procedure without distortion or damage to any other area. It's not that I'm trying to get away with anything. With parts, and cylinder heads being hard to get and the price increases, I'm doing what you say you are doing......saving the racer money. Don't you think a Tech Man has the tech tools to check the ports and combustion chamber for legality. I stand by what I do. I don't sell parts....We're done.
 
My engines have been teched by some of the best tech men in the sport. They have no problem with them.....none have been DQ'd for anything. Experienced welders can do this procedure without distortion or damage to any other area. It's not that I'm trying to get away with anything. With parts, and cylinder heads being hard to get and the price increases, I'm doing what you say you are doing......saving the racer money. Don't you think a Tech Man has the tech tools to check the ports and combustion chamber for legality. I stand by what I do. I don't sell parts....We're done.

If that photo is an example of your work and you can do that for less cost than a new head - I salute you and admire your talent.
I would not claim it legal by the photo alone but must admit it looks pretty good from here.

To my simple mind there is a difference between repair and modification. That is where quantifiable measurement, comparison to known factory part and spirit and intent of a rule applies.
 
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