Time to replace?

Normally the new heads are very good but you really can't be sure unless you leak test it.
 
What about the compression pressure? I always kept my snap-on gauge close by. I've been known to say "compression is the holy Grail". It would help to have some comparative readings from your friends. Any loss in compression is never good.
AL, you're back!!

while I don’t always agree with what you say, I’m glad you are still out there sayin it!
 
AL, you're back!!

while I don’t always agree with what you say, I’m glad you are still out there sayin it!
Thank you, it's great to be back.
On the subject of agreeing with everything I say; I'd probably be suspicious if you did agree with me on all subjects. A debate on the things you don't agree with would be fun.
 
Not to high jack the thread, but how often should the top end be rebuilt?

Thanks

That depends on the level of competition where you race. I know guys who have raced all season without freshening, others that have the heads touched up before every big race.
Generally, new heads don't leak, but I wouldn't be in a rush to go cutting on them -- they need a few heat cycles through them first, in my opinion - THEN cut the seats. Look closely, you will see what I am talking about.


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
31 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 
Copy of post #13
Often times refreshing the head and having the valves and seats professionally done makes more power than a new engine.
The stress put on the head by the head bolts, the exhaust manifold, the spark plug etc and the countless heat and cool cycles will distort the valve seats. They won't be round and will have dips in them. You can lap the valves for a very long time and it won't straighten or true up the seats. Not to mention the grooves you will get int the valve face. To get them right they need to be machined.
I do them every day and have seen countless bad valve seats.
I will say that the valves and seats work very well when new. It takes a while for them to get out of shape but they will.
The more stress and heat cycles you put on the engine the sooner it happens. A 206 junior (Kid Kart engine) in Canada will go much longer than a Senior 206 in southern California or Arizona.
If we weren't racing and wanted to get every last .001 horsepower out of the engine it would run virtually for ever.
The problem would be that the engine is so dependable that people would be lulled into forgetting to check or change the oil and guess what happens then?
Or it would ingest so much dirt through a dirty or missing air filter it would wear the rings out and use oil until it ran out.

Best of luck.
Jim
 
We just pulled a leaky head ( a ton on the exhaust - a bit on the intake). How clean does the deck need to be before putting the new one on? (with WD40 and a gentle microfiber towel there are just a few specs now I can't even feel with a fingernail). We mixed up the pushrods - they are both steel and seem identical but I'm not sure if we messed up by doing this.

Are there any tips for shipping a head to one of our experts on the board? We've had the valves replaced once already on it but if we can keep using it for racing I'd like to keep it since it has already been heat cycled like crazy.
 
We just pulled a leaky head ( a ton on the exhaust - a bit on the intake). How clean does the deck need to be before putting the new one on? (with WD40 and a gentle microfiber towel there are just a few specs now I can't even feel with a fingernail). We mixed up the pushrods - they are both steel and seem identical but I'm not sure if we messed up by doing this.

Are there any tips for shipping a head to one of our experts on the board? We've had the valves replaced once already on it but if we can keep using it for racing I'd like to keep it since it has already been heat cycled like crazy.
Mixing the pushrods shouldn't be a big problem. I like to keep all of my valve train separate -- I use clothes pins for the exhaust side.
Clean the deck well -- you can scrape if absolutely necessary with a razor blade. No visual on the deck surface, BUT be careful not to get gouges in it.
 
Jim or Brian do you have any LO206 heads that have been heat cycled a few times and the valves seats recut as you say and ready to ship? Will they pass tech?

Thanks
 
I do not. They are all on engines.
I recommend that customers send their heads to be re-cut after a few race days or practice days.
I have heard of artificial ways of heat cycling the heads, but nothing can simulate the localized heating and compressing like simply running them.
This time of year, I do not have time to heat cycle heads to sell off of the engine.
I can sell you brand new heads, but they've not been heat cycled.
 
Ok NO BS Here:
Taking a new head and heating it in an oven will never settle things in position like actually racing the engine multiple times.
You are wasting your money !!!!!
For anyone to really do it properly to a new head would require many hours of labor and simulating actual race conditions.
If you want to pay for it i'll be happy to do it for you but it will be very expensive.
I would recommend you send me one of yours that has as much time on it as possible and i can freshen that one for you.
It will be the best it can be.
I'm sorry but i do not have any used heads on the shelf for you.
 
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It sounds like have a spare head would be worthwhile. This way you can install the refresh rebuild and ship the old in for repair. No downtime and if you ever find it leaking at an inopportune time you can simply swap it out between rounds. I have spare of almost everything else why not..
 
It sounds like have a spare head would be worthwhile. This way you can install the refresh rebuild and ship the old in for repair. No downtime and if you ever find it leaking at an inopportune time you can simply swap it out between rounds. I have spare of almost everything else why not..
We just got a 2nd head and will start doing this. Makes it a lot easier to schedule maintenance.
 
Ok NO BS Here:
Taking a new head and heating it in an oven will never settle things in position like actually racing the engine multiple times.
You are wasting your money !!!!!
For anyone to really do it properly to a new head would require many hours of labor and simulating actual race conditions.
If you want to pay for it i'll be happy to do it for you but it will be very expensive.
I would recommend you send me one of yours that has as much time on it as possible and i can freshen that one for you.
It will be the best it can be.
I'm sorry but i do not have any used heads on the shelf for you.
This is GOSPEL !!!
 
Ok NO BS Here:
Taking a new head and heating it in an oven will never settle things in position like actually racing the engine multiple times.
You are wasting your money !!!!!
For anyone to really do it properly to a new head would require many hours of labor and simulating actual race conditions.
If you want to pay for it i'll be happy to do it for you but it will be very expensive.
I would recommend you send me one of yours that has as much time on it as possible and i can freshen that one for you.
It will be the best it can be.
I'm sorry but i do not have any used heads on the shelf for you.

Jimbo...
https://4cycle.com/karting/threads/the-hot-head.105349/
 
Brian and Jimbo. It sounds like there is a market for heat cycled heads and I can help. Send me a new head, a gasket and a case of beer and I will put them on my sons kart. He will work on heat cycling them while i work on the case of beer. Once complete I will ship it back and move on to the next...
 
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