degree an engine?

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ValveSpring

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I'm a little confused on how to degree the intake and transfer ports on my engine. I know with the exhaust port I start at the top of the port and move the piston down and count the degrees until the piston closes the port again. My question is, for the other ports do you start at the top of the port or the bottom of the port?

ValveSpring
 
You should take all port measurements from the top side of the ports for the open duration.
 
Alright, thanks. So if I want to increase the timing of ANY port I need to move the port up right? If thats the case, what are the effects of moving the port down?

ValveSpring
 
Not sure how you would move the ports down, unless your talking about cutting the bottom side in which case you will gain nothing. Don't touch the bottom of the exhaust port or it may open a window into the block at tdc which will have a negative effect on performance.
 
Thanks Pure for the help. I'm just learning how to do this stuff and from what I have read you are the best in the business to learn from. Thanks again.

ValveSpring
 
Its an Axial .28 spec 1. I really had no plans on modding it until the mid range needle fell out of the carb while running. Since I had to take the engine out any way to clean it, I thought what the heck lets try some modding.
 
Just be very careful as it is extremely easy to mess up, I say if you can't walk to a garbage can and toss your mill in and walk away, don't mess with it. I have worked on previously modded engines that were ruined and needed new parts just to run right again. Take your time and just remember that clean up of your grinding is just as important as the grinding itself. Good luck.
 
Great advice!! I actually have a new piston and sleeve in my shopping cart at tower just in case I ruin it on my first try.

ValveSpring
 
Here are some pics of the sleeve.

IMG00043-20090820-1844.jpg


IMG00042-20090820-1843.jpg


IMG00039-20090820-1838.jpg
 
Last edited by a moderator:
Thats where I got the ideas from. I have not run it yet, still waiting for the carb needle to come in. I have put the engine back together so I can run it before I make any timing changes. Should I make any porting changes next time I have it apart?

ValveSpring
 
The porting looks like it's all done, no need to change anything. Did you try running the piston up and down in the sleeve before you put it together? If not I would take it apart and try it. It "looks" a little rough from the pictures but it's hard to tell for sure.
 
The pictures are before the full polish was done. I also very lightly debured the inside of all the ports. The piston moves nice and smooth.
 
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