Porting 101

[Brian13]

Got it, makes sense now. Thanks.

 

[Terry Syd]

Brian, it allows the cylinder to 'blowdown' prior to the transfers opening. If there is still significant pressure in the cylinder the exhaust gases will blow into the transfers when they open.

It is usually calculated in degrees, but the area of the opening is just as important (the combination is called time/area). That is why you see the porters making the exhaust port wider. It gives more area for the blowdown period.

 

[Brian13]

Ok, its starting to all make sense. Right now all the numbers still mean nothing to me, but I am getting a general idea of how it all works. There is a lot to take into consideration when porting.

 

[parrisw]

Ok, its starting to all make sense. Right now all the numbers still mean nothing to me, but I am getting a general idea of how it all works. There is a lot to take into consideration when porting.

It'll start to make more sense when you do it. The hardest part is getting consistent with the degree wheel, check out my thread on making a degree wheel, your better off to buy one then make one out of paper, it will be more accurate, and get one that's at least 7".

 

[gink595]

Ok, its starting to all make sense. Right now all the numbers still mean nothing to me, but I am getting a general idea of how it all works. There is a lot to take into consideration when porting.

Like parris said it will make alot more sense when you physically degree one. Alot of guys will talk total duration numbers, to me that doesn't really matter. I use port openings to make sense of it. Now when I hear a exhaust is at 80* I know that the exhaust has been raised considerable, but if you were to tell me the exhaust is at 200* duration that doesn't really make it that clear on how high the exhaust is. Whatever works for someone I guess but total duration numbers are just some thing I have to reduce mathematically to get the info I really need. But it does sounds fancier:msp_biggrin:

 

[parrisw]

Like parris said it will make alot more sense when you physically degree one. Alot of guys will talk total duration numbers, to me that doesn't really matter. I use port openings to make sense of it. Now when I hear a exhaust is at 80* I know that the exhaust has been raised considerable, but if you were to tell me the exhaust is at 200* duration that doesn't really make it that clear on how high the exhaust is. Whatever works for someone I guess but total duration numbers are just some thing I have to reduce mathematically to get the info I really need. But it does sounds fancier:msp_biggrin:

Ya, what he said! I work with both numbers Frank, I feel that it allows me to be more accurate and easily check my work back and fourth. Like if ex is at 160°duration, I know it should be 100°Atdc, so I'll find TDC then check opening and if I get 100° I know I'm bang on.

 

[Brian13]

A degree wheel is on my list of things to get. One thing that I noticed when looking at them is they all seem to only go to 90* and count back down to 0*. Thats what I am looking for right?

 

[gink595]

Summit Racing SUM-G1057 - Summit Racing® Cam Degree Wheels - Overview - SummitRacing.com

 

[tlandrum]

Summit Racing SUM-G1057 - Summit Racing® Cam Degree Wheels - Overview - SummitRacing.com

thats the one i have too

 

[Brian13]

Thanks, its on the way.

 

[parrisw]

Here is an idea if you have access to a lathe you can do it up nice.

And ya Frank I know of others that do it too! LOL

 

[Brian13]

I saw that, and I like that!! Looks real nice, but I dont have access to a lathe. Me and my dad have been looking for a small one used, so we can have another piece of equipment that we really dont need LOL.

 

[parrisw]

I saw that, and I like that!! Looks real nice, but I dont have access to a lathe. Me and my dad have been looking for a small one used, so we can have another piece of equipment that we really dont need LOL.

Maybe you can find someone to do it for ya, its literally like a 2 min job to put a lip on the chuck so the degree wheel fits nicely.

 

[Brian13]

I will have to look into that for sure. Looking at the pics it looks pretty simple, just have to see if I can find somebody around here with a lathe.

 

[blsnelling]

Where's the best place to pick up a chuck?

 

[tlandrum]

lowes or home depot usually have the keyless chuck

 

[blsnelling]

lowes or home depot usually have the keyless chuck

$25, LINK.

 

[parrisw]

Where's the best place to pick up a chuck?

Any place that sells tools, its doesn't even need to be keyless, mine isn't and I can get it plenty tight enough.

I will have to look into that for sure. Looking at the pics it looks pretty simple, just have to see if I can find somebody around here with a lathe.

Yep its easy. I'd do it for you guys, but would cost a few bucks to ship them out.

 

[Brian13]

I was thinking last night( not always my strong point), for those of us with no easy access to a lathe could you just use a large flat washer to sandwich the degree wheel to the chuck? Seems plausible but I dont have a chuck in front of me just yet. I am going to see if my dad has any dead drills that I can steal a chuck from. He has enough stuff I should be able to find something laying around.

 

[gink595]

I was thinking last night( not always my strong point), for those of us with no easy access to a lathe could you just use a large flat washer to sandwich the degree wheel to the chuck? Seems plausible but I dont have a chuck in front of me just yet. I am going to see if my dad has any dead drills that I can steal a chuck from. He has enough stuff I should be able to find something laying around.

If you buy the summit wheel it comes with the adapters and you won't have to worry about it. Just find a chuck and the metric bolt and your good to go.