1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

is my practice port job okay?

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Old May 27, 2010 | 12:11 AM
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rxmadness's Avatar
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From: hudson, wi
is my practice port job okay?

im just practicing my race ports on junk housings before i do the real engine nest week, i have a few questions
1. should the intake ports be completly smooth and polished?
2. should i go deeper with the intake ports or did i do it right by tappering the top of the port out.
3. how much should i bevel the edges of the intake port?
4. when i do the exhaust ill put up some pics but im worried about that one because the race port exhaust is a freakin HUGE upside down "D". how should i go about that one? and should i remove the sleeve or leave it?
thanks

oh and if your looking at that little oops i did with the dremel off to the side of the port, dont worry about it i was just curious as to what happens when you slip lmao it wont happen on the real engine



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Old May 27, 2010 | 12:24 AM
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You want less of a lean coming into the combustion chamber. Also, a big part of porting is the actual size increase of the port itself. It looks like you left that stock. Your method might be different but I try to judge the size of the ports with my fingers. A stock 4 port, I can usually fit 2 fingers up to the knuckle on my middle finger. I'll try to port it to the point that I can get my knuckle in and finger tips in the combustion chamber (1mm off top and bottom). This is where you need to be careful because going too far one way can have you ending up in the coolant passageway real quick.

Bring the port back down about 1-2mm, see if you can get less of a lean into the chamber and more of a lip.

For a practice, the port looks good, it looks like the bit wasn't jumping around on you. The roughness of the port looks good, the shape is just a little off. You don't want a mirror finish port, the air needs to have a little bit of turbulence going into the engine.

Hope my info helps!

The ideal port your looking for is something like this:
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Old May 27, 2010 | 12:31 AM
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ya i thought it was a little wierd lookin when i got my mazdatrix raceport templates, because i was thinking the port should be enlarged a little around the bottom and on teh sides but when i lined up the template all it did was extend it up..so?? im a little lost now
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Old May 27, 2010 | 12:35 AM
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Originally Posted by rxmadness
ya i thought it was a little wierd lookin when i got my mazdatrix raceport templates, because i was thinking the port should be enlarged a little around the bottom and on teh sides but when i lined up the template all it did was extend it up..so?? im a little lost now
Sorry for the confusion, you don't want to extend the port itself down. Following the template, you should be able to take the port a little deeper. You don't EVER want to port down. The sides can go out a little bit depending on where the corner seal is riding, but then you have a chance of dropping a corner seal in the port.

If you were following a template on the port, you want to make it deeper to have a lip on the closing edge.
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Old May 27, 2010 | 12:38 AM
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heres what i got when i lined up the template with the dowels, i dont really undertsand that one, also the bottom of the template was the same diameter as the stock port.....
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Old May 27, 2010 | 12:40 AM
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Originally Posted by g14novak
Sorry for the confusion, you don't want to extend the port itself down. Following the template, you should be able to take the port a little deeper. You don't EVER want to port down. The sides can go out a little bit depending on where the corner seal is riding, but then you have a chance of dropping a corner seal in the port.

If you were following a template on the port, you want to make it deeper to have a lip on the closing edge.
ok, this makes sense, i was just worried about going to deep and making thin spots into the waterjacket but i see what youve done that makes sense
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Old May 27, 2010 | 01:03 AM
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Originally Posted by rxmadness
ok, this makes sense, i was just worried about going to deep and making thin spots into the waterjacket but i see what youve done that makes sense
Stick your finger in the coolant port next to where you are porting into. When it
starts to get hot then you are close enough
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Old May 27, 2010 | 01:09 AM
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From: hudson, wi
lol seriously? thats funny ok well im going to start porting deeper, and make it flow nicer tomorrow and see what you guys think before i go to the real engine

thanks for the info everyone
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Old May 27, 2010 | 03:14 AM
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From: hudson, wi
looking at the last pic i posted does it look like im getting the template lined up right?
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Old May 29, 2010 | 11:40 PM
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Yes. It looks like you have the template lined up pretty well. You just want to take the bowl deeper. You might also want to try making the port runner larger. This (if done right) can make more of a difference than changing port timing can.
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Old May 30, 2010 | 09:32 PM
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From: hudson, wi
thanks guys im starting to port the other irons tonight ill put up pics for yall
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Old Jun 1, 2010 | 02:59 PM
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Getting there! The port should not be shiny, polished.

gd
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