well guys, some of you know already that my head is currnetly getting rebuilt with all fresh internals and milled .002". 3 angle valve job.

my question is that my dad was messin around with my spare b18b head. and he had this porting tool from back in his day. But anyhow he took the gasket off the head that is gettin rebuild, slapped it on the spare head, traced around it and took the porting tool to the exhaust ports and ported it out all the way to the port matched the gasket. I guess this process is called gasket matching? As soon as i get my computer up and running im gonna post pics of it and see what you guys think. Wether i should go what the "old timer" dad says or just have the shop do a port n polish for say 5k - redline? Will this flow well with the dc jdm 4-1 that has larger ports anyway?

Now what it looks like:
- took about .25" on each side, making a total of about 1/4" tooken off.
- The ports are fairly rough and the sides of the ports are straight and are not , beveled in or curved in etc, i guess you would call it, well instead of the port being like / |
its like | | being the lines are the sides of the ports.

I would like to see all opinions, i was reading in the flow quality/velocity article that if i would make the ports too big i would lose power and have a peaky power band?

 

Yes, the openings can be too big. You should be good as long as the openings match the gasket. I work in aerospace, specifically the Air Flow Development Center of a company. When air makes a transition from one orefice to another and the mating surfaces are different diameters, the air will hit the mating surface and actually swirl backwards, only allowing the center column of air to pass through. Its hard to explain without drawing a picture. I just bought the EDELBROCK Victor X Intake manifold and the first thing I did was take out the Dremel and gasket match it. Its alluminum so it was fairly simple to do. I hit it 500 grit sand paper when all was said and done and the finish is nice and smooth.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Steak84SS &raquo;</TD></TR><TR><TD CLASS="quote">Yes, the openings can be too big. You should be good as long as the openings match the gasket. I work in aerospace, specifically the Air Flow Development Center of a company. When air makes a transition from one orefice to another and the mating surfaces are different diameters, the air will hit the mating surface and actually swirl backwards, only allowing the center column of air to pass through. Its hard to explain without drawing a picture. I just bought the EDELBROCK Victor X Intake manifold and the first thing I did was take out the Dremel and gasket match it. Its alluminum so it was fairly simple to do. I hit it 500 grit sand paper when all was said and done and the finish is nice and smooth. </TD></TR></TABLE>


ic so is the intake manifold gasket matched stock on a 94 ls do u know?

i understand exactly what u are talkin about tho so no need to worry.

im beginning to worry that the ports are gonan be too big and im wondering if i should just go to the shop and get it done.

 

I also have a 94LS. I had the company that ported and polished my haed do the gasket matching on the head. So to answer your question, NO the head is not already gasket matched. I did my own IM matching.

 

Port n' Polishing should not be attempted if you have no real knowledge on what you are doing. To properly PnP a head you need to understand flow caristics and have a flow bench to test what you have done. It is easy to mess up a head, you can make the car slower and ruin a good head. I'd pay someone else if you have never done.

 

well guys i just got back from the shop and they are gasket matching the exhaust ports and polishing and they said 75-100$ im thikni nabout just having htem do the whole head. and they perfectly explained to me what was anti-reversion so finally i understand.

 

I had the head ported and polished and gasket matched and it ran me $400 plus tax. Its not a super easy job.