Port Matching Heads/Intake Gaskets

Ron, Do yourself a favor here. Only do what is needed to clean the ports to each other. I would tend to lean this way no matter what the rules people want to say. Port matching is a bit different that actual Porting. I would look at the head and the intake and decide what needs the most work within the 1" rule. Keep it very clean and dont create any large bumps in the port. then clean the other component to match. creating a big as cobra neck to fit a gasket will cost you more HP than gain you. Same goes for the exhaust. I know what the rule says but sometimes being cute with a rule will cost you more than it gets you.

Joe
 
<font face=\"Verdana, Arial\" size=\"2\">you mentioned that the butterflies were there to increase intake flow velocity...which is to better atomize the fuel for a cleaner burn, right??? See where I'm going? Sounds like emission control to me! </font>
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Nope.

It's actually done to make a variable-tuned runner. Higher velocity increases some of the "stack effect". It also does help promote swirl and tumble, which contributes to clean-burn (as you're saying). The combined effect was more torque, and actually done for more drivability. I've seen a white-paper on it somewhere, but I can't track it down right now.


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Matt Green
"Ain't nothin' improved about Improved Touring..."
 
Racer bill.

Usually we mock up the gasket to the head, and dykum the area to be removed, and then mockup the gasket to the intake, and repeat.

This is something I would generally leave to a porting pro, as they know how to make the most of this job and not muck things up.

My 2 cents.
 
This is preceisely what I did. The studs make sure it will align properly and the gasket was used as a template for the dye. I blended and removed material to match the gasket, therefore, both ports should match correctly - hence port matching. I've done a bunch of these before and it is not hard, just takes a bunch of time and a bunch of cartridge rolls and a good die grinder.

Increase in flow? I wouldn't expect much, just whatever you get from not having the ports 1/8" off as they were on mine in addition to the centers not aligning. I don't think it will hurt flow either since I could not touch the runners or bowls.

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Ron
http://www.gt40s.com
Lotus Turbo Esprit
Ford Lightning
RF GT40 Replica
Jensen-Healey: IT prep progressing!

[This message has been edited by rlearp (edited November 16, 2004).]
 
Originally posted by Renaultfool:

"Match" is the defining word that limits the modification in my opinion, and it can be looked up in the dictionary for those of you who do not know what it means.
From the Websters Seventh New Collegiate, the definitions that pertain are, as a noun, (1,a) a person or thing equal or similar to to another, (1,c) an exact counterpart, (3,a) a process of matching, and as a verb, (3,a,2) to cause to correspond, and (4) to fit together.
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this argument can be torn apart too. "thing equal or similar to to another" What's the exact definition of what similar can be? What's the specification of how close you have to make it similar? There isn't one. So if you took off 0.005" too much and it isn't a match i'm illegal? You can't expect exact tolerances so you have to have some variance allowance. But that isn't in the rule and shouldn't be cause it will make it ridiculous. This leads to my next disagreement with your interpretation.

Originally posted by Renaultfool:



Quickshoe,it would be very easy to tell if someone had gone too far. If you "match" them as Festus and I think it says, you would just remove the material necessary to line them up, remove the overlaps. This would mean that if one port is bigger than the other one all the way around, only the smaller mating port would be altered up to 1" from the manifold face to match the larger port. The originally larger port would be as cast and look like the rest of the unmodified port. If one port was offset from the other one, one port would be gound on one side and the mating port would be ground on the other side. The two unmodified halves would be as cast, look the same as the rest of the unmodified port. It would not even take any specilized tools, a visual inspection would tell, the same check that would be done for any other illegal porting.
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The other thing you're missing is that not always is it a certain half of the port needs matching. Sometimes and a lot of the times there's flaws all the way around the ports on both the manifold and head that can't be matched to the other. Sometimes there's a slight curve on the floor, roof, wall of the port that you can't make identical to the other side without adding material, which you specifically can't do. And that's when you need to remove material from both sides to get them to match, which this rule allows for. And no one knows what your exact casting looked like before so it's not that easy to see visually if it's illegal. That's where the difference lies and the rule allows for. It's not always possible to "match" one side to the other and you can't even see that after the work has been done, so how do you tell someone they're illegal for that.

And 1" into the port isn't going to do anything performance wise.

And to the person that says you shouldn't do anything without a flow bench. Flow bench's are just as inaccurate and should be taken with a grain of salt as a dyno chart is. I can make a head flow 10% more than it did before at all valve lifts, doesn't mean it's going to make the car faster at all. It's just a means of comparison. You can make a head flow as much CFM as you want, it doesn't make it useful. Each head responds differently, and you can't see that in flow bench numbers.

One of the best quotes I heard from a well know head porter who has been doing them for a long time. A relative newb was talking to him about techniques and flow bench numbers of various heads, and the guy says "oh, you're a flow bench numbers guy. Yeah, well I'm a track times guy. That's how I build heads." Great quote and should always be remembered. A flow bench is a tool, but only one tool and usually doesn't tell the whole story.

s



[This message has been edited by stevel (edited November 16, 2004).]
 
I have been researching Port Matching recently as I am considering a Limited Prep EP car that follows the IT head prep rules.

I was under the impression as mentioned many times in this post that one would use dyekem and trace the gasket, etc, etc.

I recently bought a Mustang magazine that has a n article on head porting by a guy that has done heads only since the 50's.

One of the first things the article says is that people mistake GASKET matching with Port matching. Two different animals according to this head guru. Port matching,is taking your best port , transferring those dimensions to the rest of the ports and matching them up. Gasket matching is as has posted above.

Hmmm???

Victor Penner
 
Might be one of those things that needs clarification in the rulebook, your explination is logical.

But, if so then there will be a lot of illegal cars out there!

R

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Ron
http://www.gt40s.com
Lotus Turbo Esprit
Ford Lightning
RF GT40 Replica
Jensen-Healey: IT prep progressing!
 
Now you are getting it!

It is not what we want it to say, but what it says. Even if it does make a lot of cars illegal. That has been my point all along.

In most cases matching to the gasket will make them lose power instead of gain power anyway. This is because it will make your port look like a snake that swallowed a mouse. The fuel/air mixture will slow down in the fat place. Unless the intake ports are short and you open the top of the port way up to allow for a better angle to the intake valve. That won't work on long intake ports though.
 
Originally posted by Renaultfool:

In most cases matching to the gasket will make them lose power instead of gain power anyway. This is because it will make your port look like a snake that swallowed a mouse.
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In some cases, yes. But, in my personal case there is no way I'll do anything but gain. They are only a tiny bit larger, it won't kill velocity, but there are real gains to be had on crappy British parts from 1970s. Hell, the bolt holes that align the parts hardly line up well, the ports damn sure don't.



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Ron
http://www.gt40s.com
Lotus Turbo Esprit
Ford Lightning
RF GT40 Replica
Jensen-Healey: IT prep progressing!
 
I just spent a little time on GOOGLE and came up with quite a few Port Matching results. Mainly "how to" and mainly V8 but helpful none the less. Some of the articles are actually titled "Port/Gasket Matching" so, as on this board, there is MANY interpretations. I am personally favorable to the "gasket match".

Victor Penner
 
***I have been researching Port Matching recently as I am considering a Limited Prep EP car that follows the IT head prep rules.***

Victor, have you searched the Production site for the thread on IT head prep ?

Interesting
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David
 
David,

Yes I have. I didn't participate in that one but I do believe that in Limited Prep Production the GCR is talking about the Head only(as far as IT prep) because the valvetrain is addressed seperately.

Victor Penner
 
Tom, Victor rooted out the issue I was refering to. The PCS spec line IT head prep is relating to the IT bare head prep. Not the assembled head with all the components.

Have Fun
wink.gif

David
 
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