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Discussion Starter #3
no problem! Has anyone done this (thats not a professional)? or will I be the first? :eek:
 

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Not me. I guess it depends on what kind of heads your gonna try and do it on. Some cheap GM casting's, why not try it. For an expensive set of heads, personally I would leave it up to someone who knows what they are doing and has access to a flow bench.
Just my 02.
 

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Yepp, did it to a Mu$tang I had when I was younger. the heads and lower intake were aluminum and you have to be real careful if you're using a peanut grinder on such a soft material. If you're grinding on cast iron then you take less material off at once. Just take your time...it's not really that hard. I didn't read the articles you posted links to but you can match the intake to the heads and the gaskets also.


Good luck! Take some pictures and let us see your progress.

P.S. If you get feeling comfortable you can try to polish the exhaust ports on the heads....I did that one too.
 

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The best advice I can give you is find some cheapo crappy heads to practice on before you try and grind away some nice trick flows or something. Also A while back I had purchased a gasket intake template kit that came with just about every gasket ever made which is good for matching ports made by MR Gasket part #73074G. Its awesome for figuring out exactly how far you can go with the ports. Mr gasket also offers this part # 4362



Here is a link to thr port gauge i mentioned so you can see what it looks like.

http://go.mrgasket.com/pdf/promotional.pdf
 

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Discussion Starter #7
thanks for the info!

I will be port matching my Victor Jr. intake and my GM high compression heads.

I was going to try to polish the exhaust ports.. one of the links details it.
 

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Discussion Starter #8
Could we get these links sticky'd for future reference? or moved somewhere that they dont get lost?

Thanks,
Chris
 

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I'll put this in Best of Tech.
 

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What gains could I exspect And should I do it.(porting)

What gains could I exspect over what I have now If I ported my Heads.
I mean bowl blending port matching everything With out going over board.
Also including polishing the exhaust ports.

The reason i ask if I should bother doing it is the motor is in the car and will take a while to do. I figure 50+ hours on the port work its self. Would the gains ..all be it free... be worth the time?

These are G2 twisted wedge heads on a 355.Dont know what power is at this point but I ran a 12.77 at 106mph..
 

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That's a hard question to quantify. Your results are going to be directly tied to the quality of the porting. Small changes can make differences both positive and negative. Without a flow bench how will you know if you made an improvement or not? It's also possible to have inconsistant results port to port.
I'll tell you porting is an art and requires good hand to eye co-ordination. It's real easy to get wavy surfaces, inconsistant radii, take off too much (especially on aluminum) Once the material is gone it's gone.

My advice is to practice porting on heads you can afford to mess up on. I wouldn't use expensive aluminum heads as your first try.

True story:
I had a co-worker who wanted his $25 heads ported. Of course I think he wanted me to do it for free. He seemed skeptical it would take so much time and it "wasn't that hard to do". It got to the point where I finally had to invoke the "first rule of lifesaving".
I told him he was welcome to try it himself using all my expensive equipment.
I set him up on the bench and showed him what to do. He quit after about an hour and a half. His 1st port had so many ripples, waves and dips it was basically ruined along with about $25 worth of my grinding bits. I think it was a fair trade.
He got an hour and a half lesson in porting and I saved two weeks of my time.

Here's a simple formula for potential HP from head flow.

Port CFM (at 28") x .25714 x # cylinders = HP potential (at peak power rpm)

Use 0.43 for flow taken at 10" and 0.27 at 25"
 

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How many cfm's can an "expert" head porter usually get out of a set of heads?

How about a "beginner," with just enough experience and guidance to not screw it up?

Kev
 

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I saw a set of 441 SBC heads ported by a beginner that didn't know what he was doing. They looked awesome huge ports smooth as glass they shined like mirrors. He had them pressure tested for water leaks to see if he had hit the water jackets. The heads leaked water everywhere and were worthless when they were done.
 

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I just got Info that the twisted wedge heads have very thin cast ports and bowls with 360* water jacketing around them So I think I will stay away from porting them...
 

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MarkM68 said:
Wouldn't cubic inches play a large part in using this?
It's important to note that I said power potential, not how much power you will get.

(sorry I got called away before I could finish)

200 cfm SBC heads could be bolted on a 283 or a 400. The actual results will depend on many factors.

At an efficiency of 1hp per CI you could get 283hp or 400hp but the same heads won't flow enough AIR to support 450 HP even if they're on a 500 CID engine.

Best Hp is the result of burning 1 part fuel to 12.7 parts of Air (by weight).

You need to supply about 1/2lb of fuel per hour for every HP. For 450 hp, that's 225 lbs of fuel per hour or which is only .008 gallons per second (2 table spoons).

Getting enough fuel into an engine is easy. You can get it rich enough to blow black chunks out the tailpipe.
However, you also need 12.7 lbs of air for every pound of fuel. For a 450 hp engine you need 2,857 pounds of air per hour. That's a lot of air!

Getting a lot of air to go in by itself is hard unless you force it in with a supercharger or introduce it chemically with Nitrous Oxide. It takes about 60 hp to run the supercharger on a 450hp Ford Lightning. Cramming over a ton of air is a lot of work.
A tank of nitrous is cheaper than a supercharger but it doesn't last very long. An hours worth of continuous spray would be very expensive, indeed.

In a normally aspirated engine, heads are the key to power production. The bowl and valve is the most restrictive part of the path so port matching often doesn't give the best gains.
If you have a lumpy idle cam with lot of overlap then it may be more productive to leave the manifold smaller than the port to act as an anti-reversion ledge.
The actual benefit depends on how bad the before was and how good the after gets.

Heads, intakes and carburators are not superchargers. A bigger CFM rating doesn't mean the engine will get more air, but generally speaking improvements in head flow improve power output.

Here's one final comment on head porting.

The 5 axis CNC machine has revolutionized head porting. Porting heads is nasty, grueling, exacting work. It's also very difficult for even the best head porters to duplicate good ports consistantly. It's also hard to train and keep head porters. Most quit to do something else. I'd bet there are less than 100 expert head porters in the country and surprisingly, the demand for more isn't really growing.

These days once a good port is developed it's mapped and programmed into a CNC machine. A head is done overnight instead of weeks later and very little hand finishing is required. It really cuts down on labor intensive skilled work.
Aftermarket CNC ported heads are a bargain compared to expertly hand ported heads.
I think the new 505hp Z06 even has CNC ported heads from the factory! A big change from the old crappy heads from the last century.
 

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start hogging out exhaust port passages and if yer not carefull, you'll bust through to water passage...


pocket porting is one thing (matching gaskets) but a full on port job requires lots of experience....
 
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