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Discussion Starter · #1 ·
im replacing my peanut ports with some 781's and adding a magnum 286 cam (comp) in the 468 and was thinking of getting a porting kit and a book and going for it:D ......... ive never ported any heads before but the machinist in me wants to get to grinding!! just wondering if its risky without a flow bench??....................what do you guys think?? any input and past experiences appreciated- joey
 

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Joey,
I think it is very worthwhile, as long as you dont get carried away. Basic smoothing probably gives the biggest payback of all. You dont really need to make the ports any bigger, just get rid of all the nasty bumps and sharp edges. The area directly below the valve and the "short turn radius" is probably the most important. This site has a lot of interesting information and I am sure there are others:
http://www.sa-motorsports.com/diyport.aspx

One thing I would highly suggest though .... see if you can find an old, junk head and jsut do one intake and exhaust port. Most guys do not have a clue how time consuming and messy this stuff is. If you do One cylinder on a junk head and you think you can stand it long enough to do them all, then go for it. I spent almost 4 hours last Thursday after 5 doing exactly the same type of job to a set of aluminum 91 Corvette heads. Took close to 4 hours and they were aluminum ... cut pretty easy. Think of how long cast iron will take :(

By the way, Make sure that you have your valves back cut. One of my guys is working on a Ford engine for a friend of his. He flowed a port with just the valve as it came out of the box, then with a back cut ... almost 15 cfm difference :eek: It may not be worth that much on every head, but it is an easy thing to do.
 

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excellent advise above, I would really practice on a junk head. I would just smooth out below the seat and around the guide along with the short side radius. Then just smooth the rest of the port with some sanding rolls. It's very time consuming but I enjoy it. Do as much research as possible then go for. More than likely you will need a valve job as you might nick the seats.
 

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A friend has a flow bench and it is amazing at how much damage you can do to the flow by grinding in the wrong places. Odds are that the heads won't flow as well as before unless you use a flow bench.

I would highly disagree, as long as you go in there and just clean up the bumps and casting flash you will get increased air flow.

now sitting there and grinding in one area trying to make a bigger hole sure will change the port design and hurt airflow.

but just with a simple clean up and round the short radius you will make big improvement.

my first bbc head port job included 40 hours of porting with a black and decker hand drill and several grinding balls ( about a buck each) and i borrowed a friends dremal with a dull bit to get to some places i couldnt get with the hand drill. i even slipped a few times across the single cut seat a few times (oopppps). i spent time on the short turn radius ( nasty lip on those bbc heads for sure)

i lapped the valves back in on the seats i oopsed on and put the stock valves back in 2.06/1.72

ran 13.90's before the head port job, one week after the 13.90's and 40 hours of grinding my car droped to 13.60's and gained 5 mph and was spinning more off the line then before.

the mph is the sign of hp and my hard work. thats another 50 hp just cleaning up my heads and not changing nothing else.

20 degree back cut on the valves i do now.
stay off the intake runner floor removed just enough to clean up the casting.
rough the intake with 60 or 80 grit paper.
polishing the exhaust waste of time dont do it.
smooth the turn on the short radius
stay out of the "pocket" straight across from the short turn radius right under the valves. do a small amount of grinding there. dont dig into the head there to much, if you dig to much the air comes flying down the runner and slams into the wall and just piles up there if you dig there.
dont remove the guides, did this once and ouch it hurt power down low because i could feel the difference and see the lost in 60 ft time. sure made the engine sluggish. but top end seem to be really good.

just some pointers im sure i missed some but you could spend hours talking about this subject.

read read read and listen to the ones who have done this and take there advise.
 
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I have used both!!

My 30,000 rpm Die Grinder that always scared my b/c it had a nasty habit of exploding the cheap, 1/4" shanked, Chinese stones I used in it.. AND

My 1/4" B&D hand drill and the same cheap stones..

You need to do TWO things tho!!

Wear good, (at least 3-M), paper dust masks and then wear GOOD eye protection like a Bulliard full face hardhat sandblasting shield as well as good wrap around safety glasses and just ask me why..........

I hate spitting cast-iron dust out of my lungs and head for at least three to four days AND I had to get my Buddy Doc to dig a piece of steel outta one of my eye's onna the time's I did this!!!

pdq67

PS., My Buddy Doc is an Eye Dr.......

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any one got any pics?????.............thanks for the advice so far!!
i have pics of some porting I did on some cheap ebay aluminum heads. Just look for a post I started. I have other pics if you would like for me to send them. I spent most of my time smoothing. I only removed material around the exhaust valve guides and intake port matched them. The original castings sucked. Anyway, it's pretty simple. Like the others have said, don't get carried away.
 

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I would highly disagree, as long as you go in there and just clean up the bumps and casting flash you will get increased air flow.

now sitting there and grinding in one area trying to make a bigger hole sure will change the port design and hurt airflow.

but just with a simple clean up and round the short radius you will make big improvement.

my first bbc head port job included 40 hours of porting with a black and decker hand drill and several grinding balls ( about a buck each) and i borrowed a friends dremal with a dull bit to get to some places i couldnt get with the hand drill. i even slipped a few times across the single cut seat a few times (oopppps). i spent time on the short turn radius ( nasty lip on those bbc heads for sure)

i lapped the valves back in on the seats i oopsed on and put the stock valves back in 2.06/1.72

ran 13.90's before the head port job, one week after the 13.90's and 40 hours of grinding my car droped to 13.60's and gained 5 mph and was spinning more off the line then before.

the mph is the sign of hp and my hard work. thats another 50 hp just cleaning up my heads and not changing nothing else.

20 degree back cut on the valves i do now.
stay off the intake runner floor removed just enough to clean up the casting.
rough the intake with 60 or 80 grit paper.
polishing the exhaust waste of time dont do it.
smooth the turn on the short radius
stay out of the "pocket" straight across from the short turn radius right under the valves. do a small amount of grinding there. dont dig into the head there to much, if you dig to much the air comes flying down the runner and slams into the wall and just piles up there if you dig there.
dont remove the guides, did this once and ouch it hurt power down low because i could feel the difference and see the lost in 60 ft time. sure made the engine sluggish. but top end seem to be really good.

just some pointers im sure i missed some but you could spend hours talking about this subject.

read read read and listen to the ones who have done this and take there advise.
Listen to this advice. This comes from experience as anyone that has ever ported heads should be able to tell. I burned up two drills before I got an electric hi speed grinder from Sears. Also before I had a garage and compressed air. Somewhere about 35 years ago.
 

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I have used both!!

My 30,000 rpm Die Grinder that always scared my b/c it had a nasty habit of exploding the cheap, 1/4" shanked, Chinese stones I used in it.. AND

My 1/4" B&D hand drill and the same cheap stones..

You need to do TWO things tho!!

Wear good, (at least 3-M), paper dust masks and then wear GOOD eye protection like a Bulliard full face hardhat sandblasting shield as well as good wrap around safety glasses and just ask me why..........

I hate spitting cast-iron dust out of my lungs and head for at least three to four days AND I had to get my Buddy Doc to dig a piece of steel outta one of my eye's onna the time's I did this!!!

pdq67

PS., My Buddy Doc is an Eye Dr.......
Very good advice-porting and valve seat related work is very dusty. Find a way of hooking a shop vac up to the area you are porting-this will help get a lot of the dust out of the air.
 

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Hmm....I used very low speed from my grinder, much easier to control/ I second the "practice on another part". no matter how good your intentions are you will make some mistakes...

One of my backyard hackery:D attempts for an 89 TPI Vette I sold late last year. Was going to do a smog legal 406 sleeper for it.



 

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When I was 16 I took my dads die grinder traced out using the intake gasket made a oval wood piece the size of the hole after grinding one, ground out all the ports and made sure the wood piece would go all the way down with out touching. Man that 69 Nova ran good.
Just a note to fathers, No 16 year old boy should have a 300 hp plus 4 speed Nova
 

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Home-style head porting can be beneficial if you don't try to take out a bunch of material. Match the ports, grind off the excess flashing and do not change the shape of the short radius (floor) of the intake port.

As far as equipment goes, it is imperative to have a good high speed grinder (20,000 RPM or more) in order to do a respectable job, in my opinion. As pdq pointed out, cheap stones are very dangerous and should be avoided. Pay the extra bucks and get the good cutters and stones. Air powered die grinders work best for me, but I still have the old Sears electric die grinder that I have used since the 1970's.
 

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I did my own first port job on a set of 781's about 10 years ago under the guidance of a machine shop owner. I spent over 30 hours on opening the intake and exhaust runners on gasket match according to what he told me. When I brought him the heads to show my work the guy said "That is some of the best work Ive ever seen, but its enough to make me cry" "Make me cry cause you took mateterial out of the floor of the exhaust runner and now those heads are really good, for boat anchors" Moral of the story: Be sure, and know what you are supposed to do before you even put a grinder in your hand.

On a good note the machine owner felt bad as he forgot to tell me to not take material out of the exhaust runner floor...he allowed to to steal a set of unmolested 781's off a pick up he had for no charge.
 

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Discussion Starter · #16 ·
I did my own first port job on a set of 781's about 10 years ago under the guidance of a machine shop owner. I spent over 30 hours on opening the intake and exhaust runners on gasket match according to what he told me. When I brought him the heads to show my work the guy said "That is some of the best work Ive ever seen, but its enough to make me cry" "Make me cry cause you took mateterial out of the floor of the exhaust runner and now those heads are really good, for boat anchors" Moral of the story: Be sure, and know what you are supposed to do before you even put a grinder in your hand.

On a good note the machine owner felt bad as he forgot to tell me to not take material out of the exhaust runner floor...he allowed to to steal a set of unmolested 781's off a pick up he had for no charge.
i just smoothed mine (exhaust floor) didnt even gasket match......hope mine are allright..
 
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