DIY Head porting??
Thread Starter
Racer
Joined: Oct 2000
Posts: 487
Likes: 1
From: Aloha, OR, USA
DIY Head porting??
I have my engine far enough apart now (replacing cam, lifters, valve springs, etc.) that I decided it's just not that much more work at this point to pull the heads and do a port/polish job. I am thinking of getting the Standard Abrasives kit and going to work.
Anyone want to share their experiences at doing this? Especially horror stories to help me avoid catastrophies like grinding into water jackets etc.? :eek:
Thanks,
John.
Anyone want to share their experiences at doing this? Especially horror stories to help me avoid catastrophies like grinding into water jackets etc.? :eek:
Thanks,
John.
Race Director
Joined: Sep 1999
Posts: 11,358
Likes: 379
From: Plano TX
Re: DIY Head porting?? (john73bb)
I've ported a set of heads or two. My advice is to concentrate on a pocket port, with some short turn radius and valve guide work.
Once the valves are out you will notice that the port necks down just below the valve seat. Enlarge this section to 85-90% of the seat diameter. MORE IS NOT BETTER HERE: Do no go above 90%.
Next reshape the guide where it enters the port. I like a tear drop shape here.
The short turn radius should then be improved. Try to make it smoother without taking too much off. Water jacket is present below this point.
This will give you a nice power boost without getting in over your head. Leave reshaping of the actual port to the pros. Just clean up any casting flaws.
Once the valves are out you will notice that the port necks down just below the valve seat. Enlarge this section to 85-90% of the seat diameter. MORE IS NOT BETTER HERE: Do no go above 90%.
Next reshape the guide where it enters the port. I like a tear drop shape here.
The short turn radius should then be improved. Try to make it smoother without taking too much off. Water jacket is present below this point.
This will give you a nice power boost without getting in over your head. Leave reshaping of the actual port to the pros. Just clean up any casting flaws.
Le Mans Master
Joined: Feb 1999
Posts: 6,807
Likes: 0
From: Hoosier
Cruise-In III Veteran
Re: DIY Head porting?? (john73bb)
I used the Standard Abrasives kit and found it insufficient. I needed more grinding wheels than they supplied. I'd suggest getting a few extra wheels and also some carbide rotary files. They also do not supply a wheel dresser. You need that to get and keep the wheels true, or the vibration will wear everything way fast and give you a poor surface.
Thread Starter
Racer
Joined: Oct 2000
Posts: 487
Likes: 1
From: Aloha, OR, USA
Re: DIY Head porting?? (AlwaysWave)
Thanks for the advice, I will follow it. I already have a carbide cutter or two, and if need be can get some more.
Where do I get a wheel dresser? Ace Hardware?
Should I port match the intake manifold to the head? That seems pretty straight forward.
Where do I get a wheel dresser? Ace Hardware?
Should I port match the intake manifold to the head? That seems pretty straight forward.
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
Re: DIY Head porting?? (john73bb)
In addition to other posts which I agree with, I used a cone shaped carbide bit to clean up the combustion chambers by smoothing the surface and removing a bit at the outboard of both valve to unshroud them.
Conventional wisdom is to smooth the exhaust runner as much as possible but leave the intake runner a bit rough for better atomization.
When complete, have your machine shop install a three angle valve job.
I spent about 25 hours on a pair of iron heads. Alum will go much faster.
Conventional wisdom is to smooth the exhaust runner as much as possible but leave the intake runner a bit rough for better atomization.
When complete, have your machine shop install a three angle valve job.
I spent about 25 hours on a pair of iron heads. Alum will go much faster.
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Thread Starter
Racer
Joined: Oct 2000
Posts: 487
Likes: 1
From: Aloha, OR, USA
Re: DIY Head porting?? (flynhi)
I now have my heads out, and they really don't look too bad. There is some flash, and some edges, but all in all they look pretty good. I do recall from when I put my intake manifold on last time, that I will need to open up the openings on the head and manifold quite a bit to port match them.
Do I want to grind off the valve guides to be smooth, or just use the sanding wheels to smooth what is there?
Do I want to grind off the valve guides to be smooth, or just use the sanding wheels to smooth what is there?
Le Mans Master
Joined: Feb 1999
Posts: 6,807
Likes: 0
From: Hoosier
Cruise-In III Veteran
Re: DIY Head porting?? (john73bb)
I get my wheels and dressing sticks from a local industrial supply house. Grind the valve guides to a taper(up/down) and also tear drop in the flow direction, like an airplane wing.
When you grind the exhaust ports at the exit side, leave the lower half unmatched to your header, but smooth out any flash or irregularites. Leaving that material there helps a bit with the reversion pulse.
[Modified by AlwaysWave, 4:58 AM 2/3/2002]
When you grind the exhaust ports at the exit side, leave the lower half unmatched to your header, but smooth out any flash or irregularites. Leaving that material there helps a bit with the reversion pulse.
[Modified by AlwaysWave, 4:58 AM 2/3/2002]
Instructor
Joined: Jun 2000
Posts: 198
Likes: 0
From: Buffalo, NY
Re: DIY Head porting?? (john73bb)
John, you'll want to print the Head Porting guide out from SA's motorsports page here http://www.sa-motorsports.com/diyguide.shtm. I find its a pretty good guide. If you're doing iron heads - WEAR A MASK! You'll be blowing black snot for days otherwise! If aluminum, GO EASY!
If you dont already have the 2.19/1.88 valves, you might consider this. Seat/bowl blending is key for mid-lift flow numbers. And good mid-lift flow is one key to max torque. A good shop with a Serdi seat/guide machine is the key here. Hitting the water jacket as they open closed chamberts up is a common mistake.
Dont spend gobs of time port matching the intake. We used to, but every indication is that it dont hardly mean a thing.
[Modified by 427TRI, 7:36 AM 2/3/2002]
If you dont already have the 2.19/1.88 valves, you might consider this. Seat/bowl blending is key for mid-lift flow numbers. And good mid-lift flow is one key to max torque. A good shop with a Serdi seat/guide machine is the key here. Hitting the water jacket as they open closed chamberts up is a common mistake.
Dont spend gobs of time port matching the intake. We used to, but every indication is that it dont hardly mean a thing.
[Modified by 427TRI, 7:36 AM 2/3/2002]
Thread Starter
Racer
Joined: Oct 2000
Posts: 487
Likes: 1
From: Aloha, OR, USA
Re: DIY Head porting?? (427TRI)
Thanks,
I read that guide through. It helps a lot. I also read the article in Car Craft. Pretty much the same info it look like.
I have the stock valves, and I think I will stay with them. I don't want to spend money for the bigger ones, or for the valve job.
John.
I read that guide through. It helps a lot. I also read the article in Car Craft. Pretty much the same info it look like.
I have the stock valves, and I think I will stay with them. I don't want to spend money for the bigger ones, or for the valve job.
John.
