Porting Heads for Street/Strip Use
November 6th, 2010, 09:45 AM
#1
65 post sport coupe w/425
Thread Starter
Join Date: Mar 2007
Location: Oregon City, Oregon
Posts: 122
Porting Heads for Street/Strip Use
Been awhile but started my second project (65 442). Frame and suspension are done, block is getting bored this week and I'm starting the head work. Don't want to over do it on the heads (A heads - no bumps) so looking at the following for some incremental performance:
Open up (gasket match) and polish the exhaust runners and bowl. Basically opened up the port to match the gasket then blended everything back to the bowl, cleaned up the bowl and teardropped the valve guide.
Open up the intake ports and runners but leaving the bowl alone. Haven't started this yet but was thinking I'd open up the ports similarly, blend the runners back to the bowl, not polishing the runners, leaving the bowl alone but teardropping the guide?
Leave Chambers alone.
Will run stock exhaust and intake manifold. Realize I won't get much in terms of performance and read something about leaving the intake bowls alone on street cars to get better drivability/atomization of gas at city speeds. Since I'll be running stock exhaust not planning to braze the crossover or fill risers. Sound about right?
Open up (gasket match) and polish the exhaust runners and bowl. Basically opened up the port to match the gasket then blended everything back to the bowl, cleaned up the bowl and teardropped the valve guide.
Open up the intake ports and runners but leaving the bowl alone. Haven't started this yet but was thinking I'd open up the ports similarly, blend the runners back to the bowl, not polishing the runners, leaving the bowl alone but teardropping the guide?
Leave Chambers alone.
Will run stock exhaust and intake manifold. Realize I won't get much in terms of performance and read something about leaving the intake bowls alone on street cars to get better drivability/atomization of gas at city speeds. Since I'll be running stock exhaust not planning to braze the crossover or fill risers. Sound about right?
November 8th, 2010, 07:57 PM
#2
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Join Date: Mar 2008
Location: Phx, AZ
Posts: 1,012
Been awhile but started my second project (65 442). Frame and suspension are done, block is getting bored this week and I'm starting the head work. Don't want to over do it on the heads (A heads - no bumps) so looking at the following for some incremental performance:
Open up (gasket match) and polish the exhaust runners and bowl. Basically opened up the port to match the gasket then blended everything back to the bowl, cleaned up the bowl and teardropped the valve guide.
Open up the intake ports and runners but leaving the bowl alone. Haven't started this yet but was thinking I'd open up the ports similarly, blend the runners back to the bowl, not polishing the runners, leaving the bowl alone but teardropping the guide?
Leave Chambers alone.
Will run stock exhaust and intake manifold. Realize I won't get much in terms of performance and read something about leaving the intake bowls alone on street cars to get better drivability/atomization of gas at city speeds. Since I'll be running stock exhaust not planning to braze the crossover or fill risers. Sound about right?
Open up (gasket match) and polish the exhaust runners and bowl. Basically opened up the port to match the gasket then blended everything back to the bowl, cleaned up the bowl and teardropped the valve guide.
Open up the intake ports and runners but leaving the bowl alone. Haven't started this yet but was thinking I'd open up the ports similarly, blend the runners back to the bowl, not polishing the runners, leaving the bowl alone but teardropping the guide?
Leave Chambers alone.
Will run stock exhaust and intake manifold. Realize I won't get much in terms of performance and read something about leaving the intake bowls alone on street cars to get better drivability/atomization of gas at city speeds. Since I'll be running stock exhaust not planning to braze the crossover or fill risers. Sound about right?
I would clean up the bowls first, and the guide bosses.
No matter what, you want to make all of the ports equal. Don't start on one, then give up, that makes your parts junk. Do all the bowls at the same time, and make them equal, then do all the guide bosses at once (equally), then see if you are up to anything else.
Forget the port matching, no real benefit, but if you go too big, a big loss in power.
Also, I would fill the heat risers and use an electric choke, even if you use the stock manifolds. Inexpensive HP here.
My Opinions.
Jim
November 8th, 2010, 09:16 PM
#3
65 post sport coupe w/425
Thread Starter
Join Date: Mar 2007
Location: Oregon City, Oregon
Posts: 122
I would do it differently.
I would clean up the bowls first, and the guide bosses.
No matter what, you want to make all of the ports equal. Don't start on one, then give up, that makes your parts junk. Do all the bowls at the same time, and make them equal, then do all the guide bosses at once (equally), then see if you are up to anything else.
Forget the port matching, no real benefit, but if you go too big, a big loss in power.
Also, I would fill the heat risers and use an electric choke, even if you use the stock manifolds. Inexpensive HP here.
My Opinions.
Jim
I would clean up the bowls first, and the guide bosses.
No matter what, you want to make all of the ports equal. Don't start on one, then give up, that makes your parts junk. Do all the bowls at the same time, and make them equal, then do all the guide bosses at once (equally), then see if you are up to anything else.
Forget the port matching, no real benefit, but if you go too big, a big loss in power.
Also, I would fill the heat risers and use an electric choke, even if you use the stock manifolds. Inexpensive HP here.
My Opinions.
Jim
Read somewhere that cleaning up the intake side too much will cause the gas to puddle affecting street drivability? Was not going to do much on the intake side except remove any obvious flashing, square up the ports a bit and teardrop the valve guides. Make any sense or on the wrong path?
November 9th, 2010, 06:45 AM
#4
Registered User
Join Date: Nov 2008
Location: Central Fl
Posts: 7,823
I would do it differently.
I would clean up the bowls first, and the guide bosses.
No matter what, you want to make all of the ports equal. Don't start on one, then give up, that makes your parts junk. Do all the bowls at the same time, and make them equal, then do all the guide bosses at once (equally), then see if you are up to anything else.
Forget the port matching, no real benefit, but if you go too big, a big loss in power.
Also, I would fill the heat risers and use an electric choke, even if you use the stock manifolds. Inexpensive HP here.
My Opinions.
Jim
I would clean up the bowls first, and the guide bosses.
No matter what, you want to make all of the ports equal. Don't start on one, then give up, that makes your parts junk. Do all the bowls at the same time, and make them equal, then do all the guide bosses at once (equally), then see if you are up to anything else.
Forget the port matching, no real benefit, but if you go too big, a big loss in power.
Also, I would fill the heat risers and use an electric choke, even if you use the stock manifolds. Inexpensive HP here.
My Opinions.
Jim
November 10th, 2010, 06:00 AM
#5
Registered User
Join Date: Mar 2008
Location: Phx, AZ
Posts: 1,012
Do not forget to new guides, and Viton seals.
And I meant intake side, if the manifold ends up bigger than the port.
I would not worry about gas "puddling" in a 1 inch section of a 12 inch port, where everything is moving 50ft/sec<, unless the cam is flat.
Just me
Jim
May 24th, 2011, 12:18 PM
#6
Registered car nut
Join Date: Apr 2008
Location: Puyallup
Posts: 1,146
Been thinking the same thoughts on my yet to be done "C" heads.
Can't afford porting but I could do some clean up.
Warhead had mentioned inexpensive HP by filling the crossover.
Any builders know how much HP is gained? (I know it'll be a ballpark)
May 24th, 2011, 04:26 PM
#7
65 post sport coupe w/425
Thread Starter
Join Date: Mar 2007
Location: Oregon City, Oregon
Posts: 122
May 24th, 2011, 09:41 PM
#8
Your most important work is in the bowl area and the roof. I would not have touch the floors. Bowl work and guides tear drop is the place to work. Fill the heat cross over. Weld up the center exhaust divider and mill flat. They look like "A" heads. Just replace the studs with 3/8 bottom 3/8 tops and roller tip or roller rockers.
Gene
Gene
May 26th, 2011, 09:42 AM
#9
Registered User
Join Date: Apr 2010
Posts: 978
Head Work
I agree that the most significant gains will come from bowl work and larger back cut valves. Port matching on the intake side will not help very much unless the entire port is opened up. Filling the heat riser and welding up the exhaust divider is well worth the effort IMHO. The short side radius is also a good place to spend time. Here's some photos of some of the port work I've done.
May 26th, 2011, 01:04 PM
#11
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Join Date: Apr 2010
Posts: 978
455man- He mentioned stock exhaust manifolds so would welding up the exhaust divider help?
Last edited by 67 Cutlass Freak; May 26th, 2011 at 01:04 PM. Reason: punctuation
June 4th, 2011, 06:47 PM
#13
Banned
Join Date: Mar 2011
Location: Orlando, FL
Posts: 370
Cutlass Freak
Why are you showing a small block head as a before picture of the big block heads you cleaned up the intake ports on?
None of you guys have tear dropped the valve guide bosses, narrowed yes, tear dropped no.
If you want to see how to tear drop valve guides, check out this page.
http://www.angelfire.com/sports/hotrodder/
Also, you see the ridge that goes around the valve seat? You should bring that down flat with the valve seats, that'll kill your low lift flow numbers and the valves are open more @ low to mid lift than they are at full lift.
Filling your heat crossovers with aluminum is only worth a couple horsepower but when comes loose and starts rattling around in your heads making the same sound as if you spun a rod bearing, then it isn't worth crap. I had my crossovers filled by the professionals @ M&J Proformance who assured me that wouldn't happen, it did.
Why are you showing a small block head as a before picture of the big block heads you cleaned up the intake ports on?
None of you guys have tear dropped the valve guide bosses, narrowed yes, tear dropped no.
If you want to see how to tear drop valve guides, check out this page.
http://www.angelfire.com/sports/hotrodder/
Also, you see the ridge that goes around the valve seat? You should bring that down flat with the valve seats, that'll kill your low lift flow numbers and the valves are open more @ low to mid lift than they are at full lift.
Filling your heat crossovers with aluminum is only worth a couple horsepower but when comes loose and starts rattling around in your heads making the same sound as if you spun a rod bearing, then it isn't worth crap. I had my crossovers filled by the professionals @ M&J Proformance who assured me that wouldn't happen, it did.
Last edited by SBORule; June 4th, 2011 at 06:50 PM.
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