SBC Head Porting
SBC Head Porting I just finished the intake ports on my heads, mostly port matching and widening the port through the push-rods. Next I'll be doing the bowls and short-side radius. Then I'll be working on the exhaust, any insight into the d-shaped exhaust would help. I don't have much experience with the d-shaped exhaust so I'll be going off what I've read. Here's a pic of a couple of the ports.
Last edited by ProStreetZ28; Aug 1, 2005 at 08:24 AM.
I also just picked up my intake from the powder coater. I had it coated with a black wrinkle finish, then removed the coating from the the lettering. What do you think, I just wanted to try something different.
Last edited by ProStreetZ28; Aug 1, 2005 at 08:28 AM.
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From: Midland
How effective is home porting? I've been thinking about the price of getting a pair of L98 heads ported vs buying new ones from AFR. If home porting is even 80% as effective as the pro stuff, I would rather just pay someone a reasonable price to do it (provided they know what they are doing).
Originally Posted by 91Z28
How effective is home porting? I've been thinking about the price of getting a pair of L98 heads ported vs buying new ones from AFR. If home porting is even 80% as effective as the pro stuff, I would rather just pay someone a reasonable price to do it (provided they know what they are doing).
On LT-1 heads I've with stock valves I've seen in the 265 CFM range on a flow bench. That was a gain of 30-35 CFM over stock. These are Corvette/ZZ4 heads which are similar to the LT1 heads. The porting that Im doing on them isn't rocket science, but I am matching the ports as close as I can, I used telescoping gauges and a caliper to keep them as close as possible to each other. In the past when porting heads I've found the biggest gains are in the bowl/short-side radius. If you focus on these areas you can pick up considerable gains. The picture I posted was just showing the ports, I feel really good about the way they turned out. I took my time and made sure that each port is straight and blended nicely and then went back over them with a 80 grit polishing wand at a low speed to give them some texture. The bowls are next on my list, this is where I found the biggest gains in the past, While in the bowls I also like to tear-drop shape the guides for better flow and remove some of the guide. You have to be careful not to take too much of the guide out, I just trim the bronze guide down a little.
You'll want to take a look at what you're trying to do with the engine to decide which heads to get. In the past the AFR heads work better on a higher RPM engine, and the Corvette/ZZ4 heads work better on engines with mid-range power.
You'll want to take a look at what you're trying to do with the engine to decide which heads to get. In the past the AFR heads work better on a higher RPM engine, and the Corvette/ZZ4 heads work better on engines with mid-range power.
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From: Midland
I have a ZZ4 and its heads are just aluminum L98 heads. I was just asking because I know these heads are kind of crappy, and in the future I will either replace them with some AFR fully ported heads, or get my existing heads ported. If home porting can get results even close to CNC porting, then I will take the least expensive route.
The ZZ4 heads have really good stuff in them, The actually flow pretty good. Like I said earlier it's not impossible to 265 CFm out of them, which is what a set of 195 AFR heads are supposed to flow. I will say that on the same flow bench my engine builder didn't get more then 235 CFM out the AFR heads, so using that number you'd be paying over $1500 for about the same flow as the stock LT1 head (which has the same ports as the ZZ4 head. At his point I'd tell you to port your heads (carefully) and try it, you have nothing to loose.
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Well, you have plenty to lose, if...you get over ambitious!
It is better to err on the consevative side than to over size your port and lose the velocity.
But it is correct, the major gains will be seen in the bowl, most are cast very poorly, and the short turn radius.
On your D-Ports, just be careful to visually follow the air out into the header in your mind. Don't remove any more material than needed to gasket match on the floor. Also don't over grind the radius, focus more in the guide area.
Another trick, even tho you add chamber volume, its a good idea to open the chamber up around the intake valve too, this will unshroud the valve, use your gasket and scribe the lines, then put the gasket on your block, and measure how far from the inner edge you can come without going outside the cyl.
It is better to err on the consevative side than to over size your port and lose the velocity.
But it is correct, the major gains will be seen in the bowl, most are cast very poorly, and the short turn radius.
On your D-Ports, just be careful to visually follow the air out into the header in your mind. Don't remove any more material than needed to gasket match on the floor. Also don't over grind the radius, focus more in the guide area.
Another trick, even tho you add chamber volume, its a good idea to open the chamber up around the intake valve too, this will unshroud the valve, use your gasket and scribe the lines, then put the gasket on your block, and measure how far from the inner edge you can come without going outside the cyl.
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From: Midland
This is all news to me. I've asked many people about upgrading cams, and their response was always "You won't get much results, because the L98 heads won't flow enough to let a bigger cam make a difference". If the ZZ4 heads are better than normal L98s, then I will swap cams first and save some $$ until I can get some serious porting done.
One thing I've found with limited heads to get a cam with more duration. The cam I have in my engine is from Crower, it's .547/.574 lift and duration is 262/272 @.050 with 112 LS. Since the heads don't have really good flow (285+CFM) I'm using the duration to hang the valve longer. I went with the 112 LS since I'm going to spray it with a 200+ hit. The engine is a 385 stroker with 11.5:1 compression and a dominator carb. I'm not 100% sure how this combo will work, but I can't wait to find out.
My other engine has a Reed cam with .655/.695 lift and 272/282 duration @.050 with a 110 LS. This engine used to have a fogger and a plate on it. The heads on this engine flow 315 CFM@.700.
My other engine has a Reed cam with .655/.695 lift and 272/282 duration @.050 with a 110 LS. This engine used to have a fogger and a plate on it. The heads on this engine flow 315 CFM@.700.
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From: Newark, Ohio
Yes.
Its running 6.78 in the 1/8th, and I haven't been back to the 1/4 since I updated my 10 year old coilovers with a set of double adj.
I last ran a 10.77 w/the old shocks but have picked up about 4-6 hundreths in the 60'.
I'd love to see a 10.60 something. The 10.77 was with a 6.84 1/8th. I also learned my alt. isn't keeping my battery at full voltage so I hope this will help as well.
Here is a link to another thread with vids:
Thread
Its running 6.78 in the 1/8th, and I haven't been back to the 1/4 since I updated my 10 year old coilovers with a set of double adj.
I last ran a 10.77 w/the old shocks but have picked up about 4-6 hundreths in the 60'.
I'd love to see a 10.60 something. The 10.77 was with a 6.84 1/8th. I also learned my alt. isn't keeping my battery at full voltage so I hope this will help as well.
Here is a link to another thread with vids:
Thread
Prostreet, nice job on the port matching. Show us more when you get into the bowls!! 
I've ported several sets of LT1 heads with decent success and they are almost identical to a standard SBC head except for the D port exhaust runners. Here is a link to a write-up with detailed pictures I did about 5 years ago. Click on "head porting" on the left side. This is not my website, just my write-up and pictures.
http://members.***.net/gmarengo/
Mike
I've ported several sets of LT1 heads with decent success and they are almost identical to a standard SBC head except for the D port exhaust runners. Here is a link to a write-up with detailed pictures I did about 5 years ago. Click on "head porting" on the left side. This is not my website, just my write-up and pictures.
http://members.***.net/gmarengo/
Mike
Originally Posted by Mikey 97Z M6
Prostreet, nice job on the port matching. Show us more when you get into the bowls!!
I've ported several sets of LT1 heads with decent success and they are almost identical to a standard SBC head except for the D port exhaust runners. Here is a link to a write-up with detailed pictures I did about 5 years ago. Click on "head porting" on the left side. This is not my website, just my write-up and pictures.
http://members.***.net/gmarengo/
Mike
I've ported several sets of LT1 heads with decent success and they are almost identical to a standard SBC head except for the D port exhaust runners. Here is a link to a write-up with detailed pictures I did about 5 years ago. Click on "head porting" on the left side. This is not my website, just my write-up and pictures.
http://members.***.net/gmarengo/
Mike
Mike, thanks that is going to help me a bunch.
