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Old 05-20-2019, 07:32 AM
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First Port job

This is my first port job I’ve ever done. Tell me what y’all think. Ignore the spot the bit jumped on me, I’m getting better at that. I only did these two first to get tips and advice on the other 6. I started with the single cut bit for aluminum, then to the (whatever) cut hit that’s used for cast iron, then to 60 grit roll, 80, then 120. Click image for larger version

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Old 05-20-2019, 08:57 AM
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Looks like you were pretty aggressive taking material out at the port opening and went too far. You don't want to narrow up the center dividing wall in an effort to get the wall smooth and have a sealing issue. I've done a few and I generally leave the intake side a touch smaller then the gasket and the intake port on the head. No gasket overhang.

Last edited by Hipster_G; 05-20-2019 at 09:23 AM.
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Old 05-20-2019, 09:08 AM
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You should always use a flow bench when porting cylinder heads so you can measure the results of your work. Just random porting can do more harm than good. Some heads have Venturi effect flow which can be ruined by porting until the ports look good.

For example, Pontiac heads have Venturi intake ports due to the location of the pushrod passages.
You will actually hurt port flow by enlarging the intake ports.
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Old 05-20-2019, 09:46 AM
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This whole process should have started with a sacrificial set of intake gaskets and marking and assembling everything etc?????


I ask because I see a bolt taped in an intake hole and I'm hoping you didn't just center a gasket up on the bolts and start cutting. Seldom will they assemble perfectly centered. Block decked , heads surfaced, tolerance stack up, and head gasket compressed thickness will move stuff around. It's also about getting the intake and head ports lined up to each other without creating a bell-mouthed shape.


Looks like Vortec stuff?

Last edited by Hipster_G; 05-20-2019 at 10:08 AM.
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Old 05-20-2019, 10:21 AM
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Quote:
Originally Posted by Cameronluster View Post
This is my first port job Iíve ever done. Tell me what yíall think. Ignore the spot the bit jumped on me, Iím getting better at that. I only did these two first to get tips and advice on the other 6. I started with the single cut bit for aluminum, then to the (whatever) cut hit thatís used for cast iron, then to 60 grit roll, 80, then 120. Attachment 443497
80 to 90 percent of the benefit is in the valve pocket. The other major gains are opening up the push rod hole constriction and the bolt hole restriction just before the pocket on the common wall, however, the cautionary tales are don't do this unless it's a racing head and can benefit from a much larger port and be prepared to sleeve the hole with a tube and epoxy if you cut into it.

If you've never ported heads before you are well advised to buy junk heads from the local wrecker and get practice time on them both from learning how to control the cuts and the grinder and how to shape the port. This will I've you some experience as to how to drive the tool around and learn its nasty habits like spinning the burr out of the cut that you experienced along with the damage that can do. God help you if that happens by a valve seat. You need to protect areas you don't intend to cut from damage with layers of masking and duct tape and be really damn careful.

Shape is vitally important, generally the port is an divergent section from the manifold face to the pocket, unless this is a very high RPM competition engine. For the street even for a very aggressive engine these section shapes are more important that huge size. You need to study the gas laws and the considerable book knowledge available on port shape. In general as the port gets bigger for ant given RPM the flow velocity goes down. While this AIDS in getting flow around the Horst side of tight turns it also enhances the lower to mid RPM nasty habits of larger cam's. That is the ideal gets rougher and needs to be faster, and it makes for big hesitations coming into the throttle, not that big a deal with a stick gear box but a very huge pain with an automatic. Making the port bigger does not automatically make more power, it enables a bigger breath at high RPM and that develops greater power, under that point torque and power can suffer reductions. The L31 head a case in point compared to the decent L98/ZZ series heads under 3500 it surrenders as much as 15 pound feet and a similar amount of horses on a carbureted engine. Which brings up a notice that you can do things to ports for a port or direct injected engine that don't work fro crap on a TBI or carbureted engine. For the most part engines for the street are cam limited as to the RPMs they can achieve, the possible exception being the LO5 Swirl Port, but removing the TBI for a carb really wakes these motors up, so there's more going on that meets the eye with these.

For the most part short of full out racing the manufacturers get the general port shape correct and for the street and sometimes racer you are well advised to stay with the general contours that are already there. If porting just open the cornets, blend the walls into the corner cuts and all it good. Aftermarket heads generally are already a lot larger than production heads so unless going racing anything beyond cleaning up rough edges and blending transitions is not necessary for a street engine.

Looking at your pictures my impression is your work is too crude, you need to stop rather than ruin the heads completely. Then get some junk heads to perfect you technique on and do a lot of black and white reading as to the science behind this, David Vizard has piblished several books on the subject that reduces the Rocket Science to everyday language so they read well to the average guy.

Bogie
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Old 05-20-2019, 11:07 AM
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Not what'cha were expecting, huh O.P.?

Yeah the long straight (easy) parts don't benefit much from the work. But after reading the above, you'll be starting to learn.

Without a flow bench I usually just very carefully round out all the sharp places in the valve pockets (where there's going to be obvious turbulence even at low valve lifts) using a flame-shape cutter and my fingers and artistic/aerodynamic intuition (hah) to feel, and just take the worst roughness out of the rest of the ports to speed up boundary layer flow a little. I figure I can't do too much damage that way.
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Old 05-20-2019, 02:09 PM
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What I did was tape all the bolts in the holes to hold the gasket in place then I scribed around the gasket hole into my the dye I applied on the intake. It’s hard to see
Since I cleaned the dye off but I did go a little smaller than what I scribe. I took material off to right before my scribe mark.
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Old 05-20-2019, 05:48 PM
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Go to YouTube and search for "HeadBytes" vidoes onhead porting.
not everything the guy is doing is 100% correct, and ignore his drawling voice as it will drive you crazy....but pay attention to his methods, grinding technique like always keep the cutter moving across the surface, don't try to hold it tight in just one spot to cut.

forget the 80 and 120 grit steps, it is just a waste of time. Best sanding rolls on aluminum are 36 and 40 grit...use a new roll for aggressive work, they smooth out after a couple of minutes and I often then remove it from the mandrel and save it for later finer finish work, and use another new until I have several with the sharpness knocked off.
then maybe consider 60 grit .The partly used 40 grit leave about the same finish as the new 60 grit.
80 grit or finer you don't want on intake port surfaces as too smooth a surface promotes wetting out of fuel on the port walls...like water drops on the steamy glass shower door or kitchen window. The slightly rougher surface helps keep fuel kicked back off into the airstream.
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Old 05-26-2019, 10:40 PM
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Quote:
Originally Posted by Hipster_G View Post
Looks like you were pretty aggressive taking material out at the port opening and went too far. You don't want to narrow up the center dividing wall in an effort to get the wall smooth and have a sealing issue. I've done a few and I generally leave the intake side a touch smaller then the gasket and the intake port on the head. No gasket overhang.
Quote:
Originally Posted by Hipster_G View Post
This whole process should have started with a sacrificial set of intake gaskets and marking and assembling everything etc?????


I ask because I see a bolt taped in an intake hole and I'm hoping you didn't just center a gasket up on the bolts and start cutting. Seldom will they assemble perfectly centered. Block decked , heads surfaced, tolerance stack up, and head gasket compressed thickness will move stuff around. It's also about getting the intake and head ports lined up to each other without creating a bell-mouthed shape.


Looks like Vortec stuff?
Quote:
Originally Posted by BogiesAnnex1 View Post
Quote:
Originally Posted by Cameronluster View Post
This is my first port job I’ve ever done. Tell me what y’all think. Ignore the spot the bit jumped on me, I’m getting better at that. I only did these two first to get tips and advice on the other 6. I started with the single cut bit for aluminum, then to the (whatever) cut hit that’s used for cast iron, then to 60 grit roll, 80, then 120. Attachment 443497
80 to 90 percent of the benefit is in the valve pocket. The other major gains are opening up the push rod hole constriction and the bolt hole restriction just before the pocket on the common wall, however, the cautionary tales are don't do this unless it's a racing head and can benefit from a much larger port and be prepared to sleeve the hole with a tube and epoxy if you cut into it.

If you've never ported heads before you are well advised to buy junk heads from the local wrecker and get practice time on them both from learning how to control the cuts and the grinder and how to shape the port. This will I've you some experience as to how to drive the tool around and learn its nasty habits like spinning the burr out of the cut that you experienced along with the damage that can do. God help you if that happens by a valve seat. You need to protect areas you don't intend to cut from damage with layers of masking and duct tape and be really damn careful.

Shape is vitally important, generally the port is an divergent section from the manifold face to the pocket, unless this is a very high RPM competition engine. For the street even for a very aggressive engine these section shapes are more important that huge size. You need to study the gas laws and the considerable book knowledge available on port shape. In general as the port gets bigger for ant given RPM the flow velocity goes down. While this AIDS in getting flow around the Horst side of tight turns it also enhances the lower to mid RPM nasty habits of larger cam's. That is the ideal gets rougher and needs to be faster, and it makes for big hesitations coming into the throttle, not that big a deal with a stick gear box but a very huge pain with an automatic. Making the port bigger does not automatically make more power, it enables a bigger breath at high RPM and that develops greater power, under that point torque and power can suffer reductions. The L31 head a case in point compared to the decent L98/ZZ series heads under 3500 it surrenders as much as 15 pound feet and a similar amount of horses on a carbureted engine. Which brings up a notice that you can do things to ports for a port or direct injected engine that don't work fro crap on a TBI or carbureted engine. For the most part engines for the street are cam limited as to the RPMs they can achieve, the possible exception being the LO5 Swirl Port, but removing the TBI for a carb really wakes these motors up, so there's more going on that meets the eye with these.

For the most part short of full out racing the manufacturers get the general port shape correct and for the street and sometimes racer you are well advised to stay with the general contours that are already there. If porting just open the cornets, blend the walls into the corner cuts and all it good. Aftermarket heads generally are already a lot larger than production heads so unless going racing anything beyond cleaning up rough edges and blending transitions is not necessary for a street engine.

Looking at your pictures my impression is your work is too crude, you need to stop rather than ruin the heads completely. Then get some junk heads to perfect you technique on and do a lot of black and white reading as to the science behind this, David Vizard has piblished several books on the subject that reduces the Rocket Science to everyday language so they read well to the average guy.

Bogie
Quote:
Originally Posted by kso View Post
Not what'cha were expecting, huh O.P.?

Yeah the long straight (easy) parts don't benefit much from the work. But after reading the above, you'll be starting to learn.

Without a flow bench I usually just very carefully round out all the sharp places in the valve pockets (where there's going to be obvious turbulence even at low valve lifts) using a flame-shape cutter and my fingers and artistic/aerodynamic intuition (hah) to feel, and just take the worst roughness out of the rest of the ports to speed up boundary layer flow a little. I figure I can't do too much damage that way.
Quote:
Originally Posted by ericnova72 View Post
Go to YouTube and search for "HeadBytes" vidoes onhead porting.
not everything the guy is doing is 100% correct, and ignore his drawling voice as it will drive you crazy....but pay attention to his methods, grinding technique like always keep the cutter moving across the surface, don't try to hold it tight in just one spot to cut.

forget the 80 and 120 grit steps, it is just a waste of time. Best sanding rolls on aluminum are 36 and 40 grit...use a new roll for aggressive work, they smooth out after a couple of minutes and I often then remove it from the mandrel and save it for later finer finish work, and use another new until I have several with the sharpness knocked off.
then maybe consider 60 grit .The partly used 40 grit leave about the same finish as the new 60 grit.
80 grit or finer you don't want on intake port surfaces as too smooth a surface promotes wetting out of fuel on the port walls...like water drops on the steamy glass shower door or kitchen window. The slightly rougher surface helps keep fuel kicked back off into the airstream.
What I did was tape all the bolts in the holes to hold the gasket in place then I scribed around the gasket hole into my the dye I applied on the intake. I never had to center anything up, with all the bolts loosely in the holes the gasket would only sit in one spot, if I tried to move it would cause one of the bolts to be pushed/pulled that way. It literally rested in one spot. It’s hard to see Since I cleaned the dye off but I did go a little smaller than what I scribe. I took material off to right before my scribe mark.

Seems like some of you think this is a set of heads. It’s a Edelbrock air gap dual plane intake. I didn’t port the heads at all, they came CNC ported to the gaskets that I used to scribe the marks on the intake in the pictures on here. All I did to the heads were take off all the sharp edges the CNC machines left. The heads are literally a perfect match to the gaskets. They are Edelbrock e-tec 200 heads. As for the intake I’m just trying to port it to right before the scribe marks since they come narrowed down anyway. This is for a street engine not race so I’m deff not trying to completely enlarge the ports for that much more flow as I don’t need it. But the 60 grit finish was a nice tip, I thought 120 was rough enough. Deff will go back over with 60 on them. So since you guys have a better idea of what I’m Trying to do what kind of tips can you give me now?
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Old 05-27-2019, 02:37 AM
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Here`s the Headbytes vid about intake manifold porting:



first one is Performer and second is tbi intake, but you get the idea, i do not have RPM A-G in hand, so i cannot remember how the ports go from the opening on, but i assume they will enlarge just like the perfomer runners do when they go to the plenum. Last A-G i had was to big block chevy.
You can look Headbytes vids about Edelbrock E-200 heads and listen Tonys comments about those stupid cnc machined port/gasket matchings.

Eric i like Tonys voice and southern accent
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