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Porting and polishing cylinder heads

Kyle

Kyle

Formerly known as Kyle_T
Joined
May 24, 2020
Member Number
1339
Messages
602
Loc
Fort Worth TEXAS USA
I’m thinking about trying to port and polish a set of cylinder heads I have. How DIY is this? I’m no stranger to garage fab but usually I lack tools. I have a dremel and lots of time.

Any tricks or tips to do this? Seems like some places do it by hand and others do it with a CNC?
 
Been done LOTS over the years in garages with a die grinder. I tried it on a set of cast iron heads (Ford 302) and thought I was quite successful until after I was done noticed that the holes for the pushrods did not pass squarely through the head. I measured the best I could at the top of the port. "oh ya there's enough meat to cut the bump down blocking the port" Grind away happily. Afterward, I noticed that where the pushrod hole passes the lower side of the port it is tinfoil thin. CRAP. At least I had an excuse to buy some trick aluminum heads :homer:
 
I've done a few aluminum heads with a dremel. Just a basic clean up job, blend in the seats and valve guides, make it all flow smooth, short side radius is usually shitty, match ports to each other, not necessarily to the gasket. Could be placebo, but seems to make a difference.
 
The reality of doing this DIY is unless you have a guide to go by (referencing someone else's work done to the same head), you cannot gauge if you are accomplishing much or hindering flow without a flow bench. Gasket matching yes, I agree it is easy and simple to do.
 
You need to go out and get 2 40lb sacks of sand. One that's sharp, and one that has been tempered over time to be more spherical in grain.

Once you have acquired the sand, make sure you do this in a remote parking lot somewhere (a lot of sand is going to come out the tail pipe) and bring a buddy to help.

Start by removing the air cleaner assy off the intake. Have a buddy start the car and rev it to just under 500RPM below redline. SLOWLY start pouring in the "sharp" sand. This is what we call a Stage 1 port and polish, and honestly, it does most of the work enlarging the holes in the heads.

Secondly, after you have got through most of the first bag, pop open the second bag and repeat. This will polish up everything and remove the sharp edges created by the other sand.

If you want showroom quality, you can also finalize with a bottle of talcum powder in the same fashion. You can expect a smooth mirror finish.

EDIT: I forgot to add, you may want to purchase your sand sooner than later. Even if you don't use it now. Apparently there is a worldwide sand shortage.
 
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Kyle said:
I’m thinking about trying to port and polish a set of cylinder heads I have. How DIY is this? I’m no stranger to garage fab but usually I lack tools. I have a dremel and lots of time.

Any tricks or tips to do this? Seems like some places do it by hand and others do it with a CNC?
Click to expand...
watch the Engine Masters episode on the performance. It shows some things.

I want to know about dimpling, myself.

I wish Engine Masters would do an episode on that,
 
You gain the most out of bowl work, but watch your ratio's. It takes a shitton of time even with good tools. Just port matching won' t gain much.
 
CJeep77 said:
The reality of doing this DIY is unless you have a guide to go by (referencing someone else's work done to the same head), you cannot gauge if you are accomplishing much or hindering flow without a flow bench. Gasket matching yes, I agree it is easy and simple to do.
Click to expand...
you can build a basic flow bench for less than $15 if you have any sort of shop vac. Won't give actual cfm but will be a great indicator of better flow or not. Basically a fluid level gauge with a vacuum draw and your port as the restriction.

Very effective. Did several Jeep straight six heads with moderate to awesome success.

Done several mini cooper S heads. Worst case, absolute worse is trashing the head, but most often it it nothing a little welding (or even god forbid bondo) won't solve.

Modern performance heads are not as easy DIY anymore generally because the OEM CNC is not too shabby.

I found the stuff David Vizard taught very helpful, he used to do short semester classes in Denver every year, and it was some of the best money I have spent learning mechanical stuff. Not just theory but actual practice, and visits to local high performance shops to then run our experiments on the dyno's. While most of my racing has involved taking a new motor out the crate and putting it into the race car, it does help to understand the work behind it. He has written several books as well. While mostly American powerplants, he also covered those fancy Japanese motors. Was cool stuff.
 
KarlVP said:
You need to go out and get 2 40lb sacks of sand. One that's sharp, and one that has been tempered over time to be more spherical in grain.

Once you have acquired the sand, make sure you do this in a remote parking lot somewhere (a lot of sand is going to come out the tail pipe) and bring a buddy to help.

Start by removing the air cleaner assy off the intake. Have a buddy start the car and rev it to just under 500RPM below redline. SLOWLY start pouring in the "sharp" sand. This is what we call a Stage 1 port and polish, and honestly, it does most of the work enlarging the holes in the heads.

Secondly, after you have got through most of the first bag, pop open the second bag and repeat. This will polish up everything and remove the sharp edges created by the other sand.

If you want showroom quality, you can also finalize with a bottle of talcum powder in the same fashion. You can expect a smooth mirror finish.

EDIT: I forgot to add, you may want to purchase your sand sooner than later. Even if you don't use it now. Apparently there is a worldwide sand shortage.
Click to expand...
Not sure if serious or just IBB, :flipoff2::lmao: but .................

preparation for the Total Economy runs that were held in the 1980's in South Africa prepared the cars by (had to be brand new OEM of the year of the rally, the economy runs saw massive factory money for bragging rights, some companies spent more than on their motorsports programs, I was involved in the BMW, Audi and Toyota programs)
  • removing air filters
  • driving several thousand kilometers over dirt roads with pickup trucks with "sweeper booms" to lift the dust into the air only yards in front of the competition cars. Us peons got to eat dust prepping cars for the pro or celebrity drivers
  • you could "run in" the car for a max of 2500kms, not unusual for cars to show up with 2499 kms straight off the flat bed onto the start line (or run on stands for days in reverse when that still worked to turn back the speedo's, Ford were notorious)
  • you could adjust or replace consumables, so oils, bearings, brakes were all fair game
  • not cheats included stronger push back springs, and residual valves in the lines that kept the pads from dragging the rotors, which were machined to barely above minimum thickness to reduce mass (checkable) or machining inside the rotor hats or even the vanes (not checked as easy). Running castor oil weight of oil, replacing gear oil / axle oil with light weight race oils, blocking coolers to optimize temps (added aero benefit).
  • Panel matching body panels and doors to reduce panel gaps, ($$$) replacing all rubber OEM trim, technically a consumable, with silicone (aero benefit mostly, marginal weight loss)

But the first thing they did was "port and polish" the heads with the african dirt road method, not the african mud method does not work at all

Was not unusual seeing fuel economy numbers 25 - 50 % better than any consumer could hope to achieve, and guess which numbers were used to sell cars. As officially tested on the Total Economy Run South Africa 1984.
 
Get a scrap head to do some practice on. It's not "hard", but if you fuck up.....
And honestly, any common aftermarket head is gonna flow better than a ported stock head...so unless it's something that is uncommon, look at your cost/benefit ratio.
 
Norm said:
You gain the most out of bowl work, but watch your ratio's. It takes a shitton of time even with good tools. Just port matching won' t gain much.
Click to expand...
Watch the engine masters episode. They show the dyno both ways.
 
I do it sometimes
mostly smoothing bowls and knocking off anything that doesn't feel good when running a finger around in the port
Does it make a difference? probably not

you won't get anywhere with a dremel unless you're talking chainsaw porting
 
Iron or aluminum? I have ported both. Fuck ever doing a set of iron heads by hand agian.

It will take a lot of time and effort. Good burs in a couple different shapes and sizes, some cartridge rolls and your set. Dust mask, lights and head stands are optional but nice to have.
 
If performance heads are available, you'll be miles ahead just buying a set.

Without a LOT of hours on a flow bench and a dyno, and a lot of fucked up heads, you're really just sort of guessing as to what might help, and with no real testing or validation, it probably won't.

Past gasket matching, I wouldn't waste my time.
 
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Done lots of VW heads , I must have done something right because people paid me and I had repeat customers…lol

I was taught by a highly respected engine builder and we had proven profiles on various head manufacturers both factory and aftermarket. Port match and tract are just as important as bowl work and valve shrouding removal. Build yourself a downdraft box in a sturdy table to get the scrap away from you..hit hobo freight for a dust vac. I’ve got both low and high speed Dotco long snout 1/4” die grinders and lots of carbide burrs and sanding & polishing bobs.

Lots of strategically placed light and quality hearing protection are a must. Also build some down and dirty fixtures so you can position the heads and lots of different angles.

Don’t underestimate how good your eye can be at envisioning flow.
 
Also, I would start by reading this book, and a few others like it...

1717199901651.jpeg
 
Aluminum. Jag Land Rover 5.0SC. No aftermarket. A pulley and tune and exhaust can get me to 675hp. Hoping to flirt with 700
 
CJeep77 said:
The reality of doing this DIY is unless you have a guide to go by (referencing someone else's work done to the same head), you cannot gauge if you are accomplishing much or hindering flow without a flow bench. Gasket matching yes, I agree it is easy and simple to do.
Click to expand...
You can DIY a flow bench, or diy a vacuum and some string on a stick and be decent
 




The silicone moulds this dude made of the ports were interesting
 
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KarlVP said:
You need to go out and get 2 40lb sacks of sand. One that's sharp, and one that has been tempered over time to be more spherical in grain.

Once you have acquired the sand, make sure you do this in a remote parking lot somewhere (a lot of sand is going to come out the tail pipe) and bring a buddy to help.

Start by removing the air cleaner assy off the intake. Have a buddy start the car and rev it to just under 500RPM below redline. SLOWLY start pouring in the "sharp" sand. This is what we call a Stage 1 port and polish, and honestly, it does most of the work enlarging the holes in the heads.

Secondly, after you have got through most of the first bag, pop open the second bag and repeat. This will polish up everything and remove the sharp edges created by the other sand.

If you want showroom quality, you can also finalize with a bottle of talcum powder in the same fashion. You can expect a smooth mirror finish.

EDIT: I forgot to add, you may want to purchase your sand sooner than later. Even if you don't use it now. Apparently there is a worldwide sand shortage.
Click to expand...
Wow thanks just went out and did this to my whole fleet! Is the smoke “normal”?!
 
Lbhsbz said:
If you've got the heads off, take .015" off of 'em...that'll probably get you your 25hp.

Doesn't matter though....jag land rover will blow up on the road test
Click to expand...

Unless those heads have tiny combustion chambers it will take at least .040" to raise the compression enough to make a noticeable hp difference.
 
SLOWPOKE693 said:
Unless those heads have tiny combustion chambers it will take at least .040" to raise the compression enough to make a noticeable hp difference.
Click to expand...


Correct, but it has a very good chance of not making it worse....like screwing up the runner design can
 
I’m not going to run thinner headgaskets 😂 they already blow just looking at them crooked.
 
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