I am an expert.........at some things.
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| cylinder head porting and polishing kit https://ausmini.com/forums/viewtopic.php?f=2&t=94142 |
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| Author: | GundyGuy [ Wed Nov 02, 2016 4:40 pm ] |
| Post subject: | cylinder head porting and polishing kit |
Does anyone know where i can buy in Australia a porting and polishing kit The one with the small rolls of emery paper on a mandrel 1/4" |
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| Author: | cranky [ Wed Nov 02, 2016 8:14 pm ] |
| Post subject: | Re: cylinder head porting and polishing kit |
Hi Gundy Guy, Bunnings will sell you a Dremel kit with a flexible extension and a variety of grinding and polishing stones and buffs, including the little sandpaper rolls. I used it to get this finish in the chambers of my head... |
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| Author: | TK [ Wed Nov 02, 2016 9:09 pm ] |
| Post subject: | Re: cylinder head porting and polishing kit |
Porting and polishing should be left to the experienced. Just be careful you could end up with worse flow than standard. |
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| Author: | peterb [ Thu Nov 03, 2016 6:24 am ] |
| Post subject: | Re: cylinder head porting and polishing kit |
I am an expert.........at some things.
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| Author: | drmini in aust [ Thu Nov 03, 2016 7:06 am ] |
| Post subject: | Re: cylinder head porting and polishing kit |
For finishing inside the ports I use a 150mm long piece of 1/4" rod with a 20mm slot cut in the end. I use 180 or 220 grit abrasive cloth, tear off a piece 150mm long and wrap it around the shaft. As it wears, tear the worn bit off the end. I use a 20,000 rpm 1/4HP air die grinder but turn the speed down to 6 or 7000 when using this tool. For serious metal removal beforehand, you can't beat solid carbide burrs. Expensive, but last many years. If buying any grinder I'd get 1/4" shank one. More choice of burrs and stones than the 6mm size, and it will fit 6mm ones as well. Cheapo air grinders us a lot more air than good ones. Mine is a 20yo Ingersoll Rand, the Aldi one I bought a while back is a toy in comparison. Lots more air and noise, but not much torque at all. |
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| Author: | GundyGuy [ Thu Nov 03, 2016 7:20 am ] |
| Post subject: | Re: cylinder head porting and polishing kit |
Hi Kevin I have the die grinder and burrs Just need something to smooth out the ports Have seen some kits of unknown origin and I doubt the sandpaper would last Sent from my HTC_PN071 using Tapatalk |
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| Author: | GundyGuy [ Sat Nov 05, 2016 11:43 am ] |
| Post subject: | Re: cylinder head porting and polishing kit |
Was going to do a little bit of exhaust port reshaping today But after fitting the gasket to see the difference between port and gasket i decided to investigate things further The ports seem a lot smaller than the gasket opening Firstly has anyone got a ported head to show me whats been done to the exhaust ports Also Vizard apparently has written some stuff about porting Has anyone got this book Thanks Marc |
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| Author: | drmini in aust [ Sat Nov 05, 2016 12:10 pm ] |
| Post subject: | Re: cylinder head porting and polishing kit |
If serious about mods I'd buy his book Tuning the A series engine. But it is not the final gospel after 30 years, these days specialists get more torque and HP. |
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| Author: | 9YaTaH [ Sat Nov 05, 2016 2:51 pm ] |
| Post subject: | Re: cylinder head porting and polishing kit |
drmini in aust wrote: If serious about mods I'd buy his book Tuning the A series engine. But it is not the final gospel after 30 years, these days specialists get more torque and HP. Mr Trickey says "The manifold should always be carefully matched to the cylinder head port, otherwise it is impossible to obtain a really smooth tract" 
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| Author: | GundyGuy [ Sat Nov 05, 2016 4:51 pm ] |
| Post subject: | Re: cylinder head porting and polishing kit |
the Inlet is a perfect match but the exhausts are way out I found this article The inlet port size On this head does not need enlarging to any great degree. Basically all that is required is to grind the narrowest part of the port until the existing shape is merely squared off. Ie only remove enough material to acheive the slight change in shape. The port can then be blended using a stone. Do not polish, leave with the just ground finish as a guide the port should measure after grinding 26.5mm across and 30.5mm in height. Blend the area that you have prevouisly worked from the throat into the port from the manifold face. Its up to you if you want to remove the location rings from the head, (you may need them, ie and injection engine) it will not make any difference on this spec. I simply grind out enough material to remove them. At this stage you should have a head that has the inlets completely ported. Moving onto the exhaust, remember that the gasses are moving in the opposite direction, shape the valve throat to form a smooth almost bowl like shape, that leads into the port, with the exhaust try to minimise material removal as the large amounts of heat present in the exhaust tracts will be more reliably removed through a thicker casting. But do make sure that everything is well radiused, though this time not just for flow purposes so as to not generate hot spots which overtime can cause casting failure. The exhaust ports always seem to cause lots of arguments as to the ultimate shape, well heres my view. I use a standard rectangular shape. This will flow 95% as good as a carlos fandango theoretially perfect ultra high tech shape. This head is not being used in a high tech race engine it will simply not need any extra flow from sexy port shapes. Using a standard manifold gasket scribe around the exhaust ports to produce a line to work to. Grind the port at the manifold face to the shape of the scribed line. If the port has moved such that the outer wall is already over the line, just grind this wall square. Only remove significant material from the areas of flow, ie the outer sides of the end exhaust ports and the ceiling of the port, as you look in the port with the casting positioned with the thermostat face up most. Aim for a port that is 29mm high and 26mm wide, with a 1/4" radius in the corners. Continue the shape right down the port till it meets up with the valve throat porting. The centre port should be ground to a size of 30.5mm high and 26.5mm wide. Continue this size into the port. |
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| Author: | GundyGuy [ Sat Nov 05, 2016 4:55 pm ] |
| Post subject: | Re: cylinder head porting and polishing kit |
cranky wrote: Hi Gundy Guy, Bunnings will sell you a Dremel kit with a flexible extension and a variety of grinding and polishing stones and buffs, including the little sandpaper rolls. I used it to get this finish in the chambers of my head... That head looks too good to use |
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| Author: | FNQ [ Sat Nov 05, 2016 7:51 pm ] |
| Post subject: | Re: cylinder head porting and polishing kit |
Pm sent |
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| Author: | cranky [ Sun Nov 06, 2016 2:57 am ] |
| Post subject: | Re: cylinder head porting and polishing kit |
It's a race head cut from a NOS Metro head by David Anton of Advanced Performance Technologies, California. He and David Vizard set up APT together, but now Dave V is not involved. Valves are 36mm in 31mm ex, ss race thin waisted CR 11.5, all to work with their 8 series scatter cam (255 degree inlet at lift .05 and over) should be on the road soon 
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| Author: | cranky [ Sun Nov 06, 2016 10:49 am ] |
| Post subject: | Re: cylinder head porting and polishing kit |
I cannot claim much hands on expertise in this area - I have only ported/chambered two heads according to Vizard's suggestions and no flow bench or dyno to measure actual changes made. It seems there are a number of quite (very?) complex relationships between flow potential (larger ports), gas speed (smaller ports), distribution (depends to some extent on carb setup), scavenging effects (depends on cam), fuel atomisation and surface 'wetting', and a couple of elements unique to the 5 port 4 cylinder engine. TK is quite right - just getting stuck in with a grinder is unlikely to make improvements across the operating range of the engine, although may help some part of it. If you look at GR's heads, you can see the amount of thinking that goes into a number of very subtle mods that 'add up' to a significant advantage. And even the experts occasionally screw it up - only takes a pinhole leak where the casting on that particular head is thinner than usual. However, doing a bit of smoothing through the ports, some careful attention to de-shrouding the valves (particularly on the 'closed' head designs), and the valve throat/pocket, and a gentle rounding on the dividing 'beak' between the inlet valve throats (to allow smoother transference of flow) should give you some advantages. The exhaust ports are often smaller than the gasket openings or the extractor openings. This needn't be a big problem, as smaller ports keep gas speed up and the resulting lip can have an anti reversion effect for cams with a lot of overlap between the intake and exhaust phases. My suggestion, for what it's worth (which is much less than the real experts) is that if you want a really good high flow head, buy one from someone who knows what they're doing. If you enjoy a bit of tinkering and adding your own contribution to the mix, some gentle smoothing of the ports will aid flow - but at your own risk. If you can, find a clapped out head to practice on before you take the grinder to your good one. 
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| Author: | drmini in aust [ Sun Nov 06, 2016 2:24 pm ] |
| Post subject: | Re: cylinder head porting and polishing kit |
A word of warning- Vizard cautions that you may hit fresh water when working on the port divider adjacent to the inlet valves. He is right, it happened to me.  Luckily I'm a welder and it was a clean casting. I preheated it on the camp stove and gas welded it with nickel bronze. Years ago and it's still running fine on my 1412 stroker in Gafmo's van. |
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