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Cylinder head castings marks on fins removal question.
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1975 Kombi
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PostPosted: Yesterday 11:19 am    Post subject: Cylinder head castings marks on fins removal question. Reply with quote

I've heard that the raised castings marks on the fins of the heads need to be reduced to flat with the fins to prevent the blockage of air flow over the fins there fore reducing cylinder head temps. Has any heard of this before. I thought that the extra surface area of the head castings marks would help cool the heads. Even removing of the castings marks that go through the head and between the two cylinders so it is nice and clear and level with the rest of the fins is needed to be removed.
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raygreenwood
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PostPosted: Yesterday 11:41 am    Post subject: Reply with quote

Yes. Especially the inner areas around the intake tract area. You can see with a flashlight that casting flash closes off a lot of combined area. I think Jake Raby commented on cleaning, some of this up a long time ago on the STF. Others as well. I cleaned mine up with needle files, long thin drill bits with a hand drill and a riund carbide grit hacksaw blade threaded through areas. Be caeful and take it slow.
The amount of closed up air passages on some heads can be considerable. Ray
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busdaddy
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PostPosted: Yesterday 11:52 am    Post subject: Reply with quote

X2, cleaning up the casting flash is always time well spent, sometimes a few of those little deep ones are blocked completely.
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1975 Kombi
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PostPosted: Yesterday 12:20 pm    Post subject: Reply with quote

Awesome thanks.
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"I do not see things as black and white, but everything as very colourful!"

75 Westy (2.0L CV, H-Lifters, 75-79 FI mix, XR700, 003 Auto) project.
03 Jetta TDI
71 SB
74 Westy
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ihatedanrhoads
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PostPosted: Yesterday 12:23 pm    Post subject: Reply with quote

the flashing forms from where the core pieces for the fins were either damaged from being moved or if the core shifts during the pour,the type that is intruding between the fins is from when the sand mold gets damaged before it's cast. these engine blocks and heads were cast in green sand so the mixture of the sand in those places was not uniform and most likely either a dry spot formed where the sand didnt bond and cuases it to fail during the fill, it ends up just filling with a bit of metal,we call this a 'wart' or a 'protrusion'. the best way to remove the flashing etc. is actually with a hammer and a very sharp steel flat 1/4 inch chisel with lots of little PERPENDICULAR taps. this is called "chasing" and its most likely that the sheer volume of these were chased by hand in a foundry as there is no machine for this type of work. be careful that you dont snap the fins off by forcing a tool that is too big between them. a hand file will also work but be prepared to spend at least a half hour on it. good luck.
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1975 Kombi
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PostPosted: Yesterday 12:32 pm    Post subject: Reply with quote

Yep I'll take my time and slowly file the fins flat.
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75 Westy (2.0L CV, H-Lifters, 75-79 FI mix, XR700, 003 Auto) project.
03 Jetta TDI
71 SB
74 Westy
Licensed pilot (single engine land VFR)
--
Rust In Peace: 72 Bug, 73 Bug, 81 Rabbit LS D 2D, 83 Rabbit D 2D, 84 Jetta TD GL, 85 Jetta D, 68 Z28 RS 302, 91 Passat 16v
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SGKent Premium Member
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PostPosted: Yesterday 4:29 pm    Post subject: Reply with quote

The flashing will look like flashing rather than a cast area. I say that because some areas are a little more restricted than others on purpose. When you clean the fins you want to leave them with some graininess. You do not want them ultra smooth. Here is why - you want air passing thru to eddy and swirl so it picks up heat passing thru. If you make it too clean and smooth the air will pass thru and very little of it will pick up heat. Think like a soup bowl - you want air going down into the bowl to pick up heat and not passing over the soup. You want air to make contact with as much surface area as possible without the flashing blocking off the passage.
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