Rasp Burr Finish Experiment (Porting)

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12many

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Here is an attempt at replicating a burr finish on an intake manifold using common rasp burrs traditionally used in woodworking, vs. using a 6” single cut burr, which is required to be slightly bent, have teeth knocked off and carefully developed grinder control to achieve. From all indications it takes some practice to develop, and time to perform. This alternative may be a simpler way to get the same results without ruining a good burr, along with likely shortened grinder life running an out of balance and excessive chattering burr.

Tools used:

variable speed electric drill
Nordwolf 10-pc rasp burr set (for wood)
Milwaukee 6” hex extension
Trans fluid for burr lube as needed

EDIT: It may in fact not take much more time to settle on a finish, preliminary results look very good as shown in the following posts.
 
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The tools used:

3/8” variable speed drill
Rasp burrs
6” hex extension
Transmission fluid (not really required)

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Initial attempts: on 6061 aluminum plate:

Side to side burr pattern
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45° Cross hatch pattern
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Random Circular or Scatter pattern:
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Initial circular scatter pattern on intake port window openings. No gasket/head port matching has been done, the port windows of the Victor 340 were as cast, ootb before burr work:


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These are photos lifted from a thread on Yellowbullet posted by Chad Speier of examples of his “burr finish” work, posted by him in October 2020:

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A quick video showing ball rasp burr use on manifold floor. Note speed and pattern. Just keep it moving around, don’t linger. It’s not fussy or complicated. Slower speed works and offers some protection from burrowing and possibly removing too much material. This is Casual easy work.

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12many said:
A quick video showing ball rasp burr use on manifold floor. Note speed and pattern. Just keep it moving around, don’t linger. It’s not fussy or complicated. Slower speed works and offers some protection from burrowing and possibly removing too much material. This is Casual easy work.

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Those all look good. As long as the edges are sharp that’s what you want. I’d send it.

What you can do is port the manifold and finish with your papers rolls in 40 or 60 grit and go drive it for awhile. Make some passes on it. Then pull it off and burr finish it and do the same and see what you think.
 
I forgot to mention Chad has a nice video of running water across a burr finish and over a smooth surface. Pretty interesting.
 
Rat Bastid said:
Those all look good. As long as the edges are sharp that’s what you want. I’d send it.

What you can do is port the manifold and finish with your papers rolls in 40 or 60 grit and go drive it for awhile. Make some passes on it. Then pull it off and burr finish it and do the same and see what you think.
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A before and after comparison either on a dyno or drag strip would be a good thing. Breaking up those fuel droplets into smaller pieces has to help.
 
Rat Bastid said:
What you can do is port the manifold and finish with your papers rolls in 40 or 60 grit and go drive it for awhile. Make some passes on it. Then pull it off and burr finish it and do the same and see what you think.
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That is exactly what I will do.
 
Just askin....what's the point of using wood burrs? Are they cheaper? How are they holding up?
 
RustyRatRod said:
Just askin....what's the point of using wood burrs? Are they cheaper? How are they holding up?
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For me it’s purely an alternative to buying a good single cut 6” oval burr, trying to get it bent correctly, knocking off teeth and learning how to control it to get the desired burr finish. RB is about the only one posting here about the burr finish, it’s been discussed thoroughly on various other sites like yellowbullet and speed talk not to mention by a few of the guys that have perfected it and promote it like Speier, Weingartner and Meaux.
I’ve studied the Finish, Determined that it looks like somebody used a rasp burr, and like I’ve mentioned earlier I’ve used wood rasp files and burrs for aggressive aluminum removal while fabricating brackets and such for my van. While others may scoff at the thought of using a woodworking rasp on aluminum, I know from experience that it works and in mere minutes of trials I’ve come up with what looks to be the equivalent. As to whether it’s worth the effort or if there’s any benefit it’s really not the point yet.That’s pretty much the gist of it
 
So far the burrs show no signs of wear at all, but that’s with limited use. That’s why I started using them with oil, but from past experience I never used oil and the others I have are sharp so....... and yes a set of 10 various shaped burrs for about $18 and extension for $10 Not bent or chipped and still good for other use seems a pretty good value to me. What else are you going to use a 6 inch single cut Bent and chipped burr for?
 
12many said:
For me it’s purely an alternative to buying a good single cut 6” oval burr, trying to get it bent correctly, knocking off teeth and learning how to control it to get the desired burr finish. RB is about the only one posting here about the burr finish, it’s been discussed thoroughly on various other sites like yellowbullet and speed talk not to mention by a few of the guys that have perfected it and promote it like Speier, Weingartner and Meaux.
I’ve studied the Finish, Determined that it looks like somebody used a rasp burr, and like I’ve mentioned earlier I’ve used wood rasp files and burrs for aggressive aluminum removal while fabricating brackets and such for my van. While others may scoff at the thought of using a woodworking rasp on aluminum, I know from experience that it works and in mere minutes of trials I’ve come up with what looks to be the equivalent. As to whether it’s worth the effort or if there’s any benefit it’s really not the point yet.That’s pretty much the gist of it
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What the hell does the aluminum know? As long as the burr gets the job done that's all that counts, right? lol How long does it seem they are going to last?
 
12many said:
So far the burrs show no signs of wear at all, but that’s with limited use. That’s why I started using them with oil, but from past experience I never used oil and the others I have are sharp so....... and yes a set of 10 various shaped burrs for about $18 and extension for $10 Not bent or chipped and still good for other use seems a pretty good value to me. What else are you going to use a 6 inch single cut Bent and chipped burr for?
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You answered that then. I would also imagine slow RPM and oil helps too.
 
If the burr teeth load up with aluminum, soaking them in purple power type cleaner for a day or three should dissolve most of it and make it easier to clean out. Keeping it lubed obviously helps prevent the load up. I like your results, looks good.
 
An update for those interested in burr finish topics. I ended up passing on the above Victor 340 (that I applied a burr finish to) to a member here that needed one of these intakes for his build. In no hurry to do swaps of any kind, decided to hold off running it till at least spring 2023 so passed it on, just do another one later.
Anyway, having come across a killer deal on another one I couldn’t resist. After some careful porting I hit it with a combination of “rasp burrs” to achieve a really consistent burr finish. Extremely consistent sharp edges, drags skin everywhere you run a finger in the right direction at that. The first intake came out beautifully. I’m even more satisfied with the finish on this one.
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I use ATF on porting burrs as well. It stops them from clogging. When I drain an auto trans, I always keep the ATF. Also very good to stop rust forming.
 
12many said:
An update for those interested in burr finish topics. I ended up passing on the Victor 340 (that I applied a burr finish to) to a member here that needed one of these intakes who is putting together a serious effort. I decided to hold off running it till at least spring 2023 to do any swapping so figured I’d pass it on, just do another one later.
Anyway, having come across a killer deal on another one I couldn’t resist. After some careful porting I hit it with a combination of “rasp burrs” to achieve a really consistent burr finish. Extremely consistent sharp edges, Drags finger skin everywhere you run a finger in the right direction I might add. The first one came out beautifully. Even more satisfied with this one. Maybe come springtime I’ll actually slap it on....

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ABSOLUTELY BEAUTIFUL!
 
Interesting...what's the general consensus on How Much the Gains would be ? You think its worth removing an old Holley Strip Dom, and grabbing new gaskets?
 
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