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Best sandpaper to notch pistons using valve with sandpaper

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Best sandpaper to notch pistons using valve with sandpaper

Postby berres » Tue Feb 21, 2012 6:47 am

Hello!
I'm about to notch my forged pistons 0.060" on intake side using valves with sandpaper glued (epoxy) on them.
Do someone have experiences of this regarding the grit sizes (roughness), the material (if some type of sandpaper are more suitable for aluminium) and the thickness of the sandpaper?
What grit size to start with and what to finish with? I don't want to create any hot spots and I prefer to do it in a two-step manner.
I know what diameter on the sandpaper to use but just not what type of sandpaper especially what grit size to finish with.


I want to use this method because this will ensure that I only take away as much material as absolutely needed to.
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Re: Best sandpaper to notch pistons using valve with sandpaper

Postby redsmokin57 » Tue Feb 21, 2012 7:02 am

120 to 80 grit cloth backed emery type, not the paper backed, IF I was to try this, however the idea of all that grit coming loose sounds bad. The shade tree method I have seen to get out of trouble on a assembled engine was to braze a couple of pieces of ground tool steel to an old valve, at least then you are only dealing alu. shavings.
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Re: Best sandpaper to notch pistons using valve with sandpaper

Postby BigBlocksOnTop » Tue Feb 21, 2012 8:51 am

You can rent the exact tool from Isky to do what you want!With the sand paper you are talking about taking forever and a day times eight or sixteen.
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Re: Best sandpaper to notch pistons using valve with sandpaper

Postby robert1 » Tue Feb 21, 2012 9:38 am

The product we use is from Norton. It's called Norzone R821. It's 36 grit. It will cut fast then you could finish off with a touch of 80 grit. Any quality 36 grit should do fine. The grit is not going to come off of this type of paper. But you still face the problems of the aluminum grit. Again I would put shaving cream or grease around the piston to keep the grit from getting down the sides.
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Re: Best sandpaper to notch pistons using valve with sandpaper

Postby BlitzA64 » Tue Feb 21, 2012 9:50 am

I have done this before with the 36 and did a finish touch with 80. I was never brave enough to do it without a complete disassemble and scrub job although I have heard of those that have........
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Re: Best sandpaper to notch pistons using valve with sandpaper

Postby Malvn » Tue Feb 21, 2012 10:04 am

Why not buy this tool Here at http://www.etsupply.com/edgetools/index.html scroll down to you see I N H E A D P I S T O N C U T T E R S you can use a drill to do this :)
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Re: Best sandpaper to notch pistons using valve with sandpaper

Postby berres » Tue Feb 21, 2012 10:45 am

120 to 80 grit cloth backed emery type, not the paper backed, IF I was to try this, however the idea of all that grit coming loose sounds bad. The shade tree method I have seen to get out of trouble on a assembled engine was to braze a couple of pieces of ground tool steel to an old valve, at least then you are only dealing alu. shavings.


I've considered that but I couldn't find any pictures of someone who have done that or any good material to make them off.
I've only found the type of lathe cutters shown in the attached picture and that type only cut a very small area, I need a cutter that can cut a larger diameter. My english is so bad so I don't know if you understand what I mean but I mean that the sharp part of the lathe tool need to be larger.
thanks

You can rent the exact tool from Isky to do what you want!With the sand paper you are talking about taking forever and a day times eight or sixteen.

Yes, I know about the isky's tool but it will take me that time times 10 to get the part to sweden :/ but thanks for your reply, it would have been a good option if I lived in the US.


The product we use is from Norton. It's called Norzone R821. It's 36 grit. It will cut fast then you could finish off with a touch of 80 grit. Any quality 36 grit should do fine. The grit is not going to come off of this type of paper. But you still face the problems of the aluminum grit. Again I would put shaving cream or grease around the piston to keep the grit from getting down the sides.


Thanks, that product is probably exactly what I looking for! But it wasn't easy to find a dealer in sweden, but I will send them an email (there is no distrubutor search in the european sites). Also, I couldn't find the product in the sweden catalogs, only on the north american site.
I will put shaving cream or grease around the piston like you said, it's a good idéa"!

I have done this before with the 36 and did a finish touch with 80. I was never brave enough to do it without a complete disassemble and scrub job although I have heard of those that have........

thanks for your reply! how smooth (fine) was the surface after the 80 finish touch?
do you think 0.040" off with 36 and 0.020" off with 80 will be fine or can I take 0.050" off with the 36?


Why not buy this tool Here at http://www.etsupply.com/edgetools/index.html scroll down to you see I N H E A D P I S T O N C U T T E R S you can use a drill to do this

this was a really good and cheap tool, if I lived in the US i would have bought it for sure. thanks for your reply, this is really an option to concider even if it will take a very long time before I have it in front of my door!
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Re: Best sandpaper to notch pistons using valve with sandpaper

Postby Dave Koehler » Tue Feb 21, 2012 10:59 am

Berres,
If you use a mill and a flycutter, use a HSS bit and shape the end to suit your needs. Works nice.
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Re: Best sandpaper to notch pistons using valve with sandpaper

Postby miniv8 » Tue Feb 21, 2012 4:33 pm

I cut and formed a lead body file and tack welded it to old valves.

dont forget you also need radial clearance for the valve.
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Re: Best sandpaper to notch pistons using valve with sandpaper

Postby winr » Wed Feb 22, 2012 2:41 am

Can you procure a valve with a bit larger head and put a notch in it to cut the piston top ??


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Re: Best sandpaper to notch pistons using valve with sandpaper

Postby digger » Wed Feb 22, 2012 3:59 am

get an oversized valve and grind some teeth into it to make a cutter.
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Re: Best sandpaper to notch pistons using valve with sandpaper

Postby F-BIRD'88 » Wed Feb 22, 2012 5:39 pm

I can't see you doing this without gouging the cylinder wall. I'd take the pistons out.
The nice thing about doing it right is you only have to do it once.
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Re: Best sandpaper to notch pistons using valve with sandpaper

Postby bmcdaniel » Thu Feb 23, 2012 2:55 pm

I did this one time with the pistons installed 'cause we needed to do it over a weekend and have the car running on Monday. I used a slightly worn 2 1/4" diameter course wheel in an electric angle grinder. Taped up everything but the piston I was working on, grease around the edge of the piston. When I was finished I'd move each piston to the bottom of the bore and clean the cylinder walls with ATF. Actually didn't come out too bad and we made the meet on Monday. LOL

Edit: Forgot to mention how I determined where to grind each piston. I removed the valve springs and valves, coated the edges of the valves with white grease paint. Re-installed the heads with an old gasket and gave the valves a spin, left nice white marks where the valves contacted the pistons.
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Re: Best sandpaper to notch pistons using valve with sandpaper

Postby F1Fever » Thu Feb 23, 2012 6:07 pm

there was a mag article, super chevy maybe, where they did the same basic thing but used an oversized valve, a 2.05 maybe where the heads were 2.02 and cut "teeth" into it, angular on the base and edges. They then took the valve put it in an old head and used the head as a guide with a hand drill to fly cut the pistons. I thought it was a pretty simple back woods way to get the job done.
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Re: Best sandpaper to notch pistons using valve with sandpaper

Postby Ted Gerstenslager » Sun Feb 26, 2012 8:26 pm

3-M Rolock discs with the spiral removed and glued to a valve. Anything that is used on an assembled engine will leave debris behind. The finer the debris the harder it will be to clean, sanding will make fine particulate that will get in the ring lands no matter what you do. If dissassembly is part of the final procedure then sanding will work fine, just take your time and measure each finished pocket depth with a bare valve and an indicator or a caliper. Make sure each piston is at TDC during the checking.
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