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12-27-2020, 11:33 AM | #1 |
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Location: Portland, Maine
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Mode A Piston expander/ knurling tool to Buy
I am looking to purchase a piston skirt expander/ knurling tool. I have a Model A engine with a slight piston slap. If you have the tool or know where I can get it please contact me @ [email protected]
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Jon Harris Portland, Maine. |
12-27-2020, 11:40 AM | #2 |
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Re: Mode A Piston expander/ knurling tool to Buy
Don’t use these tools, it’s simply a bandaid tool. Like saw dust in the rear end.
Get a new piston or set of pistons, ball hone the cylinders and put it together. Pistons are relatively cheap, and you’ll be glad you fixed it the right way. |
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12-27-2020, 11:54 AM | #3 |
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Re: Mode A Piston expander/ knurling tool to Buy
You will probably get an earful from people telling you how knurling is a bad, outdated, waste of time, why don't you do it the right way, etc. but it does work for a while. I have one of those expanders but I have NO idea where it is, sorry. Have you considered the old "skirt expanders" springy metal things that go up inside the piston? They show up online sometimes and also in boxes of old stuff.
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12-27-2020, 11:57 AM | #4 |
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Re: Mode A Piston expander/ knurling tool to Buy
Have you taken the engine apart yet? It could be a cracked or scored piston that would need replacement. If it has the original split skirts be sure the were all facing the correct way.
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12-27-2020, 01:11 PM | #5 |
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Re: Mode A Piston expander/ knurling tool to Buy
a set of pistons is 95 bucks.. look at it this way, why go through all the labor of pulling the head and oil pan, buy a gasket set, and adjust all your rod bearings to 'patch' the engine? If the main and rod bearings are good pull the pistons, hone the bores, lap the valves and adjust the bearings..and have a good old fashioned overhauled engine you can rely on..
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12-27-2020, 06:50 PM | #6 |
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Re: Mode A Piston expander/ knurling tool to Buy
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BTW, the bottom end was loose too and I haven't been able to get it right yet.
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12-27-2020, 08:27 PM | #7 | |
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Re: Mode A Piston expander/ knurling tool to Buy
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12-27-2020, 09:53 PM | #8 | |
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Re: Mode A Piston expander/ knurling tool to Buy
Quote:
Piston slap is the result of one or both things, either the piston collapsed, or the cylinder is worn enough to taper, allowing the slap. The real solution is new pistons, or bore/hone to the next size AND new pistons. Knurling is a bandaid. It’s one best applied by the old total seal (or others) knurling machines. Far more rare and expensive than a new set of pistons. |
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12-28-2020, 10:28 AM | #9 | |
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Re: Mode A Piston expander/ knurling tool to Buy
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12-27-2020, 09:31 PM | #10 |
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Re: Mode A Piston expander/ knurling tool to Buy
Yeah, my A ening has a ton of piston slop and smokes pretty good at idle but I have a stock bore B engine under bench waiting so meh.
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12-27-2020, 09:54 PM | #11 |
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Re: Mode A Piston expander/ knurling tool to Buy
Thanks for the input. I still would purchase the tool and perform the expansion as a learning tool for my club seminars. Yes, the purchase of a set of pistons is not expensive and the cost is not at issue The purpose will be a learning tool.
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Jon Harris Portland, Maine. |
12-28-2020, 05:53 PM | #12 | |
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Re: Mode A Piston expander/ knurling tool to Buy
Quote:
Any chance your pistons are actually old split-skirt pistons? If so, there were specially designed "expanders" for correcting slap. They were called 'Piston Expanders'. Easy to install and will work as good as knurling. |
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12-27-2020, 10:11 PM | #13 |
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Re: Mode A Piston expander/ knurling tool to Buy
Pretty obvious the solution requires correcting the bore,attaining that by boring if necessary.
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12-28-2020, 10:30 AM | #14 |
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Re: Mode A Piston expander/ knurling tool to Buy
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12-27-2020, 11:39 PM | #15 |
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Re: Mode A Piston expander/ knurling tool to Buy
I own a Perfect Circle Nurlizer machine. I collected it as strictly a conversation piece and in case some pistons for which there not have been a reasonably priced replacement. Nurlizing was even suggested for new pistons as it tightened up the clearance and provided a place for lubricating oil to slide in the bores. As for all the good advice these previous gentleman have given, they are right on the money. Don't judge or predict what the real problem may be. Loose wrist pins, bent rods, ill fitting pistons, worn rings. A set of new pistons with fitted wrist pins and new rings along with proper fitting in the cylinders, a rebore may be needed, and you will be money ahead.
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12-28-2020, 10:37 AM | #16 | |
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Re: Mode A Piston expander/ knurling tool to Buy
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12-28-2020, 04:03 PM | #17 | |
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Re: Mode A Piston expander/ knurling tool to Buy
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Bill |
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12-28-2020, 06:21 PM | #18 |
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Re: Mode A Piston expander/ knurling tool to Buy
The alternative to knurling is Koetherizing, wherein the piston is squeezed through the gudgeon bores by a bolt and thrust bearings into a more cammed shape on the thrust faces. While under this compression it is shot peened inside, relieving the alloy stresses so it retains part of the squeezed in expansion when released.
There was an article on this forum about a portable koetheriser in a truck by Old Motor a while ago. I just 4-stone honed an engine to straighten worn bores and bought new Omega solid skirt pistons which I resized on my koetherizer by 0.0095 for the worst bore. The others were around 0.005 inch. That engine now runs nicely with no piston slap. Obviously not as good as a rebore, but fun to do and should last another 50000 miles at least, going on past history with older repairs by the firm which donated the machine to me. How many koetherizers are left in the USA I wonder? I think I have the only one of 2 that were sent out to NZ. The engine was a 2.5 litre Riley, not a Model A. Compression pressures are now all 167 psi. 8.8 to 1 pistons used SAJ in NZ |
12-28-2020, 06:25 PM | #19 |
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Re: Mode A Piston expander/ knurling tool to Buy
I was going to mention shot blasting but didn't because the topic was knurling. I think the shot blasting is a better method but knurling gets it done with less equipment.
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12-28-2020, 07:43 PM | #20 |
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Re: Mode A Piston expander/ knurling tool to Buy
Curious. To those that did not like the idea of knurling to expand a piston, could share your reasons please??. While my current opinion is that it's a good thing (in the right circumstances) that opinion is subject to change pending compelling arguments to the contrary.
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