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How do I press the pistons off the rods?

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Old 11-11-2017, 01:22 PM   #1
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How do I press the pistons off the rods?

This is on my original LT1. How much of a press do I need to press the pistons off the rods. Manual Arbor press or 12 ton hydraulic? Haven't looked on U-TUBE yet but any links would be appreciated.
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Old 11-11-2017, 06:38 PM   #2
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Re: How do I press the pistons off the rods?

Probably need a hydraulic to press them apart. They're a pretty significant interference fit.

You can heat the pistons a bit and freeze the pins, to make putting them back on easier; or, bush the small ends and use floaters.
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Old 11-11-2017, 08:37 PM   #3
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Re: How do I press the pistons off the rods?

Haven't done it but I've had pistons changed and the rod ends were bluish looking from heat so I'd guess there would be some serious heat involved.
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Old 11-11-2017, 09:29 PM   #4
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Re: How do I press the pistons off the rods?

Right, I'm sorry, you heat the rods to get the pins into them, not the pistons... my brain got a cramp right then... and yes, people do use A BUNCH of heat sometimes. To the point that it seems like it can't be good for them.
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Old 11-12-2017, 02:24 PM   #5
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Re: How do I press the pistons off the rods?

Yes I understand you ment to heat the rods for installing rods.. Feedback I'm getting is a 12 ton press maybe marginal. I expect an Arbor press a waist of time for this.

Not sure where this is taking me. Machine shops want like $40 to R&R the rods from the pistons and a Hobo Fake press is around $130 w/o any discount. HF has a H-frame 12 ton and a A-frame 12 ton press. Which is better anyone know??

But I need to remove the rods to weigh them just to see if I can weight match them with an aftermarket rod. If I can't I have to recon the stock rods w/new bolts to use my stock crank. FYI reusing the stock crank saves me from alignhoning/alignboring the block (balancing to) and this is a totally econo build to have a spare motor if needed. Well sorting out the local machine shops to.
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Old 11-12-2017, 03:11 PM   #6
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Re: How do I press the pistons off the rods?

Pushing pins out is easy providing you're not trying to save the pistons. If you are trying to save the pistons, the need to be pt into a jig so they don't get damaged while the pins are being pressed out.

There is a lot to getting things weight matched for balancing. Rods are weighed at both ends and all the rods are taken down the the lightest weight. Pistons are matched to wrist pins for total weight. Even having to buy a replacement wrist pin can get a different weight. Once everything is matched up including rings, wrist pin locks, rod bolts etc, you get a total bob weight which is put onto the crankshaft to balance it.

Factory balance weight is not very accurate. It's good enough for an OEM engine but that's it.
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Old 11-12-2017, 03:29 PM   #7
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Re: How do I press the pistons off the rods?

Generally if you try to do this yourself you will damage the pistons. The investment in tools will not be worth it for one set of rods.

Neither of the harbor freight presses are worth owning. I have the 20 ton in a corner somewhere and you can't get anywhere even close to 20 tons out of it. I have a real press at my shop that has a two stage pump and that's the only way you are getting to 20+ tons with a hand pump (real press has a gauge and still Chinese, but cost about $700) Trust me - not happening with a Chinese bottle jack. The handle would fold in half before you got to 10.

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Old 11-12-2017, 09:20 PM   #8
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Re: How do I press the pistons off the rods?

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Originally Posted by AlkyIROC View Post
Pushing pins out is easy providing you're not trying to save the pistons. If you are trying to save the pistons, the need to be pt into a jig so they don't get damaged while the pins are being pressed out.

There is a lot to getting things weight matched for balancing. Rods are weighed at both ends and all the rods are taken down the the lightest weight. Pistons are matched to wrist pins for total weight. Even having to buy a replacement wrist pin can get a different weight. Once everything is matched up including rings, wrist pin locks, rod bolts etc, you get a total bob weight which is put onto the crankshaft to balance it.

Factory balance weight is not very accurate. It's good enough for an OEM engine but that's it.
U-tube shows some simple jigs for this but don't really have the time to carve one out of some oak wood.

I expect a 565 gram rod should be able to replace a 565 gram rod for a stock balance though I know they could well have different weights at the large and the small ends. This is a econo build and not going to win any bracket trophies. I plan to weight and match the pistons along with the wrist pins for a combined weight. From what I understand lighter is better for the reciprocating weight than heavier. I don't see the ring pack changing total weight much and I'm trying to avoid balancing the assembly. But what is bothering me is it looks like all the cheap aftermarket rods look heavier than stock Chevy rods. Aftermarket rods look so much better and are almost as cheap as reconditioning the stock rods with new bolts (new bolts are $75) but they are advertised 20-30 grams heavier.
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Old 11-12-2017, 11:58 PM   #9
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Re: How do I press the pistons off the rods?

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Generally if you try to do this yourself you will damage the pistons. The investment in tools will not be worth it for one set of rods.

Neither of the harbor freight presses are worth owning. I have the 20 ton in a corner somewhere and you can't get anywhere even close to 20 tons out of it. I have a real press at my shop that has a two stage pump and that's the only way you are getting to 20+ tons with a hand pump (real press has a gauge and still Chinese, but cost about $700) Trust me - not happening with a Chinese bottle jack. The handle would fold in half before you got to 10.

GD
Well I got only 2 quotes to R&R the rods from the 5 shops I visited. $45 and $80. Not sure what to do. See some real bubba methods on U-tube w/o a press even. Goodson has an installing fixture for $73 - no press needed. But various tools for rod pin removal and can't determine how much and what is needed from Goodson.
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Old 11-13-2017, 01:05 AM   #10
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Re: How do I press the pistons off the rods?

I would just take the crank, rods, and pistons into my machinist and tell him to make it happen. Polish the crank journals, check the crank for straight, and balance the whole mess. What are you trying to accomplish by doing it yourself? The stock balancing is not very good...... the weakest link is the rod studs not the rods themselves and if you replace those you have to hone the big ends anyway and rebalance the assembly.

Get some used powdered metal rods from a Vortec if it's a budget build. Supposedly they are quite strong.

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Old 11-13-2017, 09:40 PM   #11
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Re: How do I press the pistons off the rods?

. What are you trying to accomplish by doing it yourself?

Well I have to look forward as I have two additional 400 blocks for builds so I would really like to be able to R&R the rods myself rather than be a helpless customer to the cheapest machine shop.

A co-worker told me he has removed Chevy rods with a socket and hammer but of course he didn't reuse the pistons or pins.

From what I'm reading a piston fixure is needed along with the correct press-out tool. And a good press.

I guess I need to slow down and sort this all out. Can't find my number stamp set anyways so the rods will stay on the crank until I can number them.
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Old 11-13-2017, 11:00 PM   #12
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Re: How do I press the pistons off the rods?

I have done quite a few,it's quite easy-I have a~10 ton press and didn't have to work it too hard to press the pins out-pistons will need to be supported correctly to avoid possible damage during the pressing out-I just used some small square stock placed to take the load-no special jigs.Going on,just heated the rod end with a propane torch and slipped the pin in.Weighed the damaged rods with a cheap digital kitchen scale,replaced with spare rods that matched weight close.
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Old 11-14-2017, 12:59 PM   #13
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Re: How do I press the pistons off the rods?

Ditto what 8t2 z-chev says. I've done it with my 6 ton A frame press. Buy a small scale to weigh the rods & match the weights of the old one. But --- be very careful fixturing the pistons & make sure you pre-heat the rods. I used wood blocks under the pistons. Put the pins in the freezer.
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Old 11-14-2017, 09:26 PM   #14
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Re: How do I press the pistons off the rods?

Thx for sharing folks. It reads like it's much easier to press the pins in than to press them out. When pressing the pins out the rods need support inside the piston somehow. Don't see any of those rod supports for sale. I do see many threaded pin removal tools for sale on line but not sure how well they work. Using the threaded tool could be an all day job.

Goodson markets all tools needed for this including the hydraulic press but cost can run over $2000 easily.

Still sorting this out. Seems unexpected so little information on doing this to the rods and pistons and so many home engine builders..
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Old 11-17-2017, 02:18 PM   #15
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Re: How do I press the pistons off the rods?

OK, I just watched a nice U-tube video using a 12 ton HF press. The mechanic did use some heat on the rod small end with a hand held propane torch but it looked fairly simple with the right torch tip. He did support the rod (using just a hammer's head) so some kind of support jig will be needed. It does take several minutes for each piston. So I have to maybe weld up a a piston/support then find a pin pressing tool. Maybe then a full hour or 2 getting the pins out.

Do I really want to do this now? Hmmm, 3 engines to build that's at least $150 in machine shop services and it could run to $250.. I'm thinking I should remove the pistons first and build the piston jig before buying anything.
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