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Boring Cylinders with Torque plates?
Posted by: jjohnsonjo ()
Date: January 15, 2020 05:14PM

I'm a slow learner here. Anyone have any cylinder pics of honing pattern differences or dial gauge readings to share, with/ without or before/ after torque plates have been used.

J.O.

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Bethlehem,Pa





Edited 1 time(s). Last edit at 01/15/2020 05:16PM by MattNall.

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Re: Boring Cylinders with Torque plates?
Posted by: vairmech ()
Date: January 15, 2020 06:06PM

I don't have any pics but I can assure you that most cylinders do not appreciably change dimensions. I only had the one cylinder that I mentioned that went out of round out of the torque plates. My people that I use do check the cylinders out of the torque plates for round that is why I know about the one.

If you have a boring machine you need some way to hold the cylinders. What better way than to use torque plates? Also torque plates can be counter bored to accept both size cylinder tops if you bore the opposite side of the top plate.

Also the torque plates are only torqued to 30 labs. ft. just like the cylinder head. Does the cylinder head put different pressure on the cylinders? Only if they are uneven but in reality pressure is pressure. It doesn't make any difference if it comes from aluminum or steel. If you want make your torque plates out of aluminum. Keep in mind that steel lasts longer!

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Boring Cylinders with Torque plates?
Posted by: joelsplace ()
Date: January 14, 2020 11:44AM

How much difference do torque plates make on Corvairs? They make a huge difference in water jacketed regular engines like Chevy v8s but they have threaded holes on the sides of the cylinders that distort them.
Next question - since Corvair heads and blocks are less than rigid at best how does that translate to nice big rigid torque plates?
A quick test I did on a 350 Chevy block of mine was to clean up the bore with a hone then bolt on a torque plate and make a light pass with the hone. The top of the cylinder had visible distortions in the bore adjacent to the bolt holes. It's been 30 years but IIRC there were 5 oval shapes next to the head bolts where the hone didn't touch.

Joel
Northlake, TX
5 Ultravans, 113 Corvairs and counting...




Edited 1 time(s). Last edit at 01/15/2020 06:00PM by MattNall.

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Re: Boring Cylinders with Torque plates?
Posted by: vairmech ()
Date: January 14, 2020 06:04PM

When boring Corvair cylinders it makes a big difference! I have a shop bore my cylinders and they use a torque plate or I wouldn't use them. One time they told me the bored a cylinder and then checked the roundness it was good, they took it out of the jig and checked and it was way out of round! He put it back in the jig and it was round again!

Think about it, how are you going to hold the cylinder to bore it? Put it in a vise? Hold it by the little tabs on the bottom of the cylinder?

Anything you do like that will distort the cylinder and you will induce out of round issues. The only way to bore Corvair cylinders is in a torque fixture.

As far as a head goes all you can really do is straighten things out by truing things and then whatever machine work you want to do on the combustion chamber side. The same it true with new castings or billet material. You make your first reverence point and everything is all measured from there. Everything is kept cool with a spray lubrication for the machining so heat distortion is kept to a minimum. No need for a torque plate for the head.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com



Edited 1 time(s). Last edit at 01/15/2020 05:59PM by MattNall.

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Re: Boring Cylinders with Torque plates?
Posted by: joelsplace ()
Date: January 14, 2020 06:10PM

Ken, good to know someone checked and didn't just assume the cylinders needed a plate.
My reference to the head is since it isn't very stiff would the pressure it puts on the cylinder be anything like a nice stiff torque plate? Maybe so since all the load is fed into the gasket surfaces.

Joel
Northlake, TX
5 Ultravans, 113 Corvairs and counting...




Edited 1 time(s). Last edit at 01/15/2020 05:59PM by MattNall.

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Re: Boring Cylinders with Torque plates?
Posted by: REM654DPG ()
Date: January 14, 2020 06:38PM

Ken no worries, I didn’t take your comments as bashing in any way. And my apologies if the reply seemed to imply that as I was more so attempting to clarify Johns concerns with the print.
Again, thanks for sharing the print as it always helps having the original to compare things against.

And John, the big chunk of aluminum came from Coast Aluminum here in Portland. It was a remnant piece that was a “little” cheaper than trying to buy a specific size big chunk.

Joel, I think the torque plate makes enough of a difference that its worth the effort it takes to make and use – for me at least. I believe it allows you to run slightly tighter piston clearance which is beneficial for ring seating and longevity. On a Corvair cylinder the torqued distortion affects both the top and bottom area. It creates tight and loose spots in the upper portion of the bore around each stud which can then affect the rings ability to seat and seal as well as they could.
And, the bottom portion of the cylinder also distorts around the studs at the base gasket area and can pinch the bore tighter in the area where the piston skirt rides affecting bore clearance. In between these two areas you can get some out of round distortion which varies with castings and bore size and has a negative effect on ring sealing.

So, all that said – in an effort to bring this thread back on topic, in my opinion if you were going to bolt on a set of racingguy2 hi-performance billet cylinder heads you would definitely want to your cylinders to be torque plate honed.
And how much distortion difference a rigid boat anchor of a torque plate fixture would have compared to the stock case and heads I’m really not sure but I suppose it’s still better than nothing.

And racingguy2 I feel your pain with all the electrical work and can only hope that you’re able to get it all buttoned up before it gets too cold or the lake overflows.

Regan Metcalf
Portland, OR



Edited 1 time(s). Last edit at 01/15/2020 05:58PM by MattNall.

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Re: Boring Cylinders with Torque plates?
Posted by: vairmech ()
Date: January 14, 2020 07:05PM

joelsplace Wrote:
-------------------------------------------------------
> Ken, good to know someone checked and didn't just assume the cylinders needed a plate.
> My reference to the head is since it isn't very stiff would the pressure it puts on the cylinder be anything like a nice stiff torque plate? Maybe so since all the load is fed into the gasket surfaces.
>>>>>>>>>>>>>>>>>>>>

The cylinder I referenced was put into my stock and at some point put into an engine with no issues as far as I know. So yes, I think the heads put enough pressure on the cylinders to make a difference. BTW, you don't just crank down on the torque plates, you torque them to specs!

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com



Edited 1 time(s). Last edit at 01/15/2020 05:57PM by MattNall.

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Re: Boring Cylinders with Torque plates?
Posted by: REM654DPG ()
Date: January 14, 2020 07:39PM

The cylinders are usually within .002 or less in length and parallel from the factory but I think they should always be surfaced which would make them all exactly the same.
The shoulder heights on the case are usually pretty parallel and square from end to end but it’s the left to right side that can vary by .010 more or less. For a performance application I think this surface should always be machined too. First to clean up the gasket surface and second to equal distance both sides of the engine so that the piston deck heights are equal.
To do this you need to locate off of the mainline from end to end and if you don’t like to pull studs a ratcheting boring head fits between them and works great.

Regan Metcalf
Portland, OR



Edited 1 time(s). Last edit at 01/15/2020 05:57PM by MattNall.

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Re: Boring Cylinders with Torque plates?
Posted by: joelsplace ()
Date: January 14, 2020 07:46PM

I'm not arguing against torque plates. I think it is a great idea.
I do think it would be a good check to use an old case half and a junk head with a hole cut in it to compare to stiff torque plates. Obviously the stiff ones are way better than nothing.

Joel
Northlake, TX
5 Ultravans, 113 Corvairs and counting...




Edited 1 time(s). Last edit at 01/15/2020 05:56PM by MattNall.

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Re: Boring Cylinders with Torque plates?
Posted by: vairmech ()
Date: January 15, 2020 06:39PM

My question to you is what difference would it make? As I said pressure is pressure. Yes the aluminum is soft and a little flexible over the length but the pressure that is put on the cylinder is put directly on each cylinder with 4 studs each just like a steel boring jig.

Thinking about it, and you to, if you only torque to the 30 lbs. ft. and the head does not deform is not the same pressure being put on the cylinders? It is that simple.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Boring Cylinders with Torque plates?
Posted by: joelsplace ()
Date: January 15, 2020 08:14PM

"If the head does not deform" Big if. I'm thinking if you had a way to measure it you would see more pressure near the studs than half way between the studs.
If you have a big chunk of steel you will probably get more even pressure all the way around. Hopefully the heads are rigid enough that it doesn't matter.

Joel
Northlake, TX
5 Ultravans, 113 Corvairs and counting...

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Re: Boring Cylinders with Torque plates?
Posted by: vairmech ()
Date: January 16, 2020 05:55AM

I really think you are trying to over think something you shouldn't worry about.

If you are trying to be that perfect you will never get there and it is not needed. Just look at all of the engines that have been built and rebuilt/repaired by non-skilled people and they run very well with no issues.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Boring Cylinders with Torque plates?
Posted by: v8vair ()
Date: January 16, 2020 06:03AM

I use a Torque Plate, It uses corvair studs and was originally the one Reeves made in the 70s. Yes the Cylinders do distort when Torqued, some more than others. Theres not a Race engine shop in the country that doesn't use them, SBC,Ford and many others. The Deck height on corvair Cylinders can be all over the place too. .001 or .002 may not matter to some but it does to me on my race motor,. Four Race weekends on 362,has not used any oil,no blow by. Mike



Edited 2 time(s). Last edit at 01/16/2020 06:11AM by v8vair.

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Re: Boring Cylinders with Torque plates?
Posted by: racingguy2 ()
Date: January 16, 2020 10:42AM

Coming from F1 and NASCAR racing industry, I tend to be very fussy about tolerances, balancing, you name it, we do it. Then I helped a team that raced dirt track, claimer class. (Anyone can buy your car if you win) Budget was almost more important than how fast it was. As kind of a joke, the owner put an sbc 350 engine together with four different kinds of pistons! Used rings, nothing matched, cheap gaskets (or silicone), no machine work, not even clean. It ran beautiful! And won quite a few races! Would I ever do it? Heck no. Did it work? Yes, very well!

Now, a little known or considered fact: When you rev an engine or are running it under load, the whole assembly twists. On a SB2 (basically a heavy duty SBC 350), on an engine dyno, when rev'ed under load to 8900 rpm, the blocks would twist from one corner to the other 1/8" or more (one new, unseasoned block twisted almost 1/4" before something failed (which for those that haven't done destructive dyno testing, it's like a bomb going off.) One trick that gave RCR racing, and Dale Earnhardt Sr. a significant advantage, was that we figured that out, and I machined the blocks so that they had ideal clearance at rpm and load. The crankshaft bore journals at rest were out of alignment by a lot...

Oh, and pistons, especially race pistons aren't round.

All that said, I have a collection of about 20-30 deck plates!

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