Torque Plate Thickness

[Anonymous]

Have seen mentioned many places that a block should be rebored using a torque plate. But they never mention how thick this plate should be.
Idd be lucky if the locals had plates for SBC, 302 and the 2.3 ohc (used in entry leval stock car racing). Could make my own but too thin would be a waste of time and too thick a waste of money. Anybody have this info?
farmer kev

 

[Thad]

About 1.5 - 1.75", the ones I have used are thick enough to use the regular head bolts; short bolts require counterbore, long bolts a spacer. SBF can be used on 300, three cylinders bolted and torqued while honing two cylinders. Not the best but better than nothing.
The 300 and SBF will decrease in bore across between two torqued head bolts as much as 0.0025", with four bolts torqued, top of bore is cover leaf in shape.

 

[addo]

You will be safe with 2". This will require studs or counterboring for the bolt heads. 2½ thou is a lot! Thanks for that number, Thad. Not sure I would want to be responsible for what happened if the un-compensated motor came unstuck...

Regards, Adam.

 

[mugsy]

How makes a torque plate for our small 200? I will be re-ringing my short block this winter and want to make sure the bores are "straight".

tanx

 

[Anonymous]

I was wondering if one could be made from a ruined head, just bore the chamber right out.

 

[mugsy]

Opps!!!

I meant to say "who makes a torque plate...." I'm concerned that the machine shop might not have access to one when I get the block re-honed.

But.......... that does bring up another point... if one is NOT commercially available... have one made up from an old head.... :roll:

 

[Falcon62]

Clifford reportedly had them for the SB6 and would 'rent' them out. Have no clue if they still have them, or 'lend for a fee.'

 

[Lazy JW]

Just curious, what material should a torque plate made from? Mild steel? T1? AR plate? 4140? Sometimes I stumble across some sizeable pieces of scrap metal in my line of work and it would be nice to know. A friend of mine is a machinist
Joe

 

[StrangeRanger]

You're concerned about deflection, not strength. All steels, regardless of alloy, have the same approximate modulus of elasticity. That means that under a given load they will all deflect the same amount. It really doesn't matter if it's some horrid piece of merchant quality 1020 or a piece of aircraft quality 4150.

Strength varies greatly with alloy and heat treatment. That means that the amount of deflection a part can sustain before it fails will vary with the alloy. This should not be an issue with a torque plate. :roll:

So to answer your question directly, the cheapest piece of steel you can get to do the job is the best. If you can score a piece of something with uniform chemistry and high machinability, your machinist will thank you. I'd hunt for a piece of A-36 if I were going to build my own simply to assure there won't be any surprise inclusions from scrap that didn't quite dissolve in the remelt furnace.

 

[addo]

It's one of the most basic machining pieces. 14 small holes, six large bores. You can draw it rough and run the dimensions into a generic CAD file, and have one billeted.

They are more common here... It's expected that a good shop will have one. My experience with making stuff and trying to rent it (albeit with takings to charity) has been that everybody wants, but only a few will pay. For the longevity of the motor, it's worth doing.

Adam.

 

[Thad]

Torque plate mat'l is not critical, compressibility equal to or greater than head, fine. Main concern is durability for re-use. It is the block that is being stressed not the torque plate, so as long as the torque plate is strong enough not to warp it will work.
When the head or torque plate is torqued to spec, the block mat'l within the grip length of the head bolt is compressed, distorting into the area of least resistance, the cylinder bore. This distortion is what is honed to a true circle and to the correct size, take the torque plate off and cross measure the cylinder bore and it will measure out of round and OS in two places. When the actual head is torqued on the block the cylinder bore will distort BACK to true shape and size.
That why it is important to use the actual head bolts and gasket and torque spec that the engine will use.
I have heard of an old cylinder head being bore through and used for a torque plate. This was a one time use for a unique engine.

 

[Anonymous]

Hmmmmm.... :idea:

I think I know where the fork is to a big forklift!

John

 

[Anonymous]

We have had a torque plate for almost five years now and have been doing all of our 200's with it. We had it made from 2" ar plate and it was cnc flame cut. You never really realize how much of a difference it makes untill you get a cylinder a thou under and spray dykem on it, then bolt up the plate and hit it with the hone real quick and see the spots around the cylinder. Especially the number one cylinder due to the lack of support. Our plate weighs close to 160 lbs so it is a little tough to move around. I can duplicate it for around $300.00 if any one is interested.

Todd

 

[Anonymous]

BHJ is the foremost manufacturer of torque plates. I have been using their products for over fifteen years. I just went out and counted the plates on my shelf and i have twenty-one of them. They make them out of cast iron and aluminum, depending on your head material. Of all those plates the only inline six plate I have is for the Nissian six. Hope this was helpful.
thanks, roland

 

[mugsy]

FYI.

Contacted Cliffy, they rent a 200 torque plate for $75 plus shipping. The beasty weighs 75 lbs. and you pay of shipping to AND from (obviously).

They ask you return it in two weeks.