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Torque plate for honing?


jacob80

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Hey guys, been reading up on using a torque plate to simulate a cylinder head being torqued down on the block to simulate the distortion while honing. We did find one, but costs $900! Does anyone have an alternative that is just as effective or possibly a torque plate that someone wouldn't mind renting out

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$900.00? Now I do not feel bad having this one made for My RB motor for $500.00

 

tplate.jpg

 

Would you ever consider renting that out so our machinist can hone it with that on it? I believe it will bolt up to an L series engine. Of course it is not necessary, but these practices are what seperate good from great engines. :)

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Actually nevermind, just called our machine shop and they said they'll just make one for us for $200 :)

 

Minimum 2" thick steel, so it stays ridged. Also, it takes ALOT of time to make one correctly, has to be machined, then stress relieved, then surface gound on both faces. Just the steel would cost more than 200.00. Watch what you pay for.

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The cat's meow in L series torque plates is owned by Don Potter and is much more than just a 2 inch thick slab of steel. He developed it by actually measuring the cylinder wall distortion between a real head and his torque plate and modifying accordingly. He also bores at temperature using a new gasket each time and only after the assembly sits for at least 4 days to get all the creep out of it. Of course, it also takes him at least a year to build a motor, that is if he actually ever finishes. But when he does, big power and long life.

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Exactly!

 

Just torque the main bearing caps.

 

Yea...considering those are on the opposite side of the engine. The torque plate simulates the head being torqued down on the top side of the block, which "flexes", if you will, the block as it would be assembled.

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Yeah I dont see the benefit of this. Im sure it will provide some small benefit (thats if *everything* is at equal tolerances) but is it worth like $200?? I bet for 200 you could do something else that will provide alot more performance.

 

What kind of performance gains are you looking at? Or is it more engine life?

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it's the equivalent of tolerance stacking. you bore something at one size, on a certain pitch and plumb 90 degrees to something that will shift when another main part is attached to it. that's not good.

 

specialized tools like this will reduce that amount of shift. if you feel it necessary, do it. if you don't, then the choice is yours!

 

*queue Rush tune*

if you choose not to decide, you've still have made a choice!

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Yea...considering those are on the opposite side of the engine. The torque plate simulates the head being torqued down on the top side of the block, which "flexes", if you will, the block as it would be assembled.

 

I completely understand what a torque plate does, it is just not needed to hone (or even bore) an L6.

 

I like 1 fast z's idea of making one from a head though. If you were to use a bare head, and when you bore from the bottom for the first time you just bore all the up through the head. then the next time you use it, you can bore/hone from the top. I suppose you could use a junk block and bore it to 90mm just locate the holes in the head.

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  • 5 months later...

I would do it that way too for a an engine that has bores offset, like a v engine, the mains get in the way so boring from underneath like on an I6 would be my choice, so you could pull pistons out from the bottom (as some stock castings have a rough area at the base of the bore because pistons are not fed through there)... but on offset mains that sounds like it's a little tricky. lol on a snowmobile or jetski engine, i guess some are v-twins or single piston, so the crank journals are on the ends of the casing... makes it easier.

 

This would make bearing replacement without head removal possible for when you REALLY need to do so... can't do that on certain v engines though, so having a head with manifolds and gear bolted on with bores cut into them would simulate a torque plate much better for that application...

 

but then the task of getting it to operating temperature. LOL.

i really don't think that part is neccesary, I think the reason for the torque plate is to get it as close as close can be to how the engine is at operating temperature as is possible with a cost effective means.

 

I guess you could attach an external (and far away to avoid vibration) electric water pump that could pump hot water through the block as your bore it, with channels built into the torque plate and sorts of gaskets to hold the water in while you bore it... I think I read something like that about older F1 engines being cast and then bored this way... that's why I'm pretty sure I'm not making this idea up. LOL.

 

if anyone has any information about a process similar to that, it may lend a hand to some other data or speculation in this thread about the use of torque plates and their advantage with some technical data to back it up.

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just noticed this post - but did you know you can use a RB torque plate on the L6 too :)

 

Same bore spacing and head bolt pattern :) this has been covered on this site before (or did I post that on CZCC it was a few years back now)

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  • 1 month later...

ALL TORQUE PLATES SHOULD BE STEEL.

 

This is a very interesting thread. I decided to ask my friend from the local Harley shop and now I have the definitive answer to this question about why the torque plate SHOULD BE STEEL.

 

 

My friend Adam wrote;

look up the dimensional stability values of cast aluminum, and then steel. then look up the stability values of billet aluminum (6061). you can't recreate the aluminum head casting if you bore a giant hole in it, so using cast aluminum is out of the question, unless it's super thick.

 

The error in your mind is in your thoughts about the cylinder head, Cast aluminum is NOT malleable. Billet aluminum is very malleable. that's why heads crack, they have very high stability, but very low yield strength. they either take the force, or crack, nothing in between. a billet aluminum plate has a low dimensional stability (flexy), but a high yield strength (take a lot to break). In this case, steel is much closer to the deflection of the cylinder head than aluminum.

 

overall, yield strength plays little importance in this, it's all about dimensional stability.

end quote

 

 

Something a lot of people are also missing in the "Plate for Hone, Bore, or both" is the quality of the equipment being used.

 

Here is the difference.

 

Hillbilly Hone: Attaches to a drill

Professional Hone: Requires 3-phase power to your building and cost $40,000 or so. Dave Rebello (guessing) would own one of these.

 

If you are using a hillbilly hone, then you need to be close (to the final hole diameter) when boring. Whether or when to use a torque plate is something others can discuss.

 

If you have a professional hone you bore the holes oversized and finish with the hone. Any shop that has a professional hone will probably build a torque plate out of principal. I doubt they would use it for boring.

 

The engine was (99.99% sure) honed to size with a very expensive hone when first manufactured. Unless you are experiencing a problem from your bottom end, you will probably make your engine geometry worse by a no plate/hillbilly hone rebuild. It takes a lot of money and time to recreate the factory engine machine specification.

 

D.L. Potter using water jackets for hot water is very trick. Monitoring the heat of the block whilst honing will suffice.

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