Torque plates for honing blocks

[Mudrat]

What are these made of??? 1" hi-tensile steel or something or full thickness (like a head) casting that has the appropriate bore???

Curious - educate me too!!

Pat

[Gremlin4ever]

Never held one, but guessing I'de say at least 2" thick and it has to be rigid enough to not warp when torqued down (Steel maybe?). The bore should be greater than the block so the boreing tools can still be used on the block.

[tarior]

It's funny that this subject comes up, I was just talking to my favorite machinist the other day about torque plates. It seems that the torque plate is made of the same material as the head that is suimulates. So, for iron heads one would use a cast iron torque plate, for aluminum heads, you would want an aluminum torque plate.

[fuzz401]

they are about 1.5 to 2 " thick with the head bolt holes counter sunk so they do not interfear with the boring or honing made out of cast steel/iron
I borried one when I did my 401
I have hears of taking a old head and cuttint it in half to make one too

[Rogue Racer]

"the technology never ends" . . . How true, how true.

There are and have been several developments in the torque plate product arena. There are plates that have the retaining bolt holes countersunk to not interfere with a boring bar when it is mounted on the top of the block surface. There are also plates with cuts for some bolts and stands or spacers for others so that stock head bolts can be used to closer simulate the stretching effect on the block when a head is bolted on. Such plates are used for honing or can be used with a Rottler or other type of boring machine that jigs off the crankshaft centerline and has a floating head that is not attached to the block. There are aluminum plates to simulate the stress an aluminum head on the block. There are some professional race engine builders who circulate hot water through the block and bolt on motor mounts, bellhousing and a head on the side of the block not being honed to more closely simulate operating conditions.

The purpose of all the efforts is to acheive cylinders that are as round and straight as possible. The same reason race blocks are filled in the water jackets with epoxies and concrete materials. Some factors are unknowns, such as block distortion due to torque and the effect of the crank assembly swinging on the inside of the case at a gazillion RPM, but the principle of round and straight cylinders has been proven to be advantageous in the racing arena and in production engines. The torque plates have been an important factor in the technology to acheive that end. How much is necessary and what really works? Lots of debate on those questions. From my experience, the AMC block is not as distorted when the heads are bolted on as most Detroit V8s from the 60s and 70s.

A little test for those of you who get into such stuff is to use a quality dial bore gauge (or maybe a good inside micrometer if you have the skill) to measure the cylinder bore at several points around the cylinder within the top inch of the block. Record your readings. Then bolt a head on the block using a head gasket and torque specs just like you would if you were assembling the engine. The turn the block over and measure the same cylinder in the same places reaching in from the bottom of the cylinder. See if the cylinder is distorted. I find 390s and 401s distort about .003". Common 360 blocks distort .002" to .003". 290s distort only about .001" or so. Publish you findings here so people can make their own judgments.

The head plate to do a valve job works well, especially on the end cylinders.

[jeepsr4ever]

See if the cylinder is distorted. I find 390s and 401s distort about .003". Common 360 blocks distort .002" to .003". 290s distort only about .001" or so. Publish you findings here so people can make their own judgments.

That is quite a bit of distortion.....are those numbers right? I guess I never checked it out...only ever had one block done up with plates

[Rogue Racer]

MC -

My records:

1 '68-'69 390 block - measured two cylinders, #2 and #6. #2 distorted .0033", #6 distorted .0021"

~'72 401 block - measured two cylinders, #1 and #7. #1 distorted .0031", #7 distorted .0026"

'76 401 block - measured 4 cylinders, #1 and #3, #6 & #8. #1 was out .0030", #3 was out .0017". #6 was out .0020", #8 was out .0018"

I have measured four 360 blocks, of unknown years except 1 which was out of '77 Matador. All would distort in the .0012" to .0025". The front two cylinders are worse than the others. I suspect this is due to less support due to the design of the block. I had one block which was a Jeep block that was better than the other three, for some undeterminable reason.

I have measured three 290 blocks and they distort less. All the cylinders except the front two would distort less than .001". Of course, the 290 block has cylinder walls that are twice as thick as the bigger engines and the cylinder diameter is less. Also, I was torquing the heads at 75 ft/lb on the 290 with a steel gasket where the other blocks were being torqued at 100 ft/lb with a composition gasket (FelPro 8266), if that is a factor.

[jeepsr4ever]

Nice...we need another post of usefull engine info

[Mudrat]

Nice...we need another post of usefull engine info

So get HOT!! You have the Collection

Mudrat
Posted LIVE from Charleston!!

[fuzz401]

Mudrat
Posted LIVE from Charleston!!

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