www.cylinderheadsupply.com/mp-6.html

Mopar 170-225 Slant-6; Billet Steel; Std. Bore In Plate=3.520/3.525"

"Head-bolt torque can dramatically distort cylinders and cylinders can not be bored or honed accurately if cylinder dimensions change so significantly after assembly. Rings won’t seal well and scuffing is likely to occur if the engine overheats. Use of BHJ Honing Plates rectifies all of these problems, leading to more consistent tolerances, better sealing and more power.

The R Model Honing Plate is the established standard for duplicating cylinder bore distortion and is a must for any high performance engine application. Used by top machine shops, racing teams and racers alike, the R Model is acknowledged to be the finest, most accurate honing plate on the market today."

It's expensive: $1,076.25

--Walt Jackson

People have used them.

I am not sure about anyone here.

If you have a scrap block laying around you can make one yourself with a sawzall and about $40 worth of blades.

Have the machine shop deck it true on both sides.

I did one like that in 2004. Still use it.

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http://www.youtube.com/hyperpack

They do work...! Doug made a homemade like Greg's that worked good too. Don't feel you have to settle on a store bought one...

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There's no such thing as too much cam....only not enough engine!

I used one I borrowed from Slant Cecil on one of my engines. I sold it to (I think team green) When I was selling parts for Cecil.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

For racing, hi revs etc I can see it. But for daily driver, low-medium rpm, mild build how much difference does using (or not) a torque plate during machining, make?

Just compare it to the bores being square if its honed without one once you torque the head. Now imagine the round rings trying to seal against a square hole....And that's whether the engine is a bone stock rebuild or a race engine!

Better machine shops also know to torque the main caps when the block is bored as well, or the bottom portion of the cylinders will distort when the engine is assembled. We made a plate for the bell housing in our race engines when they were finish honed because without it, the number 6 cylinder would egg shape when you bolted the bell housing to the engine. Took a while to figure that one out...

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There's no such thing as too much cam....only not enough engine!

IMHO, if you are doing a mild/medium buildup, this is really not worth it. I have a deck plate like that and have only used it once. Can't say it was worth any HP, but peace of mind, sure. Spend your money on bigger valves and a good head porting job and you will be MUCH happier. To be specific: Take that $1100 and add it to whatever you would have spent on your head. The trick there is to find someone reliable (not a cheater/blowhard) who can do the port work.

My 2 cents...

Lou

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Home of Slant6-powered fun machines since 1988

I agree with Lou. It is a matter of "bang for the buck". I did it because I had free use of the plate, and the machine shop only charged me a minimal amount additional. If you are a serious "class" racer, where every single horsepower and .001 sec counts, that is a whole nother ballgame.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Yes, there are places that this money can be spent to have greater benefits. Many of the Slant records here have likely been set without using one. There are better bangs for the bucks out there for sure....

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There's no such thing as too much cam....only not enough engine!