Torque Plate for Boring 340??

[Plum Crazy Chris]

I dropped off my shortblock at the machine shop today, and after we get the paperwork done and tour their facility, I learn they don't have a torque plate for my engine and it needs to be bored.

How important is torquing the block while boring? The shop guy made it out like it was no big deal, but everything I've read says it should be done.

The engine will get all the goodies in the Mopar Muscle stock 340 build, plus Ebrock heads. They got 392 hp w/out the heads.

Is it neccesary for this stock .030 over engine?

Also anyone with a desktop dyno.... what hp numbers should I get with this combo?

[mr_340]

I've measured as much as .002" difference in bore diameter without the torque plate. With the four bolt pattern around the bore on a 340, the bolts tend to pull the bore square when torqued down.

My measurements were done on a block bored/honed with my plate. After removing the plate, the bores measure differently on the diagonal between the bolt holes than lengthwise and cross wise. It definitely distorts the bore. A BB that has five bolts around the bore would probably have less distortion than on a small block.

I ended up buying a torque plate from Ed Hamburger in the 1980's because no one in Austin had them for a small block. Only one shop I ever used had plates for Mopars, that is Wayne Calvert in Denton, Texas. He has them for almost all American engines. He uses the good BHJ plates (2" thick). Mine is only 1" thick, but it seems to work.

[Christopher]

Personally,I think it's important to use one,especially on a small block.I use the BHJ unit and it is a fine piece of equipment.I highly recommend it.

[gthomas]

I personally would not have anyone bore any of my engines without using a torque plate. If it was my engine I would definitely find a machine shop that uses one.

[pishta]

A small shop out here, I cant remember which one, had a "torque plate". It turned out to be a 318 head that had holes in the top that the axle of the machine went through. I guess it would work, it looked kinda Mickey Mouse....

[Jims451]

I think the honing is done with the torque plates, but I'm not sure the boring is done with the plates?
I think it only cost me about $20 more to have the block done with the torque plates, but this was a shop that does mainly race engines.

[Doug Wilson]

Without a torque plate, the bore won't be aligned when the engine is assembled. If the the bore is not aligned, the engine will leak compression pressure. If it leaks compression pressure, it won't run as well as it could. It seems to me that being in this hobby means that you demand more from your iron than Joe Chevy. I wouldn't even think about building an engine without align boring and align honing. BUT.......whatever rings your bell, be sure to have fun.....from Doug

[sanborn]

Don't even think about honing a .030" over 340 block without deck plates. You might could get by without deck plates on an "R" block(if its small bore) but not on a stock 340.

[Locomotion]

I believe Pioneer (freeze plugs, engine fasteners, etc.) in Pascagoula, MS sells them, but I don't have any part #'s handy.

I have a 1" version I gave to my engine builder and it has worked just fine! I'm not sure if they recommend it for this particular version, but I have always had my engines honed with the same head gasket installed as what will be used on the engine to help duplicate everything as much as possible.
Myron

[Plum Crazy Chris]

Thanks for your responses. I will definately find and use a torque plate. This shop does use plates, but doesn't have one for the 340. I talked to them this morning and he said that they'll find one, and if they can't, I'll take the block somewhere else.

thanks again.