Steve Bryant

iTrader: (1)

I have a set of cast iron LQ4 heads which I've hand ported (see https://ls1tech.com/forums/showpost....51&postcount=2) and have been using on my truck for about 6 months. Now, I've bought an LQ4 block and I'm planning to build a 408 relatively low cost stroker to run on 87 Octane as my present engine does. This engine is all about NA torque through about 4,500 as the truck weighs 6,900 pounds and I tow an 8,600 pound trailer. I will be decking the block shooting for the pistons to be flush with the deck, align honing the crank and boring and honing the cylinders to 4.030".

Here's my question: Is a cast iron torque plate really better for cast iron heads (as some say) or does it really make any difference?

Thanks in advance for your input.

Steve

Rokko

iTrader: (2)

I would use the same material for torque plates.

Old SStroker

Any torque plate has bore-sized holes through it which makes it a lot less rigid than any cylinder head.

That being said, isn't a torque plate used to distort the bores around the head bolts/studs like the attached head does? Before torque plates became popular there was some use of a stack of washers or a spacer under torqued head bolts to distort the block for honing. It might be interesting to check the difference in distortion by using the bolt 'n spacer method vs. the full torque plate method. The loads on the plate are virtually 100% compressive, so it probably really doesn't matter which you use. Don't most shops have steel plates? I'd use a steel or iron plate for everything.

Steve, are you recamming for the rpm range you use for towing? You might gain some there if you are willing to work the valvetrain a bit harder. Of course the most dynamic compression you can live with is your friend even with 87.

My $.02

Steve Bryant

iTrader: (1)

My current cam is the third cam that I've had in the truck.
1. stock
2. Comp 212/218 w. 114 LSA
3. Comp 200/206 w 109 LSA

If I bore and stroke the engine as planned, I'll probably try my 212/218 first since I'll get more torque down low with the larger displacement. The 200/206 cam is excellent in a heavy vehicle like mine with the 6.0 L for general use. It looses about 25 HP and gains about 25 pound feet of torque. Off idle torque levels are excellent.

I agree that the only function of a torque plate is to allow the application of tension to the bottom of the cylinders and the distortion caused by that tension during boring and honing to get a more constant radius bore. The torque plate allows the load of the bolts/studs to be distributed across the plane of the deck in a normal fashion. Personally, I don't believe that there could be any difference between steel, iron or aluminum. You just want a rigid, flat plane.

Steve

Steve

427

iTrader: (3)

I have seen different head gaskets cause different load distortion on the top of the cylinder. We always use the gasket/fasteners that will be used in the running engine.
I have some iron plates and some aluminum. They both seem to do the same job, although the iron should be more rigid.

Kurt

Steve Bryant

iTrader: (1)

Thanks Kurt,
Your last remark, "They both seem to do the same job . . ." is very much in line with my thinking. I can also see how the head gasket will literally have a bearing on the cylinder shape.

I think that I am going to conclude that any torque plate of sufficient rigidity that is accurately constructed will be sufficient to properly apply the clamping loads applied to the cylinder head bolts/studs and result in a superior boring and honing when it is installed correctly (torque with fastener lubrication in the proper sequence with the planned head gasket).

Thanks to all who commented,

Steve

99 2500

Steve,
Curious to know what your current engine mods dyno at?
Thanks

vipex70

sorry to be a complete an utter, n00b, but just what is a torque-plate? Just though I'd ask...

caddycarlo

a torque plate is bolted to the block inplace of the head while the block is being honed ..... this is to mimic the destortion caused by the bolts so it is honed to a shape that will be round when the head is torqued to the block...

Steve Bryant

iTrader: (1)

99 2500
With the 212/218 cam running 87 Octane, I ran about 280 HP/320 Pounds-Feet at the rear Wheels. With the 200/206 cam and 87 Octane, I run about 245 HP/345 Pounds-Feet at the rear wheels. I have a lot of drive train losses with the 4L80E, a transfer case and 265/75R16 Load Range E tires. This is on an inertial dyno (dynojet).

Steve

'02 SLP#686

iTrader: (1)

It is more important to have the tourque plate match the mass of the cylinder heads to be used rather than material... that being said, like materials are probably better.

busta9876

iTrader: (3)

It is my thinking that the LSX Gen III engines head bolts pull from the bottem of the bores, not at the deck surface,

is bore distortion as large on the LSx engines when not using torque plates?

just my thoughts.