Torque plate for new std bore 350?

[tresi]

Well it depends do you want it right or do you want to use the pistons that have on hand. Don't be surprised if you have to make the block 4.005 before you get it torque plate round. If you're dead set on using the pistons you have might as well hone to fit and run it. make it right next time around.

[PackardV8]

So having a tq plate made presents the same problem as honing the block.

Been covered here many times, but some thick wall DOM tubing spacers the thickness of the head is way better than nothing. Even stacks of washers if that is all you can get.

[stock z/28]

As Mr. Packard said some hardened spacers, proper bolts, and careful tightening are certainly better than nothing.

I dont think you have to have a plate made as Im sure there are quite a few for SB Chevy on the shelves. Thats probably a sizable investment though if you are not going to use it again.

[Jeff Lee]

https://ccaracing.com/honing-plates-and ... ad-plates/

I had this company build me a torque plate for my AMC. Beautiful quality! Note they will also rent a torque plate.

[Keith Morganstein]

This the $800 mild performance block?

Stock type SBC always move when you bolt a torque plate. They go oval, pinching in and bowing out. There can be distortion at the bolt holes, this is very obvious on an SBC 400.

Problem is, it's usually at least .0015" distortion, there's no way to make it round taking .0005 to .001". Plus it takes experience to round these up, esp with an AN style hone. (Hint: coarse stone and lighter stone pressure until it's round) really you need to have at least .003" to work with and know what your doing.

[MadBill]

Good point. However if you need 0.001" more and new pistons are not in the plan, the result with a torque plate will still be better than without...

[machinedave]

I have torque plate honed a new GM 350 block and have seen a benefit. It is a little hard to read the distortion from a bore gage but if you blue the cylinders and make a couple of strokes then you can see the distortion.

[groberts101]

I must be getting some better blocks than some of you guys are seeing. I don't see my blocks going a thou and a half out of round under the plate. Usually under a thou. IMO, if you're gauge can't pick that up?.. you probably need a better gauge.

If there's a big concern with this particular block?.. why not use an MLS combined with head studs? I've seen firsthand the geometry differences going from composite/bolts to MLS/studs and it is easily measurable with the plate. Also seen a few engines with very marginal out-of-round, where the use of MLS and studs can allow foregoing the use of the plate altogether.

[MikeB]

If there's a big concern with this particular block?.. why not use an MLS combined with head studs? I've seen firsthand the geometry differences going from composite/bolts to MLS/studs and it is easily measurable with the plate. Also seen a few engines with very marginal out-of-round, where the use of MLS and studs can allow foregoing the use of the plate altogether.

Man, that's some good information. No lateral forces pushing outwards on the bolt holes. Just no way way to remove the heads in some vehicles.

[MadBill]

It's a bit of a pain, but there's benefits to using studs even if you have to take them out to remove the heads.

[Pablo]

Thanks for the replies.
This is great info. I'm encouraged to hear that I may have enough material to correct for out of round but it seems like that may be debatable. I'll try the bolts with spacers as an alternative to an actual plate and see what it looks like.

It is indeed the $800 new GM mexico block by the way. I picked up some of the GM .028 thick composite head gaskets to go with it. Not as good as a steel shim with respect to distortion but I would imagine that it has to be better than the typical fel-pro .041.

[jsgarage]

Pablo, know that the first 'torque plate' was used by Smokey Yuinck on SBCs. Legend has it he took a junk head and milled four 4" OD holes clear thru the iron casting in line with the cylinders for bore access. He later found that torquing the main caps and even the oil pump bolt measurably changed some bore ODs. Its since been found that aluminum torque plates are needed on alloy blocks and steel plates on iron blocks to more accurately simulate the stresses of torquing parts.

Somewhere around here I have a sheet of measurements on a 351-C block (8 places per bore) honed with a torque plate, then measured with and without the plate installed. Some bores did not change much, two changed by up to 0.0015" and one went the reverse dimension of the other seven. Those bore changes are changing your ring end gaps.

[MadBill]

A lot of blocks honed with torque plates get rings gapped without...

[Pablo]

I honed the block using piston pins as spacers under head bolts to simulate a torque plate. They happened to be the perfect length to get the right amount of thread engagement.
Believe it or not this setup caused noticeable bore distortion. On the dial bore gauge I measured about .0003 which didn't seem like a lot but once I began honing it became obvious. No bluing required to immediately see areas where the hone didn't touch, and I could also feel the hone hitting the high spots. Some cylinders were worse than others. I was surprised.
It took quite a bit to clean it up.

So even without head gasket fire rings, simply torquing the bolts was enough to cause distortion on a brand new stock bore 350 block. Whether or not that translates into diminished ring seal I don't know, but I'm confident I made the cylinders a lot more round.

[In-Tech]

A lot of blocks honed with torque plates get rings gapped without...

Hiya Bill, Do you have a before and after of end gap with and without a torque plate? Have you checked end gap after rotating the engine 30 times on the stand?

My opinion, end gap(within reason) is a farce. There is not enough TIME at 6000 rpm(example) for any measurable loss of cylinder pressure due to a couple thou of end gap. The rings move and for good reason. Maybe Clint can chime in.