[LeMans70Sport]

Hi all,
I'm in the planning stages of building a street/strip 455. I've been calling around
the local area trying to find a machine shop that uses torque plates when the
block is bored/honed. I talked with one old timer that says he's been building
engines for the roundy round guys for 25 years and has never used and never will
use torque plates when boring/honing cylinders. He claims that is an old wise tale
that originated from the Chevy 400. He says because the head bolt holes are so
close to the cylinder walls on the 400, they do cause a very (he stressed very small)
hump in the cylinder wall when the bolts are torqued down. He said the hump isn't
even big enough for the rings to loose the seal. he said his engines are good for
275# of compression (stoked 400). He claimed that if any shop advertises or
recommends using torque plates, they are only soaking thier customers or using
it as a marketing device. Your thoughts?

[LeMans70Sport]

Hi all,
I'm in the planning stages of building a street/strip 455. I've been calling around
the local area trying to find a machine shop that uses torque plates when the
block is bored/honed. I talked with one old timer that says he's been building
engines for the roundy round guys for 25 years and has never used and never will
use torque plates when boring/honing cylinders. He claims that is an old wise tale
that originated from the Chevy 400. He says because the head bolt holes are so
close to the cylinder walls on the 400, they do cause a very (he stressed very small)
hump in the cylinder wall when the bolts are torqued down. He said the hump isn't
even big enough for the rings to loose the seal. he said his engines are good for
275# of compression (stoked 400). He claimed that if any shop advertises or
recommends using torque plates, they are only soaking thier customers or using
it as a marketing device. Your thoughts?

[Old Man Taylor]

I always have a torque plate used on my performance engines.

[David Holmberg]

You need it if you are going to make over 400HP. You can see a difference in the leak down tests after break-in and beyond.

[larry davis]

What's the old axiom?...

"Opinions are like a$$holes?"...


You'll find an equal amount on both sides of this fence. I lean towards the use of torque plates on a pplications where your after every iota of power. The theory for their use is sound. But like your old timer said, it's mostly centered on "Chevies" & other makes that have more than 4 bolts per cylinder. Those 400 SBs have thin walls. By comparison Pontiac's have more meat between the cyl. wall and bolt holes & only 4 bolts. Thereby producing less of the distortion.
I would be interested if anyone has some comprehensive factual testing about this.
You will find a Pontiac torque plate HARD TO FIND! In most areas. I have yet to find one in the entire Chicago are? So guess what, my 500-550 HP 428+ build-up will be w/o. But, I'm not too concerned. It'll have enough kahunas to make up for the minimal loss (if any).

[myckee]

BHJ makes the torque plate for Pontiac engines in case you wanted to get one and lend it to your engine builder. I have no clue as to cost but might be worthwhile.

[ May 02, 2002, 07:52 PM: Message edited by: myckee ]

[ta406pont]

I have a 520 HP 408 with 11.5:1 compression did not use plate,and have very minimal leakdown problems,but if you can get your hands on one I would use it..

[Tom Vaught]

A simple test.
Take a ring and install it on the second ring land
of a piston. Put the piston in a hole and then install a gasket and cylinder head. Do NOT torque
down the head. Put a small 12 volt bulb in the spark plug hole and view the light showing when
looking up at that cylinder from the oil pan flange. Then torque the head down and repeat the
test. You will be amazed by what you see. Tom V.

"One test is worth a thousand opinions"
J.R. Clarke, Chief Engineer Advanced Powertrain Engineering, ret.

[Steve C.]

BHJ Products 510-797-6780, about $200 or so.
Good thing for a local club to purchase and share among its members.

[larry davis]

Tom, there you go w/ that common sense **** again!

But I like it! Nice Poor boy test.

[Injunjoe]

Total price from BHJ including shipping to SC was right at 300. Just got off the phone with them. Also called Atlas, the price from them without shiping was 330. I have been thinking about buying one and have been looking around. If anyone has an extra one or a used one for sale let me know.

[Half-Inch Stud]

LeMans70Sport ;

Your shop fella's opinion is seasoned and correct. The Small chevy block caused the craze for torqueplates. It ends there, except include the old 289 Ford.

My Street/Strip installed 472 has 12years on it, and the recent compression test shows 265+PSI per cylinder. This is after rude cold-start driving, and no air filter for most of the time.

IMHO: Leakdown measurements are a discerning indicator of damage to rings or valvseat or headgasket, after a Compresion test left you guessing. Also, please consider the leak that occurs during leakdown represents an relatively unloaded cylinder over a long observation time interval. YET, the concerning leak occurs on a loaded, moving cylinder across a brief time interval.

So, how much pop really leaked out? Check your breather at cold-start and hot-run and decide of you draw a crankcase vacuum from the PCV system.
Also, check underhood for the classic oil down on all surfaces. Probably blowby from anything else BUT the lack of a torqueplate.

H.I. Stud