[Richard Ohran]

None of the local shops have a torque plate for a Pontiac. Can I get by without it on a 455 bored 30 over planning on about 600 hp?

[Richard Ohran]

None of the local shops have a torque plate for a Pontiac. Can I get by without it on a 455 bored 30 over planning on about 600 hp?

[Rashionality]

A torque plate is extremely important when boring or honing the cylinder walls. What it does is simulate the heads being bolted on the motor so that any cylinder distortion that would normally occur when you bolt the heads on is there when you bore/hone the motor. It could seriously effect the ring seal of the motor if it was not bored with a torque plate. I recall in the "for sale" section of this board that someone was selling a BHJ torque plate. I'll do a search and post my results.

Don't believe a machinist that tells you he has one!...make him show it to you.

[Rashionality]

http://performanceyears.com/cgi-bin/...c&f=8&t=001062


It was sold.

If you are planning on making 600 horsse out of the motor and no machine shops near you have one either invest in one yourself and make them use it (Christ bolt it on yourself then send them the block) or invest in the shipping costs to send it to a reliable machinist that does have one.

[78 GHOST]

Richard: For those of us who need color pictures and small words to understand things, the Feb. '02 issue of Car Craft has an article on page 62 about sleeving a block. On page 63, picture #10 shows a graphic depiction of a cylinder that had been rebuilt without torque plates.

If LAS is lousy for builders, truck it to L.A. to a "Good" builder.

.02 from the peanut gallery, Matt

[Torment]

My experience is they'll seal up tight either way when they're fresh. But after some hard running they'll start blowing more oil if they're not torque plated.

[Cobrabill]

In addition to using a torque plate,have the main caps torqued in place also.

[Half-Inch Stud]

I hold little merit in requiring/using a torque Plate during the rebore/hone of Pontiac blocks. Chevy, and others have unfavorable wall deflections under head-torque load. Pontiac has only a little upper wall movement.

If it makes you feel good...then do it.

If you line-item the machine shop activities, and do your own assembly, then it's a skip-it. I would toss the worry dollars on balancing the crank/rods/pistons/balancer/flexflywheelplate.

In these regards, My concerns rest on the shop having the boring bar aligned dead-parallel to the bore.

Are the new rings as round?.....Regardless, I believe the bore will right itself to round nicely before the rings see excess wear.

That's what I think,
H.I. Stud

[Rashionality]

I certainly would not want a block bored without a torque plate, and like Bill said...with the mains torqued on as well.

I'm planning on purchasing a torque plate in the near future as my friend has just acquired quite a nice array of machinery from his work. Seems that they "upgraded" their tooling and allowed some of the "older" stuff to be parted with. Now we just need to get a boring bar...gonna practice on some SBC crap we both have. [img]/infopop/emoticons/icon_smile.gif[/img]

[ January 18, 2002: Message edited by: Rashionality ]</p>

[Will]

HIS - does .0015" - .002" in concentricity seem insignificant to you?

My 455 block ('70 YH 455, 2-bolt) is only .035" over and that's how much difference the torque plate makes.

Measure with torque plate in place after honing, bore is round. Remove torque plate (but mains still in place) and measure again, bore goes as much as .001" wider in one direction and .001" narrower in the other, mostly near the top of the bore.

Install head and measure again from bottom of block. bore goes back to nearly round, with only about .0005" or so out of round.

Done this twice now, I'm satisfied it's well worth the slight extra cost on a performance rebuild. After all, cylinder sealing = power.

Agree that Chevies are worse. Just tore down a low-mile 327 with blowby problems. Cylinders had 5 vertical polished "columns" in between areas were original crosshatch pattern was still visible. Polished columns were between the head bolts.

-Will

[Phil69GTO]

Well, I'll jump in here and give my .02 Had my 400 bored .060 and went to the machine shop and checked the finished bore with torque plate installed and then with the torque plate removed. Using a dial indicator, there was no difference in bore diameter. Measurements were taken at several positions in each bore. Doesn't mean a torque plate is useless, I just think for the majority of street applications it doesn't make a measurable difference. Others may have different experiences and possibly each block may be different. Now, if I was building a motor that would see a lot of strip duty, I would use a torque plate regardless, I think.

[Half-Inch Stud]

Will,

YES, .0015" - .002" in concentricity DOES seem insignificant to me, at the boring/honing stage, on a Pontiac block. Further to my point is the "perfect bore" achieved at 70F machineshop room temperature does not assure whatsoever any sort of concentricity at 180F average running temperature....

By virtue of having different temperatures throughout the block inner and outer case will distor the "Perfect Bore" to beyond .0015 - .002". I wager .003" is likely.

considering the bottom of the cylinders may be at 140F [bore cross hatch should be zero, polished], while the mid-range cylinder bore is sitting around 170F, while the 1" top-Cylinder bore region sits above 200F on the inside walls.

The pistons are not that good. I had my pistons matched to the bores, after the bore/hone. Machineshops perform the machine-hone to reach the selected piston. In other words; .030" over really means .028" to .032" range for the piston and block at the same 70F shop temperature.

Does anybody take a close look at the piston thermal paths around the pin? You see, the pin to rod is a significant thermal path, along with the rings to wall. So, the pistons are not round [Top-view], nor are they cylindrical [Pin Side-View], Yet they may be substantially cylindrical [Skirt side-View] but there is no sealing wear-force on the non-skirt sides.

So, for good sealing, we're talking about the RINGS seeing a good support system by the ring lands. I doubt the rings are as round as some folks assume, for the set-gap.

Then, I truely doubt the ring sealing force imposed upon the upper cylinder walls is uniform, particularly knowing the rings are stiff "C" clips under thermal stress.

SOLUTION:
Let the rings define ROUND at running temperature.
Obey your instincts and instructions during engine ring break-in period. ROUND will be difined best at running temperature. Cross-hatch will survive in the regions where it is most important.

NOTE:
I am surprized at how quiet this [basic, yet important] topic has been.

H.I. Stud

[Half-Inch Stud]

Counter point:

I'm sooo wrong and naive. The real racing folks run a single, gapless top ring, no second ring.

...with great success [performance, reliability, wear patterns, first-build success, blow-by, street-strip, hot&cold, etc]

Roight>?

H.I. Stud

['ol Pinion head]

I guess I just like to pay that extra $40. Just like paying the extra coin to balance every Pontiac build...to me it makes a lot of sense.


Ah really miss da Dude's comments on this one!

[Steve C.]

H.I.S. has something.
See the mention of the work being done by Harold McCormick of C-K Engineering. Pg 41 March '02 PHR.
See the story 'The gathering of the gearheads'.
Mentions efforts to research the effects of thermal dynamics on engine bores. Involves the use of a false cylinder head that is constantly circulated with 200-degree fluid while the machining is taking place.
Same issue also has a article about piston ring science for making horsepower.

http://www.popularhotrodding.com/arc...2feature02.jsp

[ January 18, 2002: Message edited by: Steve Coombes ]</p>

[Torment]

ok if distortion is inevitable aren't you still better off starting with the most concentric bore possible?

[Pro Goat]

There seems to be a lack of experienced, hard core racer/engine builders, trying to answer this question. By no means am I and expert, but it all comes down to basic common sense. 90% who read or contribute on this Pontiac forum will need to under stand that ever block reacts differently to deck plate boring and honing. Some will twist more the others, what it all comes down to is there's probably not measurable horse power gain, unless you did a before and after test, that would mean building and running that same block with out deck plate boring/honing it, then with it done. Again it would depend on that particular block " not all blocks will move the same " That's the whole reason behind deck plate boring and honing, granteed good ring seal, and ring life, cheap insurance if you ask me.

Guys who are looking to make serious horse power will never question whether or not it should be done.They already know it all depends on whether or not your particular block will twist, knowing their could be as much as a 20-30 horse power gain, if it effects ring seal and adds ring life, if they don't. Street guys or some one just looking to run a number probably wouldn't, because of the cost, or miss guided information. Basic common sense, street motor don't waste your time, high horse power 500-800 hp it's a must unless you feel you luck out and got a real good thick block that won't twist.

[ January 18, 2002: Message edited by: Pro Goat ]</p>

[Steve C.]

Years ago in HPP magazine six top engine builders were asked to reveal their combos for 500+ hp bracket racing engines.
Three of them specifically mentioned to use a torque plate. One even went as far as saying the engine will lose 25 hp without it.

[Half-Inch Stud]

Is it true that the longer a fresh motor is run-in, the cylinder walls become more true?/...

I could say more
But why
My motors have all been good on Compression tests (except a botched Total-Seal jobby) [img]/infopop/emoticons/icon_wink.gif[/img]
Guess others would rather "be safer than sorry" [img]/infopop/emoticons/icon_redface.gif[/img]
When I grow up, I'll do a motor right for once [img]tongue.gif[/img]
What me worry [img]/infopop/emoticons/icon_biggrin.gif[/img]

[Will]

When you spend $3K to $6K to build a really nice engine, what's another $50 or $100 to make sure your cylinders are as round as they can be? It's a little late to wait 'til after your block's been honed to find out if it's one that will twist more. I've checked a couple blocks so far of various makes and the difference is measureable on each of them. Research continues.

HIS - compression check vs. leak-down check might tell a tale here I think. Then again, it might not.