[steve25]

Well the dyno pulls that where done so far tells you
That the motor was making about 52 hp per cylinder.
Once all 8 are holding compression I would say that the motor should make 415 hp .

[RH68]

Originally Posted by steve25

Well the dyno pulls that where done so far tells you
That the motor was making about 52 hp per cylinder.
Once all 8 are holding compression I would say that the motor should make 415 hp .

I like that math. The one with all the leak down was firing so who knows. Hopefully the new pistons and modern 1/16” rings help a bit too. The compression ratio probably got a bump to around 10:1 with the Icon pistons.

[Dragncar]

Originally Posted by RH68

It was not done with a torque plate. He doesn't have one for a Pontiac. When he tested leakdown with the new rings he told me that he did it with just the head bolts for the bad cylinder snugged down, and then again with all the head bolts torqued, and got the same results. I am assuming that was to see if cylinder is distorted.

Well, Pontiacs distort about .004-.006 about 1/2" down right next to each head bolt. 455s do it worse than 326s.
This is why you can not bore .004 under without a tq plate and hone it out with one like a sbc. Our engines distort more.
Some shops can not bore and hone with a plate depending on their equipment. So you bore it more than .006 under and hone with plate. My last engine it was bored .010 under and hones with a plate.
Pontiacs not done with a tq plate you bores are not "round".
Machine shops usually have a place where they can rent a plate for a engine if they do not own it. Here in Humboldt our warehouse did not have a plate. So I called them up and asked for one, they bought one from BHJ and I rented that same plate 10 years later.
You are only going to see the problem in leakdown if the cylinder you are checking the piston is 1/2" down from TDC.
IMO a tq plate is a requirement for a Pontiac performance engine. Especially if you are going through the trouble and expense of a dyno.

[Formulajones]

I had pictures on my last Pontiac engine build thread showing what the cylinders looked like after the first shop bore/honed the block without plates, and pics as Paul was honing it with torque plates.
It was a real eye opener with large sections of the bore where the hone didn't even touch the bore..

[RH68]

Well the engine was bored +.030 20 years ago. It was only honed an additional .001 to put a fresh cross hatch on the bores this time around. So, boring and honing with a torque plate is a moot point. I’m sure there are millions of Pontiacs out there running just fine that weren’t bored and honed with a torque plate.

[steve25]

You should see what Chevy bore’s look like with no deck plate since there head bolts are tied to the cylinders themselves unlike Pontiacs that are tied to the deck!

[Formulajones]

Originally Posted by steve25

You should see what Chevy bore’s look like with no deck plate since there head bolts are tied to the cylinders themselves unlike Pontiacs that are tied to the deck!

Yep
It makes more of a difference than people care to admit.