[DarcyL]

Just to add some data here, I have 2 ,1976 wx code 455 blocks, originally from a 4speed t/a. One std bore, one.030 and needing a rebore. Both are 2 bolt main caps, both blocks only drilled for 2bolts. had the .030 block sonic'd, all bores, 4 places at top and half way down cyls. Thinnest spot was 0.168" .

[68WarDog]

Block is WA std. bore. Drilled for 4 bolt, but with 2 bolt caps. What's odd is my literature say a WA block was only produce for the 70 model year, and denotes 4 bolt caps. Is this right?

[Dragncar]

Originally Posted by Gary H

I know a few here have actually gone .100 overbore to 4.250. Not necessarily with a 70' block but with any block after first sonic checking it. There's actually one here in my home town that's in a race car that's .100 overbore. It's been running fine at that for years. It is hard blocked though and has a lifter brace in it

I know Ace at PPR used to bore them .100 all the time. If I use my 70 block again I would go to the smallest bore I can get and run custom pistons.
Thanks, for the info.

[Dragncar]

Originally Posted by Steve C.

Originally Posted by Dragncar
Anyone ever sonic check a 70 4 bolt block ?

18 years ago I bought a '70 455 block and its original crank, both for $300. The block had never been bored and the crank was uncut. I had the block hot tanked then all the cylinder walls were sonic checked on their front wall, rear wall, outside wall and inside wall. Checked at the top and halfway down on all these locations. For the most part the measurements taken on the front side of all cylinders were the lower numbers, again measured at the top and halfway down.

The passenger side bank on the front: lowest was 0.122, the highest was 0.257. The average was 0.165".

The Drivers side bank on the front: Lowest was 0.120", the highest 0.235". The average was 0.153".

For the '600 hp' engine build the block was bored to 4.181" then it was filled to the freeze plugs.


.

What is considered minimal thickness on the thrust side ? That block does not look to have very thick bores.
The engine I am doing now was hard blocked with a tq plate and cured for months with it on, each side then bored. Dan said it all mattered for ring seal.

[455Grandville]

I have stacks of garden variety standard 455s from big cars ranging from 70-76 and one 455HO, only the HO has 4 bolts but all the others are 2 bolts but drilled for 4 bolts.

[Baron Von Zeppelin]

Originally Posted by 68WarDog

Block is WA std. bore. Drilled for 4 bolt, but with 2 bolt caps. What's odd is my literature say a WA block was only produce for the 70 model year, and denotes 4 bolt caps. Is this right?

Yes. 70 GTO 455 Manual Trans Code

All the 1970 455's with #64 Heads i have encountered were 4-bolt Mains.
Whether GTO , Bonneville or GrandPrix
All have been Automatic Codes YA, YC, XF
Never had a manual code

I am surprised some others have had these that were 2-Bolt Mains.
But evidently they are out there.

All the YH with #15 Heads i have known were all 2-Bolt Mains

Very Very surprised your friends WA Block is 2-Bolt Mains
He should have the align bores checked to offer peace of mind to a buyer.
It's a hard code to find usually, and most will expect 4-Bolt Mains.
So its a tuffy

[steve25]

The only time you will find a 455 that started life as a 2 BBL motor will be if the assembly line ran out of the two bolt blocks and had to dig into there 4 bolt stock , as this has happened!

Also what has been seen is the the same thing with a dealers warranty repair on a 455 or any Pontiac motor that could have come with 4 bolt mains, but this sonareo is extremely rare.

[Slick]

Originally Posted by steve25

The only time you will find a 455 that started life as a 2 BBL motor will be if the assembly line ran out of the two bolt blocks and had to dig into there 4 bolt stock , as this has happened!

Also what has been seen is the the same thing with a dealers warranty repair on a 455 or any Pontiac motor that could have come with 4 bolt mains, but this sonareo is extremely rare.

I'm confused by this statement. Early 70's, certainly 71 and 72 full size Pontiacs that did NOT have a 455 as standard equipment (Catalina, Bonneville) had the option of a 455 2BBL. The "C" body Grandville had 4BBL as standard with its 455. Not sure, but I think the same was true of the full size wagons, a 2BBL was available with a 455.

Not sure what you are trying to say? Do you mean that all 455 2BBL engines NORMALLY would have had 2-bolt mains, except if the assembly line was out of those blocks? That seems plausible and reasonable.

FWIW, Bob Maxey preferred undrilled 2-bolt main blocks for his highest horsepower builds. Yes, he stayed with the 2-bolt main caps.

Stuart

[69hardtop]

Originally Posted by Baron Von Zeppelin

Yes. 70 GTO 455 Manual Trans Code

All the 1970 455's with #64 Heads i have encountered were 4-bolt Mains.
Whether GTO , Bonneville or GrandPrix
All have been Automatic Codes YA, YC, XF
Never had a manual code

I am surprised some others have had these that were 2-Bolt Mains.
But evidently they are out there.

All the YH with #15 Heads i have known were all 2-Bolt Mains

Very Very surprised your friends WA Block is 2-Bolt Mains
He should have the align bores checked to offer peace of mind to a buyer.
It's a hard code to find usually, and most will expect 4-Bolt Mains.
So its a tuffy

My 1970 455 HO block WA is 4 bolt main caps. It came out of a manual GTO

[Steve C.]

Dragncar

A fwiw, the fellow that sonic tested that 455 block stated a minimum of 0.125" on the thrust side. Those measurements I mentioned again were on the front side of the cylinders, why they were thinner than other areas I have no idea. On the inside and outsides there were many well over 0.210". ...... .0214, 0.218, 0.229, 0.230, .0232 ,0.229, 0.240...etc, etc.

Side note..
The best block filler is Race Engineering "Block Rock".
Good product and is a easy material to work with. Fast setup time and the block is machinable in 24 hours. Plus they claim it will not crack or separate with age.

.

[racegto65]

Originally Posted by Gary H

I know a few here have actually gone .100 overbore to 4.250. Not necessarily with a 70' block but with any block after first sonic checking it. There's actually one here in my home town that's in a race car that's .100 overbore. It's been running fine at that for years. It is hard blocked though and has a lifter brace in it

The '72 block in my race car sonic tested at .280"+ on the thrust side. It is .130" over at 4.280" and still going strong. It's hard block filled to about half way up the water holes in the front.

[rascal455ho]

I have 70 XF 455 4 bolt with 4 bolt caps and 64s

[Wareagle]

This 9 sec. 65 Catalina runs a punched out 455 4 Bolt main Block > Also NUNZI Mentioned he even used 2 Bolt main 455 Blocks as a starting point for some of his Blown applications - less distortions etc.

[Wareagle]

Here's one NUNZI Wrenched on 1975 T/A Blown 455 > 800 hp > Really woke up those New York Neighborhoods - Brooklyn etc.