[Jim Zeek]

looks like an aftermarket block in the pictures

[charlie66]

are those high ports?

[JSPONT]

I think you can get away with more on such a light car. It is such a gray area.

[steve25]

Let's list in no perticular order the things that need to go into such a stock block buld to hold up to 800 hp.
Let me first say that more boost from a blower and less rpm is a great start!

Splayed steel main caps.
3" mains.
Lifter valley reinforcement.
Aluminum Rods.
8 counter weight Crank.
3/4 fill block.
Deburring every possible sharp edge that could lead to a crack.
Main girdle to tie the main caps together on the 1,2,3 and 4 main cap center bolts.
Minimum stroke for needs, this ties into making power with boost!
?

[Dragncar]

I worry about my factory 455 4 bolt caps at 600ish HP. Sure would feel better with 3" mains and billit caps.
I have a 400 block with the splayed caps. Been filled but Whittmore let the hard fill cure for weeks with a torque plate on each side. Better ring seal was the idea.

[68azbird]

Made 615 hp with a 1969 400 block
Filled to plugs with hard block
Stock 2 bolt caps with ARP studs, bearings always came out looking new.
1500 + runs shifting at 6500 rpm
Bores are still perfect and round
Factory crank, aluminum rods.
Block will be used in the future.

[Glenn Lever]

Originally Posted by Jim Zeek

looks like an aftermarket block in the pictures

Yes the new block (not the current one which I would like to run for another year) is an aluminum All Pontiac block. All kinds of neat stuff going into that block.

Originally Posted by charlie66

are those high ports?

Yes those are high port heads

Originally Posted by steve25

Let's list in no perticular order the things that need to go into such a stock block buld to hold up to 800 hp.
Let me first say that more boost from a blower and less rpm is a great start!

Splayed steel main caps.
3" mains.
Lifter valley reinforcement.
Aluminum Rods.
8 counter weight Crank.
3/4 fill block.
Deburring every possible sharp edge that could lead to a crack.
Main girdle to tie the main caps together on the 1,2,3 and 4 main cap center bolts.
Minimum stroke for needs, this ties into making power with boost!
?

Ok, missing the boat on a couple of the items

No Splayed steel main caps, rather then spend the money to do this I will run 8.0 again this year.
This was a 400 block originally so I have the 3" mains
I have the Lifter valley reinforcement
I have the Aluminum Rods
what is 8 counter weight Crank?
I have not done the 3/4 fill block, rather then spend the money to do this I will run 8.0 again this year.
The block has been Deburred
I can do this, Main girdle to tie the main caps together on the 1,2,3 and 4 main cap center bolts
This engine was originally built to run with a carburetor, stroke is 4.250, I am not winding this engine up, engine is limited at 7,500, shift and top end is at 6,800.

So you think I should not push beyond the 700 HP mark?

Glenn

[charlie66]

My 400 has been together for 10 years now. It gets revved to 7000 rpm's regularly with no hard block..

[Glenn Lever]

Originally Posted by charlie66

My 400 has been together for 10 years now. It gets revved to 7000 rpm's regularly with no hard block..

How much HP?

[charlie66]

Originally Posted by Glenn Lever

How much HP?

660 hp N/A with 200 shot Of NOS . I guess 860 hp ?

[ta man]

Mike Voycey built my new shortblock it's bulletproof for my needs currently and in the near future.He was running in the low nines year after year with a iron block.He would be a good one to ask.

[Steve C.]

Not anywhere near the big boys but about 18 years ago we put together a 1970 400 factory block that produced 699.9 hp at 6900/7000 rpm with a Victor/4500 Dominator set up. However being limited street use I ran it with a Victor/ HP950 carb (680 hp). It used a custom Crower 4.125" stroke crank & 6.8" rods, 4.165" pistons with 450 cubic inches. The block was filled to the freeze plugs, Pro-Gram Engineering main caps, ARP stud kit and bolt-in lifter bore bracing. On a few occasions we used a nitrous plate system with it, If I recall correctly it was about a 200 shot but don't remember for sure. It ran a best of 9.59 at 140 mph. We ran it about a year with no issues, but then retired it for a IA2 block. Did not want to take further chances with the factory block.


.

[mgarblik]

From your list of current parts in the block, the only item that scares me a little is stock main caps. As you know, the combustion forces are trying to push the crankshaft out of the block and on to the ground. The stock, marginal quality, brittle iron, with like caps seems a little scary. I think at least 3 steel billet caps and studs would be a nice security blanket. Other than that, you have a stronger set-up than we ran at 1100 HP. You have to remember, when we ran the 455 none of these cool parts were available. It was 16-20 years ago. I would hate to say don't worry about it and then you have a failure, but I wouldn't be afraid to run your stuff harder for a year.

[69Goat1]

720 hp was the limit on this 455 block. Factory 2 bolt caps with studs, factory crank, scat rods, SRP pistons, solid roller, e heads, victor, dominator...

Block broke from the mains to the cam tunnel. Crank was ok until block broke. I should have known it was going to happen because I found a dowel pin from a main stuck to the magnetic plug when I changed oil last... Cap walk was evident in the autopsy...




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[mgarblik]

I am really sorry to see this, but see my post above. Main caps and that structure to contain the crankshaft of maximum importance. This is why the Ford FE, and the Chrysler hemi can take so much power. The contained, cross bolted main caps are a tremendous advantage. GM finally did it on the LS series. I love my Pontiacs, but having the crankshaft spinning around out in the open at 8000 RPM's, held in by 5 iron straps and 10 bolts, it's amazing they don't all end up like that.

[johnta1]

I can believe that for the 455 block.



His is a 400 block (WS?) and should stand the abuse for awhile.
Regarding Mike's comment, I would agree the stock caps would be a weak point in this setup.

[Tom Vaught]

Originally Posted by 69Goat1

720 hp was the limit on this 455 block. Factory 2 bolt caps with studs, factory crank, scat rods, SRP pistons, solid roller, e heads, victor, dominator...

Block broke from the mains to the cam tunnel. Crank was ok until block broke. I should have known it was going to happen because I found a dowel pin from a main stuck to the magnetic plug when I changed oil last... Cap walk was evident in the autopsy...




Sent from my iPhone using Tapatalk

69Goat1, I saw Marty P's 700+ NA 455 engine ONE PASS before it failed like your deal.
He took it apart and found the #2 (4-bolt main) cap cracked from block to head of inner main cap bolt. Only the bolt/washer was holding that cap together. The outside short main cap bolt and that portion of the main cap were attached to the block.

The #4 cap was split the same way 1/2 way up the cap (similar to the #2 cap).

The Number 3 main cap was just starting to crack and maybe 1/4" of a crack there.

All of the cracks were on the same side of the block/main caps.

So the 455 engines fail not only at the oil holes but also at the factory main caps.

Marty had prepped the block so there were no sharp drilled hole edges anywhere on the block. Including the cam holes.

Bad failure there.

Tom V.

[Glenn Lever]

Originally Posted by johnta1

I can believe that for the 455 block.



His is a 400 block (WS?) and should stand the abuse for awhile.
Regarding Mike's comment, I would agree the stock caps would be a weak point in this setup.

Block ID is YZ, casting number is 9799914 year is 1970, so stock HP was 366 out of a GTO California Ram Air III

YZ A-body 70 400 366 Turbo 400 L-74 1x4 9799914 4 GTO Califorina Ram Air III

So it sounds like I should do Billet mains $280.00 is cheap insurance, it is going to be apart anyway and will have to be line bored front cap is $95.00 so I might want to add that but $325.00 just for the rear cap seems a bit much (Kauffman), Recommendations?

I also have a full rear engine plate with just a hole for the crank to poke through

[PAUL K]

I don't think a billet rear cap will buy you much. However I'd recommend doing the other four.

[Dragncar]

Sure would be nice to get a block with cross bolted (FE,LS ) mains and priority main oiling.