[screamingchief]

I'll get some pics of the YS block up later,the lighting back there is giving me fits and I had to take about 40 pics of each to get usable pics,so the batteries are getting low.

HTH.

[BILTIT]

My '74 455, pics are not great but maybe you can see something i cannot.

[screamingchief]

Looks like the same basic casting as my bare 455 block, casting #485428,the Pete McCarthy bible says that casting was used '71-'74 in non H-O or S.D. applications.

Also the PM bible says the change from the #481988 400 casting,to the #500557 casting was mid year '75.

when did they stop makin the the thick version block?

The "late" (post #485428,'75 and up) 455 block info is a bit more sketchy though,I think that's that "double top secret" info Brian and Dude cryptically refer to from time to time,though I do recall Brian let that info out on another board somewhere once,but damned if I can remember where,so I cant prove it...

But I did get the "gist" of what to look for,maybe I gotta go out to my friend's place,he has a bunch of core motors around and see if I can dig up some pics and blow the lid off that,,,ahhh who am I kidding,,,too damn lazy for that,,,at least till it cools off around here....

[RoyalPurpleOil]

500557 blocks were so bad, Pontiac went back to the 481988 for the 78 Trans Am. I'd only use a 557 block for a very mild application. We actually run one in my son's 67 GTO with a RA IV cam and 6x heads. Runs high 12's but makes me nervous!

[HWYSTR455]

Pontiac Dude - Exactly my thought, why the heck did they work it and put caps on it. Like I said, I selected a block, was a 69 casting, waited 3 years, and when I dropped the stuff off to have the machine work done, they did that one. Not even going to go into it, and I'm sure it was a mistake. Someone else must have gotten my block though. So you say to bail out on the block then? Would be destine to grenade? What power level do you think I can get away with? Just do another block?

Flamedabone - What were you doing when that let go? Hammering it? Spraying it? Was that a 4.250 stroke engine? And the block was sonic/mag'd when you put it together? Doesn't really look like 4 bolts/studs would have helped that?

[70 lucerne lemans]

Im pretty upset I put the time and money into my '75 block now,I guess I could swap the rotating assy into my '70 455 thats in my Lemans and is pretty much street duty now-its due to be freshened.What do you guys think,roll the dice or spend more time and $ to build another motor?

[Skip Fix]

Mine is a 500557 with a 77 casting date. It is the same casting number as my original 1978 TA motor also. Ol Pinion Head said that is the most common casting he has seen pulling motors through 78 except for the TA 6.6 motors,eventhough McCarthy has different ones listed for later years.

Even that 74 looks stouter to the dowels.

[PONTIAC DUDE]

Originally Posted by HWYSTR455

Pontiac Dude - Exactly my thought, why the heck did they work it and put caps on it. Like I said, I selected a block, was a 69 casting, waited 3 years, and when I dropped the stuff off to have the machine work done, they did that one. Not even going to go into it, and I'm sure it was a mistake. Someone else must have gotten my block though. So you say to bail out on the block then? Would be destine to grenade? What power level do you think I can get away with? Just do another block?

I can't tell one what to do with their stuff already done. Not my call.

But I would never 4 bolt that kind of block if a customer brought me one. I would send it back out the door or tell him to keep it for a mild 455 conversion or mild 400.

It might last one pass or 100 passes or 1000 passes. I'm not Carnak. LOL.

[Motor Daddy]

I just got done pulling apart my 400. This is a 76 block. It's cracked in the exact same place as flamedabone's pic. It looks like the pieces would interchange. LOL

[HWYSTR455]

I'm shopping for a block as we speak. If anyone has a 68-71 400 2-bolt block, std bore they want to get rid of, let me know...

[PONTIAC DUDE]

I have used the 74/75 block and made over 900hp on spray without issues.
The 400 block with the 455 crank I ran at VMP running 9.30 flat on pump gas is a 74 block .090 over) so don't think that any certain year is that much better. As long as it's a pre 75 block, check the webbing, check for cracks and bore thickness, etc, most will hold up to what most people are doing.

If your gonna start putting billet caps and all the other stuff, making over 750hp and don't own a machine shop, LOL. Then I would start looking at the aftermarket block as far as dependability and longevtivity.

[Jeff Walker]

Originally Posted by HWYSTR455

I'm shopping for a block as we speak. If anyone has a 68-71 400 2-bolt block, std bore they want to get rid of, let me know...

If you're willing to pay some shipping I have a '68 block that I could spare. Never been bored, never blown up.

[HWYSTR455]

Jeff, you have a PM...

[455Dave]

Originally Posted by PONTIAC DUDE

I have used the 74/75 block and made over 900hp on spray without issues.
The 400 block with the 455 crank I ran at VMP running 9.30 flat on pump gas is a 74 block .090 over) so don't think that any certain year is that much better. As long as it's a pre 75 block, check the webbing, check for cracks and bore thickness, etc, most will hold up to what most people are doing.

Ken, are you talking about me again?

[70 lucerne lemans]

I guess Ill be giving Ken a call about a block,I dont trust mine after seeing the other 500557 blocks breaking.This projects been 3 steps forward 2 steps back the whole way.I would hate to tear up my Eagle rotating asy and Kre heads.It looks really fast sitting on the stand though.

[johnta1]

screamingchief, that first block with the lop-sided 0, must have been done on 2nd shift Friday!

Also, did the block have 4 bolt holes from the factory?

[screamingchief]

screamingchief, that first block with the lop-sided 0, must have been done on 2nd shift Friday!

Ha ha ha ha,,,yeah worse yet,looked it up,april 9 1973 was a monday,cast during the day shift!!!

So it's a post weekend "Oh man am I hungover" block,I dunno,ask me that's worse than a "I wanna get my check and go get drunk block",but that's JMO...

Yeah,sure fire grenade material,,,LOL.

Also, did the block have 4 bolt holes from the factory?

To the best of my knowledge,yes it was drilled and tapped from the factory,I got this motor when I needed to move back to Texas,traded my '73 ventura for it,was virtually zero miles beyond cam break-in and a couple blast up/down the block,guy had all the receipts,and heard it run,knew it was a pretty decent trade.

Was a lot easier than trying to move the car at that time,just stuffed this up in the front of the ryder rental,and headed south.

The 455 block is the same deal,drilled and tapped for 4 bolts,the other 400 block was'nt,I guess because it was a 2 bbl motor.

The YS 400 is also drilled and tapped for four bolts,but uses two bolt caps as well,I'll get those pics up here soon,that block has some weird casting irregularities in the crank area,almost look like cracks but they're too "patterned" to be cracks in my mind,I believe they are just a casting blemish or something of that nature.

[Region Warrior]

Most all blocks besides the 500557 are fine 5-600hp.
Some are better. H.O. and RA blocks are beefy'r.
Have used the 557's in street 450-475hp/48-5200rpm levels without problems.
Dont rec any n2o.

Kinda like stock rods vs aftrmrkt.
After building a few, and noticing differences, you start thinking; "where's the beef", and do i did more?

[75TA]

Here are some pictures of my RA IV block for comparison.

[trim]

It appears that the 500557 blocks want to break from the dowls. Could one stress releave the block (like you do when you side polish a rod) by champering the sharp edge on the main?