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 400 block- years to avoid?
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russosborne
Sitting Bull

USA
212 Posts

Posted - 31 Jan 2012 :  8:19:53 PM  Show Profile  Reply with Quote
I know about the 557 number, but is there a general range of years that it would be best to avoid if I can't find out the block number from a seller?
Specifically, I came across a 400 bare block on craiglslist for $100 but the seller says it is from a '76. Don't want to bother the seller if this is something I won't want.
I do want to build a stroker eventually so I don't want to start with the weaker block.
Thanks,
Russ

mike mcarthur
Pony that Jumps

USA
2475 Posts

Posted - 01 Feb 2012 :  06:09:54 AM  Show Profile  Visit mike mcarthur's Homepage  Reply with Quote
75-77 for sure. I believe they went away in 78?

It's the stuff you learn after you know it all that's important
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Phil
The Great White Buffalo

USA
7215 Posts

Posted - 01 Feb 2012 :  08:05:57 AM  Show Profile  Reply with Quote
Depends in your plans. If a modest street build or stock replacement, it doesn't really matter.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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russosborne
Sitting Bull

USA
212 Posts

Posted - 01 Feb 2012 :  4:08:53 PM  Show Profile  Reply with Quote
Thanks Mike. I was pretty sure the 76 was in the middle of the bad years. Guess that is why the guy isn't having much luck selling his.

Phil, wanting to do the 461(I think it is) stroker, so strength is an issue. :-)

Probably won't matter, I think I am stuck with the 350 for now.

Thanks,
Russ
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Lucas
Cochise

USA
428 Posts

Posted - 03 Feb 2013 :  9:39:06 PM  Show Profile  Reply with Quote
Yes avoid the 557 blocks. Just pulled mine apart for a freshen as the car lost 3 tenths all of a sudden this season. Chased the problem for the rest of the season and another 100 runs or so and never could figure it out. Pulled the motor down and wondered why I had a main cap dowel in the pan. Low and behold there was a crack about a third of the way around the main saddle and the dowel would just tap through the hole. I cant really complain as I have 10 years on this block running mid 12's and mid to high 11's when I would travel to lower elevation tracks. Not bad considering around 1800 runs or so. My block was a 75.

"wildfire"
Real pontiac power
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cowboy
Buffalo

USA
80 Posts

Posted - 04 Feb 2013 :  9:08:16 PM  Show Profile  Reply with Quote
According ot Rocky Rotella,s book there is 2 557,s a 500557 75- 78 and 568557 77-78

Edited by - cowboy on 05 Feb 2013 11:58:20 PM
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cowboy
Buffalo

USA
80 Posts

Posted - 04 Feb 2013 :  11:09:04 PM  Show Profile  Reply with Quote
The 568557,s don't have rear motor mount holes they won't fit A bodys
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Bill Boyle
Horse Feathers (Charter Member)

USA
4794 Posts

Posted - 05 Feb 2013 :  08:12:08 AM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
Brackets are now available to make engine swaps easy no matter how many block bolt holes.

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
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cowboy
Buffalo

USA
80 Posts

Posted - 05 Feb 2013 :  8:23:27 PM  Show Profile  Reply with Quote

Edited by - cowboy on 05 Feb 2013 11:56:57 PM
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Phil
The Great White Buffalo

USA
7215 Posts

Posted - 06 Feb 2013 :  10:05:07 AM  Show Profile  Reply with Quote
I wouldn't use the "kleenex" 557 for anything other than a stock replacement or cam/intake/exhaust type of service. It just doesn't make any sense to me spending good money on a build and utilizing one of these blocks when there are so many better 400 blocks out there to use as a foundation.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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Lucas
Cochise

USA
428 Posts

Posted - 07 Feb 2013 :  10:11:54 PM  Show Profile  Reply with Quote
I now know that Phil I am just glad it all stayed together even after it broke. I know exactly when it cracked just never suspected a cracked block. New bock at machine shop getting done. And upgrading from stock rods to H-beams and also swapping out the speed pros. I will update how it runs after it's back together.

"wildfire"
Real pontiac power
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Phil
The Great White Buffalo

USA
7215 Posts

Posted - 09 Feb 2013 :  10:28:06 PM  Show Profile  Reply with Quote
Lucas, sorry mate I was directing that to Russ. Wasn't even thinking of your block when I posted it. No offense intended. Just for the record.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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Lucas
Cochise

USA
428 Posts

Posted - 10 Feb 2013 :  12:23:49 AM  Show Profile  Reply with Quote
None taken. I'm not that thin skinned. Its funny the things a guy learns over the years and after failures. I'm just glad I found the problem before getting it back in the car.

"wildfire"
Real pontiac power
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Paul
Cochise

USA
776 Posts

Posted - 12 Feb 2013 :  4:42:22 PM  Show Profile  Reply with Quote
H.P.P. page 66 Rocky specifies the one year, 75 400 block,and its casting #500557 to avoid.
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Phil
The Great White Buffalo

USA
7215 Posts

Posted - 12 Feb 2013 :  5:25:41 PM  Show Profile  Reply with Quote
I believe the 557 to avoid was produced right through (or at least into) 77.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.

Edited by - Phil on 12 Feb 2013 5:27:07 PM
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Paul
Cochise

USA
776 Posts

Posted - 12 Feb 2013 :  6:27:00 PM  Show Profile  Reply with Quote
Rocky mentions 75 was the only year Pontiac revised the 400 block to shed total vehicle weight, resulting in a weaker block.
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frankie
Buffalo

USA
62 Posts

Posted - 15 Jul 2013 :  9:21:55 PM  Show Profile  Reply with Quote
I have come across a 77 400 481988 block that is in okay shape ,,needs boring to replace my 73 block in my 69 GTO that I stroked.
It is a pain to destroy a block because of not using lock tight and suck down a stud from the air cleaner. The Question is about the kit for the motor mounts.. Where are they that can be purchased?
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Bill Boyle
Horse Feathers (Charter Member)

USA
4794 Posts

Posted - 16 Jul 2013 :  04:54:28 AM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
Frankie--1977-79 Pontiac V8 castings have only 3 motor mount holes tapped for screws. That bad 73 block had 5 drilled and tapped holes so it didn't need an adapter to sit in your GTO.

Ames and Butler, I believe, sell the correct adapter brackets that you need.

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
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frankie
Buffalo

USA
62 Posts

Posted - 16 Jul 2013 :  11:18:55 AM  Show Profile  Reply with Quote
thank you Bill... the 73's #5 hole split in two location at a water jacket that were over two inches long... is sleeving a bad decision?
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Bill Boyle
Horse Feathers (Charter Member)

USA
4794 Posts

Posted - 17 Jul 2013 :  07:31:17 AM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
The fractures would have to be seriously assessed by a good machinist in order to determine whether a sleeve could save it.

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
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Mr. P-Body
Running Bear

USA
2258 Posts

Posted - 17 Jul 2013 :  08:45:05 AM  Show Profile  Visit Mr. P-Body's Homepage  Reply with Quote

Sleeves, if properly installed, are not a "liability", but actually strengthen the bore.

557 blocks were installed in cars, '75 through '79, depending on application. I have two here right now that were in '78 T/As. Date code on one is "C097" and the other is "L107", both indicating being cast in '77. Be careful about "absolute" statements from journalists.

Jim

Edited by - Mr. P-Body on 17 Jul 2013 08:46:06 AM
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Cowpatty69
Sitting Bull

USA
137 Posts

Posted - 21 Aug 2013 :  9:06:21 PM  Show Profile  Reply with Quote
Hey Guys, this has been a very interesting topic. Maybe I could get some clarifications/verifications?
1. If I understand correctly, any of the 557 blocks from 75-79 would be fine for a "stock" build, but not the preferred if you have another available?
2. Was the '75 year the only block that weight was shed and weakened the block, or is that across the whole 557 casting years?
Thank you!
Patrick

Got Poncho?
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cortcomp
Coyote

USA
5335 Posts

Posted - 21 Aug 2013 :  9:14:54 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
I think that it is any block with that casting number.
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Lucas
Cochise

USA
428 Posts

Posted - 25 Aug 2013 :  3:23:29 PM  Show Profile  Reply with Quote
I believe all 557 blocks are lightened. I won't get rid of any block that is usable even if it is a 557. I just had a 988 block sleeved and filled to the bottom of the water pump holes and is ready for a rotating assembly. May go stroker bottom end and might be the block I build next. The sleeve isn't even distinguishable looking at it from any angle.

"wildfire"
Real pontiac power
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goatman
Tribal Scout

16 Posts

Posted - 15 Oct 2015 :  3:32:39 PM  Show Profile  Reply with Quote
I'm about to buy a block tonight for $100 that just might be a 557. It's out of a 76 firebird, that's all I know at the moment. I felt $100 for a Pontiac 400 that looks pretty clean was a good deal regardless of the specifics. It has an hei distributor and edelbrock intake, figured those were worth it if nothing else. Did I get an okay deal even if it is a 557 casting?

Brett Humpert
69 GTO convertible
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tjs44
Cochise

USA
412 Posts

Posted - 15 Oct 2015 :  6:26:17 PM  Show Profile  Reply with Quote
for a pure street build I would not be afraid to use a 557.No way for any real HiPo use.Tom
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bluebird
Cochise

USA
292 Posts

Posted - 20 Oct 2015 :  10:33:54 PM  Show Profile  Reply with Quote
I have a 500577 in my 67 bird and its pushing 400 hp. It has been run hard for 15 years now. I had a 455 in it for about a year and noticed a huge difference in handling, as the 455 seemed to weigh a lot more, causing lots of tilt and front slide on corners. Put the 577 back in and am happy:)

"Experience is the best teacher, unfortunately, it's the costliest!"
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