[GTOLou]

Originally Posted by 2manyT/A'S

No.....just assuming that they cheaped out on the casting & it would have greater potential for similar type problems to develop......

The casting # wasn't changed for NO reason.

Anybody done a weight comparison?

I'll post a pic of a 76WX block - way more meat than was around the mains of the 557. Heck, the 557 is so poorly cast under the main caps that you can't add standard four bolt main caps - they'd drill through. I'll post a pic.

[72blackbird]

Maybe us 500557 owners can copy a page from the hi-po 403 Olds owners and run a halo girdle and a main cap brace that ties into the oil pan rail. It would be cool if we could run 4.21" and 4.25" stoker kits w/ no fear of block breakage as well.

Geno

http://www.jsmachineoldsmobile.com/images/full.JPG

[ITSBACK]

Thats an interesting setup. I guess it uses a special oil pan.

[GRX]

Have seen that too many times. I have had early '75 (488986) and late '75^ (500557) block on my workbench side by side. Definitely thinner on later casting.

[Stuckinda60s]

I know this is an old thread and not to beat a dead horse, but it might be worth a mention. I saw 2 Blocks that had splits started at the dowel hole, traveled through the block and terminated at the opposite dowel . They both had split pins instead of dowels. At the time I thought that the pins were the cause of the fracture because they weren't an interference fit and only had the spring of the pin for stability, which could be diminished by vibration and allow movement within the hole. They were the 557 block.

[tom s]

I did not know about the 557 blocks until AFTER I built one.I guess I was lucky,had the block magged and had full length dowels in the mains.The build is on this site,made a lot of HP and the engine is in a 70 GTO for a lot of years now with no issue.FWIW,Tom

[mgarblik]

I feel that the 375 HP limit mentioned in a couple posts is reasonable for a "557" block. Remember that's a 100% safety margin for the original design parameters give or take a few HP. These were designed for 185 HP and 4500 RPM's. So likely good for the 375 HP level and 5000 RPM's for an occasional blast on the street. Unless doing a numbers matching restoration, I would bypass that inferior casting for the much better ones still out there. JMO.

[Jay S]

Originally Posted by Stuckinda60s

I know this is an old thread and not to beat a dead horse, but it might be worth a mention. I saw 2 Blocks that had splits started at the dowel hole, traveled through the block and terminated at the opposite dowel . They both had split pins instead of dowels. At the time I thought that the pins were the cause of the fracture because they weren't an interference fit and only had the spring of the pin for stability, which could be diminished by vibration and allow movement within the hole. They were the 557 block.

Good info. I think the main caps for various reasons (alignment, power level ect) leverage the those non blind holes for the pins and can cause the block to crack at the dowel hole. To prevent cracking in the block at the main cap dowels it does not appear to really make a lot of difference if the 500557 block engine has dowels or roll pins, both can start a crack at the dowel hole. I think the roll pin is a little better and can handle more misalignment, but some think the dowel is better. I don’t think either is a much better than the other option. If there is some misalignment in the dowels when the main caps are tightened down even a stock 2bbl engine can fail at those dowel/roll pin holes.

I think a simple solution for keeping mildly built engines with 557 blocks together is double checking pin alignment, and using ARP main studs to increase the clamping force on the main caps. That seems to limit the stress that is sent thru those dowels or roll pins that are indexing the caps.

I have been running a main girdles on higher HP 557 base strokers for awhile now. The engines have been through some inspections. I have seen some fretting on the pan rail supports, but have not seen any negative effect on the mains themselves. One was at the track and some head porting let antifreeze get in the oil, destroying the bearings and bent the crank. It happened at MPH cones. The block took the abuse fine, but that was a bit more of a test than I was looking for. LOL

[Skip Fix]

In the process of freshening the old 400 shortblock I had under my RAIV heads I raced in NMCA a lot of years, lots of different cams, intakes, headers. Best was 12 teens @111 weighing 3900lbs through 2.5" tailpipes. It had heavy TRW 2262sm heavy Crower billet rods but was pretty meticulously balanced. Buzzed it 7000 with a SFT and a Torker 1. Magged fine, no dowels falling out. crank spinds real frrely.
Wallace calculator 438 hp.
Machine shop nor I knew about the 557 blocks either when I built it. Going to get throw together with some E heads and a mild solid roller and tossed in the 65 GTO project.

[Dragncar]

557 blocks IMO are not worth your time for a real performance builds. They might take it, they might not. This stuff is too expensive and it takes too much time to risk it. Find another block.
My friend had one and raced it with a RAIV cam, ported 62s, Warrior and it ran. 10.90s to my 11. teens with a "big" 455 with a SR at the time and he let me know it.
But, after 3 seasons every single main bulkhead was cracked. As in the crank was getting ready to be blown out the bottom of the block.

[steve25]

It’s dangerous to run those blocks with anything more then a 3.750” stroke and over 5500 rpm.

In fact I think a race motor might live longer just due to the likelihood of it being run on fuel that keeps it out of detonation.
That will hammer those blocks to pieces in no time .

[sdbob]

I remember about 1976 going to my buddies Kurt's scrap engine pile looking for Pontiac blocks. I didnt know about 557 blocks ,nothing. Pulled pan on one 400. Pulled main caps,noticed the roll pins, then the 'lightness of metal' around mains.Remember I found that SD 455 block. I thought not good. Pulled pan on 75 455 didnt notice anything lighter however the previous 400
made me sceptical.

[steve25]

Yup, the late 455 blocks never went the light route, although I think for that last year of production the part number changed.

[Skip Fix]

I have heard about the roll pins for the main caps-my 78 original 180 hp block -solid, this 577 block solid and tight in all the caps!

[Jay S]

There is conflicting information about which of the late 400s used roll pins and which had dowels. The roll pins started in 1977, and all the 1977 W72 400 engines have roll pins instead of dowels. But there are plenty of examples of 400 engines with roll pins that by all accounts should have had dowels. Dowels are most common.

That earlier post by stuckinda60s that mentioned seeing engines that had pins that had cracks is the only time I have ever heard of 557 blocks cracking at those pins that had roll pins and not dowels. I have seen the roll pin engines with main bearing issues, but had not heard of roll pins engines with cracks at the pin. It would be interesting to know what applications those engines that had roll pin were from. If that was common, it is likely a big part why Pontiac went to the XX block on the 78 and 79 W72 400s.

[Skip Fix]

"it is likely a big part why Pontiac went to the XX block on the 78 and 79 W72 400s. " I heard that also. The W72 was on my option list but missed it by a month as I wanted an auto, they were then just available in 78 and 79 in stick cars.
Found an X7 220 HP 78 W 72 I found sitting on an engine stand if I want the car like I ordered it. got the car from Gay Pontiac in Dickinson! best prices in South Texas back then and Pontiac racers!

[Jay S]

I forgot, not all 1977 w72 engines had the roll pins. The change from dowels to roll pins happened late in September 1976. The 400 w72s made before that date had dowels yet.

[Dragncar]

Originally Posted by steve25

It’s dangerous to run those blocks with anything more then a 3.750” stroke and over 5500 rpm.

In fact I think a race motor might live longer just due to the likelihood of it being run on fuel that keeps it out of detonation.
That will hammer those blocks to pieces in no time .

My buddies 557 had the original 3.75 crank, TRW flat tops and he ran a race gas mix even though he did not need it.
Save them for the 220 HP wheezers.

[J.C.you]

We are using the 557 400 and 810 350 later blocks in the dirt car. Both have dowels. No problems yet/knock,knock��. Main reason is the weight savings off the front of the car. Spin 6200. I plan on doing some dyno testing to see where we’re at on hp. Class is limited to a 4412 2 barrel Holley carb.

[Jay S]

Originally Posted by J.C.you

We are using the 557 400 and 810 350 later blocks in the dirt car. Both have dowels. No problems yet/knock,knock��. Main reason is the weight savings off the front of the car. Spin 6200. I plan on doing some dyno testing to see where we’re at on hp. Class is limited to a 4412 2 barrel Holley carb.

Cool. Are you using main studs?

Have you ever weighed the 810 350 block?

Here is photo of one my bare 500557 blocks. 154.5 lbs, pretty much the same as a bare SBC.