[chupiw1]

I'm no expert by any means, but if it doesn't have any cracks, and if it checks out fine with a sonic check, go for it. You aren't going for an all out race build, I would think it would work out fine.

[chiphead]

The 557 blocks are good for about 400+HP with the stock stroke crank. They aren't good for strokers, because of the extra loading on the main webs with the larger stroke. No NOS or forced induction either. Truck duty should be fine.

[Murf'sDad]

I looked for a "good" block within reasonable shipping distance and couldn't find one so I decided to do my build on the stock 557 block that came in my '76.

What I did do to give me more of a safety margin was to lighten the reciprocating assembly as much as possible. I used Ace's 4340 Ultralite I-beam rods and SRS forged pistons. The rods alone were worth about 250 gm each, add in the lighter pistons and pins (don't know the weight but substantially lighter than stock) and the a re-balance of the assembly took a lot of weight out of the crank counterweights. By all accounts, I should be at a power level of about 450 - 475 hp with my heads and cam combo. I haven't had a chance to dyno it yet unfortunately.

Even with these light parts I'm still going to keep my red line at 6000 and the rev limiter set at 6250. The power range of the cam is 2600 - 5600 rpm so 6000 for a redline is more than enough.

Am I concerned about the "weak" 557 block? Not in the least. Even if I hadn't used the lighter parts, a properly built 557 block with good rods should live a long time in street car. By the same token, I probably wouldn't use the 557 block as the basis for a max effort 10 second motor though.

Unless you have the intentions to hit the motor with N2O or a blower of some sort or just rev it to the moon, I'd build the block you have and enjoy the ride.

JMO, Stewart

[Conundrum]

Thanks guys.

Although my rebuild may be a ways down the road.

[amcmike]

Originally Posted by Murf'sDad

I looked for a "good" block within reasonable shipping distance and couldn't find one so I decided to do my build on the stock 557 block that came in my '76.

What I did do to give me more of a safety margin was to lighten the reciprocating assembly as much as possible. I used Ace's 4340 Ultralite I-beam rods and SRS forged pistons. The rods alone were worth about 250 gm each, add in the lighter pistons and pins (don't know the weight but substantially lighter than stock) and the a re-balance of the assembly took a lot of weight out of the crank counterweights. By all accounts, I should be at a power level of about 450 - 475 hp with my heads and cam combo. I haven't had a chance to dyno it yet unfortunately.

Even with these light parts I'm still going to keep my red line at 6000 and the rev limiter set at 6250. The power range of the cam is 2600 - 5600 rpm so 6000 for a redline is more than enough.

Am I concerned about the "weak" 557 block? Not in the least. Even if I hadn't used the lighter parts, a properly built 557 block with good rods should live a long time in street car. By the same token, I probably wouldn't use the 557 block as the basis for a max effort 10 second motor though.

Unless you have the intentions to hit the motor with N2O or a blower of some sort or just rev it to the moon, I'd build the block you have and enjoy the ride.

JMO, Stewart

Do the half-fill on the block would help too, wouldn't it?

[Murf'sDad]

Originally Posted by amcmike

Do the half-fill on the block would help too, wouldn't it?

I asked the same question last year and was told the block fill stabilizes the cylinders but does almost nothing to strengthen the area of the mains, where the problems can occur.

Stewart

[steve]

i just put my 500+ Hp "557" in service this summer. still holding strong !