[Conundrum]

I picked up a 400 to put in my 74 GMC pickup project, and after a little searching I discovered that it is a later 500557 block. I am not going for strip hero status or anything, just a strong street truck. Am I going to waste my time with this block, should I find an earlier one?

[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.

[Ragtop Man]

Break it? I can't even lift it.

Great idea for a swap, a total forehead smacker.

If the 400 made it this far, it will be fine. Glad to see some Pontiac power going into a GMC, should have kept it there to separate them from Chevy.

[GREATGTO]

I have one thats been together since 1992, street strip use, runs high 12's, makes about 420 hp

[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 !

[MandevilleBird]

Butler Performance advise that these blocks are good to 600HP.

[Murf'sDad]

Originally Posted by MandevilleBird

Butler Performance advise that these blocks are good to 600HP.

... with proper preparation and Mag'ing, sonic testing, good parts, fine blueprinting, etc. Try to short change the work and you'll end up with an iron paper weight very quickly at that power level. Course that's the outcome with almost any block where short cuts are taken, details are neglected and inexpensive parts are used.

Stewart

[HO LEMANS]

Hey just wondering if you needed a bell housing for that 400 in that pickup ?? I had a 73' GMC 4WD with a 400 4spd in it and I can tell ya it was a blast to drive I still have the lead pipes for the dual exhaust for the 400 in a pickup with factory manifolds as well laying around here somewhere. The bell housing was machined out to accept the larger front bearing retainer (of a truck 4spd)with a boring head so it's really accurate and surprisingly the clutch linkage hooked up fairly easily as well as the rad hoses let me know if you want any of this stuff and I will locate it for ya

[77 TRASHCAN]

A thorough checking of a 557 block, for a good running street engine should be all you need, as in magnafluxing.

A good visual inspection would be important to me also. If you have a good air compressor, a die grinder, and a box of those sand paper rolls, you could de-burr the whole engine, including the main web area. It might be a waste of time, but would be cheap insurance. Cracks start from thin metal, or sharp edges. If you knock them down, it's cheap insurance...

When I get to work on one of my 557's, this will be my plan of attack...

[Conundrum]

Originally Posted by HO LEMANS

Hey just wondering if you needed a bell housing for that 400 in that pickup ?? I had a 73' GMC 4WD with a 400 4spd in it and I can tell ya it was a blast to drive I still have the lead pipes for the dual exhaust for the 400 in a pickup with factory manifolds as well laying around here somewhere. The bell housing was machined out to accept the larger front bearing retainer (of a truck 4spd)with a boring head so it's really accurate and surprisingly the clutch linkage hooked up fairly easily as well as the rad hoses let me know if you want any of this stuff and I will locate it for ya

I have not decided what trans i"m going to use yet, the truck was a manual so all the pedals and linkages I have. But I was thinking of using a 2004R, i've got one from a 84-5 T-Type. And the engine came with a turbo 350 so I could always use it.

Originally Posted by 77 TRASHCAN

A thorough checking of a 557 block, for a good running street engine should be all you need, as in magnafluxing.

A good visual inspection would be important to me also. If you have a good air compressor, a die grinder, and a box of those sand paper rolls, you could de-burr the whole engine, including the main web area. It might be a waste of time, but would be cheap insurance. Cracks start from thin metal, or sharp edges. If you knock them down, it's cheap insurance...

When I get to work on one of my 557's, this will be my plan of attack...

When I get around to building it, i'm going to do this for sure.

[1967Tempest]

my 557 has had the snot beat out of it for the past 8 years. I really do beat on it. It has 2 speeds, idle and WOT.

You will be fine...

[Conundrum]

Thanks for all the replies.

I have another question, i'm going to put this in a 74 GMC and was wondering what color the pontiac engines were in 74?

[Johnny406]

I beat the total snot out of my 557 with stock rods and heavy trw forged pistons. I even supercharged it for awhile. The motor now serves as the spare until I get it in my red 81, it's still going strong.

As for paint, it's awfully hard to beat that classic blue metallic in my book. You can paint it chevy orange and tell people it's a special wide block 350...

[Conundrum]

I like the blue metallic best

[Conundrum]

Well I almost had an early 70s f-body 160mph speedo bought on ebay lastnight, for less than $20 including shipping. As i'm sure we all have seen, I lost out in the last few seconds. Of course it didn't help that I was using my phone and it takes forever to load anything, so i'm a little bummed about that. Maybe the 8k tach i'm watching will work out a little better.