[T/A addict]

I am considering picking up a package deal that is local to me and want to get thoughts on a build or should I just start with a better block and different components all together?
I have no expectations on power but would like the 400 range and good torque street motor within a low to moderate budget.

As stated it is unfortunately a 557 block but has been freshly machined and .030 over.
Comp Cam K51-224-4 Xtreme Energy 230/236 Hydraulic Flat Cam Kit
6X heads
Comes with a performer intake and Holley 750

I've read that a popular upgrade is to use a 4.0" stroke crank w/ 428 pistons and 6.625 forged rods, which ups the cubes to around 434 and increases the torque as well.

[steve25]

If your looking for 400 to 425 hp weather your sticking with the 400 cid, or especially if your going to stroke the motor then those 6X heads will need some porting work done to them.

A 1/4 “ stroke increase will not be worth the level of torque increase if you ask me .
If you want to go the stroke route then go all the way to a 4.210” crank and keep the rev’s under 5400.

That 4.210” crank will also keep a smile on your face with rear gears under 3.42.

That block will live forever at that stroke / rpm and at no more then 425 hp!

[Skip Fix]

And a bigger cam!

[steve25]

Yes, forgot that important part, thanks!

[tom s]

I think its the luck of the draw,I built one that made just short of 600 HP on Joe Shermans dyno.It went in a 70 GTO and has lived on the street for many years but virtually never sees 3000 RPMs.Some break with 350 HP.Tom

[tom s]

Just looked it up,was built the end of 2009!Still running well.Tom

[steve25]

Tom I need to ask why you invested however much money it took to get to the 600 hp level, but then use it on the street and never top 3000 , or even 4000 rpm for that matter?

If someone is breaking the 557 block with only 350 hp then that motor had build issues from the start, or it’s tune was far enough off and for long enough to hammer itself apart !

[tom s]

Steve,I dont race anymore!I like building HiPo street DRIVE ABLE pontiac engines.ALWAYS able to run on 91 gas and able to idle in summer traffic and not be chugging in high gear with a stick shift.That engine was put together from mostly left over parts that I had gathered over the years.The cam WAS more than I would have liked but with the gearing in my bird it was drivable.It came out of the bird for a RA V engine and was just sitting around and sold it to a friend of mine with a 70 GTO.He had to put a loose converter in it to make it happy.I will post the thread again just for snicks and grins.The 383 RA V 301 stroker engine should be on the dyno in a couple weeks.Tom

[tom s]

here you go!
http://forums.maxperformanceinc.com/...d.php?t=622866

[steve25]

Got ya!

[Skip Fix]

Steve I pounded on my RAIV headed 400 in NMCA for almost 10 years seeing 7000 and so far so good but around a 400 HP level . heavy TRWs zero decked and heavy Crower billet rods(before we had many good rod choices)We used the 557 before we knew they were not as strong. The RAIVs are planned to go on a better block-and a 4" crank.

[T/A addict]

Thanks guys, sounds like the block is a maybe but the rest of that package is not such a good combo.
Considering building it for my 69 Firebird, 12 bolt rear end 411 gears, Bowtie Overdrive 2004R level 2 trans - 2400 stall convertor
What is a good price for that freshly machined 557 block or should I just start with a different block?

[Dragncar]

Find another block. I would not waste my time and money on any 557 build unless it was a dead stock numbers matching deal.
My buddy bracket raced a 557, iron 62s, TRWs with 5140 rods, RAIV cam shifting below 6K.
And he cracked every single main bulkhead in the block. Almost ripped the crank out.
Others will tell you go for it. But time and money is expensive.
A few bucks more for a non 557 block is more than worth it.
I would but money into a good 389 block before I built a 557 400 block.

[ZeGermanHam]

Since you'd have to put a lot of money & work into building that 557 block to get it where you want, I agree that finding another block makes more sense. You can still find good (i.e., non-557) 400ci donor blocks for $500-600 fairly easily.

[Jay S]

I am looking for 500557s. If I have any say the 557’s are going to become the new ultra light sought after Pontiac race blocks. This one is 4.155x4.25, 11.0 SCR, fully ported 6X, 2.125 int, 1.77 exh, 302/310, .630/.630 Bullet Solid Roller cam.

[tom s]

Like I said luck of the draw,if building a 100 % street engine with light weight stuff and well balanced it might have a long safe life.I would never build one for any kind of racing.Tom

[tom s]

Jay,no offense!Putting lipstick on a pig!Tom

[Jay S]

Lol. No offense taken Tom, I remember that is exactly what you told me before I started that project. It fits on any 3” engine, even one with 4 bolt mains. I am looking for those 500557 blocks because they are better test subjects.

[Jay S]

For the OP. Didn’t mean to derail your thread. FWIW, a 400 w/flat tops, 6x heads and headers the cam in that engine is probably 330-350 hp depending on what suffix the heads are, -4 or -8. With a little milling and some pocket porting with compression in the upper 8s to 9 they seem to have 380-390 hp with that comp HFT cam.

With the stock 6 x heads and stroker crank and well chosen cam 430 hp is pretty doable. For a 4.21” crank and d ports with pretty stock heads and a nice valve job 450 hp is about all you can get and be streetable. My opinion anyway. Seems like 380- 400 hp is more common on most stock headed street builds,

Stock 500557 in my opinion with stock fasteners needs to stay under 400 hp with a 3.75 or 4” crank. After 350 hp I would add main studs. Milodon makes some mains studs that do not distort the main caps very much. At least I didn’t see much distortion when I tested them, the tq rating is quite a bit less than a ARP. From the checking I did it appears the Milidon’s could be added and not need to line hone anything. If your going to do something serious with the engine I would use ARP main studs and another line hone on the mains..

Many seem to have decent luck with those weaker blocks by honing/reaming the dowels out to 5/16” and ARP studs with a proper line bore.. The Halo girdle I designed and tie bars by itself with out the pan rail supports was intended to add about 20% strength to the bottom end of a 500557, basically pushing the engine from 400 to 500 hp with main studs. FWIW, I think it would add 15% on a earlier 400 2 bolt block. Mostly intended to help cap fretting. The full system like In the picture my goal was to add 40% strength on the 500557. So a well built 500557 with ARP mains studs goes from roughly 400-420 hp to 560-580. Well over 600 if you have the heavier .5” bridge supports on top of the mains and the pan rail supports that tie into the cap dowels for indexing the mains to the pan rails. I think after 600 hp you’d be rolling the dice on the weaker block even with that girdle. I did another one that is aluminum and supports all 5 caps, I think it is good for about 750 hp.

[STEELCITYFIREBIRD]

Can you make enough compression with those heads to support that much duration? (W/A 3.75 “ stroke)
Seems to me it would be a really ‘soggy’ street engine on the low end.
?? 🤔