I am looking into purchasing a 400 block and would like to know which is better?
thanks

 

MMMM??????????
4 always, why?
Or you could go with quality bolts on your 2 bolt.

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THAT'S RIGHT!
http://www.geocities.com/my1986transam
86' Pontiac Trans Am
305 LG4, 3.73 richmond rear

 

I have seen posts that said sometimes the 4 bolt is weaker than the just 2 sometimes?

 

On the 400 the bores are so large they really weaken the out board bolts on a 4 bolt main. It is not uncommon to find cracks around the second set of bolts. 2 bolt mains hold up fine to quite a bit of horsepower, so to prevent cracks they are generally preferred. Anyone that wants to run more power than a 2 bolt main can safely hold just moves to splayed caps. These angle the out board bolts back up to the block where it is thicker and stronger. Some people like the 4 bolt mains, which for the other small blocks are very strong and reliable, but not for the 400. If you have your choice go with the 2 bolt mains, but don't hold your breath forever. 400's were only made for 10 years with limited applications. It seems in the last couple of years the popularity of the 400 has gone through the roof with the decline of big block compatible cars. So getting one may only grow harder. Oh, another hint while shopping. If you can look at the deck of the block. Check for cracks around the steam holes. This is another area that was known to crack. Cracks between the steam holes and the head bolts are acceptable, but certainly not preferred. Cracks leading to the cylinders should be avoided. This also gives you a bargining chip if you run across one that looks good other than a few hairline cracks between a head bolt and a steam hole.

[This message has been edited by Dr. Pepper (edited July 23, 2000).]

 

If you really think you need a 4 bolt then find a 2 bolt block and installed splayed caps on it.

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Stephen's racing page

87 IROC-Z Pro ET Bracket Race Car and knocking on the SuperPro ET class
383 stroker (carbed) with double hump cast iron heads and pump gas
Best ET on a time slip: 11.857
Best corrected ET: 11.233
Best MPH on a time slip: 117.87
Best corrected MPH: 125.46
Best 60 foot: 1.662

Racing @ 3500 feet plus density altitude!

Member of the Calgary Drag Racing Association

 

yeah from what Ive seen the 4 bolts are bad at cracking the web's

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'87 Monte Carlo SS,with '89 IROC 350,700 trans, blew up 3.73 posi stuck with crappy 2.73's neeed gears! hooker headers, flow's 2 1/2" exhaust true dualls

 

As far as wanting a 4 bolt that does not matter I want the strongest possible so I guess whatever I can get due to availability.

 

My brother has been running a 2-bolt cast crank 400 in his 2600# Vega. It runs 6.30's in the 1/8th (very low 10's 1/4). He's run the same combo for several years and hasn't had any failures.

 

When's the last time you saw a crankshaft fall out?

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We need Perry Mason

 

The crankshaft doesn't have to fall out to have a cap related failure. The caps can flex and cause the bearings to spin or form a crack in the crank causing it to snap. Overall though your point is valid, for most people 2 bolt mains will hold up to whatever they will throw at it.

 

I think the the most important difference to note is that the factory 4 bolt has the outer bolts going down into the web, which can weaken it. So the 2 bolt block is prefered for high horsepower applications because you can then use aftermarket splayed 4 bolt caps. These caps angle the outer bolts into the stronger part of the block so as not to weaken the web area. I have used both 2 & 4 bolt factory blocks for drag racing engines running 11.90 ETs for years with NO problems. So if this is to be a street or weekend bracket race motor, I say use whatever you can find. If you plan on high horsepower (now or in the future), look for the 2 bolt block and with your engine builder add the 4 bolt splayed caps - remember the block has to be drilled for them and align honed after installing them. Hope this helps - Good luck !

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1992 Z28 Heritage White/Red Stripes 700R4,L98,3:23 Posi
All stock except waterpump and new Delco battery.
1972 V8 Vega

 

Bake it, Boil it, no, no, no, no,

SMOKE IT !!!!

Uh, since nobody else said it I'll hop in here. The 2 bolt block is stronger because of no invasion into the web areas.

So, instead of shelling out $$$ to have it drilled for splayed caps, just order the ARP main stud kit and use this method to build strength. Main studs, obviously, spread the torque load evenly and also serve to completely fill the voids otherwise left by the traditional bolt-in-a-hole stock setup.

406 racers all over the U.S. recommend going with a studded 2-bolt rather than a 4-bolt.

That's what mine will be.

BOR

 

hi Smokin.. if you want the Strongest thing possible.. go buy a new Bowtie block or Dart cast iron unit and have it bored and capped accordingly.. you wont have to worry about 20+ years of previous abuse, and the NEW block it built to handle MUCH more. we currently have a new bowtie blocked motor w/ 380+ cubes in a 3500 lb car running 9.60's@153mph. Let us know on what you are plannin to do so we can help you more specificlly.

 

I plan on putting this engine in a thirdgen camaro which will be fueled by a demon carb and weiand stealth intake that I will pull off my 383 when I get the 400 built up All the parts on the 383 are new so i will use them at least intake and probably the same carb I have seen some of those bare blocks go 2000.00 for like the 454 in summit I have not seen the 400 though but I would not pay 2 grand for a block that is a little much what is a good price for a 400 block?

 

I believe Wheeler Bros has a race prepped machined block for less than a $800. Just the block nothing else