Well it's official... truck motor is wounded

[Marv D]

Finished the vacuum pump install last week and there was still enough blowby to see it escaping the seperation can. So did a leak down and was acceptable all but #3. BIG leak. Expected a broken ring (assembly stupidity or something) So had some friends help (still recovering from back surgery) and yanked the motor, pulled the head and the bore isn't scored, scratched,, whew!!!! so,,,?? what's up. then I saw it..... my round bore isn't round,, it's got a big 1/4" wide flat.

Picts to come but the head apparently was trying to lift, and the deck failed. FIGURES,, spent a ton on this POS GM 509 casting to use as a backup motor, and haven't even made ONE complete pass on it. So that's it,, anyone that tells you a GM 400 casting is worth 5¢ is out of their mind. Maybe for a street motor eeking out 1 or 1.2HP per inch,, but 600+ and it's JUNK in a heartbeat!!! And this block was a virgin 3951509 400 casting, maged, sonic tested, added splayed mains / align honed, cement filled to the bottom of the waterpump holes, bored and honed with torque plate, squared and zero decked stuffed with cubic dollars and the POS still failed!!!!
Grrrr, now have to find a decent priced block, with 400 mains, and standard pan rail, and start all over clearanceing for the 4" stroke. And all this started as a simple motor change to step the truck up a 1/2 a second

[project 67 sub]

well that just blows a big one.... i hope you have better luck with the next engine you build

[Marv D]

Actually this one has been just sitting for 4 years as a backup motor for my Nova. I think the machinist would stand behind it (bought the bare block from him then spent the bucks on it) if I brought it back to him like 3.8 years ago!!!! LMAO..

check this out,, even with a droid phone cam you can see the failure is only down through the deck and first ring,, but moving down towards the second ring.

http://www.small-block-chevy.com/ima...0/400blk_a.jpg
http://www.small-block-chevy.com/ima...0/400blk_b.jpg
http://www.small-block-chevy.com/ima...0/400blk_c.jpg
http://www.small-block-chevy.com/ima...0/400blk_d.jpg

(gotta document al thes before I ream the ridge back round to get the piston out without damage ...hopefully!!!)

[ItsRandy]

Wow Marv...bummer!

[djracer]

I hate you had the bad luck. I hate having to buy aftermarket blocks but for anything serious you really need one. I have a bowtie for the 548 but my next block will be a Dart.

[fastwillie 696969]

my next build is going to be brodix 400 alum block

[Super73]

Marv, very sorry to hear the problems.

Too bad you can't just slap all that rotating assembly in a stock LS block. Brand new they are cheaper than the aftermarket Gen I blocks, and they are alum.. Did I mention they are strong!!

Really though, it sucks and I feel for you!!!

[shawnt]

I dont think those 400 blocks are even safe at 450. GM really fumbled the ball with those. Sorry about the damage!
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[Marv D]

Yeah biggest problem is the stupid 400 mains. SHP block is 350 mains,, and most everything else but the $3300 Dart,, except for the Motown. Been fine n the Nova making another 150 over what this thing did,, so,, guess I'm biting the bullet. Will see if this one can be sleeved to make a little street motor our something. If not,, SCRAP!!

[dbmx66]

what the hell caused that?

[nxtruck]

That stinks Marv. What are you looking at replacing it with? Little m or a Motown?
I guess I've been very fortunate with my junk so far. I wish they offered the SHP with 400 mains.

[BigDan3131]

Found this: SB CHEVY DART ALUMINUM BLOCK
ID#: 6557 Category: Blocks

Dart Aluminum SB Chevy Block With 400 Mains And 4.145 Bore.Fresh Hone Job And Comes With Head Studs And New Coated Cam Bearings For The BB Chevy Size 1.948 Cam Already Installed.
[Photos]

Price: $ 2600.00 Payment Method: cash-money wire
Contact Name: Terry
[ Send E-mail to #6557 ]
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At this email addy: http://usedracingparts.com/

[blackedoutharley]

Don't know if this has 400 mains but....

http://www.speedwaymotors.com/Garage...ore,33644.html

These have the 350 mains but are much cheaper on sale

http://www.speedwaymotors.com/Dart-L...isplayId=33644

[68 C-10 KID]

Dang Marv OUCH!
I hope the machinist will sleeve it for you with no grief.
I would see if he would re mic everything also.

[Marv D]

Larry Peto (Larry's engine and Marine) does all my machine work and he's a stand up guy. We put this together back in 06,, and he remembers the block and the "WTF is Marv thinking" when we spent $1400 on it. Sooo, he just knocked $1000 off the price of a Little M and should have it bored / decked and ready to go by Friday.

It's nice to have people who appreciate your repeat business!!!

Yeah the big problem is the 400 mains, wet sump STANDARD pan rail, standard cam location. Motown has one, and the Dart Little M in that configuration can be had,, just not 'common' . The SHP block only comes in 350 mains,,, and the little M is generally configured for dry sump, spread rail, raised cam. But.. I got lucky and he had one in stock.

Now I think I ought to go buy a couple of lottery tickets!!! This thing was so close to . A couple of grand in a new block is much better then loosing the crank, ProMod rods, the JE pistons were new for this block,,, and this stupid simple little 'motor change' in the truck is like the frickin energizer bunny on the budget.. just keeps costing and costing and costing........

[plummen]

I ran a streetable version of a 415" small block in one of my old 1t 4x4s for a number of years,never had a problem with the 400 block.
I did use a 2 bolt main block with main studs since everybody told me they were stronger than the 4 bolt version.
my combination was in the 425-450 hp range backed up by a truck 4speed and 4.56s and locker in the rear and 4.55s and a limited slip in the front,would take my 8,000lb 1t 4x4 dump truck and bend it like a pretzel at will!
a buddy of mine is still running that same motor in his heavy ass 64 impala wagon,ill find out what his 1/8mile times are

[djracer]

Marv is not saying they never work he is just saying they fail far to often. The guys who bought my old 67 camaro drag car have had several motor failures and most were do to the stock 400 blocks.

[Marv D]

Exactly, Chris is screaming proof you can hit it HARD and have it survive. And I believe Chris's block is a 817 (foggy memory). By all rights, reason and internet rumor he should have been sweeping up pieces of block long ago. I probably have enough fingers and toes to count the 421-434 sbc's I've built for myself and buddys,, but I don't need one hand to tell you how many of those are surviving in GM production blocks. And it wasn't for lack of attention to quality machine work and assembly. Like I said I spent $1380 on this stupid block trying to make it tolerate 650HP. The splayed mains worked, the cement fill to stiffen up the bottom 1/3 of the block worked,, head studs, studs along the center main bolts, pan studs, alll that worked.... but there just aint a darn thing to do about a deck failing. My guess is it tried to lift a head but the head studs did their job and the great clamping force took the deck with it! WHY? really no guess all I know is it, and one piston is a big pricey paperweight!

[nxtruck]

Actually, Marv, my block is a 509 casting. And I'm still running studded 2-bolt mains! I'm running head studs, also. Like you said, however, all the band-aids in the world won't keep the deck from lifting if it's too thin to begin with. The fact that mine sees more street driving to cruises and such and not nearly as much time at the track as it used to is probably the biggest reason that it's still in one piece. If and when that time comes, I won't build another one with a factory block. Mine has served me well so far, though.

[prostreetC-10]

Man....all a part of the game huh? You'll be back. ;o)

[Marv D]

Oh yeah,, and in short order. New block is bored and decked, fluff work should be done today,, one new piston on order from JE (thankfully just a shelf stock piece in this motor) Next ADRA race is Sept 9th,,, don't think I'lll make that, but should have a few shake down passes in and I'll be ready for the Oct race for sure!!

[prostreetC-10]

Well I expect to see you in Pomona!!!!

[Marv D]

Haaahaha, man I've not attended even one race this year. I don't have enough points to even go to the Div.7 ET finals, let alone Pamona