Last time I ran the car was September 14.
Fired it yesterday for the 1st time since,,low oil pressure.
Could`nt find any reason. As it built heat it got worse.20lbs.
So out it came and this is what I found.
#2-3-4 mains cracked from saddle to cam tunnel.

Machinist says"every motor that Iv`e seen with aliminum caps breaks". Blah blah blah.

So at the 600hp level as I am didn`t expect to see a block crack with good caps.3.75-stroke,.030 over etc.. Estimate 150 passes.
So prep a new block w/the BCR caps ,,,or a stock block std. stuff.

2

3

Caps

Bearings looked/ fit suprisingly good.
3 center main caps were loose,of course and walking.

A little stumped last pass 10.08 normal everything.
fast forward 7/24 busted.

Adding the main caps caps probably helped with doomed block living a little longer.

You found the most common weak link in stock blocks - That is where they normally will crack - its a bummer but that's the gamble with a stock block.

If you remember Berraducci's hemi - that's the same deal that killed his .005 over stock stroke block. No warning just lost oil pressure one day.

I have had a couple do that - some say any detonation is the problem - some say a bad balance causes it. But I think its just the weak link in Big blocks.

Really Stinks to see that - was this the Cuda?

Gee, I guess according to your machinist my motor shouldn't have lived like it did, aye? 400 block, al caps, 499 cubes, 9.30s at 3,000 lbs, five seasons, sold it to another member here and he hit it with nitrous for a while! Sorry to hear about the breakage, hopefully the next one will hold up much better.

Yep..the Cuda.

Tried getting it out 2 weeks ago..brakes on the truck went out moving the trailer in the driveway...then a funeral.... then this.

My turn I guess....

Drill the holes insert tube keep on racing, there's a lot of metal side to side on that block, can't see it spreading more.

Better days ahead - I am sure! At least you found it before you drove over the crank!

Really NOT what I wanted to see. I just ran my new engine this past weekend. I also went with the BRC alum mains and thick stud girddle set up. Stock stroke (Molnar crank), +.030" Bore, H beam rods, alum heads, mild solid cam. Pretty much the same as yours, except I did find a good block with the thicker main webbs than yours (and my last one block). And yes, I DID almost run over a piece of my crankshaft. I did run over a piece of my block and cut a right rear slick at 100 mph.
To answer your question, I would go back with the BRC set up (it's already bought and paid for!) because I feel like the stock main caps are a "weaker" link than the stock blocks.

Brian Dunnigan

Damn, Sorry to here this guys but it wasn't the caps it was the block.
I have seen them live for hundreds of runs or only a pass or two. I like the pre 74' the best if I am going to build one for somebody.

how many passes on the block?

stock block at 600+ hp maybe 400 passes total, girdle, aluminum caps don't matter.
that's all you going to get, yeah some live longer but..........\
the cracks start appearing then.

so if you get a block that's been raced with 600+ hp for maybe 200 passes and you spend $$$ to rebuild it and upgrade it you still only going to 'safely' get about 200 more passes no matter what

been thru this the last 15yrs

I'm not blaming the caps or the machine work in any way.
I've been beating on this car 34 years and this is the first block failure.
Didn't expect it to happen in my trailer.
Apparently even ZERO rpm isn't safe!!!

Got 5 years on mine so far. I just have the 2 bolt caps (no girdle )

Just the luck of the draw on a stock block, because you are NOT going to "fix" it, because it can't be fixed. Stock blocks are weak in the main webs and that will never change. Doesn't matter who has done what or how long so and so's lasted. Just is what it is.

Somebody said sleeve it and run it........well you could do that, but eventually what you will "run" is the crank over..........LOL!!!

When I have used alum caps, I prefer the standard two bolt type with no girdle. Many will argue the point, but I think the girdle does more harm than good.

I think your machinist sees those failures because an engine with aluminum caps wasnt built to put put around. Not because of the caps.

I can clearly see I got away with a potential disaster.
Block was not "fresh" and really have no record of its history.

So now the debate in my head,,,,,lots of empty space for a debate in there....

Low deck or another RB.

I was looking at some of those 383 strokers.
I DO have 3 virgin 383 blocks and 3 virgin 440`s
Don`t want more power,just a little more confidence in my engine....
Opinions

I was always told that aluminum rods help act as a shock absorber. Maybe the 440 block will live a little longer at those power levels with aluminum rods and main caps?

I would be interested in knowing what the max timing was on the blocks that cracked. the reason i ask is i run 843HP (corrected) on my 400 (aluminum caps and griddle) and we put a blower on one and made 1240 hp but kept cracking upper cylinder walls (that block was cross bolted and had a griddle on it also) I run 31 degrees of timing.



Joe