So last weekend I had something catastrophic happen to my engine. After tearing into it to see what kind of damage occurred, I noticed when pulling of the timing chain cover that the cam sprocket bolts were snapped off in addition to the opti dowel drive pin.

Could this have been caused from over revving the engine? I also bent a valve and pushrod on number 2 cylinder as well and broke a connecting rod on number 4 cylinder which punctured my oil pan.

Im trying to understand what went first which would have caused this to happen. Any input on this would be much appreciated.

Thanks,

 

Sudden stoppage of cam or crank could do it, but it might be hard to determine until it is further disassembled.

 

Thanks Shoebox, that sounds like what could have happened based off of the number 4 connecting rod snapping and lodging itself into my oil pan. I've pretty much stripped it down to just the block and am planning on extracting it this weekend. Then i'll put it up on a stand and take a closer look under the pan.

Hopefully the crank is still salvageable, but if the rod some how scared it while it was winding down then I'll probably have to get it machined or be replacing it. Looks like I'll have to replace the cam for sure since the dowel was snapped off and do some head work due to the valve being bent. I have a extra set of heads that I had cleaned up, would be a good time now to get them ported for the rebuild.

Thanks,

 

The rod broke at the cap or across the beam? If it was the beam then you're likely going to need a new block or have that one sleeved at the very least.

Post up some carnage pics when you get it all torn down.

 

That is yet to be determined, hopefully I will have some more definitive answers by this Monday. Was wrestling with my transmission tonight and it wasn't coming along nicely, I think I forgot to disconnect the clutch fork now that I've let the smoke in my head clear.

Once I get it up on the stand I'll be sure to post some of the horrific pictures.

 

I want to see it, too. It almost seems to me that the cam would have to jam up bad with the crank still spinning to snap the bolts and dowel - having trouble imagining the crank stopped and that cam momentum snapped them.

 

There shouldn't be enough rotating energy in the camshaft to snap anything much less 3 bolts and a dowel pin. I imagine he will find bits of piston/rod/bearing in the oil pump drive once he pulls it apart.

 

Ok, well here's the carnage...When I was rotating the engine on the stand it sounded like a jar of coins jingling around. So it looks like the rod snapped or bolts gave way, making the crank disintegrate the rod and stop the cam from rotating, but since the crank was still rotating the tension from the timing set snapped the cam bolts and dowel.

 

So it looks like the rod broke at the beam. Looks like i'll be shopping for a new block. How much would it usually cost to have a block sleeved?

 

Not sure about the cost of sleeving, but a used block should run ya ~ $150

 

That last picture is frightening, I'd look for a different block for sure

 

Well that's what I needed to hear. No sense trying to bring this one back then.

My next question would be, should I go with a stock bottom end again or get a rotating assembly with forged pistons and possibly I beams?

Heard that the stock set up is good until up to 750hp, is that correct? I've always toyed with the idea of a supercharger and thought forged pistons were a requirement.

Thanks

 

The crank may hold up to that kind of power but the rods and pistons certainly will not (or won't for long anyway).

I wouldn't bother sleeving a block unless it was exceedingly hard or prohibitively expensive to replace it. Finding an original 302 block for a 69 Camaro or replacing a fully machined aftermarket block for example would be when sleeving becomes an option in my opinion. LT1 blocks (or engines) can be had for relatively cheap these days. Heck, even LS1 conversions can be done pretty inexpensively too.

Best thing to do would be to make a plan and stick to it. Whether you want 400 hp from a simple rebuild or 600 hp from a FI build; do your homework, figure out what you need and stick with it.

 

Thanks for the info, I strongly believe in making a plan and sticking with it, but at this point im still trying to figure out the best price to power output I can get. FI is something that i've always wanted but knew that the stock bottom end wouldn't last long with it.

I recently looked into the cost of the ls1 conversion and thought I might as well just buy a 98up z28 based off the hassle, time and cost of the conversion. On another forum someone put together a pricing list and it was about $5k but that could be inaccurate.

For what i've been using the car for which is road racing, 320rwhp is what my prior set up was outputing. I would like to up that this time around to about 400rwhp, but would like to ensure that my bottom end could handle this as well and the possibilty of FI down the road.

Thanks,