Engine Issues...over and over again

[Sasklegend21]

I am looking to see what others are experiencing with engines right now, and some advice on how to make them last as long as possible.
Here is my situation.  I had a head gasket start leaking on my engine during a big race weekend, and started losing compression.  It was an older engine, so I kind of expect the odd issue, so no big deal.  I took a brand new 1250 that I had as a spare, which was broke in on the USLCI dyno and threw it in for the rest of the race weekend.  Immediately, it started throwing out oil into my overflow can.  After the weekend, I did a leakdown test and found 2 of the cylinders had over 30% leakage.  I figured this meant it was not broke in properly on the dyno, and since I didn't have time before the race to break it in, this must have been the issue.  So I sent it to be rebuilt.  I got it back, and this time I did 3 shop heat cycles, and 6 track sessions where I slowly increased speed, and then allowed the engine to fully cool for at least an hour in between.  I got 2 races on this motor until it started throwing oil again.  I once again did a leakdown test and had over 40% leakdown in 2 cylinders and over 20% in the other 2.  At this point, I was frustrated, and figured there had to be something wrong with this engine, so I bought yet another brand new engine.  I replaced my coolers, oil lines, and went with the exact recommendations for filter and cooling system that USLCI suggested.  The engine was broke in on the dyno before sent to me.  I did 3 shop heat cycles, and rented the track for 2 evenings, putting 8 progressive heat cycles on the engine (about 10-15 laps each, increasing in rpm slightly each time).   I allowed over an hour in between runs again to allow the engine to fully cool.  I did a leakdown test and all cylinders were 4-5%, so I was happy!  First race on it, I got 30 laps into a 40 lap feature before it threw a rod out the side of the block.  So 3 engines in 4 races!
Is anyone else having issues, or am I just that unlucky?
Is there perhaps something I am doing wrong that is not allowing these engines to break in properly?  According to USLCI, I am exceeding what they suggest for break in. 
Any suggestions are greatly appreciated.
 

[Tom Cole]

Where  are these engines leaking when you test them?  A possibility is that it is not past the rings but past the valves.  The valve seats in these heads will settle and this closes up the valve lash.  You can increase the lash by changing the discs that are in the valve spring cap.  Also called lash caps.  These discs are what the cam lobes push on to open the valve.  A thinner disc will open the lash and allow the valve to close all the way...at least until the seat gets beaten further into the head.

To check to be sure that the leaking is past the rings,  you must be certain that the valves are closed.  Best way to do thast is to pull the lash caps on each cylinder's valves.  Be sure you keep track of where each lash cap goes because their thickness is relative to that valve's lash.
You can listen at the ports for valve leakage...there should be none.
Popping out the lash caps also allows you to measure leakdown at TDC and BDC.
There is a trick little tool to help you compress the valve spring to remove the lash cap.  It is worth buying.
Leaking valves are often evident when the car won't turn up to the rev limiter.

Slinging a rod is most often caused by the rod bearing not getting enough oil.  Tight clearances require thin oil.  And I strongly recommend a multi-grade oil like a 5w15.  Its viscosity changes based on the oil's temperature so it isn't too thick when cold nor too thin when hot.  Consult with your builder on that.

[Tom Cole]

http://www.legendsracer.com/index.php?topic=22.0

More on the rod issue....It is worth mentioning that different builders set oil clearances differently and that is really the deciding factor when choosing oil viscosity.   The  link above discusses this.

[Sasklegend21]

Thanks for the response!
I have the valve set tool and check my valves regularly.  I like your thought on pulling the lash caps though, as that would make certain they are closed. 
When I did the tests, I always do my best to ensure they are closed.  Each time the leakage rate was high, I could hear it coming out of the casing between the cams.
I always also check the exhaust and carbs for noise to ensure no leaking past the valves, and could never hear anything there.  Therefore, I assumed rings.

Very interesting read on the oil.  I have always run 10W40.  Non-synthetic for the first few races, as I was told that would help the rings seat quicker,  and then switch to synthetic.  On the last engines I have never run long enough to do the switch to synthetic before they went.  I appreciate the advice to go with something a bit thinner like 5W15.

Thanks again for the advice!

[ZForceRacing01]

I have heard from a friend that oil leaking out the overflow is a common thing from the newer engines coming out of USLC. Sounds weird to me but that's what I was told by a friend. So common in fact they are selling an overflow can that mount to the firewall.

[justfreaky]

Most everyone runs an overflow can of some sort.
You can use anything from a soda can to an aluminum canister. I have the latter.
There will likely be some leakage past the rings. An overflow canister is a good thing; Even if just a small amount.
My .02 for what you think it's worth.

Steve

[Sasklegend21]

Thanks for the responses. I have an aluminum overflow can, but the pressure seemed to throw oil out of it before it was even full.  Are most people routing their overflow cans back to the engine, or just draining them frequently?

[justfreaky]

Drain.

[VMS Motorsports]

Most people run a drain back to the oil fill because the 1250's blow so much oil