oh, and to address that, I will not plan to re-use the intake either. It had been milled quite a bit to fit the heads, which had also been re-used three times, which are also now trash.
Luckily I have two extra intakes I got for free.
oh, and to address that, I will not plan to re-use the intake either. It had been milled quite a bit to fit the heads, which had also been re-used three times, which are also now trash.
Luckily I have two extra intakes I got for free.
I think I saw Craig messing with your intake and a handful of bolts after R4 @ MSRH ???
Shh! He doesn't know about the marbles I left in his t5 case when I was at his shop last weekend!
Im with James on this one but it's just a guess. What is the builder saying?
JJ
When presented with the contents of the pan his instinct was rod or rod bolt. I told them to tear it down ASAP and figure out if anything is obvious.
Gonna try to stop by there tomorrow on my way, will see what they say, I need to pickup my timing cover and a few things.
So much bigger news, went down to pickup a used 94 motor from Sean, I didn't realize it was Morgan Dawdy's old street car motor, it had never gone further than running SCCA F-Stock for autocross before he parked it for a while and sold it to Ross who then parted it out. It already has the LT4 valve springs and fresh valve stem seals (he knew of a trick to replace them without pulling the heads). Beyond the intake being off once for fresh RTV/gaskets, and the pan being off for fresh crank seals and pump, it is a virgin motor that ran mobil 1 most of its life. Heads and rotating assembly have never been messed with.
I just got done talking to him about the history where he walked me through some of the receipts/logs, and I'm pretty impressed. It is 180k miles but it is a solid motor.
Tired of engine builders and wasting money, running a clean used motor is what I intended on doing when I first built the car, I'm inclined to throw this is as in with the basic necessities.
Last edited by Pranav; 02-17-2015 at 10:55 PM.
Alright, just went by the engine builder. I had just intended to pickup my cam and timing cover to make Morgan's motor work with my 95+ opti and stuff this weekend, and already have a pan and stuff on the way to get that motor in the car this weekend. They had already torn down the broken motor and looked at everything. As expected, every single part of the rest of the motor was still perfect. All remaining rod bearings and all main bearings were perfect, all cylinder walls, pretty much everything that didn't touch the front two cylinders. There was no oiling issue, so me running over that bump had nothing to do with it, end of story on that, thank god.
The three things that stuck out to the builder:
1. One of the two the piston pins was sitting in the pan completely free of a rod. Was there a press fit issue? Like Jordan said if a piston pin walked it out would've gouged out the side of the cylinder wall, which wasn't the case here. Both cylinder walls were still clean with exception to the few craters left by the carnage.
2. There was a ARP rod bolt broken half sitting in the pan with a loose nut on it. The threads were fine inside it. Did it just back off at TWS? Maybe? Possibly? A loosely or under-torqued rod bolt can't have held up for 4+ events without an issue? Talking to the builder, he flat out stated that any motor he's personally built in the last 25+ years hasn't come back for a loose rod bolt; he didn't build this one personally, however.
3. The last motor I blew (which was my fault, 3 events of ignition issues = spun bearings), we noticed that the one piston that failed from smacking the head (when you spin a rod bearing and stack the pieces, there is no clearance left between piston/head in the LT1, so the two collide) had a broken/missing skirt and pin boss. That totally is an effect of a rod crushing a piston on a head and it buckling. Same case here with the one piston that was still intact and stuck in the cylinder. It's really hard to blame a piston for buckling when the rod is shoving it into the head, but that was a commonality with the last failure so we're inclined to go with a different piston.
Long story short without even having to fight, the builder offered all labor for a rebuild to the same level of what I've done in the past and then some. I would be out the cost on the new Canton pan, rings, bearings and gaskets and they'd take care of the rest.
We talked back and forth about the 3 points listed above, and agreed to go with a different piston, and going with new GM/Chevy PM rods since they are now being sold/offloaded cheaper than the cost of reconditioning what comes out of the motor (gets me my motor back sooner and avoids any risk of the reconditioning process being a potential root cause).
It was a difficult decision to make, given Morgan's motor was well cared for and I had every intention to just us it as is this weekend; the builder has identified/addressed the three different potential weak points (rod bolt torquing, piston pin press fit, style of piston), and has plenty of motors out on circle tracks and roadcourses (including CMC) running strong. We're also starting on a clean sheet with a new longblock with a well-known history. I have no idea what the previous shortblock had been through on the street before I had them build it twice.
If I blow this one be sure to give me as much crap as possible and make a rule allowance to just run a Toyota i-force motor in the CMC car. I have never broken one of those.
Last edited by Pranav; 02-18-2015 at 06:19 PM.
Sorry, I mispoke on the rod bolt nut. It was sitting in the pan with the snapped off half of the rod bolt still going thru it, but it was loose sitting like that. Perhaps since there was no longer a rod cap in place holding it in tension? That is what was discussed...
Here is my two cents Pranav.
Sounds like a stand up machine shop, take them up on their offer. A lot of shops would tell you that you are on your own racing a stock motor. The used motor sounds like a good one, build it up as a spare with new parts, but I wouldn't tear it down. Install a new cam, lifters and timing set if the one it has won't work for you. I would shit can the cam and everything else from the rotating assembly of the blown motor! A sudden stop will stress those parts and those stresses may or may not show up in a NDT inspection. It is a small price to pay to prevent destroying the new motor. Don't forget to flush out the oil lines, cooler and adapter very thouroughly.
Dennis
Dennis are you an A&P?Originally Posted by dtanker65
JJ
Good point, I am hunting for a 95+ LT1 cam. I have a local radiator shop flushing out the radiator, oil lines and cooler; cooler/lines are very likely clean but did so anyways.
Yes everything else from the busted motor is going in the trash and the heads/intake for scrap money. Anything else that could even be re used is less than the cost of one RR tire and not worth it.
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