Quote:
Originally Posted by wdb
Hmmm. I wonder if that's what is going on with the Moupe I just got. The prior owner was obviously skilled and had done the valves himself at 60K, and yet there is seepage at the gasket. Hmmmm. I'll have to keep that in mind when I do the VANOS this winter.
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Quote:
Originally Posted by TheAxiom
I have a N52, and my plastic (OEM - brand new) VC was cracked. So it can happen.
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Yup. Definitely check the valve cover with a straight edge when you take it off.
Quote:
Originally Posted by SaltyNC
Your post about the rod bearings has me a bit worried. I'm doing vanos work now, and plan to do rod bearings in the very near future. I do know about the ARP bolts, and some have recommended against using them due to the amount of force needed to seat them properly. I was speaking to an indy last week that said he replaced bearings on an M3 (S54) with the treated OEM bearings and ARP bolts, and the M3 lost the engine at the track within a year of replacing the bearings.
Is proper rod bearing replacement something only a race shop can perform? I was planning on using stock bolts, but leaning toward the treated OEM bearings.
Salty
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Quote:
Originally Posted by wdb
I'm not sure if I'm more worried or if I need to reach for the salt shaker. The reason car companies go to the expensive length of splitting conn rod big ends that way is that it makes it pretty much impossible to assemble them INcorrectly. Now here's this guy saying the opposite.
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Yeah, I think there's salt to be taken with anybody's opinion on the "absolutely correct" way to build an engine. My guy's position is that you're going to get different clamping force on each side of the rod depending on the mix of (1) irregular surfaces not quite mating perfectly; (2) different tensile strength in the torque-to-yield stock rod bolts; and / or (3) inability to use a bolt stretch gauge to accurately set clamping force. He has a bunch first-hand of data* about big end roundness and bearing wear in raced S54s using ARP hardware and aftermarket rods vs. stock rods and stock bolts (or even ARP bolts). He had a very strong preference for the Molnar / ARP setup.
His explanation makes sense to me, and a couple of other S54 / S65 race engine builders on the web agree**. I think it all comes down to risk management and engine goals. I want my build to be supported by my engine builder, he believes that this is the correct approach for real safety, and the difference in cost simply isn't enough for me to worry about it overall.
It's worth noting that Andrew Lang's data on ARP bolts causing the big end to oval is based on a model - it may be correct, but a lot of people's experience of the OEM -> ARP rod bolt transition is that the top / bottom bearing wear on the rod big end disappears with their engines after switching to ARP bolts.
Bottom line: YMMV. :shrug:
* I didn't ask to see it, so this is effectively me assuming that the plural of "anecdote" is "data"
** Something, something, opinions and assholes, something, something