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Ack! I'm getting valve train noise and fear I may have this as well, I'm pulling the VC tonight and hoping I don't see this too.. I do have the ST valve seals I believe though. Need to check with the machinist that assembled it. Heck of a start to 2017, eh?
Sometimes I feel like Pat. Trashed valve train on Wednesday. Running car on Saturday.
Trying to decide if I should check on the lifters before or after my track day. I kinda just want to drive. If the lifters are trashed again I'm stripping down the whole motor either way. Probably going to just ignore it until it goes away.
Sometimes I feel like Pat. Trashed valve train on Wednesday. Running car on Saturday.
Trying to decide if I should check on the lifters before or after my track day. I kinda just want to drive. If the lifters are trashed again I'm stripping down the whole motor either way. Probably going to just ignore it until it goes away.
LOL You do what you gotta do to race!
Did the valvetrain make noise with the damage you found? If so I'd run it till you hear noise. If not I'd check it at a similar mileage as you found damage last time, if not a little sooner.
If it happens again, I would inspect cam for damage, polish the cam and put stock lifters in it. Cheap option and will probably fix it given how reliable stock lifter/stock cams are.
This problem is not related to your bottom end, or the casting of the head. Those two surfaces are in sliding contact, and there's a few requirements for it to work reliably. Surface finish, hardness, flat/parallel surfaces, a supply of the right oil, and some valve clearance so oil can get in there between valve events. One of these things is off.
A bit random, but IIRC you were hand grinding valve shims for your car. If those shims are not parallel, then when the cam pushes on the lifter, and it then pushes on the shim/valve stem, the assembly could "rock" a bit from it not being parallel and that would put high pressure on the edge of one side of the camshaft lobe, which could cause the damage you're seeing. Actually I'm going to say that's my guess at what is causing all your problems. Why it's isolated to only the intake side, my best guess is the ramp rates are more aggressive on the intake cam.
Why were you using non-detergent oil for break in? I use high ZDDP conventional oil for break in. You are always supposed to use oil with detergents when using a filtered oil system and only run non-detergent oil in a filterless system (most lawn mowers and some air cooled Volkswagens). The detergents attach to suspended particles in the oil and cause them to be more easily captured by the filter. Different detergents exist to attach to different types of suspended particulates.
The ZDDP helps to prevent galling by adhering to the surface at a molecular level, forming a last-ditch sacrificial layer after the oil film breaks down. It is referred to as an extreme pressure lubricant for this reason.
The assembly lube is melted as the engine warms and the oil acts as a solvent, thinning it. It only is designed to protect until the oil reaches all the surfaces of the engine. After that you need a good film strength oil with a good additive package. But I know there are lots of opinions on the subject.
The intake side had a number of shims that were not hand ground. But worked out of the box. Exhaust side had a few shims that I had to knock over 4 thou off. Again exhaust was fine. Intake was not.
If your valve guides are shot (can wiggle the valve in the radial direction) then the valve seals can leak from that as the valve moves sideways and pulls the sealing surface away from the stem. But I assume if the guides were shot you would not have just lapped and reinstalled the valves. When you say it leaks worse, are the valve seals leaking worse than before (you inspected the valves) or is it just smoking more?
05-20-2017, 09:10 PM
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