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Here are some pics of the cam gears for some cam timing reference. I recently had a shop change my timing belt, cam seals, etc (they ripped me off, never paying someone else to do that stuff again)... Both intake and exhaust are ~2 teeth off. I've never messes with the cam timing -- is this normal?
That's the most poorly timed miata I've ever seen. Put it back together with some fresh rings, used NA8 pistons and ebay spec rods. Enjoy 300 whp.
Should I ask the geniuses who did my timing belt? I imagine that if it was like that before, they should've fixed it (I don't think it was, car ran great before I took it in) and if it wasn't like that before then they changed it.... Sadly I don't really have a way to prove it. What should the timing look like? Totally stock with the E and I pointing directly at the marks on the head?
Advanced intake cam will close the valve early and add a lot of dynamic compression. There's det damage on every piston and squish surface in that engine.
That's the most poorly timed miata I've ever seen. Put it back together with some fresh rings, used NA8 pistons and ebay spec rods. Enjoy 300 whp.
Where does one find "used" NA8 pistons? My plan was to go forged with those too but I don't have crazy power goals that really warrant it. Whats the price difference between used pistons and some forged ones?
Advanced intake cam will close the valve early and add a lot of dynamic compression. There's det damage on every piston and squish surface in that engine.
Is the intake cam advance enough to cause that detonation though? Also would some machine work be able to fix up the squish surfaces in the block and head or am I looking at a new engine?
Probably, yes. Two teeth is a lot. Regardless of why, you should ask why you didn't hear it. That much detonation wouldn't have been subtle.
At a bare minimum, you need four pistons and substantial cylinder head work (skim + chamber rework on #2). If you're lucky, the damage in the block due to the ringland failure can be taken out with an overbore, but all the aluminum that burned off the pistons had to go somewhere.
Probably, yes. Two teeth is a lot. Regardless of why, you should ask why you didn't hear it. That much detonation wouldn't have been subtle.
At a bare minimum, you need four pistons and substantial cylinder head work (skim + chamber rework on #2). If you're lucky, the damage in the block due to the ringland failure can be taken out with an overbore, but all the aluminum that burned off the pistons had to go somewhere.
I simply don't have the money for lots of head work, might just be a better idea to get a junkyard head? My plan currently (it's in another post I made) is forged pistons, rods, bore and hone 1mm over, and not quite sure with the head... maybe junkyard like I said.
i agree quite honestly. My thoughts are this: I want to make the car a track car eventually. I could throw just rods in or get a new motor, but if I’m going to build it at SOME point then why not now? With a blown motor, it’s probably worth it to put the effort in now and be ready for more boost and track duty in the future. I could be way off but I feel like putting the money in now could save me down the road... although I’m open to any advice people have!
Update: I got the engine pulled and completely disassembled. Pictures of the carnage are attached. Luckily the block and crank look good so I am going ahead with a rebuild. Inconel(?) exhaust valves, forged pistons and rods, BE oil pump, ACL bearings, all new gaskets and such... Should be good for 300ish whp which I do not plan on approaching until I get my hands on a 6 speed transmission.
^^^ It's cool seeing all the bits and pieces all apart. Rewarding sight after many hours in the garage
Another quick update: I'm currently at my least favorite part of the build stage, waiting for parts. I've got Eagle rods and Supertech dual valve springs ready to go and am just waiting on Fab9 and FM to ship me the pistons, bearings, gaskets, and exhaust valves. Still debating on whether to rebuild the engine myself or have the engine builder do it for an extra $400. Goal is currently 250whp until I get bigger injectors and fuel pump which I plan on doing down the road.
05-14-2020, 12:00 AM
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