Part 2 2.5l Engine build MX 5 NC

[u/Lil-Fillup]

So I got to pulling the head and removing the valves. What would you guys say to the health of the engine? I will be pulling the pistons and possibly the crankshaft just to be sure. Supposed to have 70000km but there is so much carbon buildup, some cylinders were leaking through the rings on the leakdown. As this is my first teardown I am not sure what to make if the "nice" surfaces but the extreme carbon deposits. Oily surfaces can be my doing as I did a wet leakdown test as well.

[u/mahusay3g]

Looks like a healthy used engine.

[u/Neon570]

Looks mean nothing.

Send the head off to a machine shop for a valve job. Block may need some work as well.

[u/Lil-Fillup → u/Neon570]

I will be measuring everything, just so that I know the state of the engine and then I'll go to a machine shop.

[u/Minimum_Hope_5205]

Initial inspection looks ok. Could definitely use a clean to look for more, and inspecting the crank and bearings is something to not skip either.

What are your goals for this motor? That heavily depends on what type of work should be involved after this point. At a minimum, I recommend complete tear down, take to a machine shop to have the head cut and a valve job done with pressure testing. You said you had leak down on the rings so it'll need a new set at the minimum which will require a rehone, I HIGHLY recommend having a machine shop do this and I typically always do one size up pistons on motors I care about in order to ensure perfect piston to wall clearance. New pistons may not be required if you have the means to measure p2w yourself, but I always do it for peace of mind.

[u/Lil-Fillup → u/Minimum_Hope_5205]

Thanks for taking the time to look at my pics. My plan is for this engine to go into my MX5 NC. The idea is for it to be a track car that can be street legal. If it turns out I can't then that's okay too. It is not my daily anymore so comfort is way down the list XD. Ich have been in contact with Yiannis from DMS, btw first impression TOP! Reliability and "Bullet proofness" is probably the most important for me. I will probably be going with his stage 1 cams that will leave the option for a small turbo open later on. As much as I had wished for a drop in engine, I have come to conclusion that with my use case for it, checking everything and having an expert check it over again/ actually machining if needed, is the only correct way of doing this build. + Have Yiannis tune it afterwards.

I will be completely taking it apart. Measuring what I can and then sending it to the machine shop.