My 350x had a SCREW in the engine!

[MulletMan420]

Ok guys, awhile back i posted a thread(i believe in the new discussion) about my 86 350x making a mystery banging noise while it was running. Well i finally got around to tearing it down, and discovered my problem. There was a freakin machine screw stuck in the bottom of my head that the piston was slamming up against! Thank god my buddy stalled it and only started it briefly afterwards or i can not imagine the damage it could of done to the cylinder. Which when i took apart looked great, you could still see hone marks in it. Now where did it come from? It looks about the size of the screws that hold the needle and plate into the slide on the carb, but they are both intact. But when i did take the top cover off the carb, i found another loose one up there! And i have cleaned the carb once since ive had it, but never replaced those, it just boggles my mind how they could get stuck in there and not fall out or not be noticed this whole time. There is a indentation from the screw in the top of my piston on the exhaust side, because the screw stuck into the head and a few knicks on the intake side where it initially came in. I believe its an original piston because it says HA5 on the top(am i correct?). Should i replace it? I will probably take the cylinder off and check the rings and stuff. Also, there is the screw indent in the bottom of the head, it doesn't appear to have messed with any of the valves, but will it affect anything? I was also considering sending it out to someone to get it all cleaned and get my valves cleaned and lapped or whatever they need. Who would be the best person to send them to? Any help would be very appreciated, thanks!!

[YTZ drew]

If the piston still fits the bore nicely, I would just smooth out the spot where it hit with some fine sandpaper and reuse it. Better yet, buy new piston clips, take the piston out, and after you smooth out the rough spot, sand it to a mirror finish and polish the top of the piston on a buffing wheel. It will help with carbon buildup and the engine will be more resistant to detonation. As far as the head goes, get rid of the rough spot where the screw hit, and take the valves out if you have a spring compressor. If the faces still look good you can just lap them with some grinding compound, but I will bet after all the years it probably needs new valves. If there are no local machine shops close to you that are up to the task of a valve job, I have had good luck with Ken O'Connor, and he ships parts if you're not local. He has a ton of videos on youtube showing how he does everything, and he knows his stuff.

http://www.kenoconnorracing.com/

[MulletMan420]

Thanks for input Drew! I will probably take the piston out and clean it up as good as i can. I have never tried to take the valves apart before on anything, and do not have a spring compressor, so that's why i am considering sending it out. I also had 1 cover bolt snap off in the top, i believe it was cross threaded before because that sucker was barely moving, if any at all and not sure how im going to get it out. I will probably replace the chain and sprockets well its tore down, so what would you recommend i get? Nore sure if i should get an o ring chain or not, right now it has one. Also, any good mods i can do well i have it tore down? Thanks!

[Dirtcrasher]

If the piston still fits the bore nicely, I would just smooth out the spot where it hit with some fine sandpaper and reuse it. Better yet, buy new piston clips, take the piston out, and after you smooth out the rough spot, sand it to a mirror finish and polish the top of the piston on a buffing wheel. It will help with carbon buildup and the engine will be more resistant to detonation. As far as the head goes, get rid of the rough spot where the screw hit, and take the valves out if you have a spring compressor. If the faces still look good you can just lap them with some grinding compound, but I will bet after all the years it probably needs new valves. If there are no local machine shops close to you that are up to the task of a valve job, I have had good luck with Ken O'Connor, and he ships parts if you're not local. He has a ton of videos on youtube showing how he does everything, and he knows his stuff.

http://www.kenoconnorracing.com/

Thanks for that link. I spoke with him, what a nice guy and he knows his chit!!

[YTZ drew]

...any good mods i can do well i have it tore down? Thanks!

I'm not an expert on the 350X, but there are cams and high compression pistons available. I know some people like to convert to the 400EX carb which is very similar to the stock one but has a bigger bore. If you do some searching on here, I'm sure you'll find some threads on what others are running in theirs.

[oscarmayer]

what makes a piston perform better is not polishing, but proper prepping of it. sanding off the rough/sharp edges all around the dome, valve cutouts and top edges. once this is done with a cartage sand roll it will help with stopping detonation and such, honestly smooth pistons help introduce fluid pooling to a cylinder and attract un-burnt fluids. you are far better have it foggy than shinny.
spending hundreds of thousands on motors and drag cars, I can promise you first hand. shinny pistons are not a good thing when mirror finished off.
anyway just thought I would offer some advice.

[YTZ drew]

Thanks, I just learned something!

[MulletMan420]

Thank guys! So oscarmayer, Should i still clean off the majority of the carbon build up off the top?

[oscarmayer]

Yup cleaning it off is fine. If it is like cakes on. If just discoloration and very small amount then ok to leave. Caked on means running rich, or bad rings as your burning oil.


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[86125m]

The valve are really easy to do buy a compressor and watch a could videos on it and you will do fine.

[MulletMan420]

Thanks for the help guys. Im not sure what i will do with the valves yet. I have never done them so i don't want to mess anything up. Plus there is the one snapped off bolt in it that i think was cross threaded i cannot get out, somebody else surely has better tools then i have to get that out

[oscarmayer]

I would take it to a shop and have them do a valve job on the motor. take a new set of valves and performance springs from MD, WEB cams, Powroll, ETC and let them do a nice valve job and install the new springs. or contact MD on here and just ship him your head. he'll do it and send it back done how you want.

[MulletMan420]

Gonna order some new valves, what brand would you recommend? Should i order new springs too?

[yaegerb]

Kibblewhite valves are good. You should be able to use the same springs if you are staying with the OEM cam.

[MulletMan420]

Where would be a good place to buy them? Has anybody had any experience with Shindy or Vesrah valves? Also what about the valve seals? Sorry for all the questions guys, i just want to make sure its done right. Its turned more into a restoration/freshen up project. Recently got a 400ex carb to put on it, still searching up about mods that have to be done to that, and have painted quite a bit. Still not sure if i am going to strip it right down to the bare frame and paint that or not. I will have some pictures soon!