Could timing cause a drop in compression?

[Havoxx]

O.k, so I got a 200sx engine, same as the 200x one, 1987, I rebuilt it, redid the valve seats, new valves, new rings, and it still has it's same 90PSI compression, could the timing be the cause of it?

[300rman]

yes, if a valve opens too early, it will de-pressurize the cylinder before it reaches max. compression. at least, i am pretty sure thats what would happen.

what do you guys think?

[RedRider_AK]

Yes, the timing WILL affect compression exactly as 300Rman said. I had a Honda ATC 110 at one point in time, and my friend stuck the wrong length plug into it, which bent the intake valve. We knew for sure that it ran before that, but couldn't figure out for the longest time why it stopped running...

:( This is back when I was like 13 and had no mechanical knowledge.

[Havoxx]

Yea, the only thing I can figure is that maybe the cam shifted from the gear, problem is, the gear has the marks aligned at TDC with the head like in the manual, but when I open the little cover on the valve adjuster things, the camshaft stick is off to one side, and it says it's supposed to be straight up in the manual.

And man, 90 compression, the poor engine tries so hard to start, puttering constantly, but it just can't compress it seems, looks like I gotta figure out how to fix the timing tomorrow, thanks for the help, wanted to make sure this could cause it before I tore it down again.

[RedRider_AK]

Sometimes, if the timing is off, it will spit gas out the intake (if the intake closes too late or not at all). Check to see that the gear is bolted onto the cam correctly. Who knows what's wrong with it... :rolleyes:

[Havoxx]

Sometimes, if the timing is off, it will spit gas out the intake (if the intake closes too late or not at all). Check to see that the gear is bolted onto the cam correctly. Who knows what's wrong with it... :rolleyes:

Oh, *Edited**Edited**Edited**Edited* why didn't you tell me that earlier.... it shot gas out of the intake since I got it lol.

Anyway, I'll get some pics of the head up tomorrow, see if I can't figure it out, I didn't know the cam had a bolt :D.

[RedRider_AK]

why didn't you tell me that earlier.... it shot gas out of the intake since I got it lol.

Anyway, I'll get some pics of the head up tomorrow, see if I can't figure it out, I didn't know the cam had a bolt :D.

I told you that in your 200SX thread, if you go back and check. You said it was spitting gas out the carb, and I replied that it might be a bent intake valve, and you said that you figured it was the carb running too rich, so I left it at that. Turns out I was right :lol:

Some cam gears have adjustable holes and stuff you can use to dial in timing. I don't know for sure if the 200SX has it (probably not, but what the hell).

Anyway, hope you figure it out.

[Havoxx]

Oh, well the valve wasn't bent :P hehe, though it sure wasn't closing due to all the rust it had :D.

[Havoxx]

YEA BABY!!!!! I tested it with the leak-down tester, or w/e it's called, it was leaking from the cylinder, took the head/cylinder off, removed the studs, buffed the bottom-end where the cylinder sits to hell, put it back together, made sure it was on timing.

And!!!! http://img2.putfile.com/main/2/5812333871.jpg
I know it's not to the specs, but it's only 10 or so PSI from being minimal, that's as good as it gets with the messed up head.

[RedRider_AK]

Very nice. Way to go! Now get it put together and running!

[Havoxx]

Yea, it doesn't even try now, not sure wtf is going on, I guess it might be the spark.