2G Timing off, but bad compression on only 1 cyl?

[A Sharp]

I'm currently doing a complete tear down and rebuild on an early 2g 7 bolt. The engine has always ran like crap, especially at low rpm. It pulls ignition timing like crazy, lopes at idle (with stock cams), is hard to start when cold, and occasionally throws a CEL for misfire.

I want to get it running right and put down about 350 hp, hence the rebuild.

Anyhow, I started with a cold compression test (since the car was not startable to do a hot one). I got:

1: 90 PSI
2: 160 PSI
3: 160 PSI
4: 160 PSI

I then put oil in cyl. 1, but it didn't help at all. This had me thinking that a valve was seating poorly.


Now the engine is out, and it looks to me like it's out of time. But that should have caused low compression on all cylinders, Right??

See pics of timing marks.

I rotated the engine numerous times to make sure I wasn't looking at it out of phase. Then I lined up the cam gears and looked at where everything else was. BTW it was impossible to get the cam gear marks to line up perfectly straight.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

I figured you guys might have some interesting comments regarding this. In the meantime I'm going to keep tearing 'er down.

 

[A Sharp]

After playing with it some more, it appears that the intake cam sprocket and oil pump sprocket are each off by 1 tooth in the clockwise direction.

Now that I've thought a little more on this, I don't think having the intake valves open and close slightly early would make any difference on a compression test, so I probably still have a burnt valve in cyl 1 :/

 

[dustyboner]

I believe you are correct. It would effect all the cylinders if it was caused by the timing.

 

[Dsmkauai]

Line up the crank properly and see which cam gear is off and how much. Could have bent a valve.

 

[OGDSM1989]

Mine had the same sort issue ... lose tensioner let the timing slip a little which cause one cylinder to have low compression as the valve was slightly open. After tearing down I could see that it wasnt because of bad valves or rings ( filled head with carbcleaner let it set all night no leak, then to be sure it didnt evaporate I filled it with some 0w20 colored red and watch through the day ) nothing happened , after that I filled the cylinder slightly with 0w20 watched it for about a hr or so ...and again nothing. I am just going ahead with the timing belt, tensioner, etc etc ARP head studs, OEM composite gasket etc etc.

 

[A Sharp]

Line up the crank properly and see which cam gear is off and how much. Could have bent a valve.

As I briefly mentioned before, the intake cam was advanced by a tooth (meaning someone put it on that way, since slipping would make it behind). Thankfully, it appears there are no bent valves.

Mine had the same sort issue ... lose tensioner let the timing slip a little which cause one cylinder to have low compression as the valve was slightly open. After tearing down I could see that it wasnt because of bad valves or rings ( filled head with carbcleaner let it set all night no leak, then to be sure it didnt evaporate I filled it with some 0w20 colored red and watch through the day ) nothing happened , after that I filled the cylinder slightly with 0w20 watched it for about a hr or so ...and again nothing. I am just going ahead with the timing belt, tensioner, etc etc ARP head studs, OEM composite gasket etc etc.

Yeah, I've heard that putting fluid in the head is a good way to check for valve leaks. I'll probably check mine, even though they appear to be fine.

This thing only gets worse the more I dig into it. My wallet is starting to sweat haha. The cam bearings were pretty badly beat up by a dirty oil supply, easily failing the fingernail test. This makes me wonder what the main and rod bearings will look like (still haven't checked them). I just pulled the oil pan and found some nice pea-sized hunks of brass and aluminum. I have no idea where these came from, but I'll probably find out soon enough. It appears that they fractured off of something.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

If anyone knows where these are from, feel free to comment.

 

[Dsmkauai]

Brass could be the turbo bearings. Def doesn't look good bro