Ok, I bought a used 2.3L 6-bolt with "approx 5K" miles on it. Supposedly it was built by SBR. The engine is supposed to be good to drop in as is. Like a moron I forgot to check the timing until the engine was in my 2g and I was installing the CAS. When doing so I noticed that both the intake and exhaust cam's are about three teeth advanced (when piston #1 is at TDC - as verified by an extension sitting on piston #1 and the crank - the dowel pins on both cam gears are at about 2:00).

Is there any particular reason that this would be done on purpose, or did SBR/the previous owner just screw up? FWIW the engine spins freely (valves not hitting the pistons...or they're already bent - through they all looked OK before I dropped the engine in).

Here's the full specs on the setup:
4G63 6 Bolt Block
2.4L Crankshaft
85.5mm Bore (.020 over)
Eagle H-Beam Rods
Wiseco Forged Stroker Pistons
New Topline Front Cover w/ Oil Pump Gears Balance Shaft Eliminator Kit
Cometic Head Gasket
Mitsubishi Cam Gears
Comp 101200 Cams
Stage IV Head
Competition Valve Job
Stage IV Port Work
Stainless Steel Swirl Polished, and Undercut Valves
Manley Springs
Manley Titanium Retainers
Fully Decked Head Surface

Also, if I have to do the timing belt, any tips on how to do so in a 1gina2g (with the tensioner inaccessible)?

Just because the piston is at the top doesn't mean TDC. Try rotating the engine around and see if all the markers line up then.

Either way take that timing belt off and replace that oil pump before you trash your motor. Get a new OEM oil pump in there.

dsmtalontsi95 said:

Just because the piston is at the top doesn't mean TDC. Try rotating the engine around and see if all the markers line up then.

Click to expand...

Thanks for the advice - I'll take a look again tomorrow and report back.

93_tsi_fwd said:

Either way take that timing belt off and replace that oil pump before you trash your motor. Get a new OEM oil pump in there.

Click to expand...

What's wrong with the new Topline front cover w/ oil pump gears that's in there now?

This is how it lines up....






When the white marks are on "T", piston #1 is at TDC.

Most likely, the outer ring of your damper has broken loose and rotated.

John-

Replace that hormonic balancer asap before it lets go, had it happen to me, not fun.

johnnytsi said:

Most likely, the outer ring of your damper has broken loose and rotated.

John-

Click to expand...

But the notch on the damper matches up with TDC on the lower timing belt cover when piston #1 is physically at TDC...isn't that where it should be?

dsmtalontsi95 said:

Just because the piston is at the top doesn't mean TDC.

Click to expand...

Actually, it does. A timing mark doesn't always mean true Top Dead Center, finding the highest point the piston reaches is always true TDC.

4G63 Camshaft Degreeing

^Scroll down to step 6.

High PSI said:

When the white marks are on "T", piston #1 is at TDC.

Click to expand...

The timing needs redone, or at least looked at. You might want to do a compression test first though, to make sure no valves are bent. Each tooth of the t-belt is about 7 degrees.

As far as to why they would be that far off... they shouldn't be. The last paragraph of this article has a good write up on the effects of advancing or retarding the cams.

delta448 said:

Actually, it does. A timing mark doesn't always mean true Top Dead Center, finding the highest point the piston reaches is always true TDC.

4G63 Camshaft Degreeing

^Scroll down to step 6.


The timing needs redone, or at least looked at. You might want to do a compression test first though, to make sure no valves are bent. Each tooth of the t-belt is about 7 degrees.

As far as to why they would be that far off... they shouldn't be. The last paragraph of this article has a good write up on the effects of advancing or retarding the cams.

Click to expand...

Thanks - that's exactly what I thought...but just wanted confirmation from someone a bit more knowledgeable before I potentially did a timing belt for no reason. Can't believe I didn't check this before I dropped the motor in the car...

Is a compression test going to be accurate with the cam timing off this much?

High PSI said:

Is a compression test going to be accurate with the cam timing off this much?

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Not really accurate, but it ought to let you know if valves are bent. A leak-down test would probably be much more helpful, but locating a gauge set to do one is sometimes a pain.

delta448 said:

Not really accurate, but it ought to let you know if valves are bent. A leak-down test would probably be much more helpful, but locating a gauge set to do one is sometimes a pain.

Click to expand...

Compression test:

175
225
225
210

?

Feeling pretty good about it considering the engine has sat for ~5-years.

(Also realized I've got no idea what my compression ratio is on this engine ...any guesses from the compression test results?)

10:1? My 2.0 8.5:1 is 185 across. I would be looking at that "175" thats 50 off. Not terrible but definitely beyond mitsu spec

175
225
225
210

Click to expand...

Did you prime the oil pump first? The lifters should be pretty well collapsed if it sat 5 years. I'd investigate the low one a little further, but I suspect you're probably okay.

(Also realized I've got no idea what my compression ratio is on this engine ...any guesses from the compression test results?)

Click to expand...

You can't make any reasonable estimates about CR until you re-time the engine. With the cams out of time as much as they are, the pressure you see on the tester is guaranteed to be way higher than it would be with the engine in correct mechanical timing.

Once you do a warm compression test with the engine correctly re-timed you'll see something more around 140-165, depending on whether or not the low number above gets corrected by a HLA being fully pumped up or a ring gap tightening. If you have a valve bent on that cylinder, it is very slight and you probably haven't even damaged the valve guide.

delta448 said:

Actually, it does. A timing mark doesn't always mean true Top Dead Center, finding the highest point the piston reaches is always true TDC.

4G63 Camshaft Degreeing

^Scroll down to step 6.


The timing needs redone, or at least looked at. You might want to do a compression test first though, to make sure no valves are bent. Each tooth of the t-belt is about 7 degrees.

As far as to why they would be that far off... they shouldn't be. The last paragraph of this article has a good write up on the effects of advancing or retarding the cams.

Click to expand...

I thought that all the markers line up at TDC. Where as the piston could be at the top but the cams are not lined up. Keep rotating the motor till everything lines up again. I'm not sure what the cams are doing to the valves on the #1 when everything is lined up but that's what I had thought was TDC. If that's wrong, I apologize for the miss information.

dsmtalontsi95 said:

I thought that all the markers line up at TDC. Where as the piston could be at the top but the cams are not lined up. Keep rotating the motor till everything lines up again. I'm not sure what the cams are doing to the valves on the #1 when everything is lined up but that's what I had thought was TDC. If that's wrong, I apologize for the miss information.

Click to expand...

They should. You're not wrong. But TDC is only a descriptor of piston/crankshaft position.

The cam alignment doesn't mean TDC has been achieved. And a stock damper can (notoriously) separate and not have the mark line up when it should.

The cam timing marks should line up along with the crank timing mark once every 2 crank revolutions -if the damper is not separated and the cams are in time. So if the marks aren't dead nuts or both exactly 180 degrees out when #1 is at TDC (good damper = crank timing mark lines up at TDC on #1), the motor is out of time.

The oil pump sprocket mark (only necessary to align if you still have balance shafts) lines up along with the crank mark every 3rd crank revolution, so only once every 6 revolutions will all the timing marks line up.

From the pictures, you can easily see that the cam timing marks will not line up with the crank no matter how many multiples of 2 you turn it over, but those weren't up until after your first post. However, being 3 cam sprocket teeth off when the piston is at a measured TDC can only mean the engine is not timed correctly.