Bad exhaust valve or timing issue?

[fyton2v]

After a compression test one of my cyls is in the 120s while the others are 145ish. I need some pointers as to how to go about fixing this.

First question. If this is a valve or timing issue will it negatively affect a smog test? I'm in CA and need this thing smogged pretty soon.

Other questions:

I'm mechanically inclined but far from an auto mechanic. Is this something I could attempt to fix myself?

If the low compression stems from a burnt valve can the single valve be replaced or should everything be replaced?

How difficult is it to set the timing correctly?

What tools would I need to buy to replace the valve and do the timing?

Looks like the head has to come off to do this. What else should be done while it's apart? The 2F has 132K miles and hasn't been rebuilt. From the receipts I found in the glove box it looks like it had a valve job done about 3 years ago.

This is one seriously helpful forum. Thanks everyone for your advice!

George

 

[Rice]

One cylinder being low on compression is not a timing issue. Valve, rings, head gasket, and hole in a piston are what can cause it. Based on your other compression readings I would be leaning towards yours being a valve. Yes, it will effect emmisions.

For the fix you have to pull the head ... once you've gone that far working the other valves just makes good sense. While pulling the head can be done at home the machining of the head and grinding the valves is something you will want to farm out. If you do the work or if someone else does it be sure to use OEM gaskets for longevity.

Total job difficulty:

Rice

 

[fyton2v]

your scale

How many bananas in your scale? 3 out of 5 bananas? or 10 bananas? I just realized I'm hungry.

 

[65swb45]

If the motor is running smoothly, work around it first, adjusting carb and distributor timing. I have seen rigs with those readings pass smog. I wouldn't pull the head unless the motor is running bad and won't pass smog.

Just my opinion.

 

[Rice]

If the motor is running smoothly, work around it first, adjusting carb and distributor timing. I have seen rigs with those readings pass smog. I wouldn't pull the head unless the motor is running bad and won't pass smog.

Just my opinion.

Agreed ... a good point

 

[60wag]

Check and adjust the valve clearance first. This may improve the compression numbers. I like the writeup by Jim Chenoweth that can be found in the IH8mud tech section.