Compression test results with questions

[Anonymous]

Well, I'm sure you probably have read I've been having some valve train issues...if not, long story short...something is ary and I believe it to be valve springs. That's a whole nother topic unto itself.

I decided to do a compression check tonight because after the rocker arm bolt broke last week and I fixed it, she just doesn't seem to have quite as much pep. I feared a blown headgasket and I may be right. Here are the results:

Cyl # Compression Reading
1 130
2 180
3 140
4 160
5 180
6 180

Anyone want to gamble where the blown part of the gaskets are. My wager is on the outside of Cyl #1 (since #2 is fine) and between 3&4. The odd thing is that the rocker arm that I lost was the #2 cylinder! :

it should be noted that I decided to check the headbolt toruqe before this test and the needed re-torquing a bit. A couple needed quite a bit. The reading above were after the retorquing. The reading before it were slightly and consistently lower across the board (except for #1...didn't change).

Would you say that it is safe to bet I've got a dead head gasket even though she's not running way hot nor do I see any foam or oil in the coolant? OR (now back to the valve spring issues)...

if #1's springs were really bad in comparisson to the rest, would it be possible that that could be causing the readings? If say for isntance, when I adjust the valves on #1, the weaker springs aren't holding the preload pressure and instead are cracking open a bit. Possible?

My plans are to pop new springs on ASAP. I guess I'll have a definitive answer at that point. i just wanted to get the opinions of the group on it.

Thanks all.

 

[AzCoupe]

You may have toasted the cam lopes, rather than the head gasket. Especially since there is no evidence of a blown gasket. I would look there first.

 

[Anonymous]

how can I check that without pulling it? This may sound amateur, but can you change a cam without pulling the head and motor apart? Can I just pull the front covers (water pump and timing chain) and get it out and a new one in?

 

[addo]

You can do it from underneath, but the motor has to be inverted (best performed out of the car).

The cam may be worn, but if you can avoid turning the motor over until you're satisfied all valve spring issues are resolved, check again then.

Can you see any metallic hint in your oil?

 

[wsa111]

Bryce, remove the valve cover & start the engine, it may be messy with oil spray, but visually check how much each rocker arm moves compared to another. This an easy way to check if you have camshaft wear.
If the lift looks equal, you may have to pull the head off. If thats the case that is the time to upgrade the valve spring situation.
I hope you are using arp studs for head fasteners. Hope you don't have a head gasket problem. but if you do now is the time to take care of your valve spring issue. William

 

[Anonymous]

Thanks Will. I thought the same thing...just look at them and see how it looks. man they move quickly! :roll: I can't see a real noticeable difference in the valve motion. Can it be measured by cranking the motor by hand to BDC on each stroke? How and what would I measure? The amount of spring compression?

If the head gasket is gone, then yes, the valve springs will be a lot easier to take care of. I'll have the steps milled and go with the doubles etc from Mike.

Fortunately, I am using ARP studs. I dread removing the header more than anything! MAN is that a tight fit in there.