In chasing my idle, performance issues, I decided to run a compression test on my engine. It is a 306 with TFS heads and intake. It has only about 100miles since the rebuild and the numbers seem really low:

1 - 119
2 - 119
3 - 119
4 - 119
5 - 119
6 - 119
7 - 119
8 - 119

They are all consistant, but I cant figure out why they are so low for a brand new engine. The only thing I can think of is if I tighted down the rockers to tight. Trick flow said to turn the 1/2 - 3/4 turns past zero lash. I was getting a lot of ticking when I used that, so I turned them 1 full turn, and the ticking went away. Would that cause issues?

 

there is an issue there

its not head gaskets though...

 

I am debating whether or not to walk downstairs, pull the valve covers, and lossen all of the rockers about 1/2 of a turn. I really hate adjusting valves. Maybe all of the ticking I heard at first was just beacuse the lifters had not pumped up yet.

 

you are supposed to tighten the rocker nuts to 15lbs/ft of torque with the valve seated on the head. you have to spin the engine over a few times to get the valves set right.

 

I used the following directions to adjust mine. Except I turned them 1 full turn:

" If you are using a hydraulic cam and no specs are available, turn the rocker arm adjusting nut 1/2 to 3/4 of a turn after zero lash. For mechanical cams, you must get the correct lash specification from the cam maker."

I just talked to a buddy of mine, and he is thinking that the timing chain is off 1 tooth. He said that is about the only way that the numbers would be all that low and equal. If he is right, I am going to shoot myself. [:@]

 

are you sure your gauge is right?

 

Redo the valve train....those valves are not closing, I've seen higher comp numbers in 200k miles lo-comp engines.....and make sure you have the correct pushrod length.....not because you were told to use them, but b/c you measured and set its geometry...... just a thought.

 

Yeah, I have used the guage before not to long ago on a car I used to have and it worked perfect.

I pulled the valve cover off and loosened the rockers on Cyl #1. I first loosened it 1/4 of a turn, and it rasied the compression to about 121. Then I loosened it another 1/4 of a turn, and it lowered the compression to 93.

I think I am going to take off the timing chain cover and make sure it is set ok. The pushrods I am using came with the TFS kit, so I would hope they are correct.

 

1.
2. If you had the timing chain 1-tooth off.......you could also have a few bent valves like.......

 

Well,

from the looks of it the timing chain was good. The picture attached sucks, but you can kind of see. It did not make any noises like valves were hitting. I made sure to crank the motor before hooing up the ignition to make sure no valves would hit.

I hate cars. [:@]