Problems (overheating) after re-installing heads

[streetstang67]

Soon after my cam change (from stock to a compxe256), I broke a rocker arm stud. So I tore the engine top-end off and took my heads to not only fix the stud but also port/polish them; but I did stick with the same size valves. The machine shop replaced the springs to more beefier ones, and I replaced the rockers with roller tipped rockers. After putting it all back together, adjusting the valves and timing good enough to get the car going, I have new problems. Doesn't take any longer than 5 minutes for the car to be running before the radiator cap 'opens'. For some reason, its overheating. Not only that, but several times when I was starting it up, it wouldn't start the first try, but instead it would backfire. and finally, vacuum plugs keep turning up missing. I'm not sure if they popped off when a backfire occurs or if they are just coming off for some reason. I still need to finalize the timing and valve adjustment. What do you think the problem(s) is?

 

[TT670]

Id bet you put the head gaskets on backwards and blocked the water passages.

 

[SoCalCruising]

That's the first thing I thought of, too. The backfiring is also bothersome. Is your timing light the kind where you can dial in the total timing you want?

 

[iskwezm]

sounds like timing is off for both problems.

 

[grego37]

sounds like timing

are you sure you have the wires in the right firing order, do you have 15426378

hopefully its not the head gaskets

 

[streetstang67]

Not the head gaskets, I've heard of people putting them on backwards before, so I was sure to get them on right. I don't have a timing light, all I used to set the timing is the harmonic balancer. Assuming it is accurate, I should be set at 12*.

 

[grego37]

I reccomend borrowing or buying a timing light before you start tearing things apart.
Double check your firing order on your cam card and at your dist cap and follow each wire to plug to verify.

 

[SoCalCruising]

I asked about the timing light because some allow you to set the timing you want (say 32 degrees) and then you read zero when it is correct. On such a light, if you then read 32 degrees, you are actually at 64 degrees. I don't have such a light, but I have heard of this issue. They say that the motor will run highlu advances, but I would imagine it could backfire.