[srob67]

I just rebuilt my sbc 406 and upon the first start up it would not fire. I tried several times to get it to start but it wouldn't. After a while I noticed that antifreeze was coming out of the passenger side header. I stopped and started tearing it down hoping for just a pinched head gasket. Found I have a cracked head. There was antifreeze sitting in the cylinders on that side and also in the oil. How do I clean all this up and how far do I need to tear this thing down?

[cobalt327]

Originally Posted by srob67

I just rebuilt my sbc 406 and upon the first start up it would not fire. I tried several times to get it to start but it wouldn't. After a while I noticed that antifreeze was coming out of the passenger side header. I stopped and started tearing it down hoping for just a pinched head gasket. Found I have a cracked head. There was antifreeze sitting in the cylinders on that side and also in the oil. How do I clean all this up and how far do I need to tear this thing down?

You have positively found a cracked head? A cracked head can put coolant into two cylinders that sit side by side but you usually don't see more than two cylinders w/coolant in them from a cracked head- unless it's well and truly CRACKED!

So if it's for sure a cracked head, blot out the coolant w/paper towels (don't get lint into everything), be sure there's no coolant in the oil pan. Drain it to be sure, if nothing is in the oil, reuse it as long as you keep it clean.

You could reuse the head gasket, but if you want to be safe, replace it. Be sure the torque sequence is followed and that you tighten the head fasteners in at least three steps to 65 ft/lbs or whatever the fastener manufacturer recommends if different from that.

Also be sure the intake gaskets are sealing around the water crossover and the intake ports so there's no coolant or vacuum leakage there. Same thing on replacing them as well as following the torque sequence.

You are using break in quantities of ZDDP in the motor oil, right?

Some info that may help:

• Firing order

• HEI distributor info

• Adjusting the valves

• Head gaskets

• Cam installation

• Valve train points to check

• Differences in SBC timing tabs and damper TDC lines

[bracketeer]

intake leak is a more likely cause. but like cobalt said if your sure its the head. antifreeze will tear the bearings out. i always start my motors with pure water. water will evaporate.

[srob67]

When I pulled the header there was water inside the combustion chamber on the #2 cylinder. I think the coolant in the other cylinders was residual from when the head came off. Very little in the oil but I'm still changing it. I can definitely tell the head is cracked. These heads came off of a circle track car and supposedly had one bent valve. I had them checked and they found 6 bent valves. I should have had them stripped down and magnafluxed then. My own fault for not doing things right the first time.

[cobalt327]

Originally Posted by srob67

When I pulled the header there was water inside the combustion chamber on the #2 cylinder. I think the coolant in the other cylinders was residual from when the head came off. Very little in the oil but I'm still changing it. I can definitely tell the head is cracked. These heads came off of a circle track car and supposedly had one bent valve. I had them checked and they found 6 bent valves. I should have had them stripped down and magnafluxed then. My own fault for not doing things right the first time.

OK, I understand. Good luck w/it, let us know how it comes together.