Engine In The Wilderness

Keith Peck

New Member
Feb 22, 2013
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Not a mechanic. Bought 66 Mustang that was running but real rough, no power. Changed Cam, Headers and distributor to HEI. NewCarb 500. Electric fule pump. Started for Break-in. Easy start, but it boils the coolant. The reserve tank shot open and was boiling for ten minutes after high RPMs for the break-in and for ten minutes after high RPM. WTF? Appreciate any insights.
 
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Not a mechanic. Bought 66 Mustang that was running but real rough, no power. Changed Cam, Headers and distributor to HEI. NewCarb 500. Electric fule pump. Started for Break-in. Easy start, but it boils the coolant. The reserve tank shot open and was boiling for ten minutes after high RPMs for the break-in and for ten minutes after high RPM. WTF? Appreciate any insights.

Sounds to me like you have either a blown head gasket or cracked head.

I'm moving your thread over to the classic tech forums so that the experts can weigh in. Welcome to the forum and good luck fixing your problem. :nice:
 
Could it be caused by pushrods that are too long and/or improperly set non-adjustable rocker arms? The head gaskets are newly installed on ARP studs and carefully torqued in three stages. E7s on a 1972 302. I think I mis-sized the pushrods though.
 
I will ensure it is filled, check thermostate and I am sure that head gasket is correct since it has the tab that hangs out in front for that purpose. I did not change water pump, but maybe I should have. I was looking on the internet and realised that before the water shot out of the overflow bottle, it was spewing from the side of the radiator cap. I guess this means that the system wasn't pressurized normally. The red release tab on the radiator cap did not open. This all happened within ten minutes of high RPMs during the break-in. There was some oil leakage from the vavle covers as well. The Intake manifold shows no leaks.

From what I understood from the research I did, it is the fact that the colling system is not pressurized (either by a head leak, hose, or something else) that can cause the coolant to boil. Of course, not filling the engine sufficiently with coolant or reversing the thermostate can also be the cause. Am I right about this?

Thank you very much for the help. This forum has been instrumental in providing insight into the various difficulties I have had working on this car.
 
Do you have breathers? Can the engine breathe properly? The first carb motor I ever did I had set up like an efi car and had a similar problem. Also does the top radiator hose get hot?
 
I know it's not the same thing, but my jeep had the same issue, they're notorious for getting air trapped in the block and causing rapid and violent boil over. what worked for me was to pull the top hose at the radiator and fill from there with the hose well above the block, until fluid ran out of the radiator, then reattached the hose and topped off, no over heating since, maybe similar might help you
 
a few things pop into mind;

1: head gasket installed backwards

2: head gasket leaking, it happens more often than you think.

3: radiator plugged up

4: head cracked

start with the radiator and make sure the passages are clear and flowing properly. after that do a cooling system pressure check to make sure the system is holding pressure properly. if it doesnt then you are going to have to pull the heads and check the gaskets for proper installation, check the heads to makes sure they are not cracked or warped. you might also check to make sure the head bolts are properly torqued, and that the heads are not loose. and yes you can have properly torqued head bolts(meaning you used the proper torque readings) but the heads can still be loose as there might be debris in the head bolt holes that prevent the bolts from providing the proper clamong force on the heads( dont ask how i know).
 
What is "clamong" force?

Same thoughts on the radiator if it has sat for some time and since you had the distributor out and mentioned you "are not a mechanic" the timing can cause a hotter burn especially when the new carburetor is probably not tuned in yet either. A lean fuel mix plus retarded timing will heat things up in a hurry. If the timing/fuel mix is the problem, and you have headers, you would have noticed them turning red/orange from the heat.