greetings...I am brand new to this forum and have found this to be the best place for accurate information. I have just installed a rebuilt 225 in my 64 Valiant, all new with .045 off deck, and .040 off head. The engine started and sounded just great, I ran it with break in oil at about 1300 rpm for about 15 minutes. No leaks or noises of any kind. The motor did get close to overheating within the first five minutes but settled in after the stat opened. Timing set at 3 btc, petronix breakerless ignition. The next day I decided to check the hot lash and upon starting the car I noticed a large amount of steam out the tail pipe. Cant smell antifreeze, no water in oil and a very small film on the top of the coolant in the radiator, and I mean just a small film. The car sat for 10 months while the motor and 904 were rebuilt. It runs and sounds awesome but there is too much steam being emitted for me to feel comfortable. I'm thinking the head gasket popped. Compression shows 155 on all six holes but one of the plugs was noticeably cleaner than the others indicative of a good steam cleaning. I just wanted to know if most here would agree about the gasket being blown before I pull the head off. The block and head were magged for fractures before assy. Thanks in advance and I will post some pics of the restoration as soon as I get over the diappointment of this weekends pitfalls.

if it was sitting for a while there may be an excessive amount of water built up in the pipe itself. that would make steam. how long have you run it? if you dont smell antifreeze i doubt it would be the head gasket. are you sure its steam? with a rebuild it will take a while for the rings to seat.

I'd agree that an unusually clean spark plug may indicate water in your combustion chamber. I can think of only two causes of this, either the head gasket has failed or you have a crack in the head. Of course there is a chance it is just condensation.

Lets start with the head gasket since its ease and cheap. What gasket did you use when installing? The original shim style gaskets are known to be more difficult to seal. However, if you've had both mating services machined this shouldn't be an issue. You also mentioned the engine nearly overheated, do you know what temp it got up to? I know overheating an aluminum head is bad news but I'd expect our cast iron heads to be fairly forgiving. So unless you were running pretty hot I don't think that is your issue.

Now for the sad stuff. What other head work was done and was the head pressure tested? If you had new valve seats cut (especially oversized valves) or had any porting work done, you may have got too close to the water jackets. If the head was only magged for cracks and not pressure tested this may be the issue.

Could to tell us more about your build? Compression, NA or forced induction, head work?

In the mean time, remove the super clean plug and pressurize the cooling system. Let it sit overnight and use a flash light to see if there is any water in the cylinder.

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'66 Dodge Dart

Take it out and drive it long enough to get the exhaust good and hot. It is likely to be leftovers in the pipe/muffler.

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Official Cookie and Mater Tormentor.

no custom work done other than mill job, new hardened seats, normally aspirated. If this was a water jacket issue why no antifreeze smell? Rings seating would be more blueish gray smoke, this is water vapor. No overheating now and no bubbles in radiator. Felpro gasket set was used. The machine shop assembled this for me, they were just going to put together the short block but I didn't mind the extra 100.00 to put the top end together. The number 4 plug was pretty clean. I did re-torque the head. Do the head bolts need sealer? The oil in the radiator is not getting worse and may just be from the atf funnel I used to fill it with. How much water could be in the exhaust...I dont remember it smoking on initial run in of 15 minutes at 1300-1400 rpm, but it was 20 degrees warmer out and I wasn't really watching the exhaust. Thanks again for the quick responses...this is very frustrating considering the amount of work I have put into the front end , interior, and tranny. This is a sweet ragtop with 25k original miles.

This jumps out for me.

I would pull all the plugs, pressurize the radiator, wait a few minutes and then spin the engine with the starter to see if you get water out of any cylinders. If you do get water I would drain the cooling system and start the engine just long enough to dry out the cylinder so it doesn't rust while the head is pulled.

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Joshua

looks like head gasket popped between water port and cylinder #4. Guess I did not bleed this good enough. Any thoughts as to the best way to bleed this system, does t stat have bleed hole or should I pull the temp sender until I get coolant out? I have a hoist and I was thinking of pulling the head with intake and exhaust attached...any thoughts. Should I pull the rocker shaft or just loosen it enough to take spring load off? Once again thanks in advance.