madkaw

a lot of work-but one of the first things people notice

Not trying to be a di@khead, but I couldn't imagine not knowing the temperature of my engine(especially aluminum head motor) and intend to race this car. This is basics and you can't properly diagnose other issues without atleast covering the basics. Just about every tuning adjustment specified in any manual- specifies to warm the car to operating temperature.

The temperature fix alone should make that engine run different and better.

Sitting around like that and then only idling the car is not good. You said you have "good gas"-so you started with fresh fuel? That fuel will be no good in your tank. take your air cleaner off and push the pistons up into the domes of the carbs and let them free fall. I'll bet they stick. If they do, you need to take the domes off and clean the inside of the so its nice and smooth. You have to rotate the float lids to get them off-counter clockwise I think. Check this stuff out first, then get back with us. Oh, and pull your plugs-all that idling-probably with the choke on has probably carboned them up

You might find that your valve guides are coming loose causing the valve to get in a bind-and there's only one fix for that. I had the same thing happen to my early z.

Took the head to a machine shop that had a good straight edge. With the head assembled he couldn't measure straight down the center, but either side of it was FLAT. Measuring diagonally he was able to get a .015 guage under the bar around the center of the head, but not sure if that was anything definitive. New gaskets are on the way and i think I will use some copper spray this time.

Try googling DIYtune. They sell and explain all that stuff!

there tight, but I don't believe they are undercutting the gasket. It is something I will watch for when putting on a new gasket and something I was aware of avoiding when doing the eyebrows--- and a good point Guy-thanks. Would I not see some evidence of a breech of the fire ring? I order some Victor Reinz gaskets today for the head-9.98 a piece closeout on Rock-auto!!

here are some pics

Cylinder read 180 on compression test and the problem seems to be coolant, so what would I be looking for under the valve cover

Pulled off the head today and good news and bad news. Good news is no detonation damage-cylinder walls looked great as well as the combustion chambers. bad news is there is nothing that jumps out at me here as to why the gasket gave out. I can't see anything apparent for the coolant getting into the cylinder. Honestly I haven't been down this road before as far as diagnosing a bad gasket visually. The gasket didn't come off in one piece-some of the material was on both the head and block. The fire rings on the gasket looked okay. I guess I will post up some pics, but number 3 was definitely not burning correctly.

So are you going to change around pumps before rechecking or richening the floats?

http://effinghamdailynews.com/local/x1953746100/Train-semitrailer-collision-closes-crossings

Well atleast look at the hoses and see if they have a tendacy to kink when moving the nozzle. It should be easily apparent if they tend to kink

I think you need to come up with somekind of temp guage

As far as the hoses, mine were brand new and would kink. I can't quite remember how I discovered this, but I believe I was just checking that the nozzles were flush after closing the choke. I would run a quality thermostat-IMHO The point i was making about the bogging is that even if the float bowls were lean, you would probably see decent acceleration until they emptied out. If they were lean you would definitely hit that wall after at WOT for a while. Mine are adjusted beyond factory specs. It would be nice if you had a wideband to see what the mixture is doing. I had SM needles in my Z and took them out and put OEM back in. The OE needles supplied enough for my mods.

I forgot to ask, why aren't you using a thermostat. I would want one in there to regulate temp. You don't want a cold engine.

Okay, I'll throw in my thoughts. You haven't said-or I missed -what theplugs look like-carboned, lean?? Check your float bowl hoses. I bought some from Bruce-sorry Bruce- that collapsed or kinked, which shut off fuel obviously. They could be kinking and unkinking under heat conditions. Float bowl adjustments-does the car bog under hard acceleration before it gets to this wall at 5k? If NOT, I would go in there and tweek those floats to maximize fuel. You'll know if you tweeked too much. It could still be running your bowls dry-been there! Sorry I was so late on suggestions-I guess i have been sulking in my own misery here lately.

The head was totally reworked

I rented from autozone a pressure tester for the coolant system to help narrow down my problem. According to the instructions, once hooked up and the car running I watched for a rise in the pressure. As the engine warmed up the pressure rose quickly and the instructions stated to pull spark plug wires to see if it diffuses the rise in pressure. My suspect cylinder #3 was the first plug I pulled and the pressure immediately stopped rising-so I would say that the headgasket is the issue and it is in the vicinity of # 3 cylinder. Hr369, I asked for the block tester you recommended and they gave me the test fluid and this pressure tester. I should have looked at it closer, but the fluid wasn't meant to use with the pressure tester-but the pressure tester still was a good diagnostic tool.

I will see if I can find that block check stuff locally! I'm not afraid to change the headgasket-I'm the one that put this engine together----maybe I should be afraid;)

I knew it was a long shot-but I've been fustrated over this issue. Don't know if I want to drive it till it get's worse-especially a fairly new motor. Like you said it's not a huge job to change the gasket. When I get back into town Im going to look at it some more. I guess I will do another compression test now that I have green plugs. I have never seen fluid out my pipes like this before-I'm betting the gasket gave out. My Z hasn't given me a lot of fun this year:(

WOW, just priced a Nissan headgasket from Courtesy-150$$ I don't think I will consider anything else. I would love to find out that this problem is tied to my persistant oil leak at the rear main. I have changed everything and she is still pushing out oil. Could a leaky headgasket around the oil passage be pressurizing the oil?? I think in the end I will have concluded that I ran this engine too lean for too long with too much timing and compression-Compression detonation- hopefully I didn't do any damage

The engine just didn't sound or feel the same, maybe a bit lethargic would be a way to decribe it . It's one of those deals that I worked on the car to fix a couple of things and suddenly it seems different. One thing I worked on was mooring down my weak trans mount. My method of fixing caused more noise to transmit into the car(semi solid mount), so I experiencing unusual noises for the first time. The car ran decent, but didn't seem to have the POP it had previous. I will state from my earlier post that I haven't done another compression test since finding the "green tint". The level in the radiator was down a little-but so little it has me second guessing. I guess I was expecting something more defining from a blown head gasket. No overheating-not even close No detonation-that I could here No laboring from the starter-like my timing was too far advanced Always run premium

Not equipped for that test, but good idea