madkaw

This will be a bit of a witch hunt. Maybe I will get lucky and something will just fall out in my hand, but I doubt it. It's been like this for literally years .

Well after walking away for a while I am back with sockets in hand. The engine is coming apart. The head is off to check HG and internals. I'd say I have a definite oil issue with combustion. Not sure if it's guides or seals but certain cylinders have that oil sheen to them. #4 is pretty bad with the top of the piston covered in a nice black oily paint. # 2 cylinder intake valve is grungy ( baked on oil?) on the back side of the valve. Head is going to the machinist

This is all learning for me Captain. I imagine the back plug is a clean out point. The 'How To Modify' books shows the oil schematic. As far as the bearings- in my case it might just be a partial covering of a oil hole that would do it.

I am going to make every effort to NOT tear it down and try what you are describing. Also remove rear galley plug to facilitate cleaning.

You did help out a bunch Zed. I believe I have a blockage deep in the block somewhere. I know I have been careless before because I found a piece of foil in the bottom of my oil pan before. It was one of the sealing foils-possibly from an additive bottle. It was all balled up and beat up like it had been beaten around my engine. So maybe something else is partial obstructing a passage way? Unfortunately, there will be only one way to find it. I will try removing the end plugs and cleaning out the main galley first. I will run pressurized air thru there and hope something lets loose. The problem is that I won't be sure I did anything unless I find something. It might be a total tear down. Maybe I will find a bearing misplaced, but I don't remember having this issue from day one. One thing about fresher motors-they come apart without much fuss.

Lots of pressure up top and a pretty shiny cam to prove it. Like I said, I have been battling this for a long time. I've been told that the pressure is NOT too high, but no one else runs a constant 70psi on a street motor. I have also been told that the high oil pressure wouldn't cause the crank seal leaks, but I have leaks both ends. I didn't trust my Datsun gauge and mounted a mechanical one to be sure. I did this latest experiment to verify gauge accuracy and to eliminate any pressure contributions from a running motor. I might just be done with this L24 block if I don't find something definitive. I have a L28 short block sitting on a stand that just needs some cleaning I believe.

I guess you can cross that off your list and shut me up at the same time- You might just go .040 on the gap. Ever consider tweaking he floats a little richer?

DJ, Thanks for all the good info. I've been down this exercise before and have traded out springs, pumps. Right now I am running stock pump and springs- but will verify. I've basically ignored the issue because it wasn't a low psi problem. Now I have my head off I want to make sure my high PSI isn't from a blockage. Not too many folks have had this issue , so not much to compare too.

Your right Captain, a cold motor or oil would drive up pressures, but my engine runs that high all the time--- hot or cold. I did this without the engine running and a NEW gauge to make sure this wasn't a false reading. The front of my engine was coated with a fine mist of oil dust from the front seal. The rear seal does need to be redone.

Old thread-current problem. I have my engine out to look into my head problems and thought I would check my oil pressure on a stand without the engine running. I drove the oil pump with a large drill and monitored oil pressure with a new gauge. With the drill running full speed-2500rpm, oil pressure runs pretty constant 75 psi. I figure that 2500 rpm on a drill duplicates about 5000rpm engine speed since the oil shaft normally runs half engine speed. Even with the drill set at 1250rpm(should be 2500rpm engine speed), oil pressure is 75psi. I don't think that's right. II am going to check all oil passages the best I can without dismantling the short block, but that might be next. Rear main seal leaks at the seal ID. I tried turning the crank by hand while applying oil pressure and I can see the oil wanting to seep at the crank. Looking at the seal carefully I can see that it is in slightly cocked on the 6-12 oclock position, so I know that's an issue.

Wasn't sure but did you say you do or do not run with vac advance? Have you experimented with float adjustments? Spark plug gap?

Hell- my car is garage art right now-

A stumble at cruise SU's and timing I'm still talking ignition:)

What makes your engine a stroker--crank? What compression are you running? I don't buy the stock cam is the culprit.

1972 DATSUN 240Z. Classic

1.5 ohm is measuring the primary resistance of the coil- nothing to do with any resistor What's the secondary resistance read? The only running voltage test I see in the instructions is at 2500rpm which you haven't done.

Actually--it says to have a 1.5 ohm coil for a 6 cylinder. Might double check all your ohm readings again just so you can cross this off your list. It's also confusing to me that the instructions imply that you should see charging voltage at the coil--12-14volts, and you say you read 9volts running.

If you didn't update your coil with your electronic ignition then you need to. If you went pertronix you need a coil meant for that specifically . Probably measure near or less then 1 ohm. From what I have read the electronic coils are meant to have 12 volts continuous , but a points coil is not

Glad you nailed your mixture. It seems these engine like fuel!!

Shipping might be cheaper then you think. I bought a WRX sight unseen and it didn't turn out to well. The shipping was the best part . I put the job out there and there was a bidding war to get my business. Buying a car unseen is really risky. Pay the money to have a neutral go out and look the car over and get a report. It can be as little as 100$ and might save you thousands.

I would think SM's would be pretty close for a stroker. How does the engine do in a heavy load low rpm scenerio- let's say pulling a hill with some moderate throttle in a higher gear?

So what needles do you have? Stock needles might be too small. You could experiment with slightly raising the needles in the piston. If the shoulder is not flush with the groove, you could push it in further or closer to being flush. This might put a smaller part of the needle in the transition zone for more fuel. How do the spark plugs look? When you synched the carbs did you do that at 2500rpm and idle?

Matt, I will be blatantly biased and say go for the early Z. With that budget you should find a decent one------------------go for the best body you can find. The Z is unique because there are so few nice ones out there, but so widely loved; it is crazy the attention the car gets. Probably the easiest one to work on from your list too.

'Running stock coil at 9v'????

The needles should be labeled . You need to pull them off the piston because they are stamped around the head.