Rebuilt engine won't "first" start

[CaptainMajestic]

Hi everyone!

So over the past year and a half I have torn my 1974 260z with an L28 and flat top carbs down to it's rusty britches and done my best to get her nice and shiny. This is my first project car, so I probably have no idea what i'm talking about. However, I have not been able to get the car to start and I am pretty stumped, even though the car ran when I bought it. FYI, I did disassemble the engine, clean it up, refresh it with new timing stuffs etc, and put it back together citing the FSM almost religiously. I also have been wiring the car myself using the speedway 22 circuit harness + some custom over engineering bits.

So far:

• Brand new battery
• Engine turns over
• Spark plugs have spark
  • plugs are 1-5-3-6-2-4 CCW on the distributor, with 1 on the radiator side and on the cap spot with the extra line.
• fuel pressure somewhere between 4 and 5 psi (my gauge is cheap)

https://photos.app.goo.gl/GuQMgZK5M82v27q36

I can get the engine to spit with starter fluid, but won't get past sputtering. My guess is there might be an issue with the carbs, but I have no idea how to proceed with debugging.

Also, is it normal to be able to crank over the engine by hand when the spark plugs are in it? I don't remember being able to do this when I first put the engine back together.

 

Thanks!

Edited April 4, 2019 by CaptainMajestic

[siteunseen]

You could pull the feeder lines off the carbs and see if they are supplying fuel when you spin the motor.  My experience with the first crank has always been the distributor timing.  Loosen the hold down clamp and have someone crank the car over and turn the distributor to see if it'll crank.  Good luck.

[Mark Maras]

2 hours ago, CaptainMajestic said:

Hi everyone!

So over the past year and a half I have torn my 1974 260z with an L28 and flat top carbs down to it's rusty britches and done my best to get her nice and shiny. This is my first project car, so I probably have no idea what i'm talking about. However, I have not been able to get the car to start and I am pretty stumped, even though the car ran when I bought it. FYI, I did disassemble the engine, clean it up, refresh it with new timing stuffs etc, and put it back together citing the FSM almost religiously. I also have been wiring the car myself using the speedway 22 circuit harness + some custom over engineering bits.

So far:

• Brand new battery
• Engine turns over
• Spark plugs have spark
  • plugs are 1-5-3-6-2-4 CCW on the distributor, with 1 on the radiator side and on the cap spot with the extra line.
• fuel pressure somewhere between 4 and 5 psi (my gauge is cheap)

https://photos.app.goo.gl/GuQMgZK5M82v27q36

I can get the engine to spit with starter fluid, but won't get past sputtering. My guess is there might be an issue with the carbs, but I have no idea how to proceed with debugging.

Also, is it normal to be able to crank over the engine by hand when the spark plugs are in it? I don't remember being able to do this when I first put the engine back together.

 

Thanks!

 I could turn my 2.4 engine by hand using the fan belt with the plugs in. It wasn't easy but it could be done.

[Patcon]

I once rebuilt an engine and I didn't check the valve lash from the machine shop. The valves weren't seating, so there was no compression. Won't run like that...

[CaptainMajestic]

15 hours ago, Patcon said:

I once rebuilt an engine and I didn't check the valve lash from the machine shop. The valves weren't seating, so there was no compression. Won't run like that...

I did do the valve lashing when I rebuilt the engine, but may be I messed up. Will check and get back to you.

[jonbill]

Could be the distributor drive spindle isn't timed properly.

[Hardway]

Austin area Z owner here if you need a hand.  Everything above is correct.  Need to be methodical and check each item off.  I agree that getting the distributor in the right spot to start is usually the culprit.  Usually easier to have some turning the distributor slightly while someone else turns the key.  Before you move too far ahead, have you confirmed your getting oil pressure?  How far down did you disassemble the engine?  Have you pulled one of the spark plugs and checked for spark at the plugs?  When it sputters on start fluid, is it actually sorta running for a few seconds?  Are you running the stock SUs or something else like dual Webers or triple Weber or similar type carbs?

[CaptainMajestic]

36 minutes ago, Hardway said:

Austin area Z owner here if you need a hand.  Everything above is correct.  Need to be methodical and check each item off.  I agree that getting the distributor in the right spot to start is usually the culprit.  Usually easier to have some turning the distributor slightly while someone else turns the key.  Before you move too far ahead, have you confirmed your getting oil pressure?  How far down did you disassemble the engine?  Have you pulled one of the spark plugs and checked for spark at the plugs?  When it sputters on start fluid, is it actually sorta running for a few seconds?  Are you running the stock SUs or something else like dual Webers or triple Weber or similar type carbs?

Hello!

What's the easiest way to check for oil pressure?

As for disassembling the engine, I  removed the head and cleaned everything up + replaced timing, oil pump, and water pump, but I did not go as far as removing the pistons or valves. I did lash the valves when I was done assembling, but it's possible i messed up. 

All of the plugs have strong spark.

SUs are stock flat tops, but I have not rebuilt them. They could be gummed up.

 

How much play should i expect with the distributor rotation,  assuming it were perfect, before the engine doesn't start. Is it within a degree or a few degrees?

 

Edited April 5, 2019 by CaptainMajestic

[Hardway]

To check for oil pressure, pull the power wire going to the coil and the power or ground wire to the fuel pump if it is electric.  If it is a mechanical fuel pump, you can leave it connected or remove the feed hose to it and plug it.  Take the valve cover off and ensure the oil pressure sensor it connected on the passenger side of the engine.  With the battery hooked up, turn the key to turn the engine over and let it spin over several revolutions.  You should see the oil pressure gauge needle lift off and start to rise.  Once you see this the oiling system is pressurized which is what you want.  If you can, have a second set of eyes watch the cam turning while you are turning the engine over to ensure oil is covering the cam as it spins.  If no one is there to help you should see it coated with oil once it has spun over.

What lash did you set your intake and exhaust valves at?

Carbs might be gummed up but if the car ran before you did all this work, they are probably okay enough to let it start.

I would have the distributor set at 0 and advance a little while you are trying to start it.  There are other things to check regarding the distributor and timing itself that has been mentioned above.  When you installed the distributor, did you ensure the engine was on the combustion stroke on #1?

[CaptainMajestic]

4 minutes ago, Hardway said:

To check for oil pressure, pull the power wire going to the coil and the power or ground wire to the fuel pump if it is electric.  If it is a mechanical fuel pump, you can leave it connected or remove the feed hose to it and plug it.  Take the valve cover off and ensure the oil pressure sensor it connected on the passenger side of the engine.  With the battery hooked up, turn the key to turn the engine over and let it spin over several revolutions.  You should see the oil pressure gauge needle lift off and start to rise.  Once you see this the oiling system is pressurized which is what you want.  If you can, have a second set of eyes watch the cam turning while you are turning the engine over to ensure oil is covering the cam as it spins.  If no one is there to help you should see it coated with oil once it has spun over.

What lash did you set your intake and exhaust valves at?

Carbs might be gummed up but if the car ran before you did all this work, they are probably okay enough to let it start.

 I would have the distributor set at 0 and advance a little while you are trying to start it.  There are other things to check regarding the distributor and timing itself that has been mentioned above.  When you installed the distributor, did you ensure the engine was on the combustion stroke on #1?

Here is what the timing chain looked like when I was done. https://photos.app.goo.gl/jA1uKULRv2WUexB1A

Just as an FYI, I'm wiring this up myself and still don't have the oil pressure bit hooked up. I can probably pull the gauge and jerry rig the wiring. I can confirm that I hear a whooshing sound when I turn the engine over by hand.

Intake and exhaust should be 0.008" and 0.010"

Honestly I cant remember on the distributor. I can always pull it and set it. Does it just need to be at TDC? Or do I have to go through the 400 or so revs to get the black timing gear back on #1?

[siteunseen]

Are the links the right number apart? I can't remember the number, Google if you don't have it.

I see you are starting on #3 timing hole on the cam sprocket. I've done that to two new motors from advice I heard/read. I will be going back to #1 on my 240. Those motors turn more rpms than the 2.8 and peter out around 6,000. I am not happy with that. My 280 is okay on hole 3 i guess but #2 would've been best in hindsight. Low end power plus still some left up top. That's my opinion.

[Zed Head]

Notch matches groove, timing mark at zero to ten on the compression stroke, front edge of rotor pointing at #1 plug wire.  Those are the things you can set up from the beginning and the engine should start.  Those are all of the "timing " things.   The links help get things right the first time around, but after that the various marks are used to confirm.   You only need to rotate the engine to the compression stroke.  Remove the valve cover and the distributor cap and check all of those things.