260z motor questions

[260 z]

I am new to the forum and currently restoring my 1974 260z after it has sat for 26 years. I have rebuilt the motor replacing the timing gears, chair, and tensioner, as well as the harmonic balancer, rings, seals etc. I went through the su 3 bolt carbs and with some help from Bruce Palmer, I think they are ready to go. The motor is back in the car and I can only get it the fire if I spray carb cleaner in the carbs. It runs for a second or two but it is not picking up the gas. I attached a vacuum gauge just behind the front carb but the needle does not move when I crank the motor. With the number one piston at TDC, and the cam lobs at 11:00 and 1:00, the timing mark on the harmonic balancer is at 10:00 when the timing scale on the motor is at 2:00

ANY IDEAS WHERE I SHOULD LOOK NEXT ???

Also, when I put the new harmonic balancer on (purchased from Damper Doctor), the crank is recessed about .100 from the face of the pulley.

SHOULD THE FACE BE FLUSH ??

[Bruce Palmer]

Ed,

Sounds like you're not getting gas to the carbs. Disconnect the gas lines at the carbs and crank the engine. If everything is working and clear you should be pumping gas into a moonshine jar in relatively short order. Electric pump at the back of the car? You went thru it. mechanical pump on the engine? Is New. And you said you had the lines purged clear back to the tank correct?

I've seen the sock in the tank inlet tube after the tank has been re-sealed get goobered up with sealer such that it can plug up. Anyway, start taking fuel line loose progressively toward the tank and crank the engine or run the pump.

SUs are a contolled gas leak, you need to starting leaking some gas to them...

[Zs-ondabrain]

How are the chokes? A cold, unran motor is likely to give you greif if the chokes aren't operating correctly.

if Bruce helped you out with the SU's then you're likely on the right coarse. You obviously have spark if spraying starter fluid or cleaner into the carbs gets it to fire. When it fires, does it backfire or seem to be running rough (wrong firing order kinda rough)??

If it's a 260Z, make sure the fuel pump is working correctly. The fuel pump won't kick over till you get some alternator juice to the voltage regulator, which powers up the relay that runs the fuel pump. Confused yet?

Try the chokes, look under each carb to make sure the knuckle that holds the needle has dropped about 1/8" when the choke is pulled back inside the car. That should be enough to get it started. Also eyeball the rod that holds the butterfly on each carb, when you engage the choke enough, does the shaft move even a little.

I ask because the butterfly needs to open just a little when the choke is used, to allow air into thru the carb.

Dave

[Gary in NJ]

As Bruce suggests, check for fuel flow at the carb. If you have fuel, double check your float height. If too low you will not get any fuel flow.

[260 z]

I have gas to the carbs. I have put a jumper to the electric fuel pump so it comes on when the key is at acc. I don't have any moonshine jars (since I returned from Saudi Arabia), so I had to test it by pump the gas into my mason jar. I have also replaced the mechanical pump and tested it by disconnecting my jumper and cranking this old girl. When I was setting the floats to 1/16" from end of nozzle, I made to large of a correction and pumped gas out of the nozzle and on to the floor. I get little or non measurable vacuum when the motor cranks. How much should there be? If I have the valves out of time, will I not get vacuum? When I spray starting fluid into the carbs, it starts instantly and for those two or three seconds...sounds smooth.

[Bruce Palmer]

Oh man! Don't tell me we have another Houstonite with an unanswerable question. Steve H. did you put him up to this??

[260 z]

:stupid::stupid:The question will get answered it is just a mater of time. Right now it is 26 years and counting. I hope not to much longer because I am running out of fingers, toes and anything else I can use to keep the count straight. Please help!

[Jeff G 78]

260Z, Welcome to the wonderful world of 260's.

I went through the same thing a few years ago with my 260Z crapcan racecar. My Z sat for 15+ years in a barn and was a mess.

I'd ditch the electric pump and then buy a new mechanical pump before you go any further. If the car fires with starter fluid, you likely have one or even two bad pumps. The electric pump isn't needed with the SU's and the mechanical pump is likely shot after sitting for all those years. Next, replace all the rubber hoses to and from the rail and run new rubber hoses into a small gas can sitting on the floor next to the car. Run one hose from the can to the fuel pump inlet and the other from the fuel rail return outlet into the gas can. This test will eliminate the guessing game of whether of not your fuel tank and filter are gunked up. You might have fuel, but no pressure due to a clogged system. Only after you try to get the car running from a gas can can you determine where the problem is.

Check out my facebook link in my sig for the story of my 260. Follow the link to the photo section and go through each picture. They all have captions and might give you some pointers.

Good luck! BTW, check www.rockauto.com for the best deal on parts. They have some great deals on engine parts, gaskets, fuel pumps, etc.

[260 z]

Thanks for the imput...I just posted what I went through on the gas side and feel that I am getting gas to the carbs but the gas is NOT be pulled into the cylinders. I am leading toward a poor or weak vacuum ???

[Jeff G 78]

Thanks for the imput...I just posted what I went through on the gas side and feel that I am getting gas to the carbs but the gas is NOT be pulled into the cylinders. I am leading toward a poor or weak vacuum ???

Just because you have fuel doesn't mean you have pressure. If it runs on starter fluid, it should run with gas.

Have you done a compression test and leakdown test?

[260 z]

ROFLWell, today I run the compression test and got 145-150 psi on each cylinder. I had someone to turn the key while I checked the compression and I also checked to see if I was getting any suction at the carb inlet. I did it just by putting my hand over the inlet and felt no draw as the motor was cranked. Since I had the spark plugs out, it was easy to turn the motor with a wrench, so I removed the valve cover and abserved the location of them as the pistion was moved up and down. On the compression stroke, and the piston was TDC, the first valve's lob was at 1:00 and the second was 11:00. but when the piston was going down on the intake stroke the second valve had not yet started to open. The cam timing gear has three holes that could line up with the pin in the cam. If I have it in the wrong hole, it could have both of the valves closed when the spark plug is fired ( letting the motor to start on starting fluid) but not have the intake valve open as the piston goes down to pull the gas into the cylinder on it's own????? Is that what I have done??

[Jeff G 78]

Wait, wait wait, did you put your hand over the carb inlets while the plugs were out? If so, you will feel no suction. Your compression readings are fine and will improve when the engine is warm. As long as the distributor rotor points forward when the #1 cylinder is TDC and the cam lobes are as you described, then you have the engine timing right. You are over thinking the problem. I still say it's a fuel delivery issue.

Edited January 17, 2011 by Jeff G 78