280z triple weber, msd, l28...wont start :(

[cassio]

hello guys i just purchased the car and everything was already as is. the previous owner installed the carbs and the ignition but never had the time to get it running.

1975 280z

stock motor

40mm tripe weber carbs

msd 6l ignition and coil

new plugs and wires

mallory distributor

Here's where i've gotten to:

I put a new battery in the car and tried starting it for the first time, car turned over but did nothing. after spining the distributor i was able to get some firing going on. using some start fluid and constantly spraying into the carbs i was able to keep car running for close to a minute.

the next day i figured the jets were dirty so i pull the top off the carbs, remove jets clean them and reinstall them. i also set the air mix screw to 2 turns out. i set the motor at TDC and set the distributor as best i can by sight. Now car wont even come close to starting even with the starting fluid.

fuel pressure: I just put in clean fuel in the tank and its getting to the carbs. A fuel pressure gauge on the fuel line is reading 3psi when the key is on and pump is priming.

spark: checked spark at each plug and im getting strong spark at each one and consistent. the spark plugs were getting pretty black however so i had to take them out already once to clean.

timing: cant really set the ignition timing since i cant get the car to idle. i am however putting the car at TDC and putting wire to cylinder one right on point and leaving it loose so i can move while cranking engine. (malory distributor allows me to spin entire cap)

carbs: this is where the problem probably lies and i have no experience with them. i pulled the jets and cleaned them, also pulled the filter and clean them also. i set the air mix screws at 1 turn out, 1.5 out, 2 out, and 2.5 out and all give me no results.

i checked for vacumm leaks but theres only 2 vacumm lines coming of the manifold and they are both fine. also the gasket for the manifold and carbs seem good and i gave them a extra snug to be sure.

i get some popping and back firing from the carbs (literally fire coming out the carbs) but nothing. and like i said before i was able to get the car running yesterday by constantly spraying starting fluid into carbs....

now im lost any help will be great!!!

[Nigel1943]

Even if your carbs are out of tune one of them will allow the engine to at least fire, so I would guess your problem is ignition timing. Check that the distributor is in correctly and go from there. Do you know what work the PO did?

For instance, has he been messing with the cam timing or had the front engine cover off ?

[cassio]

The inside of the motor has been left untouched. He actually included an aftermarket cams that he said he never got around to installing.

My guess woould be timing also. Is number on cylinder the one closest to the front? Other than that I can't thing of anything I could have done wrong.

And like you said I would think if anything was wrong with the carbs it would still do better than what I'm getting

[Pomorza]

The inside of the motor has been left untouched. He actually included an aftermarket cams that he said he never got around to installing.

My guess woould be timing also. Is number on cylinder the one closest to the front? Other than that I can't thing of anything I could have done wrong.

And like you said I would think if anything was wrong with the carbs it would still do better than what I'm getting

The number one cylinder is closest to the front of the car. There's a topic here posted about two or three weeks ago about how to set the timing if you can't get (or see) the timing mark on the crank. For what I remember you have to find TDC for the first piston and then take a look at the dizzy. I'm not exactly sure but think it supposed to be pointed at about 11ish looking from the driver's side of the car.

The simplest way I've found to find TDC on the number one piston is to pull the cover and look at the intake valve for the #1 cylinder. When it points straight up the piston "SHOULD" (and I can't stress that more) be at TDC. But make sure using a straw or something in the piston. Once you find this and make sure the timing is right you should have an idea of what should be wrong.

Jan

[cassio]

Thank you but if you read my original post I have already set the motor to tdc and set the distributor timing as best as possible. And to repeat, it's a Mallory distributor so the top spins a full 360. So it's easy to have it in the wrong spot.

Edited June 10, 2010 by cassio

[Mikez73]

I don't know that this will help but for what it's worth...a while back I bought a new rebuilt 280zx D6K8 distributor. I could never get the thing to work. Bought another one. Got spark with that one and the car tried to start but never quite caught. I started from the beginning...set TDC. Still no good. I noticed the crank timing mark was way off. I turned the crank pulley timing mark to 0 degrees and checked. The rotor was pointed towards the rear of the engine. When the dizzy was rebuilt the tech installed the top shaft backwards 180 degrees off. You may want to set your crank timing mark to 0 degrees and check. That may not help but since you have fuel and spark all you should need is compression at the right time. Or spark at the right time :stupid:

BTW, since you have a perfect 3psi I'm wondering what fuel pump you have.

[ChrisZ]

I 2nd you have a ignition problem, when you did confirm TDC dit you check that the cam notches on cyl #1 is pointing up ?, take off your oil filler cap and put a finger in there, you can actually feel if they are right.

Do you have the correct firing order ?

I don't know anything about the Mallory dizzy, but if it were me, i would put the engine at TDC, take off the plug wire on cyl #1, put a spark plug in to that wire, ground the plug and then turn the dizzy until i woukd get a spark, that way i wuld be sure i got a spark when cyl one is at TDC, then set the correct firing order and get that little lady started.

Being that Webers have corase thread i would only set the idle mixture screws one turn out.

If this doesen't get you started on fluid, you should check your cam timing as stated by Nigel.

Chris

[cassio]

Your picture is not showing anything wrong. The crank makes one revolution for every half revolution of the distributor. So when ever the crank timing marks line up the distr. rotor will be pointing to either 1 or 6.

I'm going to take the valve cover off today and check mechanical timing on the cam. But I doubt it's that as the car ran 2 days ago with the help of starting fluid.

[cassio]

Chris:

so with key on engine off ishould still get a spark when turning the dizzy? If that's true that will make checking for timing alot easier.

[Zed Head]

using some start fluid and constantly spraying into the carbs i was able to keep car running for close to a minute.

the next day i figured the jets were dirty so i pull the top off the carbs, remove jets clean them and reinstall them. i also set the air mix screw to 2 turns out. i set the motor at TDC and set the distributor as best i can by sight. Now car wont even come close to starting even with the starting fluid.

now im lost any help will be great!!!

"Thank you but if you read my original post..."

I read your original post. Here's a summary:

The car ran with starting fluid through the intake when you got it. Then you "set the motor to TDC". Did some more stuff. Now it won't run at all. It sounds like you just think that you set the #1 to TDC and/or set the distributor wrong. Any way to go back to before you did anything? You must have had the timing good enough to run in the beginning.

[ChrisZ]

You won't get a spark with the key in off position, atleast you should not ;-)

[cassio]

So I pulled the cover off to check cam timing. And it was a bit off to the left and and it was already on it's last adjustment. So I went ahead and disassembled the front yo replace timing chain. While I'm at it I'm going to go ahead and install the 270/80 schneider cam the po included along with the schnieder springs.

Once that's all done and the motor is truely on proper timing I'll update.