Stumped in New Mexico

[robox]

Hi folks-

This is my first post here.

By way of introduction, I am not new to forums and I'm also not new to working on cars. Although I will say that working on gasoline engines is not really my strong suit; I'm a bit more familiar with diesels.

I owned a 1971 240Z in my 20's, and I bought another one about a year and a half ago. I bought this Z in southern California and drove it home to northern New Mexico. The car is in decent condition, although it took a lot of tinkering to get it back here.... new plugs and a few filters along the way... but it did make it.

It's been basically sitting for the last year and a half. I drive it every once in a while just to keep it alive.

Well, about a week ago I decided to give it some attention and get it to run better. I drove it into my workshop (yes it was drivable a week ago) and installed a Pertronix Flamethrower coil and replaced the points with a Pertronix Ignitor. After that, the engine fired right up. At that point I decided to do the timing, and I observed that the pointer on the crank pulley was showing at about 35º on the little scale (which only goes to 30º). My old Chilton manual said it should be about 5º, and I'd read online that it should be around 10º, so it was way off. I moved the distributor and got it to be about 15º, which caused the idle to go way down, but the car was still running. At that point I shut the car off, and pulled the tops of both SU carbs to clean them up a little (I could see some oily residue on the round slides which I wanted to clean.) After cleaning up both slides and reinstalling them, the car would not start. Almost a week later, after doing lots of work, I still cannot get the engine to start again.

Things I've done:

• Adjusted valves (twice)

• Put timing back to 35º, and every other setting you can imagine

• installed new plug wires

• Cleaned and gapped all plugs

• Checked fuel levels in the float bowls with the 23mm clear tubing method

• Verified good fuel pressure out of pump (visual verification only; watched fuel squirt out of float bowl tops into plastic container while float bowls were disassembled)

I also checked compression, which came in between 122 and 132 for all 6 cylinders. I understand these are fairly low numbers, although I have a mechanic friend who assures me they are not TOO low. In any case I'd have a hard time believing that compression was my problem, as the car ran OK before I (minimally) messed around with the carbs and the timing.

What I can get the car to do occasionally is run VERY poorly for a minute or less. It typically dies on its own. Also it does not respond to throttle, throttle usually kills it. From feeling the headers after the engine dies I can tell it's usually only running on 2 cylinders, typically 1 and 6. Sometimes I will hear what sounds like detonations in the exhaust pipe. Also when it does run, it frequently coughs big spurts of air-fuel mixture BACK out of the carbs.

Other info: I am at 7000 feet elevation. It frequently seems to me that the carbs are too rich. I currently have the mixture nuts turned down about 1 turn, although I have played with settings between one-half turn, and two turns. Also, it got quite cold here right around the time the engine stopped starting, probably averaging in the 20's in the last few days. I did put some work lamps on the engine for a few hours this evening in an attempt to warm things up, but the car still would not start. Also, the engine seems to want to run on starting fluid, although at the moment I am out of it. Also, right around the time the engine decided NOT to start again, I filled the fuel tank (but I can't see how that could be significant).

It's a mystery to me.... as well as to my mechanic friend.

Any insights would of course be appreciated.

I am going to post this in both the HELP ME! section as well as the general engine section, because, not being too familiar with this site, I'm not sure which is really the right place.

Thanks again,

Christian

[Travel'n Man]

Did you get the correct coil? Have you reverted back to points to see if the Pertronix could be faulty? Sounds like it was running before the Pertronix and now it's not. Keep digging - you'll find the culprit.

[SteveJ]

First, post the part number for the Flamethrower. That goes with what Mitchell posted.

Next, get the engine to TDC and check the distributor position. That's your zero point for timing. After you establish zero, you can have more confidence in establishing your timing properly. I get the feeling that your plug wires were off at 35 degrees.

After you get the timing right, you can establish whether or not you have a good spark. Then you can look to see if you have any fuel issues.

[madkaw]

Start from ground zero. Like said above , check timing by finding TDC compression stroke and assuring the rotor is lined up with #1 cylinder . Put your timing light on each cylinder wire to check for spark.

Did you buy the coil and pertronix igniter as a kit? The coil impedance needs to match. So if you bought a coil for a points ignition it won't work for electronic. Ohms resistance should be around 1 ohm for the proper coil.

Edited November 28, 2013 by madkaw

[robox]

Hi guys-

Thanks for the replies.

First off, in retrospect it seems like it was a dumb idea to post this same post in two different places on the site, so I killed the other thread (the one in the HELP ME! section) and am moving the discussion over here.

One member over in that other thread suggested that i might be having fuel starvation related to the altitude and the fact that I am only using the mechanical fuel pump, and suggested I go with an electric pump near the tank. It's true that I only have the stock pump. I have thought about this possibility and considered getting an electric pump. Although it's also true that the car worked at this altitude previously. Also, just now I replaced the tubes going from the float bowls to the nozzles at the bottoms of the carbs with clear tubing, and there is definitely fuel getting into them. Maybe not enough??? I don't know.

Regarding the coil- I bought the two Pertonix items together in a kit from Motorsport in California. They sent me the 3 ohm coil. From what Madkaw says it may be the wrong coil. I don't know enough to say. I did try hooking up my old coil, with no luck.

I am getting a spark at each plug, as shown by testing the plug against an engine ground, and also by putting the timing light on each plug wire. Sparks all around.

Also put in a new fuel filter, which is clear. Good fuel flow into the filter, still no start.

I will post the part number for the coil later. Definitely 3 ohms, though.

Thanks

[robox]

One other idea...

Is it possible that the distributor shaft was installed one gear tooth off?

If the gear is 10 teeth, then one gear off would be 36º off, which is close to what it was at before. I do not know the number of teeth.

With this thought, I did pull the distributor, but found that I couldn't pull the actual shaft with the gear, as I am sure you all know.

What I do know is that the car did not run well with the timing closer to 0º. It seemed to want to run better around 35º.

Just a thought

[Zed Head]

but the car was still running. At that point I shut the car off, and pulled the tops of both SU carbs to clean them up a little (I could see some oily residue on the round slides which I wanted to clean.) After cleaning up both slides and reinstalling them, the car would not start. Almost a week later, after doing lots of work, I still cannot get the engine to start again.

• installed new plug wires

What I can get the car to do occasionally is run VERY poorly for a minute or less. It typically dies on its own. Also it does not respond to throttle, throttle usually kills it. From feeling the headers after the engine dies I can tell it's usually only running on 2 cylinders, typically 1 and 6. Sometimes I will hear what sounds like detonations in the exhaust pipe. Also when it does run, it frequently coughs big spurts of air-fuel mixture BACK out of the carbs.

Thanks again,

Christian

I see a few possible clues. Things initially went bad when you took the carbs apart. Then you did a bunch of things, possibly fixing the original problem, but also maybe creating a new one or two. One possibility is that you installed the new wires in reverse rotational order. The engine will run this way, I've done it, on fewer cylinders. The fact that you have spark on all wires but the engine won't run seems to fit. Also, once the engine starts but has some dead cylinders, the other plugs can foul. I would pull all of the plugs, clean them up and reset all of the wires. 153624, counterclockwise. Make sure the rotor is pointing at the #1 terminal of the cap when the timing mark is in the vicinity of #1's timing setting.

Edited November 28, 2013 by Zed Head

[Zed Head]

One other idea...

Is it possible that the distributor shaft was installed one gear tooth off?

If the gear is 10 teeth, then one gear off would be 36º off, which is close to what it was at before. I do not know the number of teeth.

With this thought, I did pull the distributor, but found that I couldn't pull the actual shaft with the gear, as I am sure you all know.

What I do know is that the car did not run well with the timing closer to 0º. It seemed to want to run better around 35º.

Just a thought

Do you have vacuum advance connected? If someone connected the hose to full-time vacuum, you might have been reading timing incorrectly. The vacuum advance canister should not have vacuum when setting static timing. People mess with this quite often, although many people with carbs don't even use it at all.

[robox]

Also, to be clear... the engine did run for a minute or two AFTER installing the Pertronix items. Although it might have been warm already at that point... I can't quite remember

[Dr. 240Z]

Choke working?

[robox]

Thanks Zed Head. Plug wires are definitely installed as per manual, and as you said.

I originally timed it with vacuum advance intact, although then I disconnected it and saw no difference in the timing.

[robox]

Choke working?

Yes, but choke kills it immediately.