Trying to get her started

[zbane]

Matthew, if you are thinking it is a problem with compression (perhaps from a blown head gasket) don't fret too much about it. I have limited mechanical experience, and tend to learn from watching and trying whatever procedure is at hand.

This said, pulling the head isn't all that hard, though I did have some issues when doing mine that you won't have to worry as much about since you've got a carbie car.

If you find that it is indeed a gasket issue, read up on what to do, and how to keep your timing chain in one place (you'll understand once you read up on it).

Before you go and pull your head, check to make sure that all your head bolts are torqued to spec. The paint markings on you camgear are very similar to what I did with mine to keep everything in line.

What I am getting at is this:

If your engine has been rebuilt (which it appears to have been) then perhaps it wasn't completely torqued, or the gasket wasn't put in place correctly/became damaged when the head was put on.

These are just base suggestions, but since you've gone through so many other options, this may be the direction you are going.

Check torque and compression...

[Carl Beck]

We're missing something here...

If the ignition timing is as it should be - and if you have fuel going to the cylinders.. and you have a spark at anything close to the right time - it should be at least backfiring, farting or something indicating that your assumptions are correct about the first few things...

Even with very low compression - it should be doing something...

Back to the carb's. - - - did you pull the floats, check the bowls are full of fuel... are the chokes working and are you using them....

Refresh my memory - did you preform the "finger test" Nissanman #22 suggested - to assure that you have compression on the compression stroke on #1? If you haven't done that - do it first and let us know..

I know everything seems to line up - but I'd feel better if I knew for sure that what is lining up is the compression stroke... not just the top of the #1 piston lining up with the "0" mark on the crank pulley...

Is the engine cranking over fast enough?... your battery isn't low is it?

I just feel that we're missing something here...

FWIW,

Carl

[Weasel73240Z]

I just found this post by searching, and after posting my on problem this morning, I realize it is pretty much exactly whats going on here. I guess maybe by chiming in I can revive the thread.

I know I need to 1st double check my timing, but I'm sure (sure, but maybe not 110% sure) that I was at TDC on the compression stroke when I set initial timing and re-installed my dizzy. The head was off for reconditioning, but I used my trusty wood wedge, made sure the crank never moved, and everything bolted back up with all the original timing indicators (1 hole on the cam gear, shiny link lined up with hole on the gear #1, etc). When I bring it up to TDC, the timing indicator on the crank pulley is right at the big notch (o degrees, right). The rotor is pointed at the #1 terminal (at about the :45 minutes (270 degrees) on the dizzy. Seems like everything is right, right?

My symptoms are very similar, but I'm using 2 brand new ZTherapy SU round tops, so I'm certain that the carbs aren't the problem. Getting good fuel, getting what I think is good spark. I didn't do a compression test, but the car only has 26K on it, the head was magnufluxed, so theres no cracks. The car ran before tear down, so I have no reason to think theres a compression issue.

The car backfires, will barely run once every few tries, and its expelling unburnt gas back out through the new carbs. When it does run, there no throttle there, and if I give it any gas, it'll stall.

I think somehow I ended up at TDC on the exhaust stroke. I've found that even at 180 off, they'll still run. But thats based on my experience with American muscle cars, this is my first Z. Any other thoughts based on these symptoms?

I finally have the car back together, and this is making me pull my hair out, I want to hear it run so bad. Help before I go bald!!!!

[xray]

Dumb questions....

1) Are your mixture nuts set correctly? Baseline is 2-2 1/2 turns down from full lock. Backfiring is usually a lean condition.

2) Have you checked each spark plug wire to verify that it gets spark? Are your plugs dry and carbon fouled? Wet and/or smell like gas?

3) What ignition components are being used? Is your ignition system setup correctly? Checked primary and secondary coil resistance? Normal voltage to the coil? New battery (at least good voltage from a used one?)

Post pics of what you call TDC, your distributor orientation, ignition set up etc.

Good luck!

[Weasel73240Z]

The carbs are set at 2-1/2 from ZTherapy. I haven't messed with the carbs, took them out of the box, bolted them on.

I haven't checked each plug for spark, I only checked at the coil and the #1, but I'll check them all today. The plugs have come out a little fouled, but with the way its running(couch, couch, sputter, die), no surprise. But, the plugs, wires, rotor, cap and plugs are all new. Plugs are all gapped to about .034.

The ignition is 100% original. Coil, dizzy, resistor, are all original. I pulled out the multimeter, and everything checked out to spec. New points. I have a new Beck Arnley coil, but haven't installed it yet.

Once I verify TDC, I'll take some pics of where all the marks are. Thanks.

[ktm]

1) Are your mixture nuts set correctly? Baseline is 2-2 1/2 turns down from full lock. Backfiring is usually a lean condition.

Backfiring out the intake is indicative of a lean condition, backfiring out the exhaust is indicative of a rich condition.

[sblake01]

That's why I like the terms 'frontfire' and 'afterfire' though I still have to explain those terms most of the time.

[Weasel73240Z]

Just confirmed timing. Rotor at the #1, crank indicator at the big notch, both valves fully closed at #1 (looking through the oil filler hole). Piston at TDC. Everything timing-wise looks right, but I can't keep it running long enough to use a timing light to dial it in.

Still just misfiring, and "spitting" out of the intakes. I haven't richened the mix yet, I figured with them set at the baseline 2-1/2 from ZTherapy, they should at least run. If I do play with the mix, how much (or little) should I adjust each try?

Just changed over to the new coil. Much hotter spark at all cylinders, still not running any better.

[xray]

Paul,

My mix nuts were not preset at 2 1/2 turns. My refurbed ZT carbs required some work to function well (adjust choke, adjust float level, adjust mix nuts), so they may not all be "plug and play." You should probably double check yours.

Bo,

My use of the term backfire was intentional, because that's how I interpreted his description from post #27. ("The car backfires, will barely run once every few tries, and its expelling unburnt gas back out through the new carbs") If it's loud popping etc from the exhaust the preferred term is "afterfire" or at least, "backfires through the exhaust"

[Weasel73240Z]

I guess maybe I should adjust the float level up a little bit. I double-checked it after shipping, and it was right around where it should be (9/16") from cover. But I adjusted the mixing nut out to about 4 - 5 turns from (2 - 3 more than how it was shipped), with almost no change. Since the float level is the gross adjust, I think I need to bend the tab, and bring up my float level. Sound like the next best guess?

Other than the "backfiring" through the carbs, the only other thing I can see is this fuel puking back through the carbs after I try starting.

[xray]

Paul,

I would still check to make sure you're getting spark at the end of each spark plug wire (unless you've done that and I missed it in your postings.) After returning the mix nuts to 2 turns from full lock, and with an insulated glove, place a metal punch in the end of the spark plug wire and, while holding the insulated part of the wire, place the metal end near the valve cover. When the engine is turned over (unplug the other spark plug wires) it should create a nice blue spark that (IIRC) can jump 4-6mm. If it's faint or won't jump that far, then your issue is ignition/spark related as well as possibly fuel related. Alternatively, if you can get it to run at all, you can place the timing light across each sparkplug wire and see if your light flashes.

Check to be sure it sparks on all plug wires, and check to be sure your plug wiring is in the proper order (Basic, I know, but sometimes the simple things trip us up.) 1-5-3-6-2-4 ACW from #1.

Frustrating, I know, but hang in there.

Any pics of your distributor with cap on and off? Just want to confirm wire positioning....

[xray]

Another thought....

Make sure you have good metal-to-metal contact between cap and wires, and the plugs and wires. Sometimes the ends can be pushed back into the wire insulators such that good contact is difficult to achieve, leading to weak spark and bad ignition. I assume you've checked your wires for correct resistance?

With your new points, you got a new condensor as well? I run Pertronix on mine, so I'm of little use in that regard, but some forum searching should turn up some helpful tips...