Zed Head

If you're only getting only one backfire, and your AFM tested correctly by the AFM procedure, you should probably hold off on getting a new AFM. Since I've been reading the forums I haven't seen many cases where the AFM was clearly bad. I seem to be the only one (that I can recall right now) that had one that tested bad, ran bad (lots of backfiring, popping and stumbling at mid-throttle), and was definitely the problem, completely changing the way the car ran when I got a new one. Yes, 36 +/- about 1 should be the high pressure, then the FPR will draw it down when intake vacuum is applied. So, at idle you'll see about 31, then if you remove the vacuum hose from the FPR it will rise to about 36. The backfire and the fact that you bottomed out the idle adjustment screw are signs that you might have a vacuum leak. Don't forget that the crankcase is connected to the intake manifold through the PCV. So any leaks in to the valve cover or dip stick tube will end up as a vacuum leak. And, apparently,the EGR can rot out internally, feeding exhaust fumes to the intake constantly. I don't know if this would cause your symptoms though. Here's the thread describing it - http://www.classiczcars.com/forums/thread40886-3.html I would spend more time on the small stuff before going big on the AFM.

How long had the car been sitting before you got it?

The crop is from a car that is daily driven and parked outside most of the time. Plus it's been up in the low 80s here recently. Maybe it's a soy-based life form.

It's possible to get the top of the strut out without taking the lower control arm mounting points off but the brake line will probably get stretched and it might bind up and not flex enough to come out. I've got one out on my car but the other side wouldn't come out. Removing the four bolts holding the inner control arms on is so easy though, it's barely worth trying to get around it. After I loosened mine I said "I should have done that 1/2 hour ago". If you loosen them you'll have more room to drop the top of the strut. If the springs are stock you'll need a spring compressor. If the car's been sitting 10 years, the brake lines probably need work anyway. I would just take the whole assembly out, strut and control arm, with disconnected brake lines, and do the work. You'll probably end up there anyway. Wheel cylinders replaced, check the brake lines, all of that. On the wheel cylinders - the 76 and earlier (maybe 77 too) cylinder are expensive, like ~$45. You can swap in the whole assembly from a 78 car and use $15- 20 cylinders, if you want to save some money. Just mentioning before you get too far in to it, if it's possible.

For future readers. Might be a turbo AFM. I posted the same link in your other thread - http://forums.hybridz.org/index.php/topic/108020-afm-does-this-look-right/page__pid__1010448#entry1010448

Just saw this thread over on Hybridz. You might have a turbo AFM. The counterweight may not be missing after all. http://forums.hybridz.org/index.php/topic/108020-afm-does-this-look-right/page__pid__1010448#entry1010448

Get the box end on the nut firmly, find a spot on the body to lodge it, then stick a big screwdriver in the u-joint and turn the drivehshaft to loosen the nut. The key is to get the wrench firmly placed on the nut so that it won't slip off.

Finally took my lenses off to brighten things up.

An experiment that might tell something would be to lodge a piece of rubber or urethane or maybe even wood in between the bracket and bar to see if the clunk goes away. Just a thought. I'll let the R180 guys in now.

I get it, I missed the point. Wouldn't there be signs of rubbing on the bar and brackets if they were touching when clunking?

I think that I ran in to a similar problem. You'll find that there are certain projections on the plastic pieces that stop the rotation of the various plates at certain points. You'll probably have to put it together (and maybe take it apart again) to see how it works. If I remember right, the way the whole thing worked was that one "plane" of bearings rotated a certain amount then the other plane/set took over for more rotation. The thing that I keyed on was that the ball bearings were always sandwiched between two metal wearing surfaces. Also, don't forget, that the amount of rotation is limited in usage by the travel limits of the vacuum advance canister's rod. The most vacuum advance I've seen described is 9 degrees (18 degrees of crankshaft advance) for the Z distributors (not ZX) so it's really not much rotation movement. I felt like I had it right when I could move it that small amount repeatedly back and forth and the ball bearings rode in the same tracks, and the metal wear plates were locked in place. Best I can do, I've never seen a drawing of the breaker plate taken part. Good luck.

Clunking would be caused by looseness. Do you have any loose fits on the diff's points of contact with the body, the two mustache bar ends and the mount itself? And the two nuts and studs that bolt the cover to the bar? And did you use a snubber and keep the original mount, or a GM mount and removed the original mount? I have a self-made RT-style mount and poly bushings on the mustache bare ends and don't have any clunking beyond the lash in the diff gears. I'm using the poly GM trans. mount though so the nose of the diff can't move any farther than the urethane flexes. If you had a misalignment in your RT mount you would probably a get drive line vibration, but not necessarily a clunk. If you show a picture of your setup you might get some constructive comments.

You don't need the adapter, it's for the Multi Spark Discharge (MSD) ignition module. But the Blaster coil might not be right for your 76 ignition module and ballast resistor. You should match the resistance of the Blaster coil circuit, with or without resistor, to the resistance of the original 1976 coil with ballast resistor. Otherwise, you might have too many amps through your ignition module, or you might not be getting the benefit of the Blaster coil if you use the ballast.

Where in the process are you getting stuck? If you have the parts all laid out, there may be a simple step someone would know about. I've dis- an re-assembled a couple myself.

With the flow path blocked your temp sensor is in a dead zone. Probably not very accurate. Could delay the fans coming on.

olzed makes a good point. I wonder if a long bolt was used on the front thermostat housing hole, pushing the guide in to the chain. In it's normal/proper position the straight guide, even with its plastic, doesn't touch the chain, except for the odd deceleration event when the slack might pile up in one spot. At least the ones I've seen. Looks like your guide, sans plastic, is riding the chain all the time. I second (third?) the metal on metal making the noise.

I had a 78 and its AFM had the cutoff contacts in the AFM. Not used, but they were there. The AFM looked original to the car. I now have the 78 AFM on my 76 car. I adjusted the contacts so that they worked correctly. I would guess that there was a point in manufacturing where the old inventory ran out and the 1978 AFMs didn't have the contacts anymore. But some do. The 1978 FSM shows the pins in a drawing but labels them as "useless" or something similar. Kind of funny. Just posting for a little clarity from another perspective.

It's the difference between cylinders that is important on a cylinder pressure test. 150/158 = ~95%. That's in spec. and pretty good. 80% is the worry point according to the FSM. The volume inside the gauge can have a big effect on the pressure numbers. That's why the actual pressure reading is not too important.

There should be a sticker on the bottom side of the hood with the timing spec.

For fun, I used an inflation calculator to see today's savings in real dollars - "What cost $65 in 1984 would cost $134.61 in 2010." 6 x $134.61 = $807.66 http://www.westegg.com/inflation/infl.cgi

Testing the AFM according to the procedure in the Engine Fuel section of the FSM would be the first step. All that you need is an ohm-meter for the basic testing. When things go wrong with the EFI system it's often hard to tell which piece is actually the problem. www.xenons30.com/reference More symptoms described of what's happening will also get more suggestions. Good luck.

On second thought, where's there's a dent, there will be displaced, raised, metal. Make sure that the area around the dent doesn't have a raised edge that would wear the rocker arm and screw up your lash measurements. You're in uncharted territory. Some very careful work with a whetstone might do the trick.

It is odd that the price didn't follow inflation, for new injectors. Who knows, maybe mass production benefits of injectors in general, as more cars went fuelie, kept the price down.

Still haven't seen any evidence that you know that the clutch fork is moving and pressing on the springs on the pressure plate. You can actually see the fork and slave cylinder from the engine bay, you don't even need to jack the car up. You might be spinning your wheels (pun intended!) until you know that for sure.

The gouge on your cam looks like it's on the base circle so it won't have any pressure on it, and most likely won't cause further damage. Although, in your pictures it looks like the lash might have been tight on a few lobes. The base circles are shiny like they've had the rocker arms riding tight on them. Just a couple more observations.