dangcamaro

I've got an 84 Z28 with the HO 5.0 that I've been trying to get back on the road. Overall the car is in really good shape, but we purchased from my FIL estate, and the car was sitting in a garage since roughly 2004. It's pretty much stock and that means it has the E4ME quadrajet. I've spent the last few months doing things like new fuel tank and hoses, rebuild carb, replace radiator (3 row champion), heater core, all fluids new, many other odds and ends.

Rebuilding of carb was completely new to me, never rebuilt a carb before. Carb number 17084208. It was a mess with old gas dried in every part, but it really went well I suppose. I have the FSM and followed it pretty closely. Replaced idle pickup tubes, float, needle, accel pump, etc. Used brushes and cleaning tools to get to every last bit of crap that was in every port, new bushing in primary throttle plate shaft. All plugs in bowl were solid and didn't require any work (no corrosion, no leaks).

Everything was set to FSM settings. Lean Mix Solenoid was set without gaging tool to 1.304" (I didn't have gaging tool, so I cut a narrow plastic straw and measured with dial caliper to 1.304" and set plunger/solenoid contact point to top of brass on metering jet). Set solenoid plunger travel to 4/32. Set Idle air bleed valve to 1.756" (this also required improvising a gaging tool out of a copper wire bent like a candy cane....not perfect, but close enough). Idle air needles removed, cleaned, and reset to factory 3 3/8 turns.

Car has sock on pickup in tank, and mechanical pump on engine block.

One thing I didn't do (or was afraid to push too much) was pull out the carbon canister. All hoses were frozen to it. I'm perhaps concerned the thing is filled with liquid and not functioning.

All vacuum hoses appear in good shape, and connected. No leaks. Haven't tested how much vacuum.

Got it all together, and the thing runs. Fast idle hits about 1700, kicks off after about 4 min). I should also mention plugs and wires are all new and routed per FSM, off top of head don't remember plug model or gap, but it is all back to factory settings. Attempted to check timing and it's really advanced, like off the marks to probably 18-20 degrees. Any attempt to get it closer to recommended setting and car runs rough and dies.

So, my neighbor comes by (he's a seasoned rebuilder, loves quadrajets and SBC's) says it sounds great and not concerned with timing being advanced. Actually, that's where he sees many of his SBC's with Quads set. Said it smelled ok, not rich.

That brings me to today, I take it to Air Care Colorado to see if I can pass emissions. Getting there was longest drive for car to date. It was fun. Thankfully the jangly loud gov-loc didn't blow apart on me while heading there. Ran nice, fun drive. Failed emissions on CO and unburned HC as follows:So, that sucked. Then when driving away I got about 200 yards out into parking lot and it died. Air cleaner hotter than blazes. Started up then died again. Had to wait 45 min and it did start up and get me home. Didn't smell flooded, not much of a gas smell coming out of it at that point.

Another thing I did not do is test TPS voltage, or get the plug out of the TPS adjustment port on the air horn. Not sure if TPS could be causing any issue.

Thanks in advance for any insight. This dang Camaro has been a blessing and a curse. I got some great smiles today on that drive, and I can see it's all gonna be worth it someday.

NoEmissions84TA

iTrader: (1)

Does the carb make a ticking noise? The MCS leans the mixture when running. That's the ticking sound you are looking for. Without that working, you were full rich (FAIL).

dangcamaro

Yes, I’m getting the solenoid ticking. Can actually watch rpms bounce when idling (between 500-750). I assume that’s MCS doing it’s thing.

TransamGTA350

iTrader: (2)

When you checked ignition timing, did you unplug the distributor? It would show very advanced if you did not.

dangcamaro

No I didn’t disconnect anything when checking timing. I’m ignorant on what to do with that, and didn’t find procedure in manual.

I have 3 connectors to distributor. Single wire to ‘tach”, single wire to ‘batt’, and 3 wire plug with no label. What do I disconnect?

Also, I borrowed analog tach and dwell from neighbor but never hooked it up. Any advice on how to do that would be great.

TransamGTA350

iTrader: (2)

Disconnect the 3 wire connector, start the motor and set the timing to spec. Should be 6 degrees BTDC on that motor. Is there an emissions sticker under the hood? That will tell you for sure.

After setting the timing, shut it down, plug the connector back in and start it up again.

My guess is that you are going to find that the current timing setting is retarded and if that’s the case, it would cause the HC and CO numbers to be high.

That tach and dwell meter is for older style coils with exposed terminals. You would clamp the red alligator clip on to the coil negative and the black clip to ground and it will read rpm. The tach lead should be the same as coil negative, but you would need to make an adapter. I use a timing light with a built in tach, much easier.

naf

iTrader: (7)

unplugging the est connector at the distributor to set timing to base setting will engage the solenoid plunger to bump the throttle open slightly. this keeps it running (when warm) while setting timing. plug it back in when done and the ecm will command it's idle advance and you'll see somewhere around 22-25 with the timing light. this is normal. unplugging the est will trigger a code 12, which means the ecm received no reference pulses from the dist, again normal.

use the dwell meter to dial in the IAB for the carb AFTER setting base timing. connect to green diagnostic lead coming from the passenger side ecm harness near the blower motor.

with the motor warm and idling you want to see the dwell hovering around 30 degrees (or 50%) with the meter on the 6 cyl scale. turn the IAB out some (leans mixture) to increase the dwell (richens mixture). go 1/4 turn at a time. you want to see the dwell around the midpoint of the scale and see it swing rich/lean some as it adjusts based on O2 readings. sounds like you're close already though.

the dwell is the measurement of the time the rods spend down in the jets, restricting fuel flow (more dwell - lean) the IAB lets less air into the mixture as it is screwed in (down-richer) and more air in when screwed out (leaner)

naf

iTrader: (7)

the est should plug into a lead from the base of the dist-not at the cap

Scott's 83' Z

Just a question since I have a 83’ HO. How would a oxygen sensor impact the AFR if it needs to be replaced? My car has one on the driver’s side Y pipe.

TransamGTA350

iTrader: (2)

It could definitely affect the AFR reading. The O2 sensor is relatively inexpensive. If it hasn't been replaced recently, I would go ahead and replace it.

dangcamaro

I'm away from the vehicle a couple days so I'll get to tinkering later this week. Thanks so much for responses. This forum has proven super helpful many times now. I'll keep ya posted.

Carlos89

This place is truly a blessing.

dangcamaro

So it'll be the weekend before I get to working on this issue. I'm gonna get timing set as discussed above but wondering about any of these adjustments below.

1. Lean Mixture Solenoid screw: would a clockwise adjustment (small, like 1/4 to 1/2 turn) to narrow the gap from plunger to jets be beneficial? If I did that, I'd also a adjust rich mixture plunger to maintain 1/8" (4/32") gap, and the idle air bleed to maintain the 1.756 (does changing/deviation on this gap do anything bad?).

2. Idle air needles: currently they're set at factory 3 3/8 turns, what would 1/2 turn or so do?

I might be over thinking it. I'm not sure if computer operates best at factory settings, or what impact altitude has since I'm over 5000 ft ASL. I'm guessing some of CO/HC numbers could be from lack of O2.

naf

iTrader: (7)

you're overthinking it.

adjusting the IAB screw to narrow down dwell will account for any small variations in plunger depth, idle mixture screws, etc. on a near stock motor anyway.

as long as you have the dwell responding to changes in O2 (which I think you do) all your other settings should be fine.

set your timing, adjust IAB for dwell. come back if something doesn't appear to be working.

...and double check your TPS is operating correctly while you're there.

dangcamaro

Thought I'd give an update on my emissions and tuning status. I jumped the gun on getting emissions checked before purchase of vehicle was official through estate. Once that's complete, I'll be able to get official emssions results.

I have car in storage and I go a couple times a week to start it and run it down a road and back. I did get the timing set to about 8 degrees advanced at idle (dash tach shows about 650 rpm). For some reason after taking a good drive and getting everything warm (maybe 10 minutes) then getting to idle the timing mark was closer to 12-10 degrees before adjusting.

It's probably worth mentioning the distributor is the original HEI (EST) with ESC so no vacuum advance, but a boatload of sensors. I'm gonna spend more hours reading through shop manual section 6E1 on carb emissions and driveability systems and attempt to get more familiar with all the sensors and what not.

My biggest question is could sensors be impacting any of the emissions? Should anything there be inspected? Also, with this type of ECM/computer controlled ignition is there dwell to measure and adjust or does setting IAB, lean/rich, and idle air needles determine all that?

Well, there's a long winded way of saying....it's a work in progress. I'll let you know what happens when I get emissions done. Probably need to address the noisy rear end first (the Gov-lock and rear axle are noisy). I'll keep y'all posted.

TransamGTA350

iTrader: (2)

Did you disconnect the EST connector on the distributor before setting the timing? Base timing should be 6 degrees BTDC on that motor. How does it run after changing the timing?

The only other sensor I would change now would be the O2 sensor. Relatively inexpensive and easy to change and an old O2 sensor can definitely cause issues with emissions.

If after doing that it runs good, I would stop there and go have it tested again.

dangcamaro

I did try to unplug "this one" here (in photo), but engine died. Wasn't sure what I was messing with.

Is EST same as the ECM? Wouldn't the same thing happen if I unplugged the 3 pin connector that runs to ECM (located on base of housing)? Would I have to jumper a connection for engine to run when ECM disconnected.

I'm interested in trying to set timing with EST/ECM disconnected, I just want to make sure I have say half an idea of what I'm doing.

I'll look into replacing O2 sensor, wouldn't hurt.

TransamGTA350

iTrader: (2)

No, don't disconnect that one. The EST/ECM wire is the 3-wire connector at the base of the distributor. Disconnect it with the ignition off, then start it. If the timing is way off, it may not run with that connector disconnected. You may have to move the distributor a bit to get it to start and run, then set it to the right position with the timing light and lock down the distributor bolt. Shut it off, plug the connector back in and start it up again. If you are setting the base timing to 8 degrees BTDC with the connector plugged in, the timing will be very retarded from where it should be.

dangcamaro

That’s great information, I’ll try it soon. Thanks.

theraymondguy

The one you unplugged is the connection for the ignition coil.