So I'm having issues that began with a drivability problem on my 92 Safari with the SBC conversion. 5.7L, Edelbrock 1406 carb.
Today, after rebuilding the carb (it's been 20 years since purchase), replacing the fuel filter, the coil, the cap and rotor, the ignition module, and the wiring from the distributor to the coil I attempted to check and set the timing. Since I didn't have the distributor out I didn't verify TDC. Anyway, I get the thing warmed up, disconnect the vacuum advance, and set the timing to 12* BTDC. Runs great, nice smooth idle at about 850 RPMs. So I hook up the vacuum advance and the van dies when I crack the throttle.
I check the vacuum advance. Working as it should. No leaks. Mechanical advance is free and returns when released.
I discuss with a friend and he suggests I try putting the initial timing back to 0* and see what happens. Before I do that I pop the cap on the distributor and check TDC. The rotor is not pointing at number one, but about a 1/4 inch past (clockwise) where it should be. I move the distributor housing to align the rotor with TDC. Barely starts and runs like crap, super low idle. I turn the distributor clockwise until it starts smoothly. Go though and set initial timing to 0* as discussed. Plug in vacuum advance. Van dies. Here's a pic before turning the distributor. The yellow is where #1 is on the cap.
This time when the engine dies however I'm inside the van (the doghouse is off), and I notice when the engine dies there's a clicking sound that sounds like a fuel pump. Only problem is I don't have a clacky clack pump. I have an in tank pump. I lean in and discover the noise is the distributor. Never heard that before. It goes away when I turn the key off, returns when I turn the key to the run position.
Here's the video.
Thoughts?
NOHOME
MegaDork
7/22/23 9:17 p.m.
Verify that when the vacuum loads the plate it does not move the shaft so that it hits the reluctor wheel. Had that issue and it was a pain to figure out; felt like a carb bog when I got on the gas.
Tug on the two little wires going from the module to the pickup coil.
Streetwiseguy said:
Tug on the two little wires going from the module to the pickup coil.
Because? And what should I be seeing or finding? You think their broken maybe?
NOHOME said:
Verify that when the vacuum loads the plate it does not move the shaft so that it hits the reluctor wheel. Had that issue and it was a pain to figure out; felt like a carb bog when I got on the gas.
I did check clearances in the inside the cap. The advance linkage moves freely.
If that picture is taken with #1 TDC then you're 180 out which isn't a problem as long as all the wires are rotated. Not saying that's your problem just an observation.
vwcorvette (Forum Supporter) said:
Streetwiseguy said:
Tug on the two little wires going from the module to the pickup coil.
Because? And what should I be seeing or finding? You think their broken maybe?
Give them a yank. When the vacuum advance engages, those wires flex. Flex in wires leads to...
I'm a pretty old guy. I've changed a lot of HEI pickup coils
NOHOME
MegaDork
7/22/23 11:44 p.m.
In reply to vwcorvette (Forum Supporter) :
My problem was not the rotor to cap clearance but rather the gap between the magnetic pick-up points further down. The shaft moved ever so slightly and one of the gaps was a little smaller than the other one so it just nicked the point when you transitioned the vacuum.
As stated above on a sbc the #1 terminal is usually in the front left on dist, or about 11 o'clock position if viewed from above. But that really isn't important. What is important is if that mark is #1 and your plug wires are marked correctly in the pic then your plug wires are installed wrong. They should go 1-8-4-3-6-5-7-2 going clockwise.
Are you sure your mark isn't TDC on the exhaust stroke?
Ignore the numbers on the wires. They are installed in the correct order. Yes, the distributor is 180 out. Car runs fine at idle with the distributor in this position. But when I hook up the vacuum advance it dies. I will check the felxing wires to the module as instructed.
Another method that works well for setting timing is just get it where it will idle, leave the vacuum advance connected, hook up a vacuum gauge and rotate the distributor until you get the highest vacuum reading. That is where you leave it. That's also how you set your idle mixture screws on a carb.
gearheadmb said:
Another method that works well for setting timing is just get it where it will idle, leave the vacuum advance connected, hook up a vacuum gauge and rotate the distributor until you get the highest vacuum reading. That is where you leave it. That's also how you set your idle mixture screws on a carb.
I will try that also.
A friend mentioned that maybe the outer ring of the harmonic balancer may be out of position if the rubber has deteriorated. It is over twenty years old.
Streetwiseguy said:
vwcorvette (Forum Supporter) said:
Streetwiseguy said:
Tug on the two little wires going from the module to the pickup coil.
Because? And what should I be seeing or finding? You think their broken maybe?
Give them a yank. When the vacuum advance engages, those wires flex. Flex in wires leads to...
I'm a pretty old guy. I've changed a lot of HEI pickup coils
I hit the advance with vacuum and watched the mechanism and wires move. They are kinda punky, and they are cracked right where they go into the ring under the weights. Any way to test if I'm losing connection without the engine running and the cap off?
If those two little wires are the reason for my problem, is the only fix a new distributor?
Test the resistance through the wires while wiggling. Or, grab each wire and break the insulation that's holding it together. You won't hurt anything that's not already busted.
You should still be able to buy the pickup, I presume. Pull the distributor, locate the roll pin that retains the gear on the bottom, pull the shaft and advance mechanism out the top. There will be some goo on the shaft, so spray a bit of solvent or lube up the shaft to soften it up. The pickup is then accessible, I think a snap ring, but it's been 25 years... While you have the shaft out, take the weights off, find the two little e rings that keep the trigger wheel on, slide it off the bottom, clean and lube the shaft and bushing.
Take a couple of pictures, but they are pretty simple.
Streetwiseguy said:
Test the resistance through the wires while wiggling. Or, grab each wire and break the insulation that's holding it together. You won't hurt anything that's not already busted.
You should still be able to buy the pickup, I presume. Pull the distributor, locate the roll pin that retains the gear on the bottom, pull the shaft and advance mechanism out the top. There will be some goo on the shaft, so spray a bit of solvent or lube up the shaft to soften it up. The pickup is then accessible, I think a snap ring, but it's been 25 years... While you have the shaft out, take the weights off, find the two little e rings that keep the trigger wheel on, slide it off the bottom, clean and lube the shaft and bushing.
Take a couple of pictures, but they are pretty simple.
Oh. I was really hoping I could remove it from the top of the distributor while in the car. Well.
That's the part I found online. Unavailable until August at a few places. I'll keep looking. Summit has Summit branded and blueprinted distributors for $100. Maybe I'll just go with new???
Watched a video on testing the pickup coil. Should ohm out to between 500 and 1800 ohms. I get 784. When I flex the lines no change at all. You'd expect it to go to infinity at that point, but no change. Only time it changes is with vacuum applied and the armature moving. It goes up to about 820 or so. Release the vacuum and it returns to the original reading. I. Am. Stumped.
Perhaps I should pull the crank pulley and check the harmonic balancer.
Can anybody address the clicking coming from the Distributor with the key on, engine off?
vwcorvette (Forum Supporter) said:
Watched a video on testing the pickup coil. Should ohm out to between 500 and 1800 ohms. I get 784. When I flex the lines no change at all. You'd expect it to go to infinity at that point, but no change. Only time it changes is with vacuum applied and the armature moving. It goes up to about 820 or so. Release the vacuum and it returns to the original reading. I. Am. Stumped.
Perhaps I should pull the crank pulley and check the harmonic balancer.
The resistance shouldn't change when the vacuum advance moves. If it does there's something wrong with the pickup coil or your meter probe isn't making a good connection.
vwcorvette (Forum Supporter) said:
Can anybody address the clicking coming from the Distributor with the key on, engine off?
The only thing I can think of is that the module is triggering and you're hearing the spark. Pull the cap off and run a jumper from the center post to near a ground and see if there's a spark from the jumper to ground.
Does it stall when you crack the throttle with the vacuum advance disconnected?
Did you plug the vacuum advance hose when you set the initial timing?
Can you swap in a known-good coil?
Did you replace the accelerator pump when you rebuilt the carb?
Are you using manifold (not ported) vacuum (you should be)?
What base timing value do you end up with if you adjust the distributor for best engine sound with the vacuum advance connected?
APEowner said:
vwcorvette (Forum Supporter) said:
Watched a video on testing the pickup coil. Should ohm out to between 500 and 1800 ohms. I get 784. When I flex the lines no change at all. You'd expect it to go to infinity at that point, but no change. Only time it changes is with vacuum applied and the armature moving. It goes up to about 820 or so. Release the vacuum and it returns to the original reading. I. Am. Stumped.
Perhaps I should pull the crank pulley and check the harmonic balancer.
The resistance shouldn't change when the vacuum advance moves. If it does there's something wrong with the pickup coil or your meter probe isn't making a good connection.
I'm going to get another meter just to be sure. But I had the probes buried deep in the connector terminals. And it changed and returned the same every time when putting vacuum to the advance. It did not change however when flexing or moving the wires to see if there was a break.
