2020-B2-2

Author Topic: "Pop!" while driving then engine shut off  (Read 1714 times)

EspriTA350

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"Pop!" while driving then engine shut off
« on: August 29, 2019, 02:06:22 PM »
Was taking the firebird on a routine evening drive yesterday when I got interrupted about 10 minutes in with an audible "pop!" noise. Engine was turning about 1800-2000 rpm until that occured. I immediately checked the gauges and started slowing down and pulling over, didn't realize until I started turning the wheel that I had no power steering (and that the engine was already off) but this all happened in the course of maybe 2-4 seconds. So I'm on the side of the road expecting to find the worst, but I didn't see any huge trail of oil, no leaks underneath, no smells, no obvious catastrophic damage like smoke or a rod sticking through the hood or the block etc. I check the oil level which turned out to be a little low, but not dangerously low. So I decided it'd be safe to try cranking a couple of times. Both times it cranked fine but no start at all. I'm suspecting maybe the timing chain failed completely (engine is at 118k and probably still on the original chain), or something with the ignition although I'm not sure what could've made that popping noise. All of the ignition components are only a few years old but I'm checking them regardless. The car is at home as we speak and I've only just started going through it, but I am admittedly something of a novice when it comes to these things. Anyone have ideas on what I should check/what it could be?
« Last Edit: August 29, 2019, 02:10:29 PM by EspriTA350 »

81Blackbird

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Re: "Pop!" while driving then engine shut off
« Reply #1 on: August 29, 2019, 02:48:34 PM »
Don't know the build of your engine but I don't think it's the timing chain since you mentioned it turned over fine.  Doesn't sound like you have piston to valve clearance issues.
Try pulling the distributor cap and check there first.  Not much but it's a start until someone else chimes in.

EspriTA350

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Re: "Pop!" while driving then engine shut off
« Reply #2 on: August 29, 2019, 03:16:21 PM »
Don't know the build of your engine but I don't think it's the timing chain since you mentioned it turned over fine.  Doesn't sound like you have piston to valve clearance issues.
Try pulling the distributor cap and check there first.  Not much but it's a start until someone else chimes in.
It's basically a stock 72 350. Has a qjet and an edelbrock intake, dual exhaust, nothing major. Also has one of those electronic ignition retrofit modules inside the distributor, not sure how those would act when they crap out but thought I'd add that piece of info. It's made by accel.

Topped off oil (1/2 qt did the job, shame on me for not checking that sooner) I checked under the dist cap and everything looks brand spanking new. Checked all my wires and I did notice that the main ignition wire coming off the coil came off a bit too easily, so I made sure it was back on there snug. I also noticed this:





looks like the upper heater hose is being kinked by part of the distributor advance, though I'm not even sure how... I did those hoses 2 months ago and there were no clearance issues.

Update: tried firing her up again to see if it was just the loose ignition wire, she catches and fires up but she sounds like absolute crap... like way less than 8 cylinders and she dies off pretty easily. Going to double check to make sure I put everything with the distributor back on tight and didn't knock anything loose.

Update 2: Re-tightened distributor cap and made double sure the rotor was tight, still doesn't want to stay running unless you keep giving it some gas, in which case it sounds like crap. Not gonna force her until I get some more advice on where to check. At least she starts now.
« Last Edit: August 29, 2019, 03:42:53 PM by EspriTA350 »

Bluebandit

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Re: "Pop!" while driving then engine shut off
« Reply #3 on: August 29, 2019, 03:50:05 PM »
looks like the upper heater hose is being kinked by part of the distributor advance, though I'm not even sure how... I did those hoses 2 months ago and there were no clearance issues.

If you didn't leave it like that then its possible the distributor hold down is slightly loose and let it turn.

FormTA

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Re: "Pop!" while driving then engine shut off
« Reply #4 on: August 29, 2019, 04:48:19 PM »
^^^^ That's my thought too. Get a timing light and see where it's at. My guess you need to back that cap up quite a bit.
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oldskool

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Re: "Pop!" while driving then engine shut off
« Reply #5 on: August 29, 2019, 04:56:59 PM »
"...I did those hoses 2 months ago and there were no clearance issues..."

As said, the dist has obviously rotated some, in a counterclockwise direction. So, IF that's the ONLY problem, just rotate the dist back in a clockwise direction. This will increase the ignition timing advance, since Pontiac dist shaft/rotor turns in a counterclockwise direction.

Low timing will drastically reduce engine power, produce more coolant heat, and if low enuff, make idle very difficult.

If too high, it can cause pinging, detonation, & engine damage. Most Pontiacs seem to run best at somewhere between 30° & 36° BTDC, at WOT. Most seem to idle best at somewhere between 12° & 24°. Most will set their initial @ about 9°-12°, then use an adjustable vacuum advance to achieve exactly the best idle timing setting. Too much vac advance can cause detonation, especially with low octane pump gas.

It has been posted online, many times, that it's best to set your total mechanical advance first, THEN do whatever it takes to achieve the best initial & part throttle advance. This is sometimes referred to as the timing curve. Most say it's best to have ALL the mechanical advance in by 3000 rpm. Many factory dist don't achieve max advance til 4000 rpm or higher.

To achieve it at 3000 rpm will, most of the time, require at least one weaker spring, holding the centrifugal advance weights. Kits are available, which contain 3 sets of weaker springs. Most say the lightest springs in the kit will not hold up & should be avoided. Max mechanical advance can be determined by removing one spring entirely. Removing both springs will allow the max advance to be determined at an even lower rpm.

Once max mechanical advance is set, some combination of springs will be required, to set the rpm at which you desire the max advance to be achieved. All of this is done with the vac advance unhooked & the vac source plugged.

Once max advance rpm has been set, THEN you can work on getting your initial & part throttle advance correct for your engine. If your dist has too much centrifugal advance, you'll have to make some sort of positive advance stop, or settle for lower advance at idle, before adding any vac advance. You'll obviously need a decent timing light. If the balancer is not marked, you'll need an accurate dial-back timing light, to set your max mechanical advance, since the stock timing tab does not go high enuff. 

Crane sells a kit which contains an adjustable vac advance, plus 3 pairs of springs.

https://www.oohall.com/2019-crane-cams-99601-1-adjustable-kit-vacuum-advance

https://www.ebay.com/itm/Crane-99601-1-Vacuum-Advance-Kit-Adjustable-Vacuum-Canister-Springs-Cam-Limiter/273885434550?epid=1939755269&hash=item3fc4d812b6:g:RuwAAOSw-GtdABrF

https://www.amazon.com/Crane-Cams-99601-1-Adjustable-Advance/dp/B000CIO2KY

I'm not sure of a good quality dial-back light, for a reasonable price. Maybe some of these guys know. Some pro mechanics insist on high dollar tools, like Snap-On. Most street guys don't wanna spend that much on a tool they'll use very little. Maybe some can rent or borrow a good dial-back light.
 
« Last Edit: August 29, 2019, 05:31:32 PM by oldskool »

EspriTA350

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Re: "Pop!" while driving then engine shut off
« Reply #6 on: August 29, 2019, 05:16:49 PM »
Well I'll be damned. I thought that looked out of place but wasn't 100% that'd be the issue. Guess I know what I'm doing this weekend. Never done timing before, so this will be a first. Is it normal for these things to just work themselves loose over time, or is this something that really shouldn't happen?

oldskool

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Re: "Pop!" while driving then engine shut off
« Reply #7 on: August 29, 2019, 05:33:33 PM »
Well I'll be damned. I thought that looked out of place but wasn't 100% that'd be the issue. Guess I know what I'm doing this weekend. Never done timing before, so this will be a first. Is it normal for these things to just work themselves loose over time, or is this something that really shouldn't happen?

Reach down there & turn the dist with your hands. You can tighten the bolt a little at a time, to see how tight it has to be, to keep the dist from turning.

81Blackbird

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Re: "Pop!" while driving then engine shut off
« Reply #8 on: August 30, 2019, 05:18:51 AM »
If it's an accel then it's more than likely an adjustable vacuum advance pod.  But that is not the issue.  The above suggestions will get it running again.

Grand73Am

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Re: "Pop!" while driving then engine shut off
« Reply #9 on: August 30, 2019, 09:04:25 AM »
On a Pontiac V8, the vac advance should be aimed toward the driver side where there's more room, instead of the passenger side as you have it. And that would get it away from that heater hose. But, you'd need to know how to remove and reinstall and time the distributor.
Steve F.

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Re: "Pop!" while driving then engine shut off
« Reply #10 on: August 30, 2019, 10:00:03 AM »
I've found on a number of occasions on various engine brands that the stock (or aftermarket) distributor hold down isn't holding the distributor tight enough to prevent it from turning. Sometimes it's the design of the little bracket and sometimes the bolt threads bottom out before the bracket is actually tight enough to pinch the distributor flange to the block, so it "feels" tight when tightening the bolt but may not keep the distributor from rotating.
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81Blackbird

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Re: "Pop!" while driving then engine shut off
« Reply #11 on: August 30, 2019, 10:45:17 AM »
I just rec'd a new one yesterday.  The one I had, had wings on the side.  I don't know who thought that was a great idea.  You could get a wrench on it but couldn't turn the darn thing.

EspriTA350

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Re: "Pop!" while driving then engine shut off
« Reply #12 on: August 30, 2019, 03:58:13 PM »
The distributor felt too tight to turn by hand before I loosened the bracket. Not sure what's going on if it wasn't loose. I peeked at the distributor gears and they didn't look rounded off although you could tell they weren't brand new. Now I get to try re-time this thing... yay...
« Last Edit: August 30, 2019, 11:56:30 PM by EspriTA350 »

Ryoko

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Re: "Pop!" while driving then engine shut off
« Reply #13 on: August 30, 2019, 08:52:39 PM »
I think the question is why it's so far out of timing. Did it jump a tooth on the timing chain?

EspriTA350

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Re: "Pop!" while driving then engine shut off
« Reply #14 on: August 31, 2019, 12:04:59 AM »
I think the question is why it's so far out of timing. Did it jump a tooth on the timing chain?
It must've jumped timing on one or the other, dist or timing chain. Again, far as I know it's the original chain. May be the original distributor gear too, although the guts inside the dist are aftermarket. The "pop" was probably a backfire from the engine being so out from normal timing. I've never noticed any of the tell-tale sounds of a failing distributor or timing chain like the rattling, squealing etc.

Re: "Pop!" while driving then engine shut off
« Reply #14 on: August 31, 2019, 12:04:59 AM »


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EspriTA350

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Re: "Pop!" while driving then engine shut off
« Reply #15 on: September 01, 2019, 05:32:29 PM »
Tried my best with what I had available. I took the distributor out, moved the engine by hand so cylinder #1 was @ TDC, reinstalled distributor, noted that the rotor was pointing at cylinder #1. I put everything else back on, went to start it and I got nothing but a little backfire in the intake. Tried advancing and retarding a little in either direction with the same result. I didn't want to harm anything so I stopped for now. I thought the procedure should've gotten me in the ballpark at least?

pancho400cid

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Re: "Pop!" while driving then engine shut off
« Reply #16 on: September 01, 2019, 06:55:21 PM »
If it was running fine before the pop, it may have jumped time due to failed cam gear if you used a stock nylon gear.  A broken timing chain is also possible.

Pull the wires that provide power to the distributor so the car is not firing.  Pull the distributor cap.  Crank the starter.  If the distributor rotor isn't turning, the timing chain is broken.

PS - If the chain is broken the engine cranks a bit faster than normal.
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cyber104

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Re: "Pop!" while driving then engine shut off
« Reply #17 on: September 02, 2019, 06:22:04 AM »
"Also has one of those electronic ignition retrofit modules inside the distributor, not sure how those would act when they crap out but thought I'd add that piece of info. It's made by accel."


You might want to try replacing that module...........

It seems you're focused on timing - but if the car was running down the road with the distributor in that position and it just stopped - I'd be looking for an ignition problem
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gstrandfarm9420

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Re: "Pop!" while driving then engine shut off
« Reply #18 on: September 02, 2019, 02:54:56 PM »
Find TDC on no. 1 cyl , check and see if the timing mark on the front damper lines up with the right  numbers on the cover, also see where your rotor is pointing in the distributor at that point, should be no. 1 terminal. I'd be willing to bet they are not right. Your symptoms describe a timing chain that jumped the gears. Pontiac used plastic coated gears for quieter running, eventually the plastic breaks off, not an uncommon problem.

Lewis

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Re: "Pop!" while driving then engine shut off
« Reply #19 on: September 06, 2019, 04:50:21 PM »
I have no solution to  your problem, just this. A Delco-Moraine engineer told me in 1979 that those timing sets were engineered to fail between 60 and 80 thousand miles. If you get 90 you are on borrowed time.
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NOT A TA

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Re: "Pop!" while driving then engine shut off
« Reply #20 on: September 06, 2019, 06:20:39 PM »
Tried my best with what I had available. I took the distributor out, moved the engine by hand so cylinder #1 was @ TDC, reinstalled distributor, noted that the rotor was pointing at cylinder #1. I put everything else back on, went to start it and I got nothing but a little backfire in the intake. Tried advancing and retarding a little in either direction with the same result. I didn't want to harm anything so I stopped for now. I thought the procedure should've gotten me in the ballpark at least?

Backfire in the intake under the circumstances ^^^ would indicate you were 180 degrees off. In other words you had the engine at TDC on the exhaust stroke.
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Ford5of5

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Re: "Pop!" while driving then engine shut off
« Reply #21 on: September 11, 2019, 12:40:07 PM »
Just my 2 cents but I've had 2 different Petronix units fail on 2 different Fords after a year or 2. My thought is that they are dying due to heat.
 
X2 on the dizzy being stabbed incorrect compared to factory. Someone installed it Chevy style!  :lol:  On multiple cars I've run into issues were someone pulled the distributor and reinstalled them incorrectly. The factory clocks it in certain way to have plenty of adjustment. It's likely that you're timing wasn't optimal because people tend to give up on getting the timing right when they can't get the proper amount of adjustment or they start adjusting the carb!

Best bet is to buy a new HEI distributor. Check Rock Auto, they sell a nice, complete unit with all new components that should drop right in.  Search for CARDONE 841891 Another TAC member was able to get the exact same unit off EBAY for even less money. Just be sure to check the modulator to see if it has thermal paste on it. If it doesn't add some; it's to help cool the modulator.
« Last Edit: September 11, 2019, 12:55:46 PM by Ford5of5 »

EspriTA350

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Re: "Pop!" while driving then engine shut off
« Reply #22 on: September 12, 2019, 12:30:25 AM »
Sorry everyone, got injured at work so I haven't been able to do much since my last post. Hopefully this weekend I will have time to do some more checking around.

If it was running fine before the pop, it may have jumped time due to failed cam gear if you used a stock nylon gear.  A broken timing chain is also possible.

Pull the wires that provide power to the distributor so the car is not firing.  Pull the distributor cap.  Crank the starter.  If the distributor rotor isn't turning, the timing chain is broken.

PS - If the chain is broken the engine cranks a bit faster than normal.
Good thinking, I'll definitely give a quick check under the distributor cap and see if it turns. Far as I know it's still the stock timing gear, so it wouldn't be the first nylon timing gear to fail.

"Also has one of those electronic ignition retrofit modules inside the distributor, not sure how those would act when they crap out but thought I'd add that piece of info. It's made by accel."


You might want to try replacing that module...........

It seems you're focused on timing - but if the car was running down the road with the distributor in that position and it just stopped - I'd be looking for an ignition problem

It was turned clockwise a bit more beforehand. I'd stake my life on it, because when I did the heater hoses there wasn't any vacuum advance in the way.

Backfire in the intake under the circumstances ^^^ would indicate you were 180 degrees off. In other words you had the engine at TDC on the exhaust stroke.

Crap. Well I feel silly now but at least that's an easy fix. It wouldn't have hurt anything, would it?

EspriTA350

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Re: "Pop!" while driving then engine shut off
« Reply #23 on: September 13, 2019, 03:58:14 PM »
Well I did a quick check of turning the motor while watching the distributor rotor, and it turns with the engine. So the chain isn't broken but that doesn't mean it isn't stretched at the least. Also snapped a few pics of my distributor. You can definitely tell it's an old unit. I'm not sure where the line is between healthy and unhealthy looking distributor gears so I snapped a few pics. Definitely a little wear but nothing rounded off or chipped.









« Last Edit: September 13, 2019, 03:59:53 PM by EspriTA350 »

highway star

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Re: "Pop!" while driving then engine shut off
« Reply #24 on: September 13, 2019, 08:54:41 PM »
Checked carburetor?

EspriTA350

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Re: "Pop!" while driving then engine shut off
« Reply #25 on: September 13, 2019, 10:01:56 PM »
Checked carburetor?

I checked it briefly the day it happened. Everything looked clean inside and out so don't think that'd be the issue.

Ryoko

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Re: "Pop!" while driving then engine shut off
« Reply #26 on: September 14, 2019, 07:07:21 AM »
Since the distributor gear appears to be in working order, it's time to start thinking about the timing chain gain. Yeah, those are no fun. As an easy spot check, you might put a breaker bar on the crank pulley and rock it back and forth to gauge how much slack is in the chain. How many degrees do you need to turn the crank before the distributor moves?

Ford5of5

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Re: "Pop!" while driving then engine shut off
« Reply #27 on: September 14, 2019, 09:59:30 AM »
Like others have said, it's possible that the distributor clamp just loosened up. The rotor and shaft turn counter-clockwise and that could have caused the unit to hit the coolant hose. First thing I'd try is setting the dizzy back up correctly. Correctly is a loaded word but I'd aim for factory style, it takes out guess work if you have issues later on.

Did your timing mark move around when setting timing before this incident? Do you hear any crustyness in the bearings of the dizzy? End play of the shaft should be around .015-.020 and can be checked with feeler gauges. The shaft does try to move up and down with changes in RPM. Do you notice any side to side play in the shaft bearings? Distributors are fairly stout but do wear out.

This is how the points dizzy should look when viewed from the rear of the engine. Like someone else said, yours looks to be 180* out:
dsfg by Chris Ford, on Flickr


This is a HEI from the front:
1979 TA (297) by Chris Ford, on Flickr


This guy has a good video for checking the slop on a timing chain:
https://www.youtube.com/watch?v=4_f5ukZVri8

firebirdparts

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Re: "Pop!" while driving then engine shut off
« Reply #28 on: September 15, 2019, 07:18:44 AM »
If you time to TDC on #1 you have a 50% chance of getting close.  It sounds like you got it 180 out.

You need to address that first.  It’s a lot of work to inspect that timing chain.
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highway star

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Re: "Pop!" while driving then engine shut off
« Reply #29 on: September 18, 2019, 07:33:07 PM »
Q-Jet? Power valve pop?

Ford5of5

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Re: "Pop!" while driving then engine shut off
« Reply #30 on: October 14, 2019, 03:20:42 PM »
Was there a resolution to this issue? Don't just leave us hanging! The mystery of it is killin me.  :lol:

EspriTA350

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Re: "Pop!" while driving then engine shut off
« Reply #31 on: October 26, 2019, 02:32:48 PM »
Well I apologize for leaving everyone hanging. Pinched nerve has kept me from being able to do much, but finally I'm feeling well enough so I took another shot at everything today. What I've found out is that I did not quite get to TDC the last time I tried to time it. I stopped as soon as I felt the compression, so it wasn't even that I was 180 out either. This time I'm as close as is possible without the use of a gauge, but it's just not running like a v8 that's "in the ballpark" for timing. First two times that I got it to fire up, it ran but it sounded like absolute crap. I tried to take a good video of it but the next two times I tried to start it sounded even more different and wouldn't even stay running. Since I don't want to hurt anything in the engine more than it may already be, I called it quits yet again. At least it's not backfiring now though. Here's how it sounded:

https://www.youtube.com/watch?v=cgoIzRuBdlA&feature=youtu.be

As for the vacuum canister being oriented incorrectly, I think one of the previous owners put it on the distributor that way and there's no way for me to fix that orientation without taking it all apart. I don't think it's 180 out, because if I tried to put it 180 degrees the other direction, the intake manifold and carb are gonna be in the way. Just something I'm gonna have to put up with for now.

Also, who makes a good distributor mounting gasket that doesn't rip as easily as the itty bitty fel pro ones? Mine hasn't even had one for who knows how long, so I went to put the fel pro one in and it completely ripped as I was putting the distributor back in.
Since the distributor gear appears to be in working order, it's time to start thinking about the timing chain gain. Yeah, those are no fun. As an easy spot check, you might put a breaker bar on the crank pulley and rock it back and forth to gauge how much slack is in the chain. How many degrees do you need to turn the crank before the distributor moves?
It seems to move in unison with the crank, but this is also my first time ever dealing with something like this, so take that with salt.

« Last Edit: October 31, 2019, 11:43:59 AM by EspriTA350 »

oldskool

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Re: "Pop!" while driving then engine shut off
« Reply #32 on: October 26, 2019, 02:51:32 PM »
I'll just throw this in there, for whatever it might be worth.

I recently dealt with a ruff idling, popping problem with my 455. After changing carb, dist, rotor, cap, & wires, I decided to check the plugs. Several were wet with gas, & all were black.

Well, the only other plugs I had were those that I'd taken out, to install these. They were also quite sooty. So, used a wire brush to clean 'em off as best I could, then installed 'em. Problem cured. It ran great. Idled good. Revved good.

So, I don't know if any of those other parts were causing any problems, or not. Next time, I think I'll check the plugs first.   

EspriTA350

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Re: "Pop!" while driving then engine shut off
« Reply #33 on: October 26, 2019, 03:21:54 PM »
I'll just throw this in there, for whatever it might be worth.

I recently dealt with a ruff idling, popping problem with my 455. After changing carb, dist, rotor, cap, & wires, I decided to check the plugs. Several were wet with gas, & all were black.

Well, the only other plugs I had were those that I'd taken out, to install these. They were also quite sooty. So, used a wire brush to clean 'em off as best I could, then installed 'em. Problem cured. It ran great. Idled good. Revved good.

So, I don't know if any of those other parts were causing any problems, or not. Next time, I think I'll check the plugs first.

Just so happens that I have a couple of sets of brand new plugs... guess it couldn't hurt to do, but I'm out of patience and time for any more shenanigans tonight.

Ford5of5

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Re: "Pop!" while driving then engine shut off
« Reply #34 on: October 26, 2019, 04:47:22 PM »
The next person that says shenanigans is gonna get pistol whipped! I'm quoting a movie, not threatening an entire board of people that may be better armed than me.  :lol:

The distributor can be stabbed in and will function fine in multiple positions as long as the wires are put on the correct terminal for the way it is set up. The vac canister can only be installed one way. The entire distributor is clocked wrong and/or you got the wrongs wires going to the wrong plugs. I tend to lean towards putting things like this back to factory only to avoid confusion on stuff like this. By any chance, did you hook your timing light up to the #2 wire instead of the #1 when adjusting timing? Not that I ever done something like that. :shock: It's a real easy mistake to make.

My opinion, don't pull the dizzy again until your back is better. I ruptured 2 disks over 10 years ago and this is not the kinda thing you want to be working on when your back is tweaked.

When you are better, or had enough beers, put #1 on top dead center on the compression stroke. You'll know it's the compression stroke because it will force your finger out of the hole; another way to tell is to pull the valve cover and you'll see both valves will be closed. I use a long screw driver and watch for it to start to fall. When it starts to fall you've gone past 0* TDC. Look at your timing tab and mark, they should be at 0 or really close to it. Turn the crank backwards and advance again until the mark hits 0*. Pull out your distributor and point the vac can towards 3 o'clock and your rotor should be pointing at about 2 o'clock, try for 1:30. You may need to wiggle the dizzy or bump the crank just a tiny bit. When you go to adjust your timing, if the vac can hits the intake you installed it off by a tooth. Pull the dizzy up just enough to turn it counterclockwise just one tooth and it should drop back down.

Do a search for Pontiac firing order and use that to set up your wires. Do you have a service manual? They usually have a step by step procedure and pictures that can help.

It's a lot easier than it sounds when reading...
« Last Edit: October 26, 2019, 05:00:49 PM by Ford5of5 »

EspriTA350

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Re: "Pop!" while driving then engine shut off
« Reply #35 on: October 26, 2019, 05:33:05 PM »
The distributor can be stabbed in and will function fine in multiple positions as long as the wires are put on the correct terminal for the way it is set up. The vac canister can only be installed one way. The entire distributor is clocked wrong and/or you got the wrongs wires going to the wrong plugs.

I left all the wires hooked up even when I took the distributor out. I'll admit it's clocked wrong, but I'll get to that.

By any chance, did you hook your timing light up to the #2 wire instead of the #1 when adjusting timing? Not that I ever done something like that. :shock: It's a real easy mistake to make.

Didn't even get that far. It didn't sound like it would've stayed running for very long when I took my foot off the gas, so I shut it down. No timing light today.

When you are better, or had enough beers, put #1 on top dead center on the compression stroke. You'll know it's the compression stroke because it will force your finger out of the hole; another way to tell is to pull the valve cover and you'll see both valves will be closed. I use a long screw driver and watch for it to start to fall. When it starts to fall you've gone past 0* TDC... ...Pull out your distributor and point the vac can towards 3 o'clock and your rotor should be pointing at about 2 o'clock, try for 1:30. You may need to wiggle the dizzy or bump the crank just a tiny bit. When you go to adjust your timing, if the vac can hits the intake you installed it off by a tooth. Pull the dizzy up just enough to turn it counterclockwise just one tooth and it should drop back down.

Do a search for Pontiac firing order and use that to set up your wires. Do you have a service manual? They usually have a step by step procedure and pictures that can help.

It's a lot easier than it sounds when reading...
I will swear on my life that I had it set with #1 at TDC, unless it's somehow possible to feel the compression on the wrong stroke. I go by the firing order on the intake manifold and also have a couple shop manuals. I don't think the vac can will fit @ 3:00 because then it's gonna hit the coil.

Look at your timing tab and mark, they should be at 0 or really close to it.
How in the heck did I forget to do this... though it shouldn't be the root of the problem, provided I did everything else correct.

Unless I still messed up setting it at TDC, I think we're looking at a stretched chain. How else would it go from running (albeit very poorly) after 2 cranking attempts, to barely even catching at all (the way it was behaving in the video)? Anyone else think so? oldskool mentioned plugs, maybe there's a chance they all got fouled from these and the past attempts.

b_hill_86

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Re: "Pop!" while driving then engine shut off
« Reply #36 on: October 26, 2019, 05:53:03 PM »
For what it’s worth, be careful which shop manual you use for firing order. My chiltons (or Haynes, I can’t remember) had the distributor rotation for Pontiac V-8s one direction in one part of the book and the opposite direction elsewhere.  Just something to consider.
-Brian-

1977 Trans Am 400 4 speed

Ford5of5

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Re: "Pop!" while driving then engine shut off
« Reply #37 on: October 27, 2019, 05:37:36 PM »
Let's assume the dizzy was clocked incorrectly to begin with and you left the wires attached to it. How did you figure out where to attach the spark plug ends, did you mark them or did you put them back in according to the manual?

http://pontiacformula.free.fr/en/allumage.php
https://butlerperformance.com/rt-5038-the-pontiac-engine.html

I'm basically hearing misfiring in your video. It's possibly a worn chain but first eliminate all the easy/free things that it could be.

I'm sorta working on the idea that the dizzy loosened up while you were driving and just needed to be put back to where the PO had it.

If the vac can hits the coil when you go to adjust timing then bend the bracket a little, or relocate the coil or back the rotor off one tooth like I mentioned in my last post.


EspriTA350

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Re: "Pop!" while driving then engine shut off
« Reply #38 on: October 29, 2019, 10:28:51 PM »
Let's assume the dizzy was clocked incorrectly to begin with and you left the wires attached to it. How did you figure out where to attach the spark plug ends, did you mark them or did you put them back in according to the manual?

I just did them one at a time when I replaced them with the spark plugs 2 years ago.

Ryoko

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Re: "Pop!" while driving then engine shut off
« Reply #39 on: October 30, 2019, 09:20:57 AM »
Just a wild thought -- did you drain the oil to see if there were any pieces of plastic in the pan?

Re: "Pop!" while driving then engine shut off
« Reply #39 on: October 30, 2019, 09:20:57 AM »
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