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1979 Dodge W150 Warlock Backfiring

M

Markzilla8

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Hey how's everybody doing? I have a 79 W150 warlock with a 360 that I'm trying to bring back to life to get me back and forth to work at the fire house this winter. I've run into plenty of problems along the way that I've been able to solve, however I'm having difficulties with the engine...
Ive replaced all the plugs with autolites and new wires, and also did an oil change with filter. The cap and rotor looked good so I saved some money there and didn't replace them. The truck fires up great, runs smoothly, however when it gets warm and up to temp it starts to pop/backfire out the exhaust. It pops all the way from idle to about half a pedal (haven't pushed it further in fear of damaging it). It's not rhythmic, so it pops randomly out both left and right sides of the exhaust, and not on a certain cylinder every time. I thought maybe the timing is off?? I was wondering is anyone has any other ideas on what could be causing this that I should look into.
Also, on the timing. I checked the harmonic balancer and couldn't find a timing tape under the accessory brackets. Can I time it without one?? Thanks in advaced!

-Mark
 
Which ignition system does it have? Do you have an induction timeing light? The strobe on the light will tell off the plugs are firing erratic or even. You will have to check each and every plug. If there is a problem that new parts will not fix do not rule out the new parts check them also.
 
It's the stock ignition system. I do have an induction timing light. I tried using it on the #1 cylinder and it seemed steady and consistent, but again, I only tested on the #1 cylinder. Tomorrow I'll check all of the cylinders and see how they look. Im going to go ahead and clean the harmonic balancer better and see if I can find a timing tape on it. I was originally planning on just adjusting the timing by sound, so when the backfiring stops, I was planning on just leaving the timing there. Any harm in doing that? Also, I need to make sure that all the wires are going to the correct cylinders.
 
There will not be a tape on the dampner unless someone added it just a mark across it. Turn the engine to where the rotor points to number 1 and the mark should be close to the timing marks on the timing cover.
Yes timing can be set without marks. There are various ways of doing it. I profure a good tack and vacuum gauge but reference marks are always good.
 
Hello from Minnesota. Welcome aboard. There's timing marks on the damper. I prefer Champion plugs myself, but Autolite plugs should work. As for the cap and rotor looking good, they might not be. I've had ones that looked fine but the engine ran like crap. They are cheap to replace so it wouldn't hurt to try new ones. Make sure you have the vacuum advance unhooked when setting the timing. Another thing to check is the vacuum advance. I had a car that ran like crap (people thought it had a big cam in it, it didn't) and when I took the vacuum line off the distributor, it purred like a kitten. Not saying you haven't taken the line off, just ruling things out. If you want to tune by ear, turn the distributor one way til it runs rough, then do the same in the other direction, trying to keep track of both extremes then set it in the middle. You've probably done everything properly, but you never know what some people miss.
 
Thanks for the replies so far! So today i double checked the spark plug wire order, all is good there. No wires out of place. I also cleaned and found the timing mark on the balancer and the timing indicator? on the block. Started her up, it's showing 0 degrees at idle when warm, with the vac advance plugged up. Here's the catch, I just read the reply that I'm supposed to disconnect vac advance when doing this. So I went back out and rechecked with the vac adv unhooked. Nothing changed with the timing. It sat at 0. When I gave it part throttle the timing slid to the "before" section of the timing indicator and hung around 10 and went higher with more throttle. Only thing that bothered me was that the timing would not come back down below "10 Before", until I shut the truck off and restarted it.
Now I'm assuming my vac advance is bad bc when I pulled it it didn't make a difference in idle speed/sound and no difference on timing. I tested by leaving hose connected to vac advance canister and sucking, made no difference. Then left hose connected to carb and sucked and it held vacuum.
 
Forgot to mention that you can put an Allen wrench (long end) in the hole the vacuum line goes to, and adjust when the canister opens for the advance. I just turned mine (I had to go a few turns, rebuilt distributor from the parts store I worked at) and everything settled down and the car ran fine after that.
 
Ok I'll give that a shot real quick. Turn clockwise or counter clockwise to get more or less vacuum?
 
I haven't done the vacuum advance adjustment yet, but I did go ahead and adjust the timing. I've got the timing set to just above the "Before 10", hoping to get the 12 BTDC setting. I had to adjust the idle screw on the carb slightly so that it wasn't revving so high (I don't have a tac on the truck so it's all off sound).
The results are that the truck seems to be running smoother and isn't relying on the idle screw to be pushed in so far to keep it running well. The popping has stopped at idle when it's warm, however when I give it throttle it still pops out the exhaust, but on the way back down it doesn't pop like it used to. Another side effect now though is that there's a decent bit of blue/grey smoke coming out both sides of the exhaust, more then before.
Any thoughts, suggestions, or ideas for what this could be, the popping and smoke, and how to fix it? Thanks again
 
The smoke sounds like oil being burnt. Is the vacuum line connected to full manifold vacuum or ported? With ported you don't get vacuum until the throttle opens. I am still thinking about the backfire/popping in the exhaust. Check the cap & rotor like Locu suggested.
 
I don't remember which way to turn, I do remember it was easy to figure out. Turning it one way gives it more advance the other takes advance out.
 
Markzilla8 said:
It's the stock ignition system. I do have an induction timing light. I tried using it on the #1 cylinder and it seemed steady and consistent, but again, I only tested on the #1 cylinder. Tomorrow I'll check all of the cylinders and see how they look. Im going to go ahead and clean the harmonic balancer better and see if I can find a timing tape on it. I was originally planning on just adjusting the timing by sound, so when the backfiring stops, I was planning on just leaving the timing there. Any harm in doing that? Also, I need to make sure that all the wires are going to the correct cylinders.
Click to expand...
 
I think you are spinning your wheels.

First ... off make sure the wiring is correct 1-8-4-3-6-5-7-2
Second ... Buy that rotor and cap...they cost less than an hour's labor...
Third ... Skip the timing light...slightly loosen the distributor, start the engine and retard the distributor (turn it clockwise for retard) until it slows or stumbles then advance it to the point where it just starts to speed up a little...tighten distributor.
This is close enough to proper timing so that you can drive around and see if the backfire is gone.
Fourth ... If you don't know how to time them by ear then use a timing light. I time mine by advancing the timing until I get a little rattle (knock) on hard uphill acceleration then I retard it just a skoche, and maybe again a little tiny amount until there is no-knock anywhere, then you are at the peak of power timing.
 
Ill go ahead and recheck the wires again. They appeared to all be in the correct order. One thing I did notice before I timed it yesterday, the #1 spark plug was pointing at the #2 cylinder. It's now pointing at the very front of the engine, still not at cylinder #1. Another thing I'll check is I'll take the cap off, crank it until the rotor is at cyl #1 and replace the cap to be sure the wires are lined up properly to the correct cyl.
The cap and rotor are now brand new. Haven't noticed a difference yet.
And the timing I set yesterday was based off your method of retarding it until it started to slow, then turn it back until it sped up and left it. I may back it off some today, like I mentioned, while idling it's fine, with slight gradual pedal it started to pop and it sounds almost like you can hear the valves all tapping away on the driver side, but when you get into half or more pedal the tapping is gone (engine could be just to loud to hear it I don't know), but on the way down it doesn't backfire or pop at all.
 
While trying to get all this figured out, I ran it out of gas. Went and put 5 more gallons in the tank, tried to restart it and now the mechanical fuel pump won't pump fuel. This will now be the 4th mechanical fuel pump I've put on this truck in a year
 
Markzilla8 said:
While trying to get all this figured out, I ran it out of gas. Went and put 5 more gallons in the tank, tried to restart it and now the mechanical fuel pump won't pump fuel. This will now be the 4th mechanical fuel pump I've put on this truck in a year
Click to expand...
Old Dodge trucks suck air between the fuel pump and the tank...usually at a rubber tubing joint near the tank or at the filter mounted on the frame, or at the frame...change it also..

Also, it is a classic mistake to cross thread the flared connection(s) at the fuel pump. You can set the truck on fire...check carefully.

Start your air compressor and attach your air gun....wrap a rag around the air gun and stick it into the tank....while a friend cranks over the engine, apply air to pressurize the gas tank.

4 fuel pumps means it is not the fuel pump that is the culprit.

What kind of compression readings do you get? Remove all the spark plugs and open the throttle FULL and block it so it stays wide open then do a dry compression check. DO NOT squirt oil into the cylinders...dry compression check.

You probably have a blown head gasket between two or more cylinders...
 
So I redid the fuel system about a month ago. I dropped the tank, cleaned it with a degreaser, made sure I washed it all out, put a new fuel sending unit in from LMC, connected it up to brand new fuel lines I bent with a short section of rubber hose, and it mates to the fuel pump with a short shot of rubber hose again. All rubber hose is secured with clamps. Only things I did not replace was the filler neck on the side of the truck body and the white plastic vent on the top of the tank bc the nipple broke off when I tried to remove the small rubber hose attached to it.
I completely avoided the charcoal emissions cannister up by the engine and ran the fuel line directly to the fuel pump.

I will check the compression in a couple days when I have some time. I'm hoping the headgasket is fine...

I do have a spare set of 360 heads I could try to rehab an swap out with these if the heads are the problem. I just don't have a ton of money to throw at this truck
 
Late to the party. I would start from scratch with pulling the dist, to make sure that everything is spot on and working correctly. I'd check the dist. check out everything and fix accordingly new vac.advance cheap enough, check play on timing chain. If it's good bring it to TDC and set your dist. to #1 then you know it's all good on that side of the equation. Then make sure your wire's are routed correctly and not cross firing. I would also do the comp.test mentioned B4 to be safe. If you find slop anywhere in your system it will keep your motor from running right. I had a 86 W150 that actually needed a new dist. for a worn gear and shaft. Thing would never run right until I replaced it with one from Procomp/Speedmaster now it runs awesome.
 
I haven't had the chance to do the distributor due to rain. I Threw in a new fuel pump, gets fuel fine now. Only bit of concern was the first fuel it pumped through the filter was red/orange colored, but after a minute of running it was back to usual clear/light yellow color.
I also took some videos and posted them to YouTube to hear what the exhaust is doing when I say popping and backfiring. The links are below. Again, thanks to everyone for the help so far, I really appreciate it



 
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