New here and I hope somebody can help me out.

1975 Dodge D300. Effectively a farm truck, but with a dumping stake bed. I have a love/hate relationship with this rig.

I've been dealing with vapor lock issues (or so I thought). Carb is freshly rebuilt (professionally), fuel lines routed as far from engine block as possible and insulated. Did a test run after doing that and same thing. I then noticed the sound of a vacuum leak. While searching for a vacuum leak, I, like an idiot, set the engine on fire. No real damage beyond the wires leading out of the distributor and my ego. The truck came with a spare, albeit corroded, distributor so I figured I'd swap the pick-up and leads and all would be at peace with the world again. What I found was that the guts of the distributor were out of whack and the vacuum leak noise I couldn't find was the pick-up just barely hitting the reluctor.

I ordered a new distributor from Amazon, pulled the plugs and driver's side valve cover, and set the engine to TDC, and replaced the distributor. Pretty sure I did it right. New unit was set like the old one so should have just needed a little tweaking to get timing right.

Well, that didn't happen.

I can't tell how far out I am on my timing, but it's not happy. It's not 180*, back firing like crazy out, but it's out. It runs enough that I can get a timing light on it, but the timing mark is no where to be found. It runs better with the vacuum advance hooked up, then when the hose is plugged so I'm guessing the timing is very retarded? I can't get the timing mark into view.

Any thoughts on a next step to get this thing back on the road?

Also worried about the fuel pump since I read that fuel pumps going bad can present as vapor lock. They're cheap, I still need to install it, but I have it handy.

Thanks for any advice you might have!

 

Welcome.

What engine is this? Have you turned the crank back and forth to see if timing chain is loose? A TDC piston stop procedure is warranted to be sure you can trust your timing light.

 

Sorry, it's the 360.

When I set everything up for this, I made sure the #1 piston was at the top of its throw and that both intake and exhaust were fully closed (the reason I pulled the valve cover). The timing mark lines up about 1/2* advanced of 0...pretty good for a 40 year old engine!

I turned the crank by hand when I set TDC and everything felt pretty darn firm.

Timing light is pretty new and was used to set it before I tried to fix it. It ran real well as long as there was no load on the engine before, so I assume my timing was at least pretty darn close before.

 

When you put in a distributor set the rotor before number one to give it advance, does sound like you just need to give it a counter clockwise twist.

 

I'll give it a go, but I was finding that it was running at its best (not very well) somewhere in the middle of the turning radius. But it's certainly worth a go! I'm going to try to get back at it tomorrow. I'll report back one way or another.

Thanks!

 

I got back to it today. Here's where it's at.

I have it idling well, but any guess and it back fires.

The rotor lines up with the number 1 plug wire at TDC with the timing mark on 0.

Should the pick up be between the splines on the reluctor when the rotor is pointing to the #1 plug wire?

When idling smoothly, with the vacuum advance connected, not smoothly without, the timing light shows what I think is the round, magnetic pick up at about 6* advance. Any chance the pick up is 180* from the timing mark?

I do find it odd that it's idling well, but won't take any load. Fuel pump?

 

Up the timing to 12° at idle and see if that helps.

 

That would be difficult to do for at least two reasons.

1) If I advance or retard the timing even a couple degrees, the engine stalls. and

2) As mentioned, the timing mark isn't visible. When I have the light on it, I am now seeing what I think I read somewhere is a magnetic pick-up (~1/2" dot on harmonic balancer) and that's hitting at about 6* ish. To the ear, it sounds smooth, but backfires pretty bad with a hard hit to the throttle. I can hit the throttle slowly and it won't backfire.

I have not yet test driven since it's not playing nice parked, I'm pretty sure it'll be down right evil if I drive it.

So, again, my guesses are the fuel pump is faulty or I'm 180* out. Is it possible to get it to idle nicely if it's 180* out but backfire with a little gas?

 

did you ever figure this out? I am having very similar issues. I am about to put another set of wires on, all my plugs look like the engine is running rich but cyl #4 & 6.

 

I ran a compression test. Blown valve on number 7.

Hopefully all of this has fixed the problem but I'm having a heck of a time sealing up the timing cover so I haven't started it yet to confirm that I've fixed it. The machine shop seemed certain the valve was the issue. The heads needed valve seats, guides, and every valve replaced. If this wasn't the issue, it was very expensive step in finding the problem.

 

Hope you get it running soon.... Keep us posted...

 

ok. thanks