Blue flame and backfire from side pipes

[Millersir]

Hello all,

My truck:
71 wagon
3 speed column shift
Dana 20
Dana 44
Ford 9" 3.50
Motor:
86 mustang GT 5.0L HO
Edelbrock performer intake
Edelbrock 1406 carb
MSD 6AL box
MSD blaster 2 coil
Jegs SSR pro distributor

I just finished installing the distributor, coil, and box. After install I'm idling higher than I was and I'm getting blue flames and a loud backfire out of the exhaust after punching the accelerator. Does this sound like a fuel/air situation? Thanks in advance.

 

[Action]

Maybe off a tooth

 

[Millersir]

Is there a way to isolate and test the tooth off theory? It felt like it seated correctly, and the hold down clamp was able to be torqued.

 

[AZ73]

Seated and torque have nothing to do with being off a tooth. You can be off by 180 degrees and it will seat fine and you can torque the clamp down to spec. Double check your TDC (on the fire cycle), double check your rotor against #1, are you SURE you have the correct #1 (PS front), the wires are set for CCW rotation, and you have the correct wire firing order for your cam?

As a side note, people pay top dollar for a Ferrari that produces a blue flame.

https://www.youtube.com/watch?v=3nRdFAXLt5I

 

[jckkys]

The reason a distributor won't seat fully is the oil pump drive that often needs the starter tapped to get the hex shaft into the distributor shaft socket. I only tighten the hold down enough to keep it from moving on it's own. I often tweak the timing with altitude changes. The popping out the exhaust is a symptom of an over rich mixture. Is the AFB set up with the factory calibration?

 

[Millersir]

Carb is at factory calibration, yes.

I'm sure the plug wires are on in the correct firing order. I don't have a timing light at the moment but I plan to get one in the morning and try setting the timing by finding TDC on the compression stroke in cylinder 1.

This distributor has vacuum advance and mechanical advance that can be adjusted with springs that came in the box. Could my backfire be caused by an advanced or retarded timing scenario?

 

[Rustytruck]

I'd make sure each cylinder is firing and not sending raw fuel into the exhaust.

 

[DirtDonk]

Jegs SSR pro distributor

What part number? There are two distinct shaft designs where they mate up to the oil pump driveshaft. Some don't fit with others.

I just finished installing the distributor, coil, and box. After install I'm idling higher than I was...

That's common if the timing isn't exactly as it was before. Advancing the timing increases idle speed and retarding the timing decreased the idle.

...and I'm getting blue flames and a loud backfire out of the exhaust after punching the accelerator. Does this sound like a fuel/air situation?

I'd say that's a classic fuel, air AND SPARK situation!
Actually you go back to basics and since the last (in this case the only) thing you did was change the ignition then you have to assume that you have at least an 80% chance that the problem is to do with the stuff you just touched.

And you MUST have a timing light if you're going to be messing about with distributors. It's just an unfortunate reality.
Yes, you can get away without one if you're lucky. And yes if you know your way around lots of engines you can even time it by ear to get close enough to work. But to really know what's going on you need the light.
Oh, and good timing marks to go along with it. Was your engine just installed right out of the donor vehicle? Or was there a new damper installed? If a new one, you don't even always know it's got the right timing marks. Another unfortunate fact of Ford life.

And while "a tooth off" is a legit concern, it's not always a problem. Depends on how far you are able to turn your distributor to re-find the proper timing settings. Being a tooth off means you just have to bring it back into the correct time. That might involve just rotating the distributor a LOT, or if you can't get it timed correctly, it might mean you have to pull the distributor back out and re-install it.

Good luck.

Paul

 

[Millersir]

Thanks for the info Paul. Very helpful.

The distributor part number is 40055
http://www.jegs.com/i/JEGS-Performance-Products/555/40055/10002/-1

Unfortunately, when I purchased the truck it was from a guy who knew nothing about it. He told me it was a 68 bronco with a 69 boss 302... It wasn't til I got it home that I realized he was tossing me the bull. That being said, I don't know if my damper is from the donor or new when swapped. The timing marks are visible but hardly. Before the ignition system tinkering I had it running great with very little crackle when backing off the throttle.

I will try your suggestion of resetting the timing when I get a light tomorrow.

 

[Hazegray]

Just make sure you are following the firing order for a 5.0 HO and not a early 302.

 

[Broncobowsher]

I was thinking firing order as well.

An excessively rich mixture also does it. when the hot fuel reaches some oxygen the air) it burns off. But that rich mix might be from a cylinder (or 4 if the wrong firing order) pumping fuel right through. since it isn't under pressure when it burns, it is a lazy slow (but clean blue) flame.

 

[Crush]

lets see pics of these side pipes and your bronco

 

[gr8scott]

lets see pics of these side pipes and your bronco

Pics? He's got a fire breathing dragon! We need video! ;D