[LarryM1961]

Action, Desert XL and experts,
Changed the Spark plugs with Copper - Ford Motorcraft, didn't change the cables since mechanic said it was wrong type and didn't fit. So I suppose I need to change those. Also replaced with new 6 blade fan, clutch and fan shroud.
However, left the shop and car is stalling at low speeds, when idling, waiting at lights, going up and down ramps in multi-story car parks and terrible backfiring, like a gun shot, that loud! Before changing the spark plugs it was backfiring, just slightly only occassionally, now its like a .357 magnum going off.
The mechanic did say there was a leak from manifold to the exhaust, however, its the stalling element that is more concerning, making it semi-undriveable.
Any ideas? Thanks Larry M

 

[ms fowler]

Here are some simple things to check:
Loose vacuum hose--might have been pulled of inadvertently
Spark plug wires, cap and rotor --maybe switched around a couple of wires. Look carefully inside the distributor cap for carbon tracks that might show where the spark has been jumping between terminals.
What other work was done at the same time as the spark plugs were changed?

 

[Action]

Spark plug wires, cap and rotor --maybe switched around a couple of wires.

^^^^ +1

The engine was running relatively smooth before spark plugs were replaced and now not so much.

I am guessing spark plug wires are not all in their correct position.
The firing order is on the intake manifold. Or can be found on the net knowing what engine family. (FE or Windsor)

Action

 

[Action]

FE engine (352, 390 428 and some others) 1-5-4-2-6-3-7-8
Windsor (302, 351) 1-3-7-2-6-5-4-8

Action

 

[larrymur1961]

^^^^ +1

The engine was running relatively smooth before spark plugs were replaced and now not so much.

I am guessing spark plug wires are not all in their correct position.
The firing order is on the intake manifold. Or can be found on the net knowing what engine family. (FE or Windsor)

Action

Thanks Action and MS Fowler
Yes, exactly that. Now it's backfiring like a gunshot and it's stalling on idle. It had a slight pop of a backfire before but nothing this bad and certainly wasn't stalling. In relation to the spark plugs correct position, are there numbers on the wires that match same numbers in the spark plug holes in the engine where they go?
Thanks Larry M

 

[Action]

At one point Ford was ink stamping cylinder numbers on original spark plug cables.
50+ year old wires are not going to help.
Likely what is on the engine are aftermarket cables.

You will need to find #1 and then trace wires

What engine do you have?

Action

 

[larrymur1961]

Action,
could you please paste the URL on the Internet showing the correct order of the spark plugs, I show this to idiot mechanic
Thanks
Larry

 

[Action]

I could after you tell what engine you have.

Action

 

[larrymur1961]

At one point Ford was ink stamping cylinder numbers on original spark plug cables.
50+ year old wires are not going to help.
Likely what is on the engine are aftermarket cables.

You will need to find #1 and then trace wires

What engine do you have?

Action

Hi Action
It's a 6.4l 390 cu FE Big block

 

[LarryM1961]

Hi Action
It's a 6.4l 390 cu FE Big block

Action you are a genius,
I think I;ve found it...is it..https://www.gtsparkplugs.com/firing-order-ford-390-427-428.html

 

[Action]

That is a good link.
Shows you where #1 and how the wires fit on the cap.
I would encourage YOU to do it. At least inspect to see if the spark plug cable order is correct.

As to my intelligence, hmmm not sure my offspring have the same opinion.

Action

 

[LarryM1961]

Action you are a genius,
I think I;ve found it...is it..https://www.gtsparkplugs.com/firing-order-ford-390-427-428.html

Action,
it says..."Also remember that the position of the spark plug wires does not matter AS LONG AS THE ORDER IS MAINTAINED! However, the wires represent where the spark plug is, doesn't it? I.E 1-5-4 etc?
Thnx Larry M

 

[Action]

That may be true. However, I would never do that.

In the pic of the distributor cap, there is a square looking thing just to the left of #1. That is the hold down clip.
Put #1 spark plug cable in the distributor cap tower just to the right of that clip.

Is your 390 a 4 bbl carburetor?
Is your Galaxie a US vehicle or non-US vehicle?

Action

 

[Action]

Here is a picture of the cap. (Technically this is for a small block and it works)
There are two clip mount around the exterior and an alignment notch in the bottom.

In this picture the clip mount is in the lower area just to the right of the bottom.
Count over 4 towers (from either direction)
There will be another clip mount. (Roughly in the 11 OÇlock position)
The tower in the 12 oclock position use as #1

Action

 

[LarryM1961]

That may be true. However, I would never do that.

In the pic of the distributor cap, there is a square looking thing just to the left of #1. That is the hold down clip.
Put #1 spark plug cable in the distributor cap tower just to the right of that clip.

Is your 390 a 4 bbl carburetor?
Is your Galaxie a US vehicle or non-US vehicle?

Action

Its US 1967 Ford Galaxie 500 xl - 6.4L 390 v8 2 barrel Action. I suppose I need to change the spark plugs lead as well, even though I purchased some from RockAuto, - mechanic was saying they didn't fit.
UNITED MOTOR PRODUCTS 7807 (Premium) United-Packard Premium Wire Set Info
Galaxie 500; w/ Female Distributor Cap; w/o High Energy Ignition (HEI)

Just to re-iterate, these plugs have to match the correct firing order, otherwise I would experience this stalling and backfiring? Just want to relay this to the mechanic, he may give some BS saying it doesn't matter
Thanks
Larry M

 

[LarryM1961]

Here is a picture of the cap. (Technically this is for a small block and it works)
There are two clip mount around the exterior and an alignment notch in the bottom.

In this picture the clip mount is in the lower area just to the right of the bottom.
Count over 4 towers (from either direction)
There will be another clip mount. (Roughly in the 11 OÇlock position)
The tower in the 12 oclock position use as #1




View attachment 52618

Action
Not sure if mine has a middle hole? What goes in the middle an where does it go?
LarryM

 

[LarryM1961]

That is a good link.
Shows you where #1 and how the wires fit on the cap.
I would encourage YOU to do it. At least inspect to see if the spark plug cable order is correct.

As to my intelligence, hmmm not sure my offspring have the same opinion.

Action

😄

 

[Action]

Just to re-iterate, these plugs have to match the correct firing order, otherwise I would experience this stalling and backfiring?

If the spark plug cables (wires) that come off of the distributor cap are not in the exact firing order, you will have the problem you have reported.
The spark plug cables have to be attached to the exact cylinder! No exceptions.
The spark plugs can be in any hole.

Action

 

[Action]

The middle hole of the distributor cap requires a short cable to the ignition coil.

Action

 

[larrymur1961]

If the spark plug cables (wires) that come off of the distributor cap are not in the exact firing order, you will have the problem you have reported.
The spark plug cables have to be attached to the exact cylinder! No exceptions.
The spark plugs can be in any hole.

Action

Action, let's say, the spark plugs are in the correct position. Then what could it be? Obviously the only thing that was changed was the spark plugs and the spark plugs cables were tampered with, but not changed for New.
Thanks Larry Murphy