Topic: 390 saga continues BACKFIRES

[Matt1968]

Okay, nobody likes a cliff hanger. My money has been on a sticking valve, or other valve train issue.

Hope you didn't roll it back in the garage and give up?

I rolled in into the garage and gave up  :{

Actually I never give up.  Just taking a break before I dig into the plugs and covers.

What would cause a sticking valve?  These are Edelbrock assembled heads.

[Matt1968]

Don't remember.  Why would brand and heat have anything to do with it?

I did call svo2scj and he volunteered to tale a look at it,  but I need to pull the plugs and covers first.

[WT8095]

Don't remember.  Why would brand and heat have anything to do with it?

Heat range, if they're too hot could possibly cause preignition. probably a low percentage of that. Brand - without getting too subjective or causing a ruckus, let's just say I've had more than a little trouble with Champion plugs...   

[Matt1968]

Heat range, if they're too hot could possibly cause preignition. probably a low percentage of that. Brand - without getting too subjective or causing a ruckus, let's just say I've had more than a little trouble with Champion plugs...   

Gotcha.   The thing is it ran like a swiss watch (sorta) with the same plugs prior to storage, if you didn't read the full thread. 

[WT8095]

Gotcha.   The thing is it ran like a swiss watch (sorta) with the same plugs prior to storage, if you didn't read the full thread.

I've been following it     That's not inconsistent with the spark plug problems I've encountered. Had issues with a certain brand in multiple cars (including a '68 Mustang 289), one truck, a boat, a lawnmower, a snowmobile, and I think a weed wacker too. In all cases I switched to Motorcraft or NGK (for the small engines) and the problems were gone. I don't recall backfiring being the issue, though; usually it was rough running or fouling.

[Matt1968]

One thing that I do recall is that the Edelbrock heads need a very specific plug......not sure what brand I currently have.  I will report as I start to pull them.  Surprising that Champions are problematic for you ,   maybe they are being made in China now?

Matt

[WT8095]

One thing that I do recall is that the Edelbrock heads need a very specific plug......not sure what brand I currently have.  I will report as I start to pull them.  Surprising that Champions are problematic for you ,   maybe they are being made in China now?

Matt

I don't know what the deal is, that's why I didn't want to bad-mouth them. All I know is that they've been a curse for me 

[cobrajetchris]

There is nothing worse trying to diagnose a problem and replacing a part assuming it's a known good since it's new. I never had issues with spark plugs until the last couple years where I have purchased at least 2 bad ones. One was an off beat brand for a lawn mower and the other was an NGK on my dirt bike. It's hard to have faith in any brands these days as everything is made so cheap thanks to the DISCOUNT store mentality comparing apples to oranges telling you it's the same thing. Sorry getting off topic a little.

[67gtasanjose]

... It's hard to have faith in any brands these days as everything is made so cheap thanks to the DISCOUNT store mentality comparing apples to oranges telling you it's the same thing. Sorry getting off topic a little.

NOT REALLY off topic at all. I work 40-60 hours a week on all types of cars, some call it making a living at it. (I beg to differ about the "living" part of that statement)

I REFUSE TO TUNE UP A CAR WITH A CUSTOMER'S OWN PARTS for this very reason. It isn't because "I earn less on the job" that I refuse, it is because I refuse to go with "anything unkown" about what somebody else calls out as "I already tuned it up". People stick cheap parts in to save a few bucks while costing themselves on the other end. THEN, people drop spark plugs, crack them, smash down the electrode and so on. When a tune-up arrives that somebody else has already been working on, it usually is a larger nightmare than one that was left alone. "To many cooks" sort of a thing and they don't want to here they screwed up.

This situation on this particular car is really along the same line. This car has aftermarket heads on it designed to make it "run better". Well, at this point in time as in most aftermarket "upgrades", the O.P. has an epic fail.  It might also have aftermarket ignition system, who knows. I "assumed" earlier since this is a Concours forum, it was all stock. This is obviously not true. The ONLY logical first step approach is to start with the basics and the OP claims all of that is good. The only logical next step is to pull the plugs and run a compression test and/or pull valve covers and check for proper valve function. Having listened to the sound bites in the video link provided earlier, I am over 95% sure it isn't simply "a spark plug issue" (again, "assuming" stock components & running on regular pump gas) 

"ASSUME"=ass-u-me Quit "assuming" since it ran good when it was parked, that ANY of these aftermarket components are "known good" since these aftermarket, "made to make parts stores money" items are the #1 cause of grief to the professionals and the Do-it-Yourselfers alike.

As far as "Spark Plugs" are concerned, the only "correct" plug for any car (or lawn mower for that matter) is WHATEVER THE FACTORY INSTALLED. Now, remove factory components and replace them with aftermarkets junk and you open up a can of worms. You better have it Dyno'd when you are done "re-inventing the wheel"...just like the engineers all do whenever they have a new creation. You cannot simply "bolt on new parts" and expect it to work right. These things were engineered to run on Pump Gas of the 60's, we need to have minor adjustments to make them run right on pump gas of today, but this is a science...You cannot just simply "guess" or listen to the Parts Store Geek.

[1967 eight barrel]

As for Champion plugs, they are trash. I don't care what anyone says about them. When I worked for Chrysler Corp awaiting my slot at the academy, I saw thousands of them come back from new vehicles for warranty return.

I have two sets of BF32's for my Shelby, but the only current Autolite replacement is a BF45 which is a different heat range than even the BF42.

As for the one who asked for help: People usually ask questions for a reason, and snippy replies don't make people want to jump through hoops for you.
I thought a couple here were very generous with their time, and being you don't have a thermactor system to contend with, the 30 minutes required to answer a simple query. If it ran before you pulled the distributor, likely the issue is the distributor/firing order.

[Bob Gaines]

As for Champion plugs, they are trash. I don't care what anyone says about them. When I worked for Chrysler Corp awaiting my slot at the academy, I saw thousands of them come back from new vehicles for warranty return.

I have two sets of BF32's for my Shelby, but the only current Autolite replacement is a BF45 which is a different heat range than even the BF42.

FYI your 67 GT500 is supposed to run BF 42 not BF 32 from the factory according to the owners manual and the Ford service specification manual . Other owner engine modifacations may cause the needs to vary.

[dave6768]

Time table of "saga"

See original post for background
1000 miles on newly rebuilt engine,  running fine, clutch breaks,  Mustang sits 3 years without starting. 
Pulled dist to oil prime
Won't start. Looked at plug wires.  Somehow plug wires are mis-wired (from engine rebuilder) as compared to ford specs.  Don't understand how it ran like that.
Wired routed correctly now. 
Backfired few timed from carb.

It ran fine, then you moved the wires around and now it runs rough.  I would move the wires back where the engine builder had them.  He may have a different cam that requires a different firing order.

[1967 eight barrel]

Bob, question.
There was a blue performance book that is about the size of the owner's manual. It calls for BF32 as a performance plug for the 428 and 427.
Was this book part of the factory supplied manuals? I noted it covers most of the high performance engine combinations.

[1967 eight barrel]

Bob, question.
There was a blue performance book that is about the size of the owner's manual. It calls for BF32 as a performance plug for the 428 and 427.
Was this book part of the factory supplied manuals? I noted it covers most of the high performance engine combinations.

I have never seen an FE with a cam that required a firing order change. I have only seen that when 289/302 cams are used in 351W.

[Bob Gaines]

Bob, question.
There was a blue performance book that is about the size of the owner's manual. It calls for BF32 as a performance plug for the 428 and 427.
Was this book part of the factory supplied manuals? I noted it covers most of the high performance engine combinations.

There was a 65 ,66,and 67 high performance supplement .The 65.66 ones are reproduced .The 67 one is not reproduced .  They were among other things supplements to the 65,66,67 Shelby's owners manuals and came in the glove box. The High Performance supplement  typically covered information NOT covered in the owners manual. Since they were designed to be supplements to a wide spectrum of vehicles some of the information did not apply to other vehicles and the Shelby specific owners manual information SUPERCEDED anything that was also covered in the performance supplement in a different way. Case in point the supplement mentions a BF32  for the 428 but the owners manual supersedes that information with specifying the BF42 plug. FYI the 67 service specification manual also specifies the BF42 for the 428.  That is if we are talking factory specifications. Owner engine modifications and usage may require different needs. BF 42's work better then BF 32 especially on a duel four 428 where there is typically so much extra fuel on a street driven occasional spirited driving type of useage  . The BF32 plug will foul out much more quickly then a BF42. It was typical for us to switch out the BF32 plugs on single four CJ engines so that they didn't foul out quickly on a street car when they were every day transportation let alone the short use you got out of BF32's before fouling on duel four 67's. . If only drag strip service the needs are different.