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10/16/2019 11:19 AM  #1


Running Rough

Need some help (again) with my '67, 302, Edelbrock heads & intake, Edelbrock 600CFM carb. It idles great but when I try to accelerate even moderately it will stumble badly and backfire. I thought it might be the carb accelerator pump so I switched that but no change. Any suggestions for what to try next? Many thanks.

 

10/16/2019 1:42 PM  #2


Re: Running Rough

Can you state what all components the engine has as far as distributor, cam, etc?  What is the static timing set at?  Is vacuum advance connected to the timed port on the carb?
When you say you changed the accelerator pump, what exactly got changed?  What squirter cam and squirter size are you running?

How old is the gas in your tank?  That can have a huge effect if old.

That carb typically runs better with the RED accelerator pump cam in position #2 and larger squirters than stock..  Usually it comes with 28, I think.


Money you enjoy wasting is NOT wasted money... unless your wife finds out.
 

10/16/2019 5:30 PM  #3


Re: Running Rough

When did the problem start?  Did you do any work to the car or make any changes prior to the start of it?

 

10/16/2019 6:31 PM  #4


Re: Running Rough

Thanks for the question. It has been running great for the longest time. This issue began out of the blue a couple of weeks ago without any recent work or mods done to the engine. The local performance shop suggested changing the acceleration pump plunger in the carb but that didn't help. Could the fuel filter cause this? I think I'll change it on spec. I haven't found a vacuum leak but could that be a cause? Maybe some grunge clogging up the carb? Even though I buy supposedly "ethanol free" gas, it is all garbage these days. Something happened to make a good running engine start to do this. I'd love some suggestions as to where to trouble shoot. Thanks for any help.    

     Thread Starter
 

10/16/2019 9:00 PM  #5


Re: Running Rough

I was thinking plugged fuel filter or worn points if it has them.


John  -- 67 Mustang Coupe 390 5 speed
 

10/16/2019 9:09 PM  #6


Re: Running Rough

My 66 started running really poopee (a while back) and I did EVERYTHING!  plugs/timing/carb adjustment/dumped a gal of stuff in the gas tank/ EVERYTHING.........butt the filter in my little glass see-thru filter right before the carb. THAT straightened it out perfectly.
Ruined a weekend at Cruis'in-the-Coast and the Bash in FWB.
Sometimes its the little things.
6sally6


Get busy Liv'in or get busy Die'n....Host of the 2020 Bash at the Beach/The only Bash that got cancelled  )8
 

10/17/2019 8:41 AM  #7


Re: Running Rough

Speaking of cruddy gas.

Might try blowing out main line from carb to gas tank...of course disconnected from gas tank.
If you leave tank connected, take gas cap OFF and LOW pressure so ya don’t damage in tank pickup screen/filter or tank.

How often do you drive it?
Could possibly have varnish plugging carb jets.
Even newer gas and gas line cleaner will cause varnish to roll off carb bowl in big pieces.
Been there, done that too.
Hopefully this helps.

 

10/17/2019 11:06 AM  #8


Re: Running Rough

Thanks for the replies. This is kinda embarrassing but I guess I'll fess up. While staring at my stumbling engine this morning I noticed that some klutz (probably me) had pulled off a red & green wire from the positive coil terminal. It joins a bundle that runs through the firewall so I think it is ignition. Anyway, I hooked it up and went for a short spin and the engine ran great. I'll have time later to take it on a longer test but I think this may have been it. I'm surprised that it ran at all with that wire off.
It wasn't a total waste because while checking "stuff" I noticed that the distributor cap and rotor are showing some corrosion so I'll get those changed before that becomes an issue.
Thanks again for responding to my self-generated problem. 

     Thread Starter
 

10/17/2019 11:23 AM  #9


Re: Running Rough

And that's what's great about these old cars and engines.  A fix like that on a modern car is almost unheard of.  Glad to hear you got it sorted out.

 

10/17/2019 12:43 PM  #10


Re: Running Rough

Yeah..............I get that "klutz" hanging around my Mustang too!!                     Stupid old white guy!!!!!!
6sally6


Get busy Liv'in or get busy Die'n....Host of the 2020 Bash at the Beach/The only Bash that got cancelled  )8
 

10/17/2019 4:14 PM  #11


Re: Running Rough

Ok, so in the future, when a question like this one comes up, I will start with HAVE YOU ERRONEOUSLY DISCONNECTED YOUR COIL WIRE LATELY?   


Money you enjoy wasting is NOT wasted money... unless your wife finds out.
 

10/18/2019 7:06 AM  #12


Re: Running Rough

Look at bright side, at least you had the rotor IN the distributor. 😂

 

10/18/2019 7:18 AM  #13


Re: Running Rough

Yes, it has been that kind of a week.

     Thread Starter
 

10/18/2019 4:01 PM  #14


Re: Running Rough

"Speaking of.....THAT kind of week!"   I changed out the motor mount/or is that engine mount? Anywho........fingered I'd change the oil since it was up-in-the-air, fine.  Drained oil-primed the filter-changed that too- then commenced to dump in 1/2 gal on anti freeze before I... 'regained  consciousness' !  . Drained..flushed (and dumped) that ...put in fresh oil...got it fired up with zero leaks. Great, back on track!
  While listening to it idling I heard a 'different' sound. Found a hole in my pass. side header. OKaaaaaayy so I drop the header. No biggie...its the EZ side and it IS up-in-the-air. Pulled the plugs (so I won't break one dropping the header.)  Broke a plug pulling it out of the engine I actually broke it because.... while using a ratchet and short extension 'to do the deed' I got the ratchet/extension combo jammed between the shock tower and the engine! I couldn't "ratchet" it back into the engine because the direction control is on the BACK of the ratchet! managed to twist it in just enough to get the socket off the plug (which broke!  
  Since they are "old skool" headers with No chrome-No ceramic coating-No powder coating-No paint (because they are HEADERS! "I know a welder" that can patch'em up tomorrow.
I have discovered....working on these thangs is a process!
I'm having a THAT kind of week also.
6sal6


Get busy Liv'in or get busy Die'n....Host of the 2020 Bash at the Beach/The only Bash that got cancelled  )8
 

10/18/2019 4:31 PM  #15


Re: Running Rough

Well, I really enjoyed this post. Nice to know that there may be others that have "senior moments". Thanks 

     Thread Starter
 

Board footera


REMEMBER!!! When posting a question about your Mustang or other Ford on this forum, BE SURE to tell us what it is, what year, engine, etc so we have enough information to go on.