The Ford Barn

Terry,NJ · 10-20-2014, 10:51 PM

This sounds very much like the problems with my coupe. I was ready to blame the carb, and did. I "Refreshed" a "B" carb that I had and it duplicated the results from the "A' carb. Either both have the same problems or I'll have to look at the spark. Shorting the plugs produces a predictable result. The engine staggers until the screwdriver is removed. But it still misses. I too, run it fast to keep it from stalling. I'm thinking the coil, then there's the condenser. It's has modern points. I leaned close to the engine while it was running and could hear intermitant thudding from deep in the engine and the compression is low so I'm gonna pull it. I have another I'll stick in in the interim.
Terry

Giles · 10-21-2014, 10:30 AM

I've been following this thread with interest because I have a similar prob and I'm now at my wit's end (not a long distance, you may say). My A runs rough, smokes slightly and has lost its idle. Backfires when the throttle is opened, not on the overrun.

Things I have done: cleaned the carb and jets - though I haven't blown through with compressed air, as I don't have a compressor, and I have not removed and replaced the brass plugs. Reset fuel level to 15/16ths as recommended on this forum. Checked ignition timing: spot on. Have not checked compression, as I've just replaced head gasket and valves and pistons looked fine then. I've replaced condenser and coil - no change.

The car is a '28 and is stock except for a Model B carb (manifold is bored out to match), a Jim Brierley touring cam, "police" head and low-pressure exhaust.

Any thoughts? I imagine the next step is to dismantle the carb again (have done so 6 times so far, in the course of curing a sticking float and valve...) but it would be helpful to have an idea of which area of the carb might produce my symptoms. The GAV and idle air adjust seem to be working fine. The car is normally v reliable - I've done 72,000 miles in it - so this is very uncharacteristic.

Best wishes to you all from soggy, foggy England ...

johnbuckley · 10-21-2014, 11:09 AM

"Backfires when the throttle is opened,....." back firing through the carb throat or through the exhaust system?
"..I have not removed and replaced the brass plugs." Don't! ( unless it is abolutely necessary which it usually isn't!)
Check you have a good fuel flow- disconnect fuel pipe at carb and blow through it so that it bubbles into the tank.
Check for air leaks at manifold/engine gasket and carb manifold gasket (I spray easy start in that area and see it if makes any difference- carfeul it's very explosive).
Best wishes to you all from soggy, foggy Wales!!-

tbirdtbird · 10-21-2014, 11:23 AM

Giles do a compression test anyway

BILL WILLIAMSON · 10-21-2014, 11:36 AM

For a quick compression "TEST", with the key OFF, give it a LOOOONG constant crank & LISTEN for a SMOOTH constant RYTHYM. If it has a weak cylinder, you'll detect a difference in the RYTHYM.
Bill W.

1931 flamingo · 10-21-2014, 05:42 PM

Sponsored Links (Register now to hide all advertisements)

Vacuum leak, see post #23.
Paul in CT

Mitch//pa · 10-21-2014, 05:59 PM

Quote:

Originally Posted by BILL WILLIAMSON

For a quick compression "TEST", with the key OFF, give it a LOOOONG constant crank & LISTEN for a SMOOTH constant RYTHYM. If it has a weak cylinder, you'll detect a difference in the RYTHYM.
Bill W.

thats right a skip but sometimes that takes a trained ear

BILL WILLIAMSON · 10-21-2014, 11:08 PM

Quote:

Originally Posted by Mitch//pa

thats right a skip but sometimes that takes a trained ear

That's EASY, just have yo' Dog listen with you ! If you want to train yourself, do the same test, with 1 plug removed, then you'll know what the rhythm change sounds like. This test is a good thing to do when shopping for a used work hack. I can even test the condition of the transmission synchros, without actually driving the car.
Bill W.

Terry,NJ · 10-22-2014, 02:14 PM

Hmmmmm ,Reminds me of when I was working on airplanes. With the ignition off, pull the prop through a couple of turns. If there's a weak jug, you'll feel it. And since most causes of weak compression are bad valves, you'll probably hear it too.
Terry

HotRodHell · 10-22-2014, 07:39 PM

I'm still looking for a spark plug recommendation. Post#20
The car currently has Champion C-16C. What would you replace them with?
Thanks
Dean

Terry,NJ · 10-22-2014, 10:34 PM

Autolite 3076, available at your local Autozone or is it Advanced Auto Part? I always confuse the two.

RandyinUtah · 10-23-2014, 12:23 AM

I have been using Champion 3X plugs for 30 years and have had good service

Mitch//pa · 10-23-2014, 06:50 AM

Quote:

Originally Posted by HotRodHell

I'm still looking for a spark plug recommendation. Post#20
The car currently has Champion C-16C. What would you replace them with?
Thanks
Dean

put these in they have the proper heat range and also look decent. amazon is cheaper / plus rebate and free prime shipping....
second choice would be champion w-18

Giles · 10-24-2014, 09:14 AM

Thanks for all the good tips, guys! I've checked compression - I'm getting 79psi on #1, 74 on #2, 78 on#3 and 76 on #4. Plugs are sooty, and backfiring is in exhaust not carb, so I'm inclined to suspect I'm running rich. As regards airleaks, I'll try the easystart test, but manifold to block is nice and tight, with a new gasket, and carb to manifold also has a new gasket and a good fit.

John - whereabouts in Wales? I take the A to Carmarthenshire every summer ...

10-20-2014, 10:51 PM	#21
Terry,NJ Senior Member Join Date: Nov 2013 Location: Northern Bucks Co. Pa Posts: 632	Re: Runs/Idles rough and what I've done so far This sounds very much like the problems with my coupe. I was ready to blame the carb, and did. I "Refreshed" a "B" carb that I had and it duplicated the results from the "A' carb. Either both have the same problems or I'll have to look at the spark. Shorting the plugs produces a predictable result. The engine staggers until the screwdriver is removed. But it still misses. I too, run it fast to keep it from stalling. I'm thinking the coil, then there's the condenser. It's has modern points. I leaned close to the engine while it was running and could hear intermitant thudding from deep in the engine and the compression is low so I'm gonna pull it. I have another I'll stick in in the interim. Terry

10-21-2014, 10:30 AM	#22
Giles Junior Member Join Date: Jul 2012 Location: Leighton Buzzard, UK Posts: 23	Re: Runs/Idles rough and what I've done so far I've been following this thread with interest because I have a similar prob and I'm now at my wit's end (not a long distance, you may say). My A runs rough, smokes slightly and has lost its idle. Backfires when the throttle is opened, not on the overrun. Things I have done: cleaned the carb and jets - though I haven't blown through with compressed air, as I don't have a compressor, and I have not removed and replaced the brass plugs. Reset fuel level to 15/16ths as recommended on this forum. Checked ignition timing: spot on. Have not checked compression, as I've just replaced head gasket and valves and pistons looked fine then. I've replaced condenser and coil - no change. The car is a '28 and is stock except for a Model B carb (manifold is bored out to match), a Jim Brierley touring cam, "police" head and low-pressure exhaust. Any thoughts? I imagine the next step is to dismantle the carb again (have done so 6 times so far, in the course of curing a sticking float and valve...) but it would be helpful to have an idea of which area of the carb might produce my symptoms. The GAV and idle air adjust seem to be working fine. The car is normally v reliable - I've done 72,000 miles in it - so this is very uncharacteristic. Best wishes to you all from soggy, foggy England ...

10-21-2014, 11:23 AM	#24
tbirdtbird BANNED Join Date: May 2012 Location: inside your RAM Posts: 3,134	Re: Runs/Idles rough and what I've done so far Giles do a compression test anyway __________________ '31 180A

10-21-2014, 11:36 AM	#25
BILL WILLIAMSON Senior Member Join Date: Dec 2010 Location: FRESNO, CA Posts: 12,560	Re: Runs/Idles rough and what I've done so far For a quick compression "TEST", with the key OFF, give it a LOOOONG constant crank & LISTEN for a SMOOTH constant RYTHYM. If it has a weak cylinder, you'll detect a difference in the RYTHYM. Bill W. __________________ "THE ASSISTANT GURU OF STUFF"

10-21-2014, 05:42 PM	#26
1931 flamingo Senior Member Join Date: May 2010 Location: new britain,ct 06052 Posts: 9,390	Re: Runs/Idles rough and what I've done so far Sponsored Links (Register now to hide all advertisements) Vacuum leak, see post #23. Paul in CT

10-21-2014, 11:09 AM	#23
johnbuckley Senior Member Join Date: Jul 2010 Location: United Kingdom Posts: 1,442	Re: Runs/Idles rough and what I've done so far "Backfires when the throttle is opened,....." back firing through the carb throat or through the exhaust system? "..I have not removed and replaced the brass plugs." Don't! ( unless it is abolutely necessary which it usually isn't!) Check you have a good fuel flow- disconnect fuel pipe at carb and blow through it so that it bubbles into the tank. Check for air leaks at manifold/engine gasket and carb manifold gasket (I spray easy start in that area and see it if makes any difference- carfeul it's very explosive). Best wishes to you all from soggy, foggy Wales!!-

10-22-2014, 02:14 PM	#29
Terry,NJ Senior Member Join Date: Nov 2013 Location: Northern Bucks Co. Pa Posts: 632	Re: Runs/Idles rough and what I've done so far Hmmmmm ,Reminds me of when I was working on airplanes. With the ignition off, pull the prop through a couple of turns. If there's a weak jug, you'll feel it. And since most causes of weak compression are bad valves, you'll probably hear it too. Terry

10-22-2014, 07:39 PM	#30
HotRodHell Junior Member Join Date: Aug 2014 Location: Crook County Illinois Posts: 29	Re: Runs/Idles rough and what I've done so far I'm still looking for a spark plug recommendation. Post#20 The car currently has Champion C-16C. What would you replace them with? Thanks Dean

10-22-2014, 10:34 PM	#31
Terry,NJ Senior Member Join Date: Nov 2013 Location: Northern Bucks Co. Pa Posts: 632	Re: Runs/Idles rough and what I've done so far Autolite 3076, available at your local Autozone or is it Advanced Auto Part? I always confuse the two.

10-23-2014, 12:23 AM	#32
RandyinUtah Senior Member Join Date: May 2010 Location: Ogden Utah Posts: 242	Re: Runs/Idles rough and what I've done so far I have been using Champion 3X plugs for 30 years and have had good service

10-24-2014, 09:14 AM	#34
Giles Junior Member Join Date: Jul 2012 Location: Leighton Buzzard, UK Posts: 23	Re: Runs/Idles rough and what I've done so far Thanks for all the good tips, guys! I've checked compression - I'm getting 79psi on #1, 74 on #2, 78 on#3 and 76 on #4. Plugs are sooty, and backfiring is in exhaust not carb, so I'm inclined to suspect I'm running rich. As regards airleaks, I'll try the easystart test, but manifold to block is nice and tight, with a new gasket, and carb to manifold also has a new gasket and a good fit. John - whereabouts in Wales? I take the A to Carmarthenshire every summer ...