The Ford Barn

BIG MIKE · 10-15-2015, 06:58 AM

My flatty backfires Right on the start when you push starter button. Would that be Crossed wires? it Idles nice but when under a load it backfires like a sharp bang. thanks BIG MIKE

51 MERC-CT · 10-15-2015, 11:01 AM

Sticky valve

WestCoast · 10-15-2015, 11:27 AM

like 51 merc said , possible sticking valve, dribble 8 oz or so of mmo down the carb, and then put 5 or 6 oz in ten gallons of gas, run car for 100 miles or so, see it that cures the problem

1932 V8 · 10-15-2015, 12:04 PM

Need way more info. Check all the ignition wires to make sure they are correct on both ends . Check plugs to make sure you don't have any fouled. Check supply voltage to coil (6v or 12v) or less if you have a ballast resister in line . Also, does it do it all the time or just cold or just hot ? Did you change anything recently and this started ? As they say, most ignition problems are fuel and most fuel problems are ignition. Is this a worn engine ? rebuilt ? low miles etc etc ?
To have any chance of doing an internet diagnosis you need to give as much info as possible. From there I would bet you will get good help and be directed to check certain things as a process of elimination.

We will wait for your reply with info

keith oh · 10-15-2015, 12:34 PM

Sticky valve will sure act that way, I would try the MMO treatment first.

BIG MIKE · 10-15-2015, 12:36 PM

Sponsored Links (Register now to hide all advertisements)

I put in New plugs new wires new rotor new electrode caps new points Plugs are gaped correctly, I put mmo in all the time, its just i turn on starting ign, push button and Bang , but after warm up she idles fine when I drive her out it stats banging again , Its in a (Tank Mk 2 Bren Gun Carrier) my engine .

BIG MIKE · 10-15-2015, 01:08 PM

west Coast I got a Tank kinda hard to run 100 miles mate LOL

but thanks fer your help

petehoovie · 10-15-2015, 01:34 PM

The carb is leaking while sitting awhile....

BIG MIKE · 10-15-2015, 02:03 PM

I wonder where it leaks from I never see any leaks, maybe ill give it a cleaning now that vehicles done for the season , thanks

51 MERC-CT · 10-15-2015, 05:35 PM

Quote:

Originally Posted by BIG MIKE

I wonder where it leaks from I never see any leaks, maybe ill give it a cleaning now that vehicles done for the season , thanks

If it leaks internally you are not going to see it, but it still takes something like an open valve to ignite it.

ford38v8 · 10-15-2015, 05:42 PM

If it backfires through the carb, it will have ruptured your power valve.

BIG MIKE · 10-15-2015, 05:43 PM

got it thanks

BIG MIKE · 12-21-2015, 02:56 AM

Still as soon as I push starter button , Bang (backfire) runs smooth on idle , But when I push gas pedel it starts running uneven rough etc batt Good Gen Charging oil psi Good , new plugs wires condensor rotor electro caps , and it still bangs

BIG MIKE · 12-21-2015, 03:04 AM

Could the miss fire be from a Vacuum leak? or not enough fuel? i have a Gas reg on at 3 1/2 PSI? should it be more? would Engine Constantly miss fire if Wires were crossed? just asking that ?

SofaKing · 12-21-2015, 10:07 AM

If it didn't backfire before the tune-up, it is most likely a result of the tune-up. If your points are set incorrectly it will affect timing, advanced or retarded. If it is backfiring through the carb your timing may be too far advanced, if tailpipe too far retarded. Check that plug wires are not crossed. Did you get a good cap and rotor? ( I bought one from MACS and the rotor will move more than .100" on shaft, can't time that out) It could be any number of things but that's not how the smart money is betting.

1932 V8 had it right, please provide more info, type engine/ distributor, etc.

Barry-ct · 12-21-2015, 10:14 AM

I would definitely check your firing order first for a crossed wire. Did this problem start after you did the wires, plugs, etc...? It would idle fine sitting there, but run poorly under a load. flatheads don't run a lot of fuel pressure, 2-4 lbs max. On a single carb, I'd say closer to 2-3lbs. If it started after the work, it has to be something you did during that process.

JSeery · 12-21-2015, 10:18 AM

3 1/2 psi fuel pressure is most likely to much, not to little.

JM 35 Sedan · 12-21-2015, 11:56 AM

Hey Big Mike, welcome back!! Where have you been hiding?? Are you sure someone is not lobbing mortars near you?

What carburetor and distributor are you actually running? I think I have seen pictures of the engine setup in this tank before, or maybe it was another tank you own, but maybe a couple pics added here would refresh my memory, and allow others to see it as well. Actually, as someone else already mentioned, with all the things you have just added or changed doing a tuneup, something you have done is most likely the problem. Some of my best guesses would be.... a couple spark plug wires in the wrong place, either at distributor inner cap, or at the plugs, points not set correctly, timing not set correcrly, bad capacitor, low voltage to coil, loose/intermittent connection of coil wire, and/or loose wire terminations at the wire wound coil resistor, etc., etc. This is all guess work, but may be things to check out. Keep plugging away, you will find the problem. Good luck!

BIG MIKE · 12-21-2015, 01:40 PM

all this stuff started after i took off the Govenor , it acts like a 2" riser now its a 34 flathead old helmet style dist, ill check my wires again for the 3rd time,

BIG MIKE · 12-21-2015, 01:46 PM

youi know after xmass ill take a vid of it , the vehicle only goes out 6 times a year in parades or reenactments sometimes at car show static displays and when i take her out i only go less than 7mph i think this past year i only did less that 15 miles LOl, im just sick of listening to the banging under a load going up a hill

10-15-2015, 06:58 AM	#1
BIG MIKE Senior Member Join Date: May 2010 Location: Boston, Mass Posts: 358	back fire or misfire or something else My flatty backfires Right on the start when you push starter button. Would that be Crossed wires? it Idles nice but when under a load it backfires like a sharp bang. thanks BIG MIKE

10-15-2015, 11:01 AM	#2
51 MERC-CT Senior Member Join Date: May 2010 Location: East Hartford, Ct Posts: 5,898	Re: back fire or misfire or something else Sticky valve __________________ DON'T RECALL DOING SOMETHING FOR MYSELF BASED ON SOMEONE ELSE'S LIKES OR DISLIKES

10-15-2015, 11:27 AM	#3
WestCoast Senior Member Join Date: Sep 2014 Location: oroville calif Posts: 893	Re: back fire or misfire or something else like 51 merc said , possible sticking valve, dribble 8 oz or so of mmo down the carb, and then put 5 or 6 oz in ten gallons of gas, run car for 100 miles or so, see it that cures the problem

10-15-2015, 12:04 PM	#4
1932 V8 Senior Member Join Date: May 2010 Location: Windsor California Posts: 492	Re: back fire or misfire or something else Need way more info. Check all the ignition wires to make sure they are correct on both ends . Check plugs to make sure you don't have any fouled. Check supply voltage to coil (6v or 12v) or less if you have a ballast resister in line . Also, does it do it all the time or just cold or just hot ? Did you change anything recently and this started ? As they say, most ignition problems are fuel and most fuel problems are ignition. Is this a worn engine ? rebuilt ? low miles etc etc ? To have any chance of doing an internet diagnosis you need to give as much info as possible. From there I would bet you will get good help and be directed to check certain things as a process of elimination. We will wait for your reply with info

10-15-2015, 12:34 PM	#5
keith oh Senior Member Join Date: May 2010 Location: Millersport, central ohio Posts: 668	Re: back fire or misfire or something else Sticky valve will sure act that way, I would try the MMO treatment first.

10-15-2015, 12:36 PM	#6
BIG MIKE Senior Member Join Date: May 2010 Location: Boston, Mass Posts: 358	Re: back fire or misfire or something else Sponsored Links (Register now to hide all advertisements) I put in New plugs new wires new rotor new electrode caps new points Plugs are gaped correctly, I put mmo in all the time, its just i turn on starting ign, push button and Bang , but after warm up she idles fine when I drive her out it stats banging again , Its in a (Tank Mk 2 Bren Gun Carrier) my engine .

10-15-2015, 01:08 PM	#7
BIG MIKE Senior Member Join Date: May 2010 Location: Boston, Mass Posts: 358	Re: back fire or misfire or something else west Coast I got a Tank kinda hard to run 100 miles mate LOL but thanks fer your help

10-15-2015, 01:34 PM	#8
petehoovie Senior Member Join Date: May 2015 Posts: 8,181	Re: back fire or misfire or something else The carb is leaking while sitting awhile.... __________________ The only thing nice about being imperfect is the joy it brings to others.... *"Silver rings, your butt! Them's washers!"* "We shot our way out of that town for a dollar's worth of steel holes!" - from 'The Wild Bunch' - 1969 https://www.youtube.com/watch?v=7NReUd2_0u0

10-15-2015, 02:03 PM	#9
BIG MIKE Senior Member Join Date: May 2010 Location: Boston, Mass Posts: 358	Re: back fire or misfire or something else I wonder where it leaks from I never see any leaks, maybe ill give it a cleaning now that vehicles done for the season , thanks

10-15-2015, 05:42 PM	#11
ford38v8 Senior Member Join Date: Jul 2011 Location: SF Bay Area Posts: 6,648	Re: back fire or misfire or something else If it backfires through the carb, it will have ruptured your power valve. __________________ Alan

10-15-2015, 05:43 PM	#12
BIG MIKE Senior Member Join Date: May 2010 Location: Boston, Mass Posts: 358	Re: back fire or misfire or something else got it thanks

12-21-2015, 02:56 AM	#13
BIG MIKE Senior Member Join Date: May 2010 Location: Boston, Mass Posts: 358	Re: back fire or misfire or something else Still as soon as I push starter button , Bang (backfire) runs smooth on idle , But when I push gas pedel it starts running uneven rough etc batt Good Gen Charging oil psi Good , new plugs wires condensor rotor electro caps , and it still bangs

12-21-2015, 03:04 AM	#14
BIG MIKE Senior Member Join Date: May 2010 Location: Boston, Mass Posts: 358	Re: back fire or misfire or something else Could the miss fire be from a Vacuum leak? or not enough fuel? i have a Gas reg on at 3 1/2 PSI? should it be more? would Engine Constantly miss fire if Wires were crossed? just asking that ?

12-21-2015, 10:07 AM	#15
SofaKing Senior Member Join Date: Jun 2014 Location: Salt Lake City, Utah Posts: 756	Re: back fire or misfire or something else If it didn't backfire before the tune-up, it is most likely a result of the tune-up. If your points are set incorrectly it will affect timing, advanced or retarded. If it is backfiring through the carb your timing may be too far advanced, if tailpipe too far retarded. Check that plug wires are not crossed. Did you get a good cap and rotor? ( I bought one from MACS and the rotor will move more than .100" on shaft, can't time that out) It could be any number of things but that's not how the smart money is betting. 1932 V8 had it right, please provide more info, type engine/ distributor, etc.

12-21-2015, 10:14 AM	#16
Barry-ct Senior Member Join Date: May 2010 Location: Newington, Connecticut Posts: 1,374	Re: back fire or misfire or something else I would definitely check your firing order first for a crossed wire. Did this problem start after you did the wires, plugs, etc...? It would idle fine sitting there, but run poorly under a load. flatheads don't run a lot of fuel pressure, 2-4 lbs max. On a single carb, I'd say closer to 2-3lbs. If it started after the work, it has to be something you did during that process. __________________ Barry 50 F-1

12-21-2015, 10:18 AM	#17
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: back fire or misfire or something else 3 1/2 psi fuel pressure is most likely to much, not to little.

12-21-2015, 11:56 AM	#18
JM 35 Sedan Senior Member Join Date: May 2010 Location: Near Rising Sun, Maryland Posts: 10,859	Re: back fire or misfire or something else Hey Big Mike, welcome back!! Where have you been hiding?? Are you sure someone is not lobbing mortars near you? What carburetor and distributor are you actually running? I think I have seen pictures of the engine setup in this tank before, or maybe it was another tank you own, but maybe a couple pics added here would refresh my memory, and allow others to see it as well. Actually, as someone else already mentioned, with all the things you have just added or changed doing a tuneup, something you have done is most likely the problem. Some of my best guesses would be.... a couple spark plug wires in the wrong place, either at distributor inner cap, or at the plugs, points not set correctly, timing not set correcrly, bad capacitor, low voltage to coil, loose/intermittent connection of coil wire, and/or loose wire terminations at the wire wound coil resistor, etc., etc. This is all guess work, but may be things to check out. Keep plugging away, you will find the problem. Good luck! __________________ *John* *"Never give up on what you really want to do. The person with big dreams is more powerful than one with all the facts". Albert Einstein*

12-21-2015, 01:40 PM	#19
BIG MIKE Senior Member Join Date: May 2010 Location: Boston, Mass Posts: 358	Re: back fire or misfire or something else all this stuff started after i took off the Govenor , it acts like a 2" riser now its a 34 flathead old helmet style dist, ill check my wires again for the 3rd time,

12-21-2015, 01:46 PM	#20
BIG MIKE Senior Member Join Date: May 2010 Location: Boston, Mass Posts: 358	Re: back fire or misfire or something else youi know after xmass ill take a vid of it , the vehicle only goes out 6 times a year in parades or reenactments sometimes at car show static displays and when i take her out i only go less than 7mph i think this past year i only did less that 15 miles LOl, im just sick of listening to the banging under a load going up a hill