The Ford Barn

jon laing · 07-05-2015, 06:30 AM

I have a completely rebuilt stock engine, rebuilt carb.,new points, plugs, condenser, in line fuel filter and plug wires. It ran good for 100 miles after rebuild but now it backfires upon rapid acceleration. Any suggestions on what to do would be appreciated. My next move will be to check points setting and timing. HELP!!! Jon Laing

slowforty · 07-05-2015, 10:12 AM

change condenser first

lonewolf · 07-05-2015, 11:57 AM

Or coil

jon laing · 07-07-2015, 02:40 PM

AS I understand it the car would not run at all if the coil was bad and the condenser is new. Am I missing something? I will next check the point settings and tightness of the condenser wire. Anyone have any other thoughts? Jon L.

Terry,OH · 07-07-2015, 03:01 PM

If it backfires through the Carb. it is a sign one or more of the intake valves is not closed properly. Have you considered using some MMO in the motor oil, or the fuel. The Holley 94 Carb is very sensitive to backfire that can rupture the power valve. This will cause very hard re-starting due to flooding, excessive crank time before cold starts, rough idle, poor acceleration.

jon laing · 07-08-2015, 05:46 AM

Sponsored Links (Register now to hide all advertisements)

The backfire is out the exhaust. It starts very good with little turn over. The carb. was just completely rebuilt. Jon Laing

JSeery · 07-08-2015, 07:16 AM

Quote:

Originally Posted by jon laing

AS I understand it the car would not run at all if the coil was bad and the condenser is new.

That is not true, the car can start and run fine with a bad coil. Then it will start to act up as the coil gets hot. Once the coil sits for a while and cools down it will appear to be fine again. The same thing can happen with the condenser, fine when cool, not fine when hot. If you read some of the past postings, even a lot of new condensers can cause a problem.

rockfla · 07-08-2015, 07:40 AM

@jon laing
JSEERY is just like E F Hutton, "When he speaks, people listen!"

JSeery · 07-08-2015, 07:45 AM

Quote:

Originally Posted by rockfla

@jon laing
JSEERY is just like E F Hutton, "When he speaks, people listen!"

That's just conveying info from the experts, like Bubbas, Charlie, etc!

rockfla · 07-08-2015, 07:45 AM

And just to, I guess add credence to JSEERY which doesn't have to be done, Especially new condensers, doesn't necessarily mean they are good and as JSEERY said, we have experienced the "Coil Phenomena" many times throughout the years (and condenser too) to the point of "baldness". Even after repair and the car sitting for two months, condensers can go bad.

deuce_roadster · 07-08-2015, 08:58 AM

In my "travel kit" I keep a known good condenser with 16" leads with alligator clips on the ends so if on the road it starts to act up like that I can temporarily clip this on the distributor to get home. If you had one like this you could eliminate the condenser as the problem if it didn't help and would point the finger at the coil. It will run fine with both bad and good condensers hooked up, the bad one won't prevent the good one from doing its job.

jon laing · 07-08-2015, 10:59 AM

Thanks for the advice. I will double check the coil and condenser and let you know the results. Jon L.

jon laing · 07-22-2015, 07:34 AM

All she needed was adjustment of the distributor vacuum brake. Jon Laing

lonewolf · 07-22-2015, 07:58 AM

Glad you got it figured out

jon laing · 07-23-2015, 06:10 AM

Picked up the 39 yesterday. Mechanic adjusted the distributor vacuum brake adjuster and it solved the backfire problem when accelerating; however it still misses when I accelerate. Perhaps I should replace the vacuum brake plunger, spring and adjuster. Anyone have any suggestions on what to do next? HELP & THANKS. Jon L.

koates · 07-23-2015, 08:05 AM

Hi there, Your distributer contacts could have closed up in that 100 miles. Recheck the contacts. They must meet up nice and square to each other. Do some bending with a pair of sidecutters if need be. Many of the current crop of new contact sets are badly made and don't fit like the originals. Contact faces nice and clean shiny metal. Set contacts (both) at .015" and a little smear of high temp bearing grease on the cam. You need to be very fussy on how well you do this job. If you now know that the contacts are correct then you can move on to other things if the trouble is still there. To test condensers you really need a good automotive condenser tester that tests capacity, leakage and series resistance. I have had brand new condensers that were faulty and old ones that were faulty. Correct capacity for early Ford V8 condensers is .36 mfd. As a starting point on the vacuum brake adjustment leave 3 threads showing between the lock nut and the underside of the adjuster bolt head. Regards, Kevin.

07-05-2015, 06:30 AM	#1
jon laing Senior Member Join Date: Oct 2013 Location: DRUMMOND iSLAND, Mi. Posts: 247	39 deluxe not running right I have a completely rebuilt stock engine, rebuilt carb.,new points, plugs, condenser, in line fuel filter and plug wires. It ran good for 100 miles after rebuild but now it backfires upon rapid acceleration. Any suggestions on what to do would be appreciated. My next move will be to check points setting and timing. HELP!!! Jon Laing

07-05-2015, 10:12 AM	#2
slowforty Senior Member Join Date: May 2010 Location: Tinley Park Ill Posts: 1,176	Re: 39 deluxe not running right change condenser first

07-05-2015, 11:57 AM	#3
lonewolf Senior Member Join Date: May 2010 Location: Michigan Posts: 485	Re: 39 deluxe not running right Or coil

07-07-2015, 02:40 PM	#4
jon laing Senior Member Join Date: Oct 2013 Location: DRUMMOND iSLAND, Mi. Posts: 247	Re: 39 deluxe not running right AS I understand it the car would not run at all if the coil was bad and the condenser is new. Am I missing something? I will next check the point settings and tightness of the condenser wire. Anyone have any other thoughts? Jon L.

07-07-2015, 03:01 PM	#5
Terry,OH Senior Member Join Date: May 2010 Posts: 5,187	Re: 39 deluxe not running right If it backfires through the Carb. it is a sign one or more of the intake valves is not closed properly. Have you considered using some MMO in the motor oil, or the fuel. The Holley 94 Carb is very sensitive to backfire that can rupture the power valve. This will cause very hard re-starting due to flooding, excessive crank time before cold starts, rough idle, poor acceleration.

07-08-2015, 05:46 AM	#6
jon laing Senior Member Join Date: Oct 2013 Location: DRUMMOND iSLAND, Mi. Posts: 247	Re: 39 deluxe not running right Sponsored Links (Register now to hide all advertisements) The backfire is out the exhaust. It starts very good with little turn over. The carb. was just completely rebuilt. Jon Laing

07-08-2015, 07:40 AM	#8
rockfla Senior Member Join Date: Mar 2014 Location: Jacksonville FL Posts: 4,804	Re: 39 deluxe not running right @jon laing JSEERY is just like E F Hutton, "When he speaks, people listen!"

07-08-2015, 07:45 AM	#10
rockfla Senior Member Join Date: Mar 2014 Location: Jacksonville FL Posts: 4,804	Re: 39 deluxe not running right And just to, I guess add credence to JSEERY which doesn't have to be done, Especially new condensers, doesn't necessarily mean they are good and as JSEERY said, we have experienced the "Coil Phenomena" many times throughout the years (and condenser too) to the point of "baldness". Even after repair and the car sitting for two months, condensers can go bad.

07-08-2015, 08:58 AM	#11
deuce_roadster Senior Member Join Date: Oct 2011 Location: Shelton, WA Posts: 3,971	Re: 39 deluxe not running right In my "travel kit" I keep a known good condenser with 16" leads with alligator clips on the ends so if on the road it starts to act up like that I can temporarily clip this on the distributor to get home. If you had one like this you could eliminate the condenser as the problem if it didn't help and would point the finger at the coil. It will run fine with both bad and good condensers hooked up, the bad one won't prevent the good one from doing its job.

07-08-2015, 10:59 AM	#12
jon laing Senior Member Join Date: Oct 2013 Location: DRUMMOND iSLAND, Mi. Posts: 247	Re: 39 deluxe not running right Thanks for the advice. I will double check the coil and condenser and let you know the results. Jon L.

07-22-2015, 07:34 AM	#13
jon laing Senior Member Join Date: Oct 2013 Location: DRUMMOND iSLAND, Mi. Posts: 247	Re: 39 deluxe not running right All she needed was adjustment of the distributor vacuum brake. Jon Laing

07-22-2015, 07:58 AM	#14
lonewolf Senior Member Join Date: May 2010 Location: Michigan Posts: 485	Re: 39 deluxe not running right Glad you got it figured out

07-23-2015, 06:10 AM	#15
jon laing Senior Member Join Date: Oct 2013 Location: DRUMMOND iSLAND, Mi. Posts: 247	Re: 39 deluxe not running right Picked up the 39 yesterday. Mechanic adjusted the distributor vacuum brake adjuster and it solved the backfire problem when accelerating; however it still misses when I accelerate. Perhaps I should replace the vacuum brake plunger, spring and adjuster. Anyone have any suggestions on what to do next? HELP & THANKS. Jon L.

07-23-2015, 08:05 AM	#16
koates Senior Member Join Date: May 2010 Location: Melbourne Australia. Posts: 2,185	Re: 39 deluxe not running right Hi there, Your distributer contacts could have closed up in that 100 miles. Recheck the contacts. They must meet up nice and square to each other. Do some bending with a pair of sidecutters if need be. Many of the current crop of new contact sets are badly made and don't fit like the originals. Contact faces nice and clean shiny metal. Set contacts (both) at .015" and a little smear of high temp bearing grease on the cam. You need to be very fussy on how well you do this job. If you now know that the contacts are correct then you can move on to other things if the trouble is still there. To test condensers you really need a good automotive condenser tester that tests capacity, leakage and series resistance. I have had brand new condensers that were faulty and old ones that were faulty. Correct capacity for early Ford V8 condensers is .36 mfd. As a starting point on the vacuum brake adjustment leave 3 threads showing between the lock nut and the underside of the adjuster bolt head. Regards, Kevin.