HELP - Still having engine backfiring issue

[AZCOWBO]

Here is the scoop. After driving the T for 40mi and running great, as I approached the house a mile away, I felt a dragging vibration and surging as if a brake or wheel bearing was dragging. I replaced the rear wheel bearings, but when I fired up the motor it started backfiring and toasted my new headers. Since then, I have replaced the old dual-point Mallory and coil with an MSD vacumn advanced dist and MSD Blaster-2 coil, new plug wires and plugs, rebuilt both carbs and installed smaller jets, reset the timing and fired it up BACKFIRE. When it engine warms up is lessons and it runs better, but not great. I am thinking due to the motor setting sol long the cam bearings have burned up and possibly the cam has some flat spots. HELP!

 

[Duke]

I would run a compression check, That should give you some idea what is going on. I would be thinking a sticking valve and valve guides - make sure you are getting oil to the top end.

 

[AZCOWBO]

There is plenty of oil circulating in the top end, as indicated by the oil collecting around the rockers, when I remove the valve covers.
Thanks for your reply,

Ron

 

[Duke]

Good you have plenty of oil circulation. I would still do a compression check, If you have good compression that would eliminate many possibilities and get you closer to a fix. Is it backfiring on only one cylinder or more than one.

 

[putz]

With the valve covers off make sure all the rockers are moving when cranking over. This will check cam without teardown.

 

[AZCOWBO]

Thanks for your suggestions. PROBLEM SOLVED simple when you finally get it. If we had replaced the coil first instead of distributor, I would have solved the problem. For future reference when you switch from a dual-point set-up to electrical be sure to disconnect the ballast resistor. While we were scratching our heads for hours again today, an old-timer (even older than me) looked it over and ask if we removed the ballast-resister. We said it didn't have one. It did, it was mounted under the dash wraped in insulation covered tin-foil. Disconnect and wallaa it started right up and ran perfect. My "master" mechanic was embarrassed to say the least. Remember "Out of Site Out of Mind". If there is something wrong maybe you know it but can't see it. Just got back from a drive for the first time in a couple of months. It was great. Now to the carpet guy and will have it back in time for the local annual car show and fly-in in October.

 

[Duke]

HA-HOO - :wall: :think: :witsend: :hmmm: :crap: :woops: :dance:

 

[AZCOWBO]

Yep, all of the above and a few more wahoos! The weather in the mornings and evenings are perfect for drivin now, and the daytime is down to 102-104, which is much better than 115-117.

 

[putz]

You got it going:toast: put some miles on her. It is 60 here just got home with the bucket in shorts and t shirt.They are talking 48 tonight.

 

[AZCOWBO]

Still having issues!! The motor runs great until it hits 1850 RPM or if I get on it from the start, it coughs and dies. The same as it does when I hit 1850 RPM. We have checked everything, adjusted everything. The compression averages 111-112, oil pressure 40-50#, fuel pressure 9-10lbs, valves are in range, new msd elec. vacumn advance dist and coil. vacumn line is connected to front carb, closed chamber intake, rebuilt the 525 Demon Jrs., new plugs and wires. The strange thing is it runs and starts exactly as it did with the dual-point mallory, which if we had changed out the coil first, I never would have needed to change out the Mallory dist. I did notice the battery cables got hot after starting it a few times, but it sits overnight with no drain. When I turn off the switch it still runs a few seconds, which I was told was a reult of energy stored in a resistor. Anymore suggestions appreciated.

 

[putz]

You say resistor but the energy is stored in a capacitor. Where would you have one of these other than for noise cancellation or coil.That could be your problem. Capacitors store energy then send it out in spikes.

 

[Lee_in_KC]

When I turn off the switch it still runs a few seconds...

How do you have your radiator fan wired? If it is wired to the ignition side of the switch and you don't have a relay, the fan will generate enough electricity as it winds down to keep the coil energized for a few seconds.

 

[JeffBorn]

Fuel(?) fouled new plugs... Help

Long story short for 1st timer...New build 27 roadster...newly rebuilt 305 / 4bbl edelbrock more than likely cfm 500 w/ manual choke. Standard V-8 point distributor and coil. Would not start after idling on and off for the last 10 months. After many wrong conclusions pulled old plugs and they were severely fouled and in need of replacement. Put in new autolite 25 came to life like never before on 1st crank. Idled great....set timing at about 12...set dwell 24....backed idle back down to 600..started running less smooth..attempted to adjust fuel mixture screws from initial 2 turns from lightly seated..not running any better...gave throttle to check for hesitation..none. Let off gas and engine died...won't restart...pulled new plug and covered in blackened fuel. This was after about 10-15 minutes of idling. I do not know what bad gas smells like and am thinking about draining tank and replacing filter. Any ideas including rebuild of carb in part or in whole will be greatly appreciated.
Thanks.. Jeff in Orlando

 

[AZCOWBO]

Well, I am still coughing,sputtering, and backfiring. I have had two master mechanics playing with it, and still no progress. The plugs are black and sooty, which indicates to much fuel. Also, I am getting about 2MPG I have already downsized the jets on the 525s, and set the timing at 22 degrees. After reading some older posts about 2/4 tunnel ram set ups (mine is a closed chamber Weiand) being notoriously frustrating for street driving, I go for progressive linkage, and for sure go to a ratchet shiter, because I now have drive only and shift to second in about 5ft. and at 1200RPM I am cruising 40MPH, change the gears from 2.88 to 3.73.

 

[AZCOWBO]

KC you were correct on that, changed sides on the ignition switch and it shuts down like it is supposed to. Thanks. Also, discovered that when I changed out the distributor and didn't change the tightening clamp, that it wasn't holding the distributor in place when I tightened up the bolt. As soon as I drove it a little bit the timing would change. Little things like that really pxxxes you off or perhaps I shoud say dumb things.