Old problem revisited, rough running 8BA
 

8BA ran great on engine stand but not since installed in car. Distributor and carb. are working as they should and think problem lies elsewhere. Changes since engine was on test stand are the following: 12V battery that was on engine stand is now located behind rear seat with double 00 positive cable (engine starts immediately) had on/off toggle switch for ignition switch on test stand, am now using stock '36 ignition switch, start button on engine stand was more heavy duty than the one now mounted in my dash and now have added two fuse panels, one hot all the time, the other switchable and a 50 amp circuit breaker. The ignition switch is wired directly to the battery and not going through fuse panel. Have also added engine to ground strap. Car has negative ground and is equipped with alternator with internal regulator. Compression and vacuum good and plugs look good. No crossed plug wires. Any ideas?

Re: Old problem revisited, rough running 8BA
 

Maybe a little more info as to how it runs? Is the problem at idle, driving, acceleration. We are not mind readers.

Re: Old problem revisited, rough running 8BA
 

Won't idle, runs rough at all RPM's under no load conditions, un-driveable. I know I'm in the wrong venue for mind readers, will try harder.

Re: Old problem revisited, rough running 8BA
 

Vacuum leak?

Re: Old problem revisited, rough running 8BA
 

I think your assumption that the distributor and carb are working as they should is a bad one. I'd suspect distributor first. Is it stock?

Re: Old problem revisited, rough running 8BA
 

Make sure you have the correct coil and resister for 12 volts.
Then wire direct to resister wired to coil.
if it runs good your problem is all the mickey mouse wiring.

Re: Old problem revisited, rough running 8BA
 

If I remember right, the first problem was because of bent rods in the carb and new ones were on order. At that time the idle was fine, and ran bad above idle. Bubba had checked your distributor to be fine. You have been tutored on how to time it. As already mentioned, verify good voltage to coil, Unless you have a new carb on it, I would look there.

Re: Old problem revisited, rough running 8BA
 

When you say you have no crossed wires there is a Motors manual and the firing order is wrong,
You may want to check it with Mercury v8 49 to 53
I had it happen to me.

Re: Old problem revisited, rough running 8BA
 

is it misfiring or is it a vibration you're feeling?

Re: Old problem revisited, rough running 8BA
 

That's interesting, am using the firing order as found on the VanPelt site; will look into this further. The carb. is a new Edelbrock with new metering rods installed, this solved my over rich condition that was fouling the spark plugs. The Mallory electronic disturb. has been gone through by Bubba's and is in good working order; Bubba supplied the correct matching coil. Firing order am using is 15486372. The problem seems more like a misfire than a bad vibration.

Re: Old problem revisited, rough running 8BA
 

No vacuum leak between manifold, adapter & carb, all three ports on the carb. are blocked off. Vacuum measures 17" which am told is about right for the cam (L-100) am using.

Re: Old problem revisited, rough running 8BA
 

Have 12.6V at the battery and only 9.7V at the coil with no resistor, that can't be good!? Bubba also supplied correct resistor but said only to use it if coil overheats.

Re: Old problem revisited, rough running 8BA
 

If you by passed and went to coil direct you should have 12 colts.
Some times when going to 12 volts the resister under dash is still in use.

Re: Old problem revisited, rough running 8BA
 

No resistor under the dash, have replaced all wiring and therein lies the problem I think. Will explore why I'm not getting 12V at the coil with ignition switch on. Thanks everyone for the help.

Re: Old problem revisited, rough running 8BA
 

ballast resister, your melting down the coil

Re: Old problem revisited, rough running 8BA
 

Maybe, maybe not. What are the specs for voltage at the coil with the Mallory? What about plug wires?

Re: Old problem revisited, rough running 8BA
 

Have Taylor 8mm spiro wires. Will find out what the voltage should be to the coil from Bubba, am wondering why I don't have 12V at the coil. Will investigate tomorrow.

Re: Old problem revisited, rough running 8BA
 

The voltage at the (+) terminal on the coil should be 12v or whatever the battery is at; the voltage at the (-) terminal would be dropped by the coil resistance if the points are closed.

You said "Have also added engine to ground strap." The negative battery cable should be going to the block or trans bellhousing. Is that how you have it?

Re: Old problem revisited, rough running 8BA
 

I would clean the contacts in the stock ignition switch. You have 12 volts to the switch and 9 volts after the switch?

Re: Old problem revisited, rough running 8BA
 

I agree with Bill. Voltage drop thru the ignition switch. Place a jumper across it and see if it comes up to 12v.