Tuning question

[rommaster2]

Ok well over the past few months i've done a few ignition mods to my 65 Falcon. These being the duraspark 2 swap, then an msd box and coil to ignite it, and some bigger plug wires.

Now during the coarse of each install whenever I would restart the car it would idle higher then it did before so i would tune it down. Well after the MSD swap no matter what I do it will not idle lower then 900rpms and at 900 it gets pretty rough but if i raise it up to 1000 then its smooth really smooth.

It did this with my one barrel and its doing it with my two barrel that I have recently added exact same symptoms idles great at 1,000 anything lower though it barely responds to the changing of the screw and it just gets rougher no matter what i do with mixture.

The optimistic side of me wants to say its just burning so efficiently that letting any less fuel in is like choking it out but I'm fairly certain that can't be it so any ideas?

 

[Mercury Mike]

What's your timing set at?

 

[66 Fastback]

I agree with Mercury Mike that it could be a timing issue. I know when I added a Pertronix and or an MSD to a car, my timing typically advanced a bit. If this is the case, you may have to set your intial timing a bit lower in order to get the idle down.
Doug

 

[rommaster2]

My timing is at 12 degrees advanced.

I'm not too worried about actual like rpms more just worried about gas consumption, will I be consuming more gas if its like this?

 

[BIGREDRASA]

You'll be consuming plugs and valves. Maybe an occasional piston, too!

 

[wsa111]

This is a longshot, but MSD has the wires crossed in the harness from the duraspark to the MSD.

This occured in a small part of the production run of the MSD to duraspark harness's resulting in reverse polarity to the MSD box.

The timing mark would jump all over the place & the engine seemed spastic at various speeds.

I had 2 of these harness's i had to pull the pins in the connector to MSD & reverse the wires???? Check it out. Bill

 

[rommaster2]

Mine is wired kind of differently I will look into it though because this sounds somewhat like what i'm experiencing as it will act slightly odd at times (shuddering while accelerating, kind of like not enough advance when cruising.

So basically I would just have to swap the wires and see what happens? It will run with the wires swapped incorrectly?

 

[66 Fastback]

You may need to check to see if your outer ring on the harmonic balancer has slipped. Chect to see if the indicated TDC is actually at TDC of the #1 cyl compressions stroke. These old balancers deteriorate and the outer ring may slip.

Another thing to check would be to check if the distributor is functioning and wheter or not the advance mechanism is stuck.
Doug

 

[rommaster2]

balancer is good only about 15,000 miles on it. I'm gonna recheck timing and pull plugs to see if i'm rich or lean or what on monday and also I might try reversing the wires.

 

[fordconvert]

If the pickup wires are reversed the signal occurs 'somewhere' between the poles on pickup in the dizzy. It could easily change based on rpm with no real consistency. Other problem is this usually moves the spark event to a point where the rotor is no longer aligned with the terminal on the cap. When the polarity is correct the signal comes pretty much when everything exactly lines up.

 

[fordconvert]

Another thing to check if you are using a vacuum advance is unhook the dizzy from the control box and connect an ohm meter between purple and orange. Flex the harness around then operate the advance. As the advance moves it will change the reading because of the coil moving but it should not drop out completely. If it does there is an internal break in one of the wires. When the vacuum moves (like under acceleration) it looses the connection which looses the spark. This was real common with GM's but less common with fords I assume because ford used much larger wires.

 

[rommaster2]

Well I am stumped, I did a few checks on things broke out the vacuum guage lowered the timing and now the problems have become a bit more extreme.

So before I mentioned it had a little bit of a shudder, well now it is a full on mis\backfire. I can hear the exhaust go *PHUMP* and cough everytime it does it and it will do it frequently when cold and still every now and then while warm.

What annoys me the most is with the one barrel I had a solid 19lbs of vacuum no matter what i did to it. With timing retarded I can barely push past 15 lbs with this two barrel. Usually I would think vacuum leak but I can't think of anywhere it could be leaking. If its not raining tommorrow I will break out the carb cleaner and spray around.

What worries me though is that backfire\misfire because its acting like its not getting enough fuel and I have pressure from the pump so that would mean something is clogging it right?

 

[rommaster2]

Well I am stumped, I did a few checks on things broke out the vacuum guage lowered the timing and now the problems have become a bit more extreme.

So before I mentioned it had a little bit of a shudder, well now it is a full on mis\backfire. I can hear the exhaust go *PHUMP* and cough everytime it does it and it will do it frequently when cold and still every now and then while warm.

What annoys me the most is with the one barrel I had a solid 19lbs of vacuum no matter what i did to it. With timing retarded I can barely push past 15 lbs with this two barrel. Usually I would think vacuum leak but I can't think of anywhere it could be leaking. If its not raining tommorrow I will break out the carb cleaner and spray around.

What worries me though is that backfire\misfire because its acting like its not getting enough fuel and I have pressure from the pump so that would mean something is clogging it right?

 

[JackFish]

Does the vacuum guage read steady?
Bad spark plug? Are they new and clean?
Do you have a guage to check the compression?

 

[BIGREDRASA]

Are you absolutely sure you don't have crossed plug wires? Did you bypass/remove the ballast resistor?

 

[rommaster2]

Ballast resistor was removed but has been working fine for the last probalby five months prior to msd and 2 bARREL Installation, the only time i started having this issue was when i put the two barrel on.

Plug wires should be good as well as they were recently changed and did not have any problems.

oh and the vacuum guage reads fairly steady it just is low

 

[BIGREDRASA]

Are you absolutely sure you don't have crossed plug wires?

 

[rommaster2]

Now are you asking me if i have the plug wires installed in the wrong order? Please explain? I may do alot of stuff (rebuild carbs, engines, suspension) but sometimes the simple things slip by and baffle me .

 

[BIGREDRASA]

Sometines it's easy to switch two wires on the cap or connect two wires to the wrong plugs. Not likely your problem, but doesn't hurt to double check that the firing order is correct. There are times when two simple problems coincide, and it drives us crazy looking for one solution.

 

[rommaster2]

Well after trying once more to tune it and the miserable backfiring drive home i finally decided to go for the shot in the dark and swap the wires to the distributor and the damn thing fired right up and idled at 2,000 rpms which wasn't unexpected because in order to keep it running i had that idle screw way in before.

Even better was that it actually pinged on the drive back to work instead of backfiring and yes I'm aware pinging is bad but this was good because it didn't matter how much I had it advanced before it wouldn't ping and that kind of freaked me out because it should have been pinging.

So now I will know for sure whats going on when I drive home tonight, also I've been looking at some livewire cables from CI, the accell ones I got are cool but those livewires look so nice.