engine and drivetrain Another Ignition Question

[pilotnbr1]

When timing my 74 tii I have noticed my timing mark is jumpy by quite a few degrees. In addition through about 2500 to 3000 rpm the car seems to buck slightly in gear and decelerating. Car seems to idle and run well otherwise. However I have never been around another tii (I know I need to get out more), so I have nothing to compare it to. I believe I can get more power out of it by improving my ignition situation.

Here is what the PO left me-

Wrong distributor- It is Mechanical advance only and I don't have the numbers available (traveling) with new rotor and cap

Standard plug wires

Blue Coil

Fresh Mechanical Points

Delta Mark 10 with the switch on the top

My questions-

I do have an additional distributor which appears to be the correct one for a 74tii as it has the vacuum retard part on the side, but once again I dont have the numbers... If it is the correct dizzy for a 74tii should I swap it in? I understand that the 74 tii dizzy had its own map to match the KF pump which was also slightly different than other years, is this correct? I don't think I have much to lose by experimenting and maybe I will eliminate some of the jumpy timing. The dizzy on there may be worn....

should I ditch the blue coil? I know this is the incorrect, internally resisted, weaker coil of the blue, red, and black options. I have an untested black coil laying around however I would have to buy a resistor. Does the resistor come with the mounting bracket so it attached above the coil? MOST importantly does the coil even matter with the Capacitor Discharge system?

Does anyone have experience with these "period correct" Delta Mark 10 units? I press the switch on top and notice no difference in engine performance. When the Mark 10 fails will the engine die or does it just continue running as if the switch on the Mark 10 has been pushed off?

What I am thinking-

is to put in the 74 tii dizzy with the vacuum retard (if its the correct dizzy I have) and time it to see if that eliminates some of the jumpy timing. If the jumpy timing is still present than install a crane optical trigger which I understand will work fine with a worn dizzy.

Second swap out the blue coil and put in black but only if I can find a mount for the resistor. Hopefully the mount comes with it..

Finally keep the Mark 10 if someone can confirm my switch question..

What would you guys do? I will take reliability over having a stock car and would rather buy a crane instead of rebuilding the dizzy.

Sorry for all the questions and thanks for the replies as always!

[Guest Anonymous]

I thought that the only diz with retard was for a '76 CA model for smog purposes..

[bkerr]

Pilot,

My 74tii came with a mechanical advanced distributor. There are three 008 tii distributors. 151 008 is the mechanical advanced. There was a vacuum retard on some later 74tii models. Send us the full set of numbers on the side, and we can go from there.

Brian

[pilotnbr1]

This is what I see in the manual for a 74 tii.. Which I am pretty sure is a mechanical advance, vacuum retard distributor. I also have the 2 vacuum ports on the top of the intake manifold as well as the corresponding vacuum ports on the air box. Currently all capped as the car was "desmogged".

But you are right- I need the exact numbers from the two dizzys I have to really make an informed decision on what to do.

[bnam]

The 74Tii has a resistor wire built into the harness (has clear plastic jacket -- which looks like a speaker cable) -- so you don't need a ballast resistor.

B

[Mike Self]

Then press the button on the end of the unit and you go back to conventional ignition (why I like the Delta units--you have a backup mode).

The reason you can't tell the difference with it o or off is that your engine is in good condition--it it used a lot of oil and fouled the plugs easily, you would be able to tell the difference when you switched the Delta unit off--the plugs would misfire.

Also with the Delta unit you should gap the plugs at about .038-040, not the .025 in the shop manual. They will tend to misfire with the narrow gap and the Delta unit switched on.

One more thing--a jumpy timing ball is usually indicative of a worn dizzy or at least a worn point plate (the part that carries the points and moves back and forth to advance/retard the ign timing).

cheers

mike

[pilotnbr1]

Thanks for all the replies! Good to know about the resistor wire as part of the harness. Anyone have a picture or a specific location to look? I am sure I can track it down other wise. With the harness resistor and the resistor in the blue coil I probably have too much resistance in the system. If I can verify that my resistor is present in the harness I am going to put the black coil back in...

Thanks for the response regarding the Delta MK 10. That clears up some things and I will need to correct my spark plug gap. Anyone know if the coil makes a difference with a CD system?

Sounds like its time for a Crane system or a dizzy rebuild.... Thanks again all