stock DVDA dizzy replaced with SVDA with Pertonix

[jackstar]

I have a stock newly rebuilt 79CA 2.0l FI with all new except the crank and cases. Cam is a Webcam i107. I want to replace the stock Hall's effect dizzy that surges up and down with an AD.net SVDA with Pertronix. There are no vac leaks as I had it smoke tested prior to installantion with no leaks.
My CHT are 400 to 425* on flat ground at 60-65. The heads are Len Hoffman's. I am running strict mechanical advance without the hoses as it runs like crap with them connected. The timing is about 20* advanced. At 3500 rpms I get about 32*.

I am trying not to burn my heads/engine up by having a timing issue that seems out of control. I need some guidance as to how to connect this new dizzy up. I say that because the 3 wires that come from the side of the dizzy (red, green/white and brown/white) go to the connection on the back wall.

I have been told today that I probably can not do this running FI with this SVDA dizzy. Is that true? If true then what can be done to fix my timing/hot heads problem? running out of options. AFM is unmolested as far as I know. Dont want to screw it because I know nothing about it. Needing some help here. Thanks.

Jack

[Amskeptic]

newly rebuilt 79CA 2.0l FI
Webcam i107
stock Hall effect dizzy
surges up and down no vac leaks
CHT are 400 to 425* on flat ground at 60-65
strict mechanical advance
timing is about 20* advanced. At 3500 rpms I get about 32*
without the hoses

it runs like crap with them connected.

I have been told today that I probably can not do this running FI with this SVDA dizzy. Is that true? If true then what can be done to fix my timing/hot heads problem? running out of options. AFM is unmolested as far as I know. Dont want to screw it because I know nothing about it.

Hello Jack.
I get the sense that you have been stunned by too much good advice.
Please tell me how many miles are on the rebuild, what type of pistons/cylinders were installed, and whether or not you are running an oxygen sensor/catalytic converter.
Colin

[jackstar]

Colin,

Thank you for your time. I am running stock pistons and cylinders with the former being balanced. I dont remeber the vendors, the paperwork is at work. Yes I am running an o2 sensor and a catalytic converter. The bus came from oregon and before that California so it appears to have been kept stock.

The cause for the rebuild was #3 intake valve seat failed and I found out I had GEX heads. Len Hoffman did my new heads. I will reconnect the vac lines to both sides of the can tomorrow as I ran out of time today. I will time it as you suggest and will get back to you with the results.

ONe of my biggest concerns has been my CHT and the timing. I am trying not to burn up Len's good work. Or my wallet for that matter. Thanks again. Stay warm.

Jack

[airkooledchris]

Running with the stock CA computer and the O2 sensor connected you can almost guarentee itll run extremely hot as that is setup to be really lean. Only way to know for sure is ti run a CHT sensor and check the mixture

[jackstar]

Chris,
Is yours still set up stock with the computer and O2 sensor? If not, what did you do different? Thanks.

Jack

[Randy in Maine]

And Jack,

The offer to use the LM-1 is still out there. If you want to borrow it, let me know.

[Amskeptic]

Colin,

Thank you for your time. I am running stock pistons and cylinders with the former being balanced. I dont remeber the vendors, the paperwork is at work. Yes I am running an o2 sensor and a catalytic converter. The bus came from oregon and before that California so it appears to have been kept stock.

The cause for the rebuild was #3 intake valve seat failed and I found out I had GEX heads. Len Hoffman did my new heads. I will reconnect the vac lines to both sides of the can tomorrow as I ran out of time today. I will time it as you suggest and will get back to you with the results.

ONe of my biggest concerns has been my CHT and the timing. I am trying not to burn up Len's good work. Or my wallet for that matter. Thanks again. Stay warm.

Jack

A GEX seat drop does not blame the rest of the engine.
Len Hoffman heads, I expect, will hold together. If you have new rings in your rebuild, the engine will run hot until the rings have broken in. Keep your driving short the first 100 miles, normal driving driving but for short 20-30 minute intervals with cool-down between.

The only timing that you can trust is to *adjust* at 3,400 rpm to 25-28* Do not worry about the idle timing. If the idle speed cannot be brought down, you need the functional retard unit of the DVDA distributor.

If you have a CHT gauge, disconnect the oxygen sensor, plug in the bypass plugs for idle stabilizer, set speed to 950 rpm, go ahead and adjust the AFM mixture screw clockwise as far as it takes to get the idle speed up as far as it wants to go. Pay attention! We know you adjusted the idle speed to 950 with the speed screw! We know. Now we are looking for a change in speed *due to mixture*. If mixture screw CW makes the idle speed go up, then it suggests a lean condition down near idle. You may readjust the idle speed screw to bring idle back to 950+/- 50. Read up on the AFM adjustment in the Fuel Delivery sticky, and only do a 6-10 teeth COUNTER-CW experiment with the black cog AFTER you have made an initial setting reference mark.

Drive the car with the ox sensor off. Note power, heat, driveability.
Now plug in the idle stabilizer. Note any change in idle speed. Report CHTs at 65mph with an engine that has been working for at least 20 minutes.

For fun and enlightenment, re-plug the ox sensor back in on your drive back home. Report CHT readings unless you have grossly different variable like a tail/headwind.

Remember, you are the mechanic here, you can easily reverse any fooling around, so feel free to experiment.
Colin

[vdubyah73]

from my own experience, take notes of every change youve made. how many teeth on the cog, how many turns of a screw, etc... memory is a fickle thing.