Resistance wire removal or replacement.

If installing an electronic ignition system the resistance wire most likely has to be removed or bypassed. There are several ways to do this and the solution depends if you have the 1963/64 4-speed Hydra-Matic transmission or the 1964 3-speed Turbo Hydra-Matic transmission. There is also a Ignition Power Relay supplied by PerTronix but that will not be discussed in this thread.

If your car is equipped with the 3-speed Turbo Hydra-Matic the easiest way is to remove the resistance wire from the coil and secure it or remove it completely. After that take a new fresh wire and connect it to the switch on the transmission downshift. The pink wire going from the ignition switch on the dash to the switch, is the same wire the resistance wire is connected too. So just connect to that pink wire and you are home-free.

If your car has the 4-speed Hydra-Matic life is a bit more tricky. So now its time for some pictures and explanations.

1. The red arrow is pointing to the brownish resistance wire. It is normally taped together with the yellow wire (starter solenoid) and the green wire (temp gauge). 2. At the yellow circle the wires will go three ways and you have to open this up. 3. The blue circle is showing the wires going through bulk-head into the cock-pit.

Here is the device on the bulk-head partly removed.

Here is all opened up and as suggested by Jason Edge you should be able to carefully pull out the resistance wire and free it from the pink ignition wire. (Red arrow is pointing to the resistance wire)

However on my car it was not possible to pull trough the hole in the bulk-head and I had to do the job inside the instrument panel. To facilitate the job I removed the dash and the steering column lower cover. Found the connection between the two pink wires and the brownish resistance wire.

Removed the tape. (Hard to focus with the phone camera)

Connected the two pink wires (the ignition switch and the fuse box) with the new wire to the ignition coil. If you have a Turbo Hydra-Matic you will have three pink wires here instead of two, as the third wire is going to the transmission downshift switch.

When this job is done you have to secure it all again and pay attention to protection of the wires.

Here the new red wire is connected to the plus on the new ignition coil together with the yellow wire from the starter solenoid and the wire from the electronic ignition. The green arrow is for the green wire to the temperature gauge.

After this new rotor, distributor cap, spark plug wires and spark plugs. Remember that you might have to increase the gap size on the spark plugs as you now will have a hotter and cleaner spark. Depending on plugs used you might have to increase distance to 0,035-0,040".

When all is set and done. Start your car. Run it until normal working temperature and do a complete ignition timing adjustment as per 1964 Cadillac Shop Manual page 12-17 to 12-18 (I don't have a 1963 Shop manual so don't know the pages in that book).

Good luck

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We are talking Race engine here -- do not think about a total advance of 38 degrees on anything you are driving --------please


I think Kevin is running 10 -12 degrees in his 64-429 .-with points if i am not mistaken


Correct, but my dizzy has been calibrated to suit and always remember, you can't always hear detonation.

Just Sayin - try it you might like it ( or not ! )


I think 32 degrees is safe in any car of this vintage.  As Jason pointed out there are trade offs. The factory set timing based on many reasons and could have moved initial timing higher if they wanted. But they would have been compromising something else in what they thought at the time they wanted to achieve.  Jason I thought you ran manifold vacuum?  If you are you do actually have an advanced idle timing. Total timing may not be effected but it is advanced 12.5 degrees from the vacuum advance for a total of 17.5. This will drop a bit as the vacuum drops from the throttles being opened but it is still more at idle than the factory wanted. I think my problem was carb related but ill never now know as I'll never have a carb on it again. I'm moving up to ten degrees timing to give it a try. I'm not sold on petronix being anything other than dependable. I do not believe it will boost performance where you can feel it in the seat of your pants over a good points set up. The benefit of a hotter longer spark really only comes into play at very high rpm's. All of this is obviously debatable these are just my views and observations and what I learned over time. 

One last thought on timing, there are advantages and disadvantages to both ported and manifold vacuum sources for your vacuum advance, it comes down to what you want to trade to get to the finish line first.

Ok your vacuum advance is 10.75 and harmonic balancer is 5 then you have 15.75 degrees advance at idle. When you have moved to a manifold vacuum you have changed the timing curve. You are assuming that the vacuum advance, as you are running it, is getting the exact same signal as a ported signal once off of idle. Your making assumptions. If you map out the vacuum signal from a ported source vs a manifold source throughout the entire rpm and throttle position range they are two different animals. My fuel injection system allows me to monitor both vacuums and they are not the same. This is not an assumption it's an observation. When you give it throttle input the vacuum does not drop to zero. Our cars run around 18 inches max at idle and higher when we come off an accelerated run or sprint. Lets say we pass a car on the highway, when we give it gas a manifold vacuum decreases, timing drops, when I get back in my lane my foot is off the gas and manifold vacuum increases again. Your total timing at any given point on the curve is affected by that. Ported vacuum will be different at every point because the throttle position determines the vacuum signal to the advance not the actual vacuum in the intake at a given time. This is very basic and old technology much less confusing than the comfort control system. 


You talk about timing being high, cruising on the highway, when damper timing is set to ten vs five. Well lets look at that.

Running down the highway with 10 damper, 8 inches ported vacuum and 10 mechaical vacuum we will have a total that coincides with the ported amount, which is less than a full vacuum amount.

Running 5 damper, 10.75 vacuum (we know it's fully in as throttle position causes full vacuum) an 10 mechanical. The total is higher on the highway with your set up than mine because my vacuum advance is less as it's getting less vacuum at high speed. So again your timing curve is no longer the factory 

By Edelbrock telling you to use the vacuum port on the carb --that has vacuum just off idle they are basicly telling you to run more timing advance thru the RPM range and on the highway for improved engine performance
The vacuum port you are using is giving you more timing advance quicker than the stock Carter carbs single vacuum port  thus advancing your timing more rapidly than stock vacuum does
After all they are the engine performance people so they --are selling you a carb --but want your car to run as good as it can in the mean time --so they are adding more timing thru the RPM range by changing the stock type porting and giving you more power that way
it is an increase in dist timing advance available over that of the stock timing advance
So it is not the stock advance curve the engine was designed to use but Edelbrocks improved version with a timing increase they build in --with there directions to use a non stock type porting with there carbs
All back to more timing more power just being done a different way


Some how we have not included the 1.50 degrees of --centrifugal advance
--that is added at 450 RPMs ( as the stock idle is 480 RPMS ) to the total advance -- at idle
Making the 15.75 total advance suggested above to really be a total of 17.25 total degrees of advance --at idle on manifold vacuum
That does make The number Clovis is using of 17.50 to be closer to actual number than the 15.75 total that Jason is using for the total advance number at idle
So now we have more total advance than stock when we go for the gas peddle that will be producing more horse power the second we get into the gas peddle even though the vacuum advance will be dropping off as expected but adding centifical advance very quickly
By 1050 RPMS --which comes up real quick when accelerating --the vacuum advance has dropped off but 5-7 dgrees of centrifugal advance is added
Not knowing how much the vacuum advance has dropped off --
going off idle --makes it difficult to determine the actual advance you are using at 1050 RPMS unless you know the actual vacuum in inches the manifold is producing At that moment
Somehow i think the total number could be higher than the stock total at the same RPM as you are staring out with a higher advance number and as that number drops some ( unknown ) and then adding centifugal timing to that number rather quickly the total advance at 1050 RPMs could have the timing a higher number than stock at the same RPM until we reach the total which does not change of 25.75 max


We know the vacuum advance does not drop to zero when we come up off idle and on the gas
Lets say the Vacuum advance drops off 5 degrees for example for a momemt when accelerating off idle
5-7 degrees is -- very quickly added back --by the centifugal advance having you running just about the same total timing you were just running at idle which SB a higher number than the stock timing running at the same RPM
If the mercury drop is less than 5 inches at the vacuum advance when accelerating you could be running a few degrees more at 1050 RPMS than you were at the idles total advance number
The total advance numbers would appear to be be higher thru the RPM range but will not exceed the total 25.75 max allowable



Although I've kept an eye on manifold vacuum I can say that I didn't see it dropping below 12 inches most of the time. A pedal smash may drop it lower but my eyes are on the road when that happens lol. It stays much higher with steady driving and light pedal input. I do have the ability to record this and any other parameter if I desired. The information can be loaded to a laptop for analysis also. So it would could tell me manifold vacuum at any given rpm and throttle position.  Gotta love modern technology. 

The mercury drop of 5 inches is not correct above 

it should read a drop of 5 degrees at the vacuum advance when accelerating 

I made the correction with the edit feature that does not always correct the wording when I press save to make the correction 

Have no idea what that is about 


This is the —most complicated —simple math ever  —LOL  ! 

Discussing the Edelbrock vacuum porting —Which we have two of —only on this  brand carb —unlike the stock carbs— is a very interesting subject regarding the engines performance 

if you have the stock carbs this info —does not apply 

Just so we are not confusing the stock carb boys at all 




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