300 distributor in a 223 advance/retard question

[Christmas elf]

Ok folks new to the group and I'm hoping someone has the answer .
I have done the 300 distributor swap and it has been doing my box in and I'm ready to check myself into the nut house.
I have a 59 edsel with the two speed mile o matic and 223 motor
I used a duraspark for a 74 Econoline with the GM module

So after issues with the GM module going faulty and stalling in gear unless I had a very fast idle and a faulty distributor with to much free play in the mechanical advance I tried a different brand module and a replacement distributor it's certainly better nice slow idle and no stalling when in gear.and will rev nice

Now my latest issue has me stumped
The mechanical advance is actually retarding the timing and it's only when the vacuum starts to work that the mark's start to line back up.
With the timing set at 6'btdc it will retard past tdc to something like 4'atdc before it starts to come back as the vacuum takes over

Is this normal for this type of distributor
I currently have the vacuum line on the 1904 carb with the scv but I can drill and tap the inlet if required to go direct
Thanks for any suggestions

 

[manglass]

Are you having any drivability problems or detonation (spark knock)? If not, enjoy your car.

What you are describing sounds like what normally happens with manifold vacuum connected to the vacuum advance. As you "tip in" the throttle the vacuum drops off, then recovers either before or about the time the centrifugal advance begins. The load-o-matic carburetor initially provides manifold vacuum to the distributor, once the spark control valve opens venturi vacuum is added to the mix. Venturi vacuum increases as the throttle opens. The problem with using the load-o-matic vacuum source for your Duraspark is that it can, along with the centrifugal advance, provide too much timing advance and cause detonation. Along with the caution about detonation, I should mention that people have used the stock load-o-matic vacuum source successfully. Most distributor conversions on these engines revolve around a conversion to ported or manifold vacuum which is what the Duraspark distributor is designed for. If you want to use the original load-o-matic port, it should work okay as long as you limit your vacuum advance to prevent detonation. Vacuum advance should be adjustable on a 74 Econoline distributor.

If you would like to learn more about the load-o-matic system, venturi vacuum, or the spark control valve; there is an excellent article here:

Load-O-Matic Distributor & Spark Control Valve

How The Stock Load-O-Matic Distributor Works Here is a little clarification on how the "Load-O-Matic" distributor works, along with the infamous "Spark Control Valve" (or SCV). Not only is it important to know how they work, especially if your...

fordsix.com

Let us know how it's driving and, perhaps, we can provide more specific information to help you dial it in.

Lou Manglass

 

[Christmas elf]

Thanks for the reply
Driving wise she seems fine can't hear any pinking etc.
Even with the vacuum disconnected it still retards as I build the rpm.
it will return to base as the rpm comes back to idle
Thing I have noticed are
The dizzy turns clockwise the mechanical advance also turns the rotor arm clockwise so this is why it's retarding as I build the rpm
The vacuum pulls the base plate anti clockwise so advance
I'm probably over thinking it as every other vehicle I have as rpm build the system advances
I have not seen any way to adjust the vacuum but I can work it out

 

[sixtseventwo4d]

I would try locking the mechanical advance.

 

[Christmas elf]

Locking is looking like a option and just use the vacuum from the manifold.
But mine can't be the only one like it

 

[manglass]

From your descriptions, your vacuum and centrifugal advance are both working properly. The vacuum advance moves the breaker plate against rotation to move the points or magnetic pickup contact earlier (advance). The centrifugal advance moves the "cam lobe" with rotation to bring timing earlier (advance). It's possible that the centrifugal advance curve is designed to pull a couple degrees out in the beginning before it starts to increase timing. Does it keep going back as you raise rpm or will it start to advance as rpm climbs? A stock centrifugal advance curve probably won't start to come in until 2500 rpm or more. I don't know the condition of the engine but it's also possible you're seeing timing chain stretch retard the camshaft and ignition timing.

If you lock out the centrifugal advance, you'll have nothing more than the load-o-matic that you started with. The vacuum advance should be adjustable through the vacuum port with a 1/8" allen wrench but if it's running well, I wouldn't mess with it.

If you wish to go to the next diagnostic step, I would suggest sending your distributor to someone with a distributor machine to have it checked and, possibly, recurved. You could also do a quick check on the timing chain. Set the timing mark at 10 degrees BTC then crank the engine backwards, carefully, by hand until it begins to move the distributor shaft. If it moves more than 10 degrees or so the timing chain is suspect.

Lou Manglass

 

[Christmas elf]

From your descriptions, your vacuum and centrifugal advance are both working properly. The vacuum advance moves the breaker plate against rotation to move the points or magnetic pickup contact earlier (advance). The centrifugal advance moves the "cam lobe" with rotation to bring timing earlier (advance). It's possible that the centrifugal advance curve is designed to pull a couple degrees out in the beginning before it starts to increase timing. Does it keep going back as you raise rpm or will it start to advance as rpm climbs? A stock centrifugal advance curve probably won't start to come in until 2500 rpm or more. I don't know the condition of the engine but it's also possible you're seeing timing chain stretch retard the camshaft and ignition timing.

If you lock out the centrifugal advance, you'll have nothing more than the load-o-matic that you started with. The vacuum advance should be adjustable through the vacuum port with a 1/8" allen wrench but if it's running well, I wouldn't mess with it.

If you wish to go to the next diagnostic step, I would suggest sending your distributor to someone with a distributor machine to have it checked and, possibly, recurved. You could also do a quick check on the timing chain. Set the timing mark at 10 degrees BTC then crank the engine backwards, carefully, by hand until it begins to move the distributor shaft. If it moves more than 10 degrees or so the timing chain is suspect.

Lou Manglass

Thanks the chain has about 5 thousand miles on it .
As rpm increases it will go back to 6' it's slow to go but like I say it is pulling through the scr .
I think my best option is reduce the mechanical retard increase my base timing so as it pulls out timing it doesn't go past tdc (at the moment it will pass tdc) and then run the vacuum from the inlet
What do you think

 

[PSIG]

Locking the mechanical and vacuum advance will allow you do determine where the issue is located. Zero timing change means the issue is in the distributor. Timing change indicates the issue is before the distributor (timing set, gear drive, etc). Locking is commonly by wiring the spring posts inward, drilling to insert a self-tapping screw through both plates, or wiring the plate to the advance limiter tab.

Is this normal for this type of distributor

No. However, check if you have a dual-advance vacuum canister, where one side advances with vacuum while the other retards.

I currently have the vacuum line on the 1904 carb with the scv but I can drill and tap the inlet if required to go direct

Refer to the link posted, but know that LOM/SCV vacuum is incorrect for standard distributor operation. The carb can be modified to supply 'normal' ported vacuum, or the distributor curves can be altered to use direct manifold vacuum. You can always try manifold advance easily, but unless you are familiar with re-curving to use manifold advance most effectively, I'd suggest sticking to ported by modding the carb or using a conventional carb.

The dizzy turns clockwise the mechanical advance also turns the rotor arm clockwise so this is why it's retarding as I build the rpm

The other way. The rotor advances ahead of rotation with mechanical advance, carrying the reluctor with it, triggering the sensor earlier. Verify your rotor can be turned by hand in the direction of rotation, and snaps back under spring pressure when released. Your reluctor tooth and sensor bar face should be perfectly aligned at your base timing. If it retards from there, you definitely have an issue to correct.

All mechanical advance should be positive from base timing, and same for vacuum advance, except if using the retard side of the vacuum advance canister. If you have a dual vac canister, I'd replace it so there is no opportunity for retard from base timing at any point.

The vacuum pulls the base plate anti clockwise so advance

Correct, the sensor plate moves against shaft rotation, advancing timing.

 

[Christmas elf]

Such fun
Ok then the two dura spark dizzy I have on both the rotor can be turned in direction of rotation and will snap back one has free play in both springs so gives it a unstable base timing.

Both are single vacuum
Will have a read on the carb mod

 

[Christmas elf]

. You can always try manifold advance easily, but unless you are familiar with re-curving to use manifold advance most effect

So I have gone direct to manifold and it's certainly helped the issue .
base set at 6' with no vacuume
At idle as soon as I attach the pipe it advanced I did not check how far I will do that tomorrow night .
as rpm is increased it drop's back to around 6 and then starts to advance and settles down I have not checked what full advance is yet but it's certainly working better and more how I expect it to act
Is it best to set the base with or without the vacuume
Thanks again for the help

 

[manglass]

Set Base timing with vacuum blocked off. The easy button is to set base timing to spec, then advance 2 degrees at a time until it starts to "ping" and retard until it stops. That will be as good as you can get short of having the distributor professionally curved or the car dyno tuned. If you want to attempt to adjust the curve yourself, get an adjustable dialback timing light and we can take you through it one step at a time.

 

[PSIG]

as rpm is increased it drop's back to around 6 and then starts to advance and settles down

Better, but this means you still have a problem to solve. What is your ''normal' warm curb idle rpm? What is the timing during cranking?

Is it best to set the base with or without the vacuume

Always with vacuum disconnected and plugged.

As you do not know the mechanical timing curve, vacuum curve, or the maximum applied timing of this distributor, I would play it safe and (vacuum disconnected) rev the engine parked and watch the timing for the max it will advance at high rpm. Set the timing to 36° and let it settle to idle. Adjust warm idle rpm. Read the idle timing. That is your current base or curb idle timing. Connect the vacuum advance and read again, and make note of it.

Setting the max advance is much safer for your engine than a guess at idle, or by pinging at some mid-range point that can be far off of proper timing, where either will result in unknown and possibly damaging advance at higher load and speed. Setting by max advance does not make your weird timing OK or acceptable, it just makes it safer for test-driving your engine until you solve the weird timing problem as soon as you can. It's not a crisis, and as long as you are not in detonation at higher loads or overheating from under-advance, it's OK for right now. I wouldn't wait long however, as for example a local with a 200 had his new valves and seats sink to failure in less than 50K miles from bad timing.

While you can do your own distributor re-curving, it will take some info, time and effort. Another option is to have a distributor tuner provide a re-curve on your distributor for you, that although not true custom is typically better than factory. WSA111 here on the forums, or Dan at the Mustang Barn have extensive experience and an excellent reputation for getting these puppies to work better than ever.

 

[Christmas elf]

Ok thanks everyone for the advice I don't have a clue whats going on.
So I have done some checks with my timing light and this is what I get with the duraspark
Set base at 6'btdc no vacuume and pipe plugged 650rpm (vacuume direct from manifold )
Still no vac increase rpm to 2000 and it's retard to poss 4' (can't get accurate reading as my light stopped at 0'
Connect vac line and idle increase on its own to700rpm and advance to 23' (according to my adjustable light )
Increase the rpm to 2000 and it will advance to 26'
I made marks on the vac arm for full travel and at idle the vac is about 3/4
Is there a way to alter the amount of vacuume so it doesn't pull so hard at idle
I refitted my old load o matic and sits happy at 6' and 650rpm idle.and advance is working as well as it can
So until I can get the dura spark to work correctly it looks like keeping it on points for my trip round Germany .