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Pertronix - Pros & Cons - Video & Pics

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Re: Petronix - Pros & Cons

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HI Dave, none of mine say that and they work just fine.---Keoke

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Well good for you. You might find this interesting.
https://dragracingonline.com/technical/vii_10-lights-1.html
D /ubbthreads/images/graemlins/yesnod.gif

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Thanks for the great link, Dave...great stuff. That's what I like about this hobby - there's always something to learn (for us mere mortals anyway) /ubbthreads/images/graemlins/wink.gif
 
Re: Petronix - Pros & Cons

[ QUOTE ]
[ QUOTE ]
[ QUOTE ]

HI Dave, none of mine say that and they work just fine.---Keoke

[/ QUOTE ]
Well good for you. You might find this interesting.
https://dragracingonline.com/technical/vii_10-lights-1.html
D /ubbthreads/images/graemlins/yesnod.gif

[/ QUOTE ]

Thanks for the great link, Dave...great stuff. That's what I like about this hobby - there's always something to learn (for us mere mortals anyway) /ubbthreads/images/graemlins/wink.gif

[/ QUOTE ]

Well Basil, if you want one of those "older Model" Sears timing lights like mine I saw one being auctioned on E-bay just recently.---Keoke- /ubbthreads/images/graemlins/grin.gif
 
Re: Petronix - Pros & Cons

A further note:
My newer super digital timing light gives very erratic readings with solid core wire. I've noted that the instructions for this light & a couple of other newer "dial back" lights warn to use resistor plug wire.

I just happen to also have an old Sears #2134 as mentioned in the article. Even it gives more consistent operation when a resistor type wire is used.

This may be a moot point if timing is only being checked at idle. However, the really important timing number is the maximum advance achieved at the maximum advance rpm, vacuum advance disconnected. Most distributors are lucky to be within 5 degrees of spec on their maximum advance. This maximum should almost never exceed 32 to 38 degrees total advance, static plus centrifugal. To just set the timing at idle & hope that the centrifugal advance will not exceed this limit at higher rpm is like playing Russian Roulette.

A few degrees too much advance at high rpm can destroy an engine before you even know anything is wrong. A couple of degrees too little advance only reduces power a small percentage.
D
 
Re: Petronix - Pros & Cons

Yes that is true.Personally, I do not like the digital units.However, when setting the dizzy up I rarely do it on the car. There are a couple of shops here that have the old distributor testing machines and I use them. Checkered Flag even has one on display in their show room. I keep tellig them it would be better off in my shop---Keoke- /ubbthreads/images/graemlins/grin.gif
 
Re: Petronix - Pros & Cons

How do the newer timing lights connect to get a reading? Mine has a clip that conects to the #1 plug, and allows the plug wire to be connected to it... the only other connections are the battery leads for power. I know there are ones with just a EM loop that clips over the #1 plug wire instead. Just curious what's the norm these days?
 
Re: Petronix - Pros & Cons

Hi Kenny, I have one of those old fellas too. However most of the more recent light designs utilise an inductive pickup[EM Loop] that clamps over the spark plug wire and snaps shut. The only other leads are those for power--Keoke
 
Re: Petronix - Pros & Cons

"really important timing number is the maximum advance achieved at the maximum advance rpm, vacuum advance disconnected"

Help me understand please. Why disconnect the vacume advance at advanced RPM if vacume is only available at low power settings. Will it not become a moot point.
 
Re: Petronix - Pros & Cons

At high rpm and no load, you're in a low power situation -- you can still have some vacuum. Best to take the vacuum advance out of the picture entirely, just to eliminate an unnecessary variable.

HTH!
 
Re: Petronix - Pros & Cons

[ QUOTE ]
Well Basil, if you want one of those "older Model" Sears timing lights like mine I saw one being auctioned on E-bay just recently.---Keoke- /ubbthreads/images/graemlins/grin.gif

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I already have one.
 
Re: Petronix - Pros & Cons

I don't think my dizzy has a vacuum does it? '67.
 
Re: Petronix - Pros & Cons

Hi Jack, no it may not be just a moot point.If there is a potential for some advance at low load due to the Vacuum advance unit then you certainly want it included when you are seting the maximum. Fwiw---Keoke
 
Re: Petronix - Pros & Cons

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Hi Jack, no it may not be just a moot point.If there is a potential for some advance at low load due to the Vacuum advance unit then you certainly want it included when you are seting the maximum. Fwiw---Keoke

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I don't understand. If you set the advance at low load, which is the only way that you can set it, (short of running the engine under load on a chassis dyno) & you set the maximum advance with vacuum advance included, -- at high loads the advance will be severely retarded as the vacuum decreases. The maximum at high load & high rpm should not exceed around 35 degrees. At light loads, the maximum would be the 35 degrees plus 15 degrees of vacuum advance for a total of 50 degrees which is fine at low loads. The total advance retards back to 35 degrees as the load is increased. If you set it at 35 degrees with vacuum connected, It would retard to 20 degrees as the vacuum decreased at high loads, Not near enough advance.

I reiterate. Maximum advance, at 4,000 rpm & above, static plus centrifugal, no vacuum, should not exceed about 35 degrees. The vacuum advance only increases this 35 degrees at light engine loads & goes back to the original 35 degrees at higher engine loads. The centrifugal advance & the vacuum advance are two completely different things & should be checked & set independently. I hope we are just on different pages & really saying the same thing?
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Re: Petronix - Pros & Cons

If I am looking at the cap, are the wires 4321 left to right? I cannot find this in Bentley or Haynes.
Plugs are also 4321 L to R.
 
Re: Petronix - Pros & Cons

Forget the wires.

How bad is this?

tn_7-20-06-SparkPlugscompression002.jpg

tn_7-20-06-SparkPlugscompression010.jpg


I think you all know what this is.
 
Re: Petronix - Pros & Cons

The source of your running problems?
 
Re: Petronix - Pros & Cons

regarding the wires...

there's an arrow on your rotor - it points in the direction of rotation. When the brass point is in the general direction of the #1 spark plug that is #1. Look at the cap and imagine which wire it will fire next as it rotates. That will be the one that fires #3.... then #4... then #2... then back to #1... That's the 1-3-4-2 firing order on your car. Sorry but I cant remember exacly how they line up on the top. But if you had your firing order set to 1234 I doubt you would get it running much at all.

Your plugs look nice and sooty. That means your carbs are running too rich. Clean up the plugs and then re-adjust the mixture on your car.

Remember... 95% percent of carb problems are ignition... so you're probably a 5 percenter now !!! Congrats!

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Re: Petronix - Pros & Cons

So having sporadic 0 - 110 psi in my #3 cyl is ok?
 
Re: Petronix - Pros & Cons

So having sporadic 0 - 110 psi in my #3 cyl is ok? That single soot plug is #3 and it's caked. These plugs might have 5 hrs running time & 80 driven miles. I know I had gas problems but I am worred about the compression.
 
Re: Petronix - Pros & Cons

Hi Dave ,low load in this case simply refers to the car at a cruising speed as apposed to low RPM Running thats all.Just include it all if its there I think that was clear.---Keoke
 
Re: Petronix - Pros & Cons

I honestly didn't notice the numbers and didn't realize you were posting compression figures.

Obviously 0~110 is not good. It might just be a sticky valve. Or it's so burnt that it jams open sometimes?

You definately have a problem.

You might want to pull off the valve cover and see if you can see it sticking while someone cranks the engine.
 
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