Distributor Timing (200 Six)

adamscm

Well-known member
Hello All, I've got a question about installing the distributor in a rebuilt engine. Here's what I did--Got motor at TDC compression, installed dist. with rotor lined with #1 cylinder position on dist. cap....Ok, that seems like standard procedure. But what I notice is that the points are not open at that position. It seems physically impossible, as when the rotor points to #1 (or to any cylinder), the flat side of the dist. cam is contacting the points. What am I missing? Did I do this correctly? Should I be ok if I followed that installation procedure? Thanks.....Oh, and one more unrelated question...The Holley 1940 carb that I use on my 144...can it be used on a 200? Ive seen specs that say it can be used on 144-170-200, and I know it will fit physically, but will it be enough?
 
If it's as far off as you describe any chance the cap is wrong? Rotor, Cap and Points should all be in proper alignment in or out of the motor.
 
The rotor IS pointing correctly at the #1 post on the cap when engine is at TDC. But the rotor fits in the top of the distributor shaft such that when it is pointing directly at a post, the flat side of the cam is contacting the points. Maybe this is normal, I'm just wondering if anyone has noticed this on theirs. Now, when I advance the distributor about 8 or so degrees, the points do just start to break open, and the rotor is on its way to passing the post...the tip of the rotor, since it flares out wider, does just still line up with the post. I had just always assumed that the points would be nearly wide open at TDC, but maybe not. I'll post some pics either tonight or tomorrow when I have my laptop.
 
Turn the distributor till the points are just beginning to open, this will get you close.
What you are seeing is the difference between "TDC", and ~ 8 degrees before TDC, which is the "timing/firing" spec.
DannyG
 
The points start to open before the rotor gets to be straight across from the number 1 distributor post. Ignition Timing is going to be set at 10 or more degrees Before Top Dead Center. Good luck :nod:
 
Thanks for the replies...I'll post pics in the morning if you could take a look, but basically it seems that even at 8* btdc, the points are just opening while the rotor is centered on the post, not prior or near the beginning.
 
@0*TDC the rubbing block of the points should be riding on; the six edges of the cam. This where you set the point gap; opening position.
Generally, You would run 10-12* BTDC on your initial timing.
You can adjust timing to 10=12*BTDC, after starting. Remember to disconnect and plug vac advance, when using timing light. I assume you are using vacume /mechanical advance unit.
 
It's still the Loadomatic (vacuum advance only). Since the relation of the cam lobes to the rotor is fixed, it seems the only way the points could be more 'open' When the rotor is centered on the #1 position is for the breaker plate to be in a different position (like when the vacuum is advancing it). But again, when I'm at tdc, and the rotor is 'centered' on #1, the points seem to just be starting to open. I hope it's not possible for that breaker plate to be not installed correctly. This is a rebuilt dist from O'Reilly's.
 
You still have to adjust the breaker plate, installed on the engine. To set proper gap. Gap set by loosening screw, than twisting slot with screw driver. Light drag on feeler gauge. Tighten screw.
it usually takes a few tries, as points tend to move when you tighten the nut. Try two screw drivers at same time..it helps to have a third hand for the feeler gauge.......Of course you do have to keep bumping the starter to get the rubbing block to rest on the narrow high point of the cam. It's gear backlash that your dealing with.
 
I understand about adjusting the point gap, tha'ts ok...I was referring to the whole plate that the points are screwed down onto. (BTW, the motor is on a stand, not installed). The first photo below shows the dist at tdc, with points open. The circular plug in the housing at the bottom of the pic is lined up with the #1 cap position. Notice how only the back edge of the rotor (the wide part) is in line with the #1 position. Photo #2 shows the crank at 8* btc...notice more of it is lined with the post position, but the points are not completely open. (And if I were to turn the housing so the rotor EXACTLY lined up with #1, the points would be nearly closed)

 
adamscm":29jjc04q said:
Hello All, I've got a question about installing the distributor in a rebuilt engine. Here's what I did--Got motor at TDC compression, installed dist. with rotor lined with #1 cylinder position on dist. cap....Ok, that seems like standard procedure.

1. :beer: yes that's the standard procedure.

But what I notice is that the points are not open at that position. It seems physically impossible, as when the rotor points to #1 (or to any cylinder), the flat side of the dist. cam is contacting the points. What am I missing?

2. :shock: what your missing is that the points would not be open at TDC, ignition needs to occur at BTDC otherwise the engine is going to lack power. It takes a little bit of time for the spark and flame front to build and move across the cylinder.

Did I do this correctly? Should I be ok if I followed that installation procedure?

3. (y) yes it looks as though you did! All that's left after everthing else gets installed and hooked up in your car will be to use a timing light to set the base timing. IE the plug wires, coil, wiring from ignistion switch, etc.

Thanks.....Oh, and one more unrelated question...The Holley 1940 carb that I use on my 144...can it be used on a 200? Ive seen specs that say it can be used on 144-170-200, and I know it will fit physically, but will it be enough?

4. :nod: yes measure the carb opening on your 200 is it the same size and bolt spacing as on your 144? If it is then it should fit and work fine.

5. :D So to review the ignistion system parts and operation: The coil has two top posts one is connected (Bat. Or +) to the power coming from the ignistion switch through a resistor block or resistance wire (depending on the year of your car). When engine is running the coil will only see 6 to 8 volts. For starting there is an adistional wire coming from the starter solenoid (Ign) post going to the (Bat. Or +) post supplying 12 volts for extra starting power only when ignistion switch is in the start position. The other post (Dis. Or -) is connected to the distributors points this is from the coils Primary windings. When the points just start to break open it causes the coils Secondary windings to be saturated raising its voltage much higher. Depending on type of coil, plus resistance of the ignition system (it can be roughly 30,000 to 50,000 volts). The voltage goes through the coils center tower, by the coil wire, and into the distributor caps center post were the distributors rotor directs that voltage to the right cylinder by its position. Though the spark plug wire and next firing that cylinders spark plug jumping it's gap. So Now you have your ignistion source to make the engine run. :mrgreen:

6. :unsure: in your last two pictures I see nothing wrong with how the distributor is assembled, they are basically made to go together only one way. There is not much else you can do to adjust an LOD system unless you have a distributor machine to use and likely is about as good as it needs to be. So just set points dwell and base timing it to the factory tune up specs. You should have no worries and it will all work as it is designed too! Good luck and I hope that clears up some of the confusion for you. :nod: Edited
 
As picture explained, points should be fully opened @ 0*TDC. Points should be partial open @ 8*BTDC. Distributor cap may not be 100% indexed correctly to #1.
 
Thanks, guys, for all your input. I'll let you know how it works out. I should be swapping engines this weekend, but that's no guarantee it will be ready to run!
 
Hi, I wouldn't worry about where the lobe starts to open and close the points. Just gap them properly and put a small dab of grease on the cam. Gap should be set at .024-.026, on the high spot of course. I always go on the larger side so as the rubbing block wears you stay within specs. Setting by dwell (Look it up it may be between 36 to 40 degrees depending on year) is more accurate, but the engine must be cranking (or running to check it). Remember dwell affects timing, but timing does not affect dwell. I like a lot of advance on my engines. I set the timing with the light, and just snug down the hold down bolt. I'll advance the timing until it pings on a hill in second gear, and than back it off until it does not ping any more. If you have a timing light with a dial you can see total advance, on my old light I just see the mark move up under the water pump when I rev the engine. If you are starting a rebuilt engine for the first time make sure you don't just let it idle while you fuss with timing and other adjustments. Get it to run smoothly and gently raise and lower the RPMs. make sure to check the water level as it warms up. After it is running a while and warmed up do your timing and set your idle. Good luck
 
78 granada":3jbo3a85 said:
Hey, any of you guys ever set ignition timing by vacuum alone?

no, but it can be done by RPM alone (at least ball park), just turn up the idle until all the advance is in, then adjust timing for highest RPM, then back retard timing till RPM falls 200 RPM. If it pings after that, retard as needed.
 
So since we are on this topic... I just installed a new D.U.I. Distributor and followed the procedure to the T. TDC, made sure points were aligned, and dropped it in. It looked like it went in perfect. so after hooking up the new 8mm accel plug wires and changing the spark plugs out to autolites with a gap of .055, the motor cranks and cranks away but will not fire off. checked to make sure I had the 12 volts going to it with a meter and even pulled a plug, hooked up the wire and saw spark from it. could it be actually 180 degrees out and firing backwards for say? or is that too much of a gap? the product website (Performance Distributors) called for that gap size. little frustrating bc that's the only thing keeping me from being able to drive it. :banghead:
 
DannyB-67":1ap8zdvi said:
So since we are on this topic... I just installed a new D.U.I. Distributor and followed the procedure to the T. TDC, made sure points were aligned, and dropped it in. It looked like it went in perfect. so after hooking up the new 8mm accel plug wires and changing the spark plugs out to autolites with a gap of .055, the motor cranks and cranks away but will not fire off. checked to make sure I had the 12 volts going to it with a meter and even pulled a plug, hooked up the wire and saw spark from it. could it be actually 180 degrees out and firing backwards for say? or is that too much of a gap? the product website (Performance Distributors) called for that gap size. little frustrating bc that's the only thing keeping me from being able to drive it. :banghead:

Just go back to TDC and check if rotor points to number one on distributor. Gears are angle cut, so they twist as distributor goes back in. Could be off a tooth or two.
 
Make sure w/ your finger you are on the compression stroke. Dbl check your plug wires. Turn the dist ever slightly and try either way. If you've got fuel and spark it will fire
 
Hi, may be a tooth off. Get the timing marks lined up and pop the cap. The rotor should point at #1 spot on distributor body. Some people mark this sweet spot with a sharpie. If you are 180 degrees out it means the plug on #1 is going to fire on the exhaust stroke. It will probably backfire instead of just crank. You should be slowly twisting the distributor back and forth to see if it wants to catch. Just a note of distributor installation, because of the hex shaft and gear alignment the distributor may not fully seat when you change only one tooth. I like to slowly lift the distributor while turning the rotor in the direction I want to go. You will feel the teeth click and there you are. It is not much of an adjustment. Now check where the rotor points to. Hopefully that is where it is supposed to be. But you see the distributor is not fully seated in the block! The hex shaft oil pump drive is holding it up! All you have to do is tap the motor over while gently pushing the distributor down and it will drop into place. Now you are ready for the hold down bolt. Good luck
 
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