Points Question

[bigcatchdaniel555]

I was out today giving my car a tune up ya know points plugs oil etc. the plugs were fine so i regapped them and cleaned and put em back in. the points were still in good shape so i regapped them to .25 (they were largly undergapped like .12) and left them they are only a couple months old however when i took the car out for a drive at about 45mph it stumbles a little it accelertaes and runs smooth at lower and high way speed. the main reason i did the tune up was because it stumbled a little before the point regap did smooth out my idle a lot! Timing is set at 14 doesnt ping the carter rbs runs smooth at all other times and idles great no missing at all. if i am correct the mixture controls all settings both idle and cruising so all suggestions are appreciated.

 

[bigcatchdaniel555]

the rbs does have the right dizzy a non load o matic from a 68

 

[fordconvert]

Setting points with the gap method only gets you in the ballpark with new points. Used points tend to not be smooth so the gap method is not accurate. The proper way to set points is with a dwell meter. A dwell meter also eliminates the possibility that you dont have it centered on the the lobe when you gap them. If the bushings are worn in the dizzy the shaft could be flopping around. Its hard to tell while its in the motor. If its real bad the reading on the dwell meter will jump at certain rpms.

 

[Anonymous]

Just to be certain, did you check the timing before AND after you adjusted the gap?
If you change the gap, you're also altering the timing slightly.
Usually, when you increase gap (as you did), they are starting to open earlier, so your timing would typically be advanced.
Anyway, check points with a dwell meter, as another poster said, and also check for correct timing afterward.

Mike.

 

[bigcatchdaniel555]

i did check my timing befor and after it was abour 14 before and 16 now however i dont think thats the problem because the motor doesnt misfire at idle and has no spark ping. as far as a dwell meter goes where can i get one how to use one?

 

[bigcatchdaniel555]

i fixed half my problem i rechecked the points and di the timing once more now it doesnt misfire at all however when i take of from a standstill and throttle it the car bogs and stalls if i am going and give it gas accelerates smoothly. i know the dizzy i have is not a load o matic however if i take the carb vacuum port off and rev the engine i have no vacuum on the carb even though its a non scv i still should have some vac right. also i eliminated the possibility of it being adjust i played witht the time aft 14 adjusted the carb and point none made a difference in bog.

 

[66 Fastback]

however if i take the carb vacuum port off and rev the engine i have no vacuum on the carb even though its a non scv i still should have some vac right.

Can you clarify what you mean?
I'm confused what you are asking.
Doug

 

[bigcatchdaniel555]

on the carburetor there is a vacuum port which gives vacuum to the dizzy when the throttle is opened wide if i take off the hose i have no vacuum on the carb meaning there is nothing to aid to the mechanical advance in the distributor. i took tyhe car over my uncles house this moring who happens to be a retired mechanic and we looked at the car and determined the above problem. One thing i brought up was the duraspark 2 upgrade this would take a way for the need of vacuum advance and rely soley on mechanical am i right. what could expext to pay for a system from a junkyard also what parts besides the dizy do i need.

 

[james singleton]

What size engine, and do you have a manual or auto transmission?? Since you are talking about points, that would mean that you don't have electronic ignition! Someone correct me if I am wrong, but isn't his timing a bit advanced for a non-electronic system??? Jim

 

[66 Fastback]

True if you disconnect the hose from carb to distributor, you are disabling the vac advance. However, the vac advance does increase when the throttle plate is openned wide. It is the opposite of that. At idle when the plates are closed, the vacuum is high and the vacuum advance would be highest. (This assumes the port on the carb is mainifold vacuum) If you are using a ported vacuum source, the vac at idle will be low and the resulting vacuum advance will be low. Better drivability is achieved using a manifold vacuum source.

At wide open throttle, there is low engine vacuum and thus there will be low vac advance (true for both manifold vac & ported vac sources).

You can run a car without vacuum advance and some vehicles came without vacuum advance. My '61 Vette is not equipped with vac advance. However, better drivability and fuel economy is achieved with vac advance. There is a false belief that high performance engines do not need vaccum advance. But if you do any street driving with the vehicle it makes sense to have one. In fact later high performance-engined Vettes came equipped with vacuum advance. I would recommend that you keep a vacuum advance mechanism on your distributor.

I do not know the workings of a Durraspak 2 upgrade. However, I suspect that it too had engine vacuum control. Even on new cars, engine vacuum is measured and the the timing is adjusted in the computers via a preset map.

Are you saying you do not have any vacuum in the hose when it is connected to the carb? If so, then hook the vacuum line to a manifold source.

You can test your vac advance on the distributor by disconnecting the hose at the carb and with the engine running suck on the hose and check the timing to see if is advancing. You can do the same thing with the engine off. Pull the distributor cap and such on the hose. The plate in the distributor should move.
Doug



Are you getting any centrifugal advance? When you rev the engine is the timing advancing?

 

[66 Fastback]

I re-read your post about not having vacuum. Yes when you rev the engine, the vacuum should rise when the car is in the driveway on a non SCV equipped carb. However, you should have high vac with the engine idling. If you slam open the plates you should see the engine vac drop and then it will increase.
Doug

 

[bigcatchdaniel555]

ok i hooked up the vacuum from the distributor straight to the manifold i still had the same bog on hard acceleration from a standstill i checked the the dizzy and it seems to me the advance is very hard and yes the mechanical does work when the engine revs. then i took the fuel bowl off the carb and checked the needle and seat they were clean plus i have a fuel filter 2 inches from the carb so its unlikely anything went into the carb. plus it runs good at all rpms so i would think if there was something in the cvarb the idle would be very unstable.

 

[66 Fastback]

Is the accelerator pump on your carb working. It should be squirting in a shot of fuel to overcome the bog when you step on the pedal.
Doug

 

[bigcatchdaniel555]

i am uploading a video to youtube soon once its done i'll post the link the accelerator pump is squirting fuel how much is enough or TOO much i dont know. i am starting to lean towards the carb because it has a worse bog when its cold plus its not misfiring at all it runs quite nice opinions welcome and it turns out the vacuum on the carb is woring just it doesnt have a lot but since3 its not an scv it shouldnt.

 

[bigcatchdaniel555]

the sound quality is not the best but it gets the message across the sucking sound is just the carb without the air cleaner

http://youtube.com/profile?user=bigcatchdaniel555

 

[addo]

Considering the apparent vacuum behaviour, there could also be a more significant internal problem with the motor (an ailing cylinder). I'd suggest a series of compression tests, both cold and hot, wet and dry.

A dwell meter is usually one function of the basic tune-up tools you can buy, that do RPM, points testing and a few other things.

 

[bigcatchdaniel555]

the motor has great compression and was rebuilt about 1500 miles ago. i could be wrong about this but the other vacuum leaks i have had with the car always make the car idle and stumble on normal cruise. this runs great in idle drive and cruising at any speed. i just cant punch it off the line because the motor will either hesitate heavily or stall and i messed with the timing and other ignition parts yesturday for about an hour and it never made a difference in the least so i dont think my tune up job had anything to do with it . maybe this would be a good time to try the 2bbl carter bbd i have laying around.

 

[bigcatchdaniel555]

i think i rueled out vacuum advance because i put the timing light on the motor and when i rev the motor the advance rises and falls with the rpms the same if i punch it quick correct me if i'm wrong but that alone says the vacuum is working in the dizzy along with the mechanical.

 

[66 Fastback]

IF the vacuum line is disconnected and plugged, the ignition advance should rise and fall with engine rpm on a centrifugal advance equipped distributor. If the vacuum line is connected to a manifold vacuum source, when you reconnect the vacuum with the engine running, the ignition advance should increase and the engine rpms should pick up.

Regarding the accelerator pump. Can you see a shot of fuel going into the carb when you blip the throttle? Based on what I am hearing on the video, it does not appear the accelerator pump is working since it bogs badly. When you move the throttle slower, the engine seems to accelerate and that could happen even if the accelerator pump did not work or is not giving a full shot. I have an old motorcycle with a carb that does not have an accelerator pump. You pop the throttle and you can expect to bog and sometimes backfire due to a lean condition. You have to roll into the throttle on engines that don't have an accelerator pump.
I would pull the top of the carb and look at the accelerator pump condition.
Doug

 

[bigcatchdaniel555]

the rpm does pick up considerably when i hook itup to manifold vacuum the accelerator pump does give a squirt of furl too much or too little i am not sure the thing thats weird is that it ran fine a day before the next day right on start up it had a bog can an accelerator pump go bad that quick.