……..for some maybe but there was a comment on Facebook the other week on engine tuning that only the technogeeks could do it the easy way……i just don’t think that’s right so lemme give a shot at it here…..no charts, timing light, Sun diagnostic machine……..just a vacuum gauge. Now this works only on an Olds motor……….why is that? Well ok then, let’s get started………..
Addage is ” never have a Chevy man tune an Oldsmobile”. Their distributer turns backwards so timing is backwards! Now knowing this, things start to simplify not get harder to understand.
So when a motor is put together the machinist and builder can twerk many internal parts in the build but after the motor is in and hooked up, there are only 2 things you can adjust that will directly effect the performance of the motor:
Fuel (carb or fuel injection)
Fire (ignition system)
This holds true on pretty much all motors…..so lets unpack these 2 subjects one at a time:
{Fuel} Lets cover a carb then compare it to fuel injection. There are 4 levels of air/fuel flow in a carb:
Idle jets
Primary jets
Secondary jets
Power valve
They work in that order. There really is only 2 adjustments though. There are 2 screws at the front bottom of the carb….these are idle jets. Turn them 3.5 turns from all the way in each and leave them. If the carb runs badly from this it needs to be remanufactured…….move on.
The other adjustment is idle, the screw that is a stop for your throttle cable and lever. So here comes the Olds unique stuff…..
To idle smooth, the carb has to be running on only the idle jets, if it’s idling using the primary jets it will idle rough. How can you know this? On an Oldsmobile setup, there’s a “ported output” vacuum connection half way up the front of the carb. This port should have no vacuum (I set it at 2″…. Close to 0) on it at idle (950 rpm). Fire up your motor with a vacuum gauge connected to this port. For this adjustment, plug the distributer vacuum hose (that should have been connected to the ported output to constant manifold vacuum on the intake manifold. If you have more than 2″ on the gauge of vacuum, throttle back your adjustment screw slowing the rpm of the motor as you will see the vacuum to this port will also lower.
Adjust idle until you have 2″ of vacuum on the ported output. If the motor is starting to run too slow, loosen the 9/16 bolt holding the distributer down and turn the distributer clockwise enough to keep the motor rpm’s up.
Ok, you have 2″ of vacuum on the ported output of the carb., now turn the distributer to 950 rpm….with the trans in park, ac off and of course the motor running.
It’s pretty much tuned…..you can check things by plugging the distributer vacuum hose back into the ported output of the carb and connecting your vacuum gauge to manifold vacuum. You should now read @ 18″ of vacuum which verifies the motor is running efficient.
Now fire the motor again, it should turn over nice assuming your battery and starter are good.. If not, turn the dist. lightly counterclockwize just a bit till it starts easy……drive and see if it pings. Pushing the motor too hard will cause this too so again lightly turn the dist til it tries to ping when you drive it like you stole it!
That’s it, the motor should run well. You have given it what it wants based on all the stuff that was put into the motor….not what some 45 year old manual says………things have changed, fuel formulation are different….if you set your motor at the factory recommended 8 degrees it will never hit hidway speeds! Initial timing means what the motor wants…not 8 degrees
This now also set the {fire} or ignition. There are 3 advances to the ignition system for it to automatically adjust timing to rpm……there is nothing you can do about these save turning the distributer which you did.
Initial advance
Vacuum advance
Mechanical advance.
Mechanical advance is preset and not adjustable by you. Also, vacuum advance is built into the distributer with no adjustment for you. There is adjustment but it should have been set initially. Initial advance was set when you twisted the distributer to get 950 rpm
So that’s it. There are some other things that I could explain but this will get tour motor in tune pretty well.
Let me know if this makes sense…..you can comment at the end of the post here. Hope this helps…….lemme hear from you.
