After changing my transmission I was resetting my distributor cap and I couldn't find any connection to the Vacuum Advance? I pulled the cap during the transmission change so it wouldn't get crushed when the engine tilted. When I put it all together I cant remember if it ever was hooked up? It ran great as I had it professionally tuned but I cant find any disconnected hose anywhere? Either it fell off in the process or it was never there? Any thoughts what may have changed?
Restored by me. Not a professional. Restaurant worker by trade. YouTube forums and some trial and error built this beauty. Sheet metal replacement. Body work. Paint. Rear gears. Interior. And engine. ALL ME. Toot toot
A lot of old school tuners either don't really want to bother or sometimes even understand how to tune the vacuum advance. It's more for driveabiltiy and mpg. So they eliminate it and only run mechanical. Could be what happened on yours.
If it's not hooked up, then you should have a vacuum leak, which should be noticeable by how the engine runs. That would be a clue as to how it was setup before you messed with the trans.
On anything but a full out race engine you need vacuum advance. At WOT the vacuum advance doesn't operate. the rest of the time it does and advances the timing to improve drivability and fuel efficiency. Great and simple invention.
This is where my issue is. The car ran tip top at the end of last year. I haven't driven it yet since new trans went in. I just didn't want to get it out and running without everything hooked up. The vacuum advance is turned all the way to the firewall, this I know was the correct position when I took the cap off to lower the transmission so the cap didn't get smashed. But I never took a vacuum hose off of it. IF there was one on it, I don't see any hose not hooked up anywhere. My engine compartment is full dress. So its not like its a random mess of garbage under there it is in pristine condition. That's why I cant figure why there's no hose? Also no vacuum ports anywhere are not plugged. So is it possible it ran well without vacuum advance or should I keep looking?
Restored by me. Not a professional. Restaurant worker by trade. YouTube forums and some trial and error built this beauty. Sheet metal replacement. Body work. Paint. Rear gears. Interior. And engine. ALL ME. Toot toot
You have a '68? Could you be seeing the open retard port on the back of the distributor vacuum unit? Is there a second port on the opposite side of the can that does have vacuum tubing connected?
In '68 they had both advance and retard as part of the early emissions control Pontiac tried. Pontiac later recommended on a Tech Bulletin that the retard function be eliminated on several V8 engines.
Ok. I got the car running it was missing a mile. Turned crank to top dead center and discovered the rotor was almost one full plug off, I couldn't turn the cap any further as the vacuum advance would hit the fire wall so I just moved all the plug wires by one spot. Car ran perfect, set timing so it was just a little before the mark would show on the scale. Keep in mind still no vacuum advance connected because I just couldn't find it set up from before. Took car on road ran great except when I throttled down and secondary opened as rpm went up car began to miss and sputter? Is this where vacuum advance might fix it or do I have the timing off a bit?
Restored by me. Not a professional. Restaurant worker by trade. YouTube forums and some trial and error built this beauty. Sheet metal replacement. Body work. Paint. Rear gears. Interior. And engine. ALL ME. Toot toot