1972 Coronet w/ Slant 6 timing questions

On early to mid-1960 225's, the vacuum advance would connect to a port on the base of the carburator. When emission control equipment started to arrive later in the decade, that most likely changed.

-Kirk Matheson

I think it comes off a small port on the intake manifold. If it's not there, maybe it fell off and is causing a (small) vacuum leak which will affect performance.

There are a few things you should measure on this engine if you have the inclination.

1) If the engine really did come from a '68 truck, then it probably does not have hydraulic tappets - which means the rocker arms are manually adjusted (valve lift) while running (interesting experience). 2) set the idle RPM to 550 and connect a vacuum gage to the intake manifold. Leave the vacuum line connected to the distributor. Rotate the distributor so that the vacuum reads the highest value (which is dependent on your altitude but at sea level if the engine has good valves/seals/rings you should be able to pull 20 to 23 inches of mercury. Once you've found the max setting, lock down the distributor. (this setting may not give you the best emissions but it should give you the best milage and performance). 3) If you're so inclined, get new plugs and points/condenser and set the distributor up properly (dwell). Gap the plugs before you put them in. Maybe new primary coil and wires, fuel and air filter. If you do any of this, do it before performing step 2. 4) If you're really keen, you can get a carb kit and take the Carter apart. Change needle valve, check the floats, replace the gaskets, etc. Note that the upper and lower surface of the air horn are prone to warping and don't always seal nicely. I've sanded mine down to insure a good seal. Be carefull that you don't turn down the long screws too tight or you'll warp the air horn. If your float and needle assembly isin't set correctly you'll have gasoline gushing all over the engine so be ready to shut it down the first time. 5) Get a compression guage and check the cylinder compression values. I think that you should get values of 100 psi (+/- 20) - the higher the better, and the more even or similar the better (although I wouldn't be happy with all 6 giving 80 psi vs 120 psi. 6) perform a leak-down test (crank the engine so that the valves for each cylinder are closed and then with compressed air give the cylinder a charge and then watch how quickly the charge bleeds away. This will give you some indication of the health of the valve seals, rings, valve seats, etc.

Oh man looking back (15 years ago) boy did I spend too much time working on my slant-6. Was nice when I had the time...

The vacuum advance hose gets connected to the one and only appropriate-diameter hose nipple on the passenger side of the carb. This is ported vacuum.

Head over to

for quality advice on this car.

DS

"" wrote: > Hi There: > > I just bought a '72 Coronet with a 225 automatic and it seems > to work > pretty well aside from being a bit pokey in the acceleration > department. My question is this - where does the distributor > vacuum > advance connect to - is it ported, or does it get connected to > manifold > vacuum like it is now? It still has points ignition, and a > one barrel > Carter Carburetor. > > The engine is supposedly out of a 1968 truck, and was an > engine used at > a vocational college here for students to rebuild. > > Thanks for any advice!

Base of the carb. You?ll know which one it is by pulling off the plug and checking for vacuum at idle. If there is no vacuum at idle gently hit the gas and see if vacuum presents itself. If so thats the baby...... Chrysler used timed advance..

Bzzt.

Chrysler used ported vacuum *or* manifold vacuum for spark advance, depending on year, engine, transmission and emissions package. In either case, the spark advance hose nipple is in the same place on the carburetor.