I have recently bought a LH Torana with a 308 and found its vacuum advance was disconnected. The previous owner said it had tuning issues but wasnt able to help as to why the line was disconnected. It runs a standard Quadrajet (now with a manual choke). This car was originally a 6 cyl and understand the 308 engine was out of Statesman which was probably an auto. The carby has only 2 vacuum ports both on its front. The right hand port appears to be originally used for the vacuum line for the distributor but was unplugged at the distributor and blocked. The other port is used for the vacuum break on the choke. The vacuum line from the canister was also disconnected. The car idles fine and no problem starting from cold with a bit of choke and 2 pumps on the throttle. It cruises ok but does seem to run hot so still need to check timing. Under load when the rear throats open it misses so have been thinking that the disconnected vacuum advance may be the problem or it might be timing or both. Connecting a vacuum gauge to either of the 2 ports shows they are manifold vacuum (20 at idle) and not ported vacuum as expected. Vacuum at idle is consistently about 20 and steady.
The Torana workshop manual for the 308 shows that vacuum advance should be between 6-8 peaking to 14 -16 which suggests to it should be ported vacuum and not manifold vacuum.
If I connect the vacuum line that was fitted it would be using a vacuum of 20 at idle which drops off as it revs hence is clearly not what the engine expects from what I can make out. The workshop manual does not give the picture of the Quadrajet but refers off to the HQ manual which I dont have so aren't sure if the available ports are suitable. A check On-line shows there are many models of the Quadrajet with some having 3 or more ports both manifold and ported. The discussion seems to suggest manifold vacuum can be used but others say ported, so I dont know the right answer.
A couple of questions....
1. Is it common to not use vacuum advance with an electronic distributor.
2. If it is used, should it be using manifold vacuum for ported vacuum and which port on the carby.
3. Is the documented timing setting the same when using a electronic distributor ie.6 BTDC.
Appreciate any help anyone can provide on the above.
Attached Files
-
Vacuum ports.jpg 96.89K
6 downloads
