I got my van on the road over the weekend and have noticed it is pinging under light load. I think part of the problem is that the AOD is shifting to soon and lugging the engine when going up any kind of grade. This is happening at low speed. I have filled it with premium now and it may have helped slightly, but it is still pinging when it gets bogged by the trans. I have been slowly increasing the tension on the tv cable trying to move the shift points up a bit. I started out with it set to 0 then 35 with the 5/16 spacer in, in nuetral. Then I went to 2-3 psi, then yesterday I turned the adjuster a little bit tighter, but haven't hooked the gauge back up. The shifts aren't hard so I assume it's not to high yet. I may try and tighten up a bit more.
The engine is a 250, SCR is ~9.5:1, DCR is ~8:1. I'm at sea level. Rear end is 3.7:1. The initial timing is set 12 deg advanced, around 32-34 total.
I haven't checked the plugs yet, but it seems to be good. Btw, the spark plugs are 1 level colder than stock. Engine idles great, starts perfectly, doesn't run hot. No pinging at any throttle with no load.
So earlier today I rechecked the timing and it is all the same. I checked total timing with the vacuum advance hooked up and it get's up to 50 and 3000+ rpm or so. As an experiment I disconnected the vacuum line from the carb and plugged it, drove it around all morning, going up grades ect and no more pinging! It's hooked to ported vacuum, I don't have a way to hook it up to manifold vacuum right now so I haven't tried that yet. What I don't understand is why the vacuum advance is putting in so much advance at high throttle? I thought vacuum advance was supposed to drop out as the throttle increased. At idle with the vacuum advance hooked up I'm @ 12 still and at moderate throttle similar to where it would be under load it's going to to 35 or so then up to 50 all in.
Not sure what to try here. Any advise is appreciated. Would trying manifold vacuum be a good idea? More TV pressure? I think if this were a manual I wouldn't be having this problem. I'm going to retard the initial timing back to 10 and see what that does for me.
The engine is a 250, SCR is ~9.5:1, DCR is ~8:1. I'm at sea level. Rear end is 3.7:1. The initial timing is set 12 deg advanced, around 32-34 total.
I haven't checked the plugs yet, but it seems to be good. Btw, the spark plugs are 1 level colder than stock. Engine idles great, starts perfectly, doesn't run hot. No pinging at any throttle with no load.
So earlier today I rechecked the timing and it is all the same. I checked total timing with the vacuum advance hooked up and it get's up to 50 and 3000+ rpm or so. As an experiment I disconnected the vacuum line from the carb and plugged it, drove it around all morning, going up grades ect and no more pinging! It's hooked to ported vacuum, I don't have a way to hook it up to manifold vacuum right now so I haven't tried that yet. What I don't understand is why the vacuum advance is putting in so much advance at high throttle? I thought vacuum advance was supposed to drop out as the throttle increased. At idle with the vacuum advance hooked up I'm @ 12 still and at moderate throttle similar to where it would be under load it's going to to 35 or so then up to 50 all in.
Not sure what to try here. Any advise is appreciated. Would trying manifold vacuum be a good idea? More TV pressure? I think if this were a manual I wouldn't be having this problem. I'm going to retard the initial timing back to 10 and see what that does for me.