Thread: tried towing with the 3.9!!!!!

It depends what you expect, personally I think they are too slow without a trailer

Rangie is running old fashioned jungle juice, seems happiest on 95 octane, tried 98 and didn't notice any difference!

will try turning off the aircon, but don't have any trouble pulling away with or without a caravan, its holding onto speed once I'm moving that seems to be the issue!

thanks again for the ideas, going to have a busy weekend!

Originally Posted by rovercare

It depends what you expect, personally I think they are too slow without a trailer

you can get them supercharged you know

Originally Posted by finallyrangie

you can get them supercharged you know

I know, I had a supercharged 3.9

Slightly off topic, and sorry for the high jack, but would a 3.5 take to turbo charging at all - just mild boost, of say 4 to 6 pounds?

Originally Posted by bacicat2000

Slightly off topic, and sorry for the high jack, but would a 3.5 take to turbo charging at all - just mild boost, of say 4 to 6 pounds?

i am rounding up the parts to do that exact thing, got the turbo, external wastegate, and intercooler at the moment, i still need to get some oil lines, intercooler piping, and then adapt it to my 3.5 V8

i am hoping to have it done in a couple of months

Hi finallyrangie et al,
Reading this discussion with interest as I recently did a full reco on my 3.9 (in a 1989 RRC) and have notched up 10,000 k's on it now.
I raised the CR to 9.35:1 because I have dual fuel. Runs very well on LPG.
As someone else said it needed 95 octane to eliminate pinging on petrol.
Timing is set to 10 degrees advance as recommended by Bee Utey for the LPG.

Like you described mine has sluggish acceleration from about 40 km/hr to 80 km/hr - both on petrol and LPG. Good off line and strong above 80km/hr. 1500to 2000 rpm seems to be the zone of the dead.

Adjusting the kickdown cable for higher upshift speeds helped a bit.
Vac and centrifugal advance are operating as can be seen under timing light but don't know of course exactly what amount of advance I'm getting/ should be getting and the curve may be awful. Also some episodes of variable idle speed despite near new stepper motor.

I'm suspecting the dizzy which is 205,000 km old. Timing looks steady at idle. Air gap set to specs. New vac diaphragm, leads, rotor, plugs cap etc.
What are people's experiences with weight springs?
Also I wonder about the narrow vacuum outlet and tube for the dizzy - does it allow reasonable response when throttle closes and enough "suck"???

I'm thinking of fiting a Bosch "Scorcher" as many readers rave about it.

Originally Posted by aRRon

Also I wonder about the narrow vacuum outlet and tube for the dizzy - does it allow reasonable response when throttle closes and enough "suck"???

I'm thinking of fiting a Bosch "Scorcher" as many readers rave about it.

The vacuum advance hose size should have little bearing on throttle response. It can block up at the manifold though and should be cleaned by using a thin wire etc..

Your distributor advance can be modified and a Bosch amp & coil fitted, or get the Scorcher which runs the same Bosch amp and coil. I personally haven't found the Lucas advance curve to be a problem with the upgrade amp.