Distributor timing curve V8 Marlin

[HunterV8Spain]

Hi, has anyone remapped their distributor advance curve in a 3.9 V8 Marlin? I am running the Mallory dual point dizzy and have ordered the spring kit to try and fine tune the curve for better response. At the moment it is factory set at 24º maximum centrifugal advance at 3,000 rpm (plus 10º static). I believe that due to the low weight of the Marlin a faster curve topping out at lower rpm should improve things. Anyone have experience with this?

[HunterV8Spain]

Re: Distributor timing curve V8 Marlin

The engine in my car is a 3.9 built by RPI with a Piper 270/110 camshaft and stage 1 heads. The documentation for the car reflects a gross weight of 750 kilos.
With this very low weight it is pointless having a slow advance curve as a good amount of torque and some total power will be lost. (This engine is not in a 2 ton Range Rover!)
I changed the distributor from the Lucas that it had to the current dual point Mallory –
the improvement in torque/power was very surprising, with no fine tuning of the advance curve.
Having found that my engine prefers an idle advance of 14º (smoother running with higher rpm) will now lock out the total mechanical advance from 24 to 20º to still have a total of 34º.
Plan on trying 1 purple and 1 orange advance spring to bring in the total advance at I believe around 2750rpm which may be a little too fast but a good starting point.
Has anyone tried this?

[HunterV8Spain]

Re: Distributor timing curve V8 Marlin

I haven’t been able to try experimenting with the curve as yet as I received the wrong spring kit (my fault!).

[stevejgreen]

Re: Distributor timing curve V8 Marlin

Have you considered something like this?

http://www.123ignition.nl/id/50.html

[HunterV8Spain]

Re: Distributor timing curve V8 Marlin

Very interesting, although it does say that there are two mechanical/centrifugal advance curves available I assume that these can be modified. Have you found a curve that particularly suits the Rover V8 in a Marlin?

[greyV8pete]

Re: Distributor timing curve V8 Marlin

Do you have any cooling problems with the V8? What radiator do you have? I have the Marlin 3 row crossflow with the tanks either side. Cooling is marginal but worse in the UK summer. Peter.

[HunterV8Spain]

Re: Distributor timing curve V8 Marlin

I also have the 3 row crossflow radiator with tanks at each side, I have added a heater core from a bus underneath this one. With the engine set up correctly (timing and mixture are vital to attack an overheating problem) I have no trouble with it even in the hot summer here, although the electric fan does tend to get busy if its a very hot day!

[greyV8pete]

Re: Distributor timing curve V8 Marlin

I have been thinking for some time to put an extra rad under the front apron but always wince at the thought of such a vulnerable location . It would also need ducting for, or re-location of, my 13 row oil cooler. Any chance of some photos of your bus heater installation and supplier / part number details? Peter.

I also have the 3 row crossflow radiator with tanks at each side, I have added a heater core from a bus underneath this one. With the engine set up correctly (timing and mixture are vital to attack an overheating problem) I have no trouble with it even in the hot summer here, although the electric fan does tend to get busy if its a very hot day!

[HunterV8Spain]

Re: Distributor timing curve V8 Marlin

Hi Peter,
found the extra rad on a shelf in an old radiator repair shop, they told be it was a heater core for a bus but I have no idea which.
I have fitted it with a protective cage in front of it, this is sealed hermetically to it and forms a very effective ducting pushing air through the rad after which it mixes with the turbulent air under the car and hits the oil cooler. It’s a bit of a bodge but works fine. By the way, if your engine is running with the maximum advance retarded it will create much more heat than normal.MARLIN EXTRA RADIATOR 016.jpgMARLIN EXTRA RADIATOR 003.jpgMARLIN EXTRA RADIATOR 005.jpgMARLIN EXTRA RADIATOR 013.jpgMARLIN EXTRA RADIATOR 012.jpgMARLIN EXTRA RADIATOR 011.jpgMARLIN EXTRA RADIATOR 010.jpg

[greyV8pete]

Re: Distributor timing curve V8 Marlin

Wow! That's one heck of a thick matrix. It must be about the same coolant capacity as the Marlin rad itself? From the size of the hoses I guess it is plumbed into the Marlin heater line? I was hoping to plumb mine in series with the existing rad so it was controled by the engine thermostat as one in the heater line could overcool the engine in say winter or when descending long hills. Peter.

[HunterV8Spain]

Re: Distributor timing curve V8 Marlin

Wow! That's one heck of a thick matrix. It must be about the same coolant capacity as the Marlin rad itself? From the size of the hoses I guess it is plumbed into the Marlin heater line? I was hoping to plumb mine in series with the existing rad so it was controled by the engine thermostat as one in the heater line could overcool the engine in say winter or when descending long hills. Peter.

No it has a much less capacity than the original rad but yes it is pretty thick! It is tee’ed into the heater pipes at the water pump and inlet manifold but never over cools the engine – even on a very cold day, it has been down to 3C here last Sunday which is the coldest I have seen in the 32 years that I’ve lived here! I was out for a blast in the Marlin though, hood up and heater on! (Wimp!)

[greyV8pete]

Re: Distributor timing curve V8 Marlin

The engine in my car is a 3.9 built by RPI with a Piper 270/110 camshaft and stage 1 heads. The documentation for the car reflects a gross weight of 750 kilos.
With this very low weight it is pointless having a slow advance curve as a good amount of torque and some total power will be lost. (This engine is not in a 2 ton Range Rover!)
I changed the distributor from the Lucas that it had to the current dual point Mallory –
the improvement in torque/power was very surprising, with no fine tuning of the advance curve.
Having found that my engine prefers an idle advance of 14º (smoother running with higher rpm) will now lock out the total mechanical advance from 24 to 20º to still have a total of 34º.
Plan on trying 1 purple and 1 orange advance spring to bring in the total advance at I believe around 2750rpm which may be a little too fast but a good starting point.
Has anyone tried this?

Following a recent misfire problem at full throttle and poor idling on my Hunter (Rover V8 3.9injection 14CUX ECU) I have just replaced my ignition amp which has cured the misfire. While I was at it it I then reset the timing to give 34deg max advance with vac advance temporarily blanked off. The result is amazing as you said it would be! Wish I had done it ages ago. A smoother engine, less jerky throttle reponse and boy does it sound good when you press the loud pedal! Only 8 degrees C ambient today so too early to see the effect on engine running temperature. Many thanks for the timing tip.

Interestingly there is a groove machined across the crankshaft damper disc that has a reflective strip at the bottom which really shows up well with the strobe light. Would you believe that this groove is at the 34 degree point! Makes me think that is how Rover intended the timing to be set? Peter.