High output transfer case highway speeds?

[Cutter]

Hi all,
I am the new owner of a 1974 series3 109 with a euro spec 6 cyl. The truck was for sale on this forum(deadhead derek's listing). Anyways I am curious the speed I should expect out of it since it has the high output transfer box that RN sells. As is I can get up to 50mph on the highway, but I expect it can go faster. The tires aren't aggressive, so the resistance isn't too bad there.

I know there's still some mixture issues as the truck runs better with the choke out, but I think I need to replace the needle/tube as it's as rich as I can get now. Just curious what I can hope for, the engine seems healthy and if it wasn't for the transfer box I'd be almost satisfied.

[rwollschlager]

Congrats on the purchase!
^^^^ Providence RI? If you're ever in southeastern CT (mystic, stonington) drop a line!
If you need any help with repairs there is Rover Special Vehicles on Jamestown Island (Just outside of newport ...he has my stage 1 109 now...) Or kane's motor sports also in RI. (deal with all sorts of old british vehicles)

As for the high ratio t-case you should be able to reach 60 no problem i think.

Good luck and welcome!

-Rob

[KevinNY]

Is that flat out, foot on the floor? If so you have some tuning to do.

[SafeAirOne]

Is that flat out, foot on the floor? If so you have some tuning to do.

I agree; With my 1973 UK-spec, former euro 2.6, 109, I can get up to 60 with my stock transfer case and transplanted 65-horsepower 2.5 diesel. This is without headwind, of course.

You should be able to do better than that with your 6-cylinder AND hi-ratio transfer case.

[Cutter]

Yep, that's pedal to floor. I've gone faster on downhills.

[KevinNY]

Sounds like you are running too lean, that motor needs more gas. You should be topping out 3rd at 50MPH with a Hi Ratio transfer case.

[Cutter]

Thats what I was thinking too, running lean still. I've got some calls to make. The truck has apparently always lived at altitude in either the Rockies or Alps, so I wouldn't be surprised if the jet was swapped out to accommodate and now it just isn't happy at sea level. Just curious if anyone knows of any carburetor swaps to replace the zenith-stromberg on there? My friend who had a 2.5 SIII swears it will be worth it, but from my research there aren't many options better than what's on there.

Someday I want a turbo diesel in there, but I'm going to have to let the penny jar fill up again for a while.

[greenmeanie]

For the 2.6 the ZS carb is fine. They are really simple to work on too. You just need to find out what needle is called out in the parts book and order that. Throw in a diaphragm and replace the o-ring in the base as well while you're at it. I use Joe Curto in NY when I need parts for the pair on my 101.

[I Leak Oil]

Along with tuning you may want to make sure the accelerator is operating through the full range of motion.
Jason T.

[Eric W S]

In theory, your HO transfer case, if healthy, wouldn't affect you rspeed in anyway. It's the engine that you need to address if you want more speed. If it can't push the gears then...

[Cutter]

yes, I've pulled the carb a few times and made sure the linkage was going through the full motion. The distributer weighted bobs were seized as well so that improved things quite a bit.

I don't think there is anything amiss with the transfer case, don't think I implied that. The focus is on the fueling and ensuring the vacuum for now.

[SafeAirOne]

You might want to check the electric fuel pump mounted on top of the chassis underneath the driver's (RHD) door to make sure it is operating properly and that any internal filter within the pump itself is not clogged. I'm not 100% postitve that this electric pump has an internal filter, but they often do.

Since this electric pump is unique to 6-cylinder rovers, it must be necessary to supply adequate fuel to the engine during high-rev operations, or else the factory would never have put it there in the first place. Also check all other fuel filters installed in the system.

You might also open up the forward access panel in floor of the rear tub, remove the fuel quantity sender and clean out the fine-mesh screen at the bottom of the fuel pickup tube.

[Cutter]

Thanks for the good points-
I pulled the fuel pump apart I think the day I got the truck to make sure the filter was clear and that the pump worked and to clean up the wiring mess attached to it. Thankfully all was in order- I also checked the filter up by the engine which seemed in good condition. I didn't know there even was an access panel in back, there's carpet in mine, so I'll definitely give that a look.

[dmurrell]

Have someone put the pedal to the floor and see if there's still room to go with the bellcrank on the carb. In my experience the throttle isn't opening all the way as the bellcranks slip on the shaft mounted to the bulkhead and/or the pedal has slipped.

When I get my Series III it would only go 45 MPH ......

Eventually I tack welded the bellcranks and pedal on the shaft and "Bob's your uncle".

PM me if you want more details.

[adkrover]

You say you purchased this truck from a guy named "deadhead". If he was anything like the deadheads I've known, you should definitely get the truck properly sorted. It's sounds like a solid truck that needs a proper "shake down".

[Cutter]

Nah Derek is a straight up guy, I just think he hadn't driven the truck in a while. It started and ran fine sitting in place, at least at 3500'.

I am going over the truck entirely as time permits to familiarize myself with every nut and bolt and because it is so damn fun.

I did the linkage/bellcrank drill a few weekends ago with my friend, we made sure it had the full travel- lengthened the thread about .5"!!

[TeriAnn]

So far no one has bothered to reply to your question so I'll give it a try.

The Ashcroft high range ratio is 0.87:1.

So the overall fourth gear, high range axle ratio with the stock 4.7 R&P is:

1 X 0.87 X 4.7 = 4.089, or 4.1:1

4.1 and the overall diameter of your tyre can be used to calculate engine RPM at different speeds.

For instance, with 32 inch diameter tyres (stock dia for a 109)

65 mph = 2798 RPM

70 mph = 3014 RPM

75 mph = 3229 RPM

Taller tyres will lower the RPM for a given speed.

I have Ashcroft high ratio kit with 33.3 inch dia tyres so at 65 MPH my Land Rover's 5.0L engine is turning 2689 RPM at 65 MPH.

Of course all this assumes your engine can push the taller gears. Hopefully the six can.

[Cutter]

So far no one has bothered to reply to your question so I'll give it a try.

The Ashcroft high range ratio is 0.87:1.

So the overall fourth gear, high range axle ratio with the stock 4.7 R&P is:

1 X 0.87 X 4.7 = 4.089, or 4.1:1

4.1 and the overall diameter of your tyre can be used to calculate engine RPM at different speeds.

For instance, with 32 inch diameter tyres (stock dia for a 109)

65 mph = 2798 RPM

70 mph = 3014 RPM

75 mph = 3229 RPM

Taller tyres will lower the RPM for a given speed.

I have Ashcroft high ratio kit with 33.3 inch dia tyres so at 65 MPH my Land Rover's 5.0L engine is turning 2689 RPM at 65 MPH.

Of course all this assumes your engine can push the taller gears. Hopefully the six can.


Thanks Teri, you are my hero - great site!