How to increase speed

I think you might be right about gearing a Green Diamond too high.

A saving grace is the two speed axle.

lang

Not strictly original, but I'm thinking a 6-281 would drop straight in for a quick power up, if required. This would pull somewhat higher gearing than standard. Will sit on 2500 revs all day.
Would be easily reverted to standard when you're done.

Jarrod.

Yes Jarrod but where do I get one with enough life left for a drive to Darwin and back. Gearbox? Any suggestions as to ease of fitting a 281 welcome.

If I am going to rebuild an engine may as well do the original for future sale. The current one seems OK.

My 230 Dodge engine cost $6,000 to rebuild. Jeeps are around $5,000 now. The Inter would be more than I paid for the whole truck.

Lang

Lang , my experiences with my KB5S ...for what it's worth.
I have done 32.000 mls over the last 25 years on truck shows,camping trips etc. It will drive all day at 70 to 75 kph, but if you try to maintain a higher speed it will be driving it flat out on many occasions and is too hard on the motor.
8.25 x 20 is as tall as you want to go with the rubber, even then any little rise becomes hard work. The fact is that they just haven't got enough power for more gearing . Fitting another Inter motor is not as easy as some would have you believe, the GD motor is 2 1/2" shorter than most of the others so you would have to move the Trans. mount back ( I have done the measurements), and the cooling would also become a problem with the extra power generated. I have looked at exactly the same problem you are working on and came to the conclusion I just needed to drive it at the speed it was designed to do, and I've had lots of fun in it just the same, just taken a little longer than the others to get there. Don't forget...you have to stop it too.

I had been led to believe a 6-281 was a near bolt in fit. Seems not. (They do use all the same crank bearings!)
Suggestion based on the apparent commonness of good used ones.

Jarrod.

Murray

Great information from the horse's mouth. Exactly what I wanted!

As everyone suspected, it is all very well putting a 200kph diff under the back or giant overdrive, the squirrel on the wheel is just not strong enough to turn it.

I think I will work to get this KBS 5 up to a nice everyday truck, leaving the tipper etc in place and continue to look for a KS/KBS 6. Although I would love an 80kph cruise, if nothing turns up I am happy to go with the slower speed. I have driven my Dodge Weapon Carrier family, Blitz, GMC's and vintage cars maybe 150,000km at 70/75kph (and sometimes much less) all over Australia and overseas and can quite happily sit there waving to the cyclists as they pull out to pass you.

But the truest thing I ever saw was "You never have enough power until you can leave two continuous black lines from the start of the straight all the way to the braking area at the far end"

Lang

The early Inters used a strange front engine mount under the waterpump,and might need a front crossmember installed for the under timing cover mount of a 281....I cant remember details exactly,but my old man had a K5 with a later 240 ohv fitted,which has the same block length as a 281...And is drilled the same on the rear face for the housing.He also replaced the crash box with a T98,so thats a direct swap too.