Hotting up an Inter 6

Spun a bearing in my C1300 coming home from Sydney a few weeks back.
Had thoughts of replacing it with a 345 or 392 V8 but the 281 pulled pretty well and was surprisingly good on fuel too where as the V8 are renowned to be thirsty.

I have a taller diff that I can get hold of and talking with a fella about a 5 speed as well but a tad worried that doing these changes might bog it down a bit as well.

Has anybody done any hotting up of these engines over the years and what did you do.

Extractors should be easy enough to get a hold of and a port job on the head will help it breath better as well.
Was wondering if there was any issues in shaving some off the head to up the compression as well.

Also thought about making my own intake manifold and running a 500 Holley or something similar as well.

Anyone's experiences and advice would be greatly appreciated

Cheers. Cobba.

Hi
When modifying an engine I would keep in mind what fuel you are going to use
Holden is bringing out a car to run on E85 and very soon there will be no unleaded fuel only Premium unleaded and E85, the unleaded pumps are all ready starting to disappear around Sydney
I

Thanks ian, and a pretty valid point.
Will take that up with the engine reconditioner when he is doing the head.

I am also going to put it on LPG as well so the valves and seats will need to be right for the job.

I work for a company that manufactures a portable saw mill and sell there stuff into Brazil. I remember a few years back they were having issues with the B&S engines not liking there Ethanol fuel.
I am pretty sure that it was only a rejetting of the carbi needed to fix the problem, but then again, the motors were already designed to run unleaded fuels so what needs to be done to upgrade a vintage stationary engine is an unknown for sure.
Hope you get it worked out.

sometimes on ebay the twin carb manifolds become available ..modifiying the original single carb 1bbl manifold for a holley is almost impossible (ive tried it) .. extractors are quite available ..shaving the head would be a good idea what do they run stock? 6.5:1cr? . .also for lpg you want a decent size intake manifold to get more air into the motor . . twin thermo fans mite also help for a couple of extra horses

There is a 6 X 6 ex army Inter at Rocklea Truck Parts at Wacol in Brisbane that has the motor still in it, and the twin carby set up on it. Kenny, I've got an old clinker ski boat with a 202 Holden motor in it, it origonally had a 186, the marine manifold has 3 carby mounting holes fo strombergs, so you can put on 1 or 2 carby's. Someone has got a bit of exhaust pipe bent like a bit of a U and made an adapter for the Holley using the 2 outside carby mounting holes. I had a heap of trouble with it when we got it because it was all brazed, nothing was flat and it sucked air everywhere. We got the mounting surfaces surface ground and the fixed it. I reckon you could do soething similar on an Inter with a 2 carby manifold. This picture is the best one I've got here, as the boat is down at my parents place, and it isn't 2 clear, but you can see the U shaped pipe under the carby.

Didn't know you could get a factory twin carb manifold.
I was looking at a truck on Ebay recently that had a Y piece in the air intake pipe which looked like it was feeding twin carbies. Do you reckon I can find the ad now. Not a hope

Bigcam. I went on and had a look at Rocklea Truck Parts website but couldn't find anything matching a 6x6 army inter. Will give them a call tomorrow and see what they've got.

Hey Kenny. I just had a good look at the inlet manifold and I can see why you would have had issues getting a Holley to fit. There's not much intake area is there.
Would fitting a W stromberg twin barrel be a better option maybe? I could build out on the manifold with metal and diegrind it out to accept the base I should think.
Alternatiely I could make an entire manifold using aluminium tube to fit the Holley although getting the flow right could make that impractical too.

I didn't even know Rocklea Truck Parts had a web site. If you call, ask for Ryan, it's an ex army 6 X 6 that is ex Hawkins, looks like it's come off Straddie or Morton island, the cab isn't flash, someone has made fibreglass doors and other bits on it.

Hi Cobba,
I wouldn't discount the idea of going to a 345 V8. I get a reliable 13 mpg from mine on LPG. They are made to run on gas so you don't need to worry about valves etc. As the 4wders in the US love them in the IH Scouts there is plenty of info on the net about hotting them up, even a few people who have fitted multi-point fuel injection. And parts are still easy to get.

Hadn't given up on the V8 idea completely but as all things, I am trying to do this to a budget.
Seein as I already have the 281 and also as I am reasonably sure it is the original motor from the truck it made logical sense to stick with it.

It still starts and runs and sounds pretty normal at idle but starts hammering as soon as the revs pick up past 1500RPM so I am hoping it's gunna be a cheap rebuild.

13MPG. That's pretty impressive. I have heard stories of them only getting half of that which is what really scared me away. I was getting pretty much the same from this motor before it went rattle rattle klunk.

don't forget that vehicle mass has an input to fuel economy as well as diff ratios, tyre sizes etc. A 345 in an IH Scout my give 13mpg but in a heavier vehicle it may struggle to give 8mpg