1967 GMC 910 Fleetline

[johnnyswanepoel]

Hey All

I am new to the site so excuse if I am adding it to the wrong place.

I need to get my truck lighter on fuel.

It's a straight 6 carburettor and travels at the moment at 3km per litre.

Any suggestions as to where to start?

I know it's a wide question here, but any help will be appreciated.

Thanks and look forward to any help

Johnny

[dmartin1]

welcome! wow, what a sweet exotic old gmc.


any engine or interior shots?

[Coley]

Welcome to the forum Johnny....and cool truck.
You've come to the right place for a wide spectrum of knowledge on these trucks.
Better gas mileage?
-We need to know more about your truck.
What is your transmission? manual...3 speed, 4 speed? Automatic ? 2 speed? 3 speed?
That 6 cylinder can be tuned up but things will dead head for better mileage at that point.
Then you have to look at your gear/group....from the trans all the way back.
I would think that switching to a 4 speed automatic and maybe find out what your rear gear ratio is will be helpful....maybe change those to a 3:07 or similar.
Anywhoooo, get us some more info on the rest of your drivetrain!
All Good
Coley

[Coley]

...wow just ran the number on that fuel mileage (3km's/litre), particularly for a 6 cylinder? (250? or?).....thats about 7-9 mpg....that ain't great for sure. You should be doing way better than that with a 6 cyl.
Some questions for you:
Have you tuned this thing up lately?
Electronic ignition or?
Timing?
Carb condition/adjustment?
compression test?
.....get us some more info Johnny...because you should definitely be well above 7-9mpg.
My two bits.
Coley

[BLT gmc]

If the inline 6 is still running a points type dist. your could upgrade to an HEI dist. Make sure it is timed and tuned well ( plugs/wires/filters/tire pressure). As Coley suggested overdrives and gearing in the rear differential. More radical adjustments like engine trans swaps to a coil over plug LS engine trans combo. Bruce

[alsriv2]

That is one cool GMC.
'67 small window, 3/4, right hand drive, opposing windshield wipers, just a great cool looking truck.

Love the two tone front marker/turn signal lights!

Thanks for sharing...now others will help with the situation you are asking about!

[BrianG]

So.... In the US, we say we are looking for better "fuel (gas) mileage", would you say better "fuel kilomage"??? LOL... just kidding. Welcome to the board, like others, I'd love to hear and see more about that truck. Take care of that beauty, probably would be very hard to find replacements for some of its parts. I'd also recommend a complete tune-up including converting to an hei system to get rid of the points if that hasn't already been done. Do you have any connections in the area with similar old trucks which you could compare your fuel economy with? Our fuel contains ethanol at various levels. This hurts our motors in many ways including the fuel economy.

[johnnyswanepoel]

Hey All

Thanks for the awesome replies.

As far as I know there's only 3 in South Africa and my dad had the other one.

@dmartin1 - Attached are some more pics of the interior.

@Coley - It's a 2 speed automatic at the moment. I have no idea what the ratio is and will have to go test it so will let you know.
Have you tuned this thing up lately? - My dad built it up from scratch so he has done it about a year and half ago, but is time for a new one though.
Electronic ignition or? - Yeah we added a push button starter in that's on the dash to the left underneath the radio.
Carb condition/adjustment? - I am looking for a monojet carb which I want to add in, so far I think that'll help a bit.
compression test? - Will have to do this for sure and let yu
ou know.

@BLT gmc, @alsriv2, @BrianG - Thanksa guys this is very helpful.

My dad is the one that built it up from scratch so will need to ask him some questions especially about the HEI system. I am not sure and will post a reply again later today to let you know. So far thanks for the help. Appreciate it.

We chat again soon. Getting parts for my truck is a bit of a difficult one to get hold of. I will most properly order my parts from www.lmctruck.com

We chat soon

Johnny

[70cst]

Hey johnnyswanepoel ...

to the forums and from Ohio, USA.

That is one ride

[johnnyswanepoel]

@70cst - Thanks very much. I really enjoy it a lot.