unhappy with my new boy

MightyBoy tech questions and answers.
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manni
Posts: 5
Joined: Wed Jul 23, 2014 11:15 am
Location: brisbane

Hey guys I just picked up an 87 mighty boy (500cc I think and the 2 speed auto. Gave it a full service etc and I can only get 80kmph out of it and if I stretch it out 90 will come but it heats up nice and quick. Anyone got any options for me to help? Money concious obviously. Cheers guys!
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arklan
Posts: 392
Joined: Fri Oct 14, 2011 1:31 am

thats pretty normal
the auto boys r fing rubbish
mine has the 800cc but the f5a gearbox and it screams its tits off if i make it go to 90
it used to overheat a LOT until the radiator place who checked it out discovered the fan was plugged in backwards
you could consider putting a mini radiator in it which will cost around 100 bucks but u will also need a new fan to match

reality is that this car was not designed to do highway speeds so anything you do to make it go faster will be 3rd party

one easy thing u can do that i did to mine was put the biggers wheels that fit, it raised the max speed by 10-15km (from the stock 12s)
manni
Posts: 5
Joined: Wed Jul 23, 2014 11:15 am
Location: brisbane

Thanks for the response mate. How does the 800cc pick up off the line? Might do the tires like U said do U know what size got you to that speed? Cheers
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Brayden
Posts: 9101
Joined: Sun Apr 11, 2004 3:09 am
Location: Canberra ACT
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An auto F5A should be capable of 100kph without overheating - at least on a flat stretch of road! I suggest checking the secondary throttle on the carby is working properly, and setting the timing/points gap, as well as flushing the cooling system. A compression test would also be worthwhile to see if the engine is lazy.

I wouldn't advise putting bigger wheels on it, because the F5A lacks the necessary torque to turn them. It makes sense in arklan's case because the F8B has more power, but the final drive of the F5A box is woefully short.
F8B EFI turbo - Three pots and a snail.
manni
Posts: 5
Joined: Wed Jul 23, 2014 11:15 am
Location: brisbane

Thanks brayden! I'll take that into consideration mate and yeah its not bad on the flat but god help me on inclines!! I wanna find somewhere to do a cheap engine swap for me..
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Tez
Posts: 1176
Joined: Wed Sep 03, 2008 9:38 pm
Location: Croydon, Vic

And so now might be a good time to read this article...:
http://www.teammightyboy.com/workshop/3 ... onversions
Tez
So the adventure continues...
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Brayden
Posts: 9101
Joined: Sun Apr 11, 2004 3:09 am
Location: Canberra ACT
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manni wrote:its not bad on the flat but god help me on inclines!
I've experienced a few auto F5A MightyBoys and they certainly do struggle on hills. In fact I'd say they're almost dangerously underpowered. My missus got hers stuck in an underground carpark once because it wouldn't make it up the steep exit ramp because there was no room for a run up! :lol:
After upgrading it to an F8B with matching slushbox it is actually a really enjoyable ute to drive... although fitting a supercharger is a very tempting thought for me. :twisted:
F8B EFI turbo - Three pots and a snail.
manni
Posts: 5
Joined: Wed Jul 23, 2014 11:15 am
Location: brisbane

Hahaha that is gold!!!!
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gadj
Posts: 1074
Joined: Thu Feb 02, 2006 9:22 pm
Location: Maleny, Queensland
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I was running F8b & matching auto in mine until half a tank of E10 shattered the rings (if only I'd been aware of that risk). I was able to get her out to 120Km/h for short stretches. I could only make 65 Km/h on a steep grade though. I also had the dual core radiator with that motor - some were single core.
She's still stuck in the garage waiting for me to finish cutting rust & complete the re-installation of the G10a & 5 sp the former owner had done (poorly but plated). I am told it will go more alike a V6 Commodore & be capable of hitting 135+ on that same steep grade...not that I need it to.
So many delays to getting my MB back in order with 993cc & 5 speed transaxle... neighbor issue gone, donor shell up on rotisserie, new sheds on the way.... another project also..
manni
Posts: 5
Joined: Wed Jul 23, 2014 11:15 am
Location: brisbane

If anyone knows anybody or anywhere to get a cheap f8b motor and box, let me know cause I plan on doing the swap as soon as I find one for the right price!!

Cheers guys
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