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Crustydog

351c fuel economy

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Just wondering what sort of economy figures people are getting out of there 351's? My motor is in a xd ute with the original 6 cyl diff and is only running a 2 barrel carby atm. Any idea what sort of feul usage i can expect?

 

Next question is it will need a blue slip before I get it back on the road.

Will the 6 cyl diff pass the slip or will i need disk?

I can source a xh lonreach diff, will the ratio help the feul consumption or make it worse.

The ute will be a daily driver, most of the mileage will be at 100klm/h.

Cheers

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If the rego guy is doing his job, it won't pass without disc brakes and LSD. Mandatory along with any V8 option on XD-XEs.

 

You didn't specify auto or manual, but for reference, my 302 gets high 14s doing mostly country runs with 3.27 gears and 5-speed. A 351 with a 4 speed and 2.92s would be roughly the same but for auto add another litre per 100. That's jetted and timed properly with decent compression and non-smog cam gears.

 

Two barrels are false economy IMO as you have 2 large barrels doing the work all the time whereas a good street 4-barrel will be on the small primaries until you mash it.

 

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my mild 302C with 650DP, 2800 stalled C4, 4.11LSD, 27" tyre, 100km/h at 3350rpm uses 23lt/100km,

Has only been tuned for Drag Racing, have done 17.8lt/100km but not sure how.

 

Bros 302C ZH with 350 holley used 15.3lt/100km going to the AFD last year with a stuffed slipping C4, 3.00 9", 245/60r14's

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I'm an old fart, my XA ute got 18 MPG highway use.....dunno what that is in metric.

 

 

16L/100km

 

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Depends if using Imp gallons or US:

 

1 US gal = 3.785 litres

1 Imp gal = 4.54609 litres

 

So 18 US gal = 14.98 Imp gal

 

18 mpg in US gal: = 12.9 l/100

In Imp gal: = 15.5 l/100

 

I generally use US gal when converting because our engines/carbys, etc are US based so should be compared as such.

 

Ah the wonders of the imperial system

 

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I didn't even know there was more than one type of gallon...

 

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There's even 2 kinds of US gallon: liquid and dry.

 

If you ask me, anyone who wants to rubbish the metric system can keep their 660 feet to the furlong, 3 leagues to the mile or 32 fluid ounces to the quart... My brain has fucking better things to do

 

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There's even 2 kinds of US gallon: liquid and dry.

 

If you ask me, anyone who wants to rubbish the metric system can keep their 660 feet to the furlong, 3 leagues to the mile or 32 fluid ounces to the quart... My brain has fucking better things to do

 

Sent from my CPH1607 using Tapatalk

 

...and the Firkin.

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my 351 c4 2.77 diff get around 5km per litre on long trips on highway about 6.5km per litre

i have to convert all these figures to litre per 100km..

5km per litre = 20litres per 100, i used to get that on LPG with my 351 and C4 with 2.92.. 

6.5km per litre is about 15 litres per 100 which seems pretty normal from what i have been reading

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There's even 2 kinds of US gallon: liquid and dry.

 

If you ask me, anyone who wants to rubbish the metric system can keep their 660 feet to the furlong, 3 leagues to the mile or 32 fluid ounces to the quart... My brain has fucking better things to do

 

Sent from my CPH1607 using Tapatalk

 

ab201aa676fbe0db8cbfa01ae4539f48.jpg

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There's even 2 kinds of US gallon: liquid and dry.If you ask me, anyone who wants to rubbish the metric system can keep their 660 feet to the furlong, 3 leagues to the mile or 32 fluid ounces to the quart... My brain has fucking better things to doSent from my CPH1607 using Tapatalk

 

A Chain is 22 yards isnt it ,,?

Or a cricket pitch ,?

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There's even 2 kinds of US gallon: liquid and dry.If you ask me, anyone who wants to rubbish the metric system can keep their 660 feet to the furlong, 3 leagues to the mile or 32 fluid ounces to the quart... My brain has fucking better things to doSent from my CPH1607 using Tapatalk

 

 

 

A Chain is 22 yards isnt it ,,?

 

Or a cricket pitch ,?

 

Fucked if I know... But sounds good

 

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Funny timing with this topic actually. Despite my less than helpful earlier comment my ZH has been pushed into daily duties by the demize of my XR8. So far I'm finding the economy atrocious. My carby is a standard thermoquad that's a bit tired. Car is dead stock.

 

I'm not measuring the economy but it feels like 30 per hundred. And the gauge is against me. And honestly I'm cruising not pushing it.

 

Why must our beloved Clevos drink so much.

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Why must our beloved Clevos drink so much.

 

I've wondered the same thing, especially since 302 Windsors are so much better on juice than 302 Clevos. I have a theory: that many of the clevo's faults conspire together to make for poor overall economy

 

• 351s are all open chamber (with poor efficiency) unless they're early 4Vs.

 

• they run high oil pressure

 

• large main and big end bearings, causing extra friction

 

• despite large ports, they are inefficient and have dead spots (yes even 2Vs), atomisation suffers. Exhausts are poor too.

 

• on 302s, factory piston to deck height is huge, resulting in poor quench action. Zero decking helps a lot.

 

• factory timing is very conservative. Advancing a few degrees helps, especially if running 98

 

• standard camshafts are retarded from '76 onwards, which is bad for efficiency.

 

• they're a physically big engine with a large surface area, losing a lot of heat from combustion.

 

• they're cold-blooded: 82 deg thermostat means that even more heat gets lost to the radiator.

 

• crank and flywheel are heavy, with lots of inertia to overcome

 

• They're a race engine de-tuned for the street.

 

In your case Gspec, it sounds like you need a new carby. Thermoquads were considered pretty good on fuel and while the above reasons would all explain bad economy regardless, 30 l/100km is just ridiculous. You might actually have a flooded or stuck float.

 

Instead of trying to find bits for it and fix it, you'd actually be better off screwing on a clapped-out eBay Holley. My 600 vac was an $80 gumtree special and got 17 l/100km with just a bit of jetting. Not great but at least average.

 

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Yeah a few of those things are true for mine. Stuffed old carby, stock headers and shitty twin system, currently had no thermostat and i run 98 petrol.

I've bought the thermostat, I've got a full exhaust waiting (need headers actually) and I will overhaul the carby.

 

I have a spare 600 holley off my 350 chev land cruiser I may rebuild.

 

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My old zh. Had a proper full exhaust had a proper thermostat and a rebuilt thermoquad. It was much cheaper to run. Faster to.

 

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