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Poly stroker fresh build mileage query

katmachine62

katmachine62

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I have a 62 Dodge Dart Sedan (in Australia!) which I've had a stroker 318 Poly (now 392) built with mild cam ([email protected], .450 lift, running a 2bbbl Holley 500cfm. Everything is new, and engine is balanced 10:1 compression, running standard 727 with 3.23 rear end.

I'm currently running small radials while I wait for my large diameter WW's so almost at 3000 rpm at 100ks. Having said all of this, I'm still experiencing questionable fuel mileage of around 18l/100km! Only running 98 Octane fuel, predominately fwy cruising to test, but keeping in 2500-2900 rpm range mostly.
Thought I'd throw it out there to see your thoughts?! Cheers from down under!
 
Jason Maitland said:
I have a 62 Dodge Dart Sedan (in Australia!) which I've had a stroker 318 Poly (now 392) built with mild cam ([email protected], .450 lift, running a 2bbbl Holley 500cfm. Everything is new, and engine is balanced 10:1 compression, running standard 727 with 3.23 rear end.

I'm currently running small radials while I wait for my large diameter WW's so almost at 3000 rpm at 100ks. Having said all of this, I'm still experiencing questionable fuel mileage of around 18l/100km! Only running 98 Octane fuel, predominately fwy cruising to test, but keeping in 2500-2900 rpm range mostly.
Thought I'd throw it out there to see your thoughts?! Cheers from down under!
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Most of our members work with gallons and miles you know?
Mike
 
That's 13 miles to the US gallon. That seems steep. There are RPM calculators online to see if anything funny there. I personally don't have any experience with 3:23 rear diffs. Maybe a 4bbl carb and some experimental tuning would help?
 
Jason Maitland said:
I have a 62 Dodge Dart Sedan (in Australia!) which I've had a stroker 318 Poly (now 392) built with mild cam ([email protected], .450 lift, running a 2bbbl Holley 500cfm. Everything is new, and engine is balanced 10:1 compression, running standard 727 with 3.23 rear end.

I'm currently running small radials while I wait for my large diameter WW's so almost at 3000 rpm at 100ks. Having said all of this, I'm still experiencing questionable fuel mileage of around 18l/100km! Only running 98 Octane fuel, predominately fwy cruising to test, but keeping in 2500-2900 rpm range mostly.
Thought I'd throw it out there to see your thoughts?! Cheers from down under!
Click to expand...
My 70 383 Challenger got 12 with 3.23's and it jumped to 16 with 2.94's. That surprised me a bit....
 
Holleys aren't the most fuel efficient. Naturally low gears and loose converters aren't fuel efficient.
 
lewtot184 said:
Holleys aren't the most fuel efficient. Naturally low gears and loose converters aren't fuel efficient.
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Yes however it's only a 2bbl 500 CFM so I would have expected better mileage with my fresh 10:1 compression and 98 Octane with mostly freeway driving and if anything my plug is indicating a slightly leanish condition at cruise; I pulled a plug yesterday after cruising on the fwy and shutting it down and pulling over to pull the plug etc
 
I've got a 354 stroker poly with virtually the same camshaft (Schneider 264F Solid Lifter). Also have a stock converter 727, 3.23 rear, 10.8:1 compression and cruise about 3,000 rpm, 4 barrel Holley 600 vac sec, now 650 AVS2.

I'm getting about 13.5 litres/100km on a cruise, whether Holley or Edlebrock carb.

Your 18 litres/100km is more like my around town figure.
 
66 Sat said:
I've got a 354 stroker poly with virtually the same camshaft (Schneider 264F Solid Lifter). Also have a stock converter 727, 3.23 rear, 10.8:1 compression and cruise about 3,000 rpm, 4 barrel Holley 600 vac sec, now 650 AVS2.

I'm getting about 13.5 litres/100km on a cruise, whether Holley or Edlebrock carb.

Your 18 litres/100km is more like my around town figure.
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Yes I have same cam albeit mine is hydraulic, from Gary P!... You must also be running a low diameter rear tyre? I'm currently running a 24.5inch overall diameter wheel, but my new tires will be approx 28 inches overall, so that will help my overall rpm
Interestingly, on my last ride I actually had a 650 Holley dp which was giving approx the same mileage on a 318, then I tested a TQ (thinking it would be better ) but it delivered exactly the same mileage! 318 recent rebuild with 727/3.23 rear end in a 68 Dart, strictly fwy cruising at 55miles per hour/ 2750ish rpm
 
kiwigtx said:
73 washing machines per football field. ..... or 7 burritos to the KFC family bucket :lol:
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IMG_3305.png
 
Don't know how much, but fresh motors use more fuel as they break in.
 
One thing you might check, is the right speedometer gear being used for the 3:23 rear and tire diameter. That could throw your calculations off.
1962-1965-speedometer-pinion-gear-chart.jpg
 
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khryslerkid said:
One thing you might check, is the right speedometer gear being used for the 3:23 rear and tire diameter. That could throw your calculations off.
View attachment 1626214
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Yes makes sense, I'm currently in the process of receiving some 28ish inch diameter tires to replace the original style I'm wanting to maintain. What concerns me even more at this point is that my current 24.5inch diameter (approx) tires are actually giving me a reading of more miles than I am actually covering in reality, I e. My speedo is actually reading approx 70mph when I'm actually travelling at 62mph due to this factor!!
 
What are those 245/60/14s??
I guess! a 28 will help.
old cars with 3 something gears run high rpm. Just like they did new.
 
Are you sure it's a 3.23?
3,000 rpm seems too high to me even with a short tire.
Should be more like 2,600 rpm.

But if it is a 3.55 then it would be closer.
Or you have a slippery torque converter.
 
I would like to see the OP add(?) some long tube TTI Poly headers and a 2.5" dual exhaust with a X over and proper mufflers. No mention read of the ignition. An All in one MSD digital Distributor to help insure all the timing is being added when usable would also be a nice upgrade mileage wise, after that it will only be his carb limiting power and gearing effecting his mileage.
 
kiwigtx said:
73 washing machines per football field
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How many swimming pools is that?

For what it's worth, my 64 has a rebuilt stock 318 poly with a 2 barrel, 2:76 Sure-Grip, 14 inch wheels, TTI headers, H pipe dual exhaust, MSD.

It gets such great gas mileage/litres that I never even bothered to calculate it.
Better than any vehicle I have by a long shot.

I'm upgrading to 15 inch wheels, however I'm keeping the 2:76 Sure-Grip, what a difference in highway cruising too.
 
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