My 340 getting 6 mpg

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71GSSDemon said:
So, unless you are using Google Maps from specific address to specific address, then it will take you to city center, which it can be miles different from where you are going. Just looking to help with actual miles recorded.
Click to expand...
Yes Im using from exact location to exact location. not city to city. believe me my tracking of miles driven is on point.
 
64whiteghost said:
Yes Im using from exact location to exact location. not city to city. believe me my tracking of miles driven is on point.
Click to expand...
Go for a real drive. Top off tank in Malibu South of Pepperdine and drive to Neptune's Net or beyond. Check your odometer by CalTrans markers on Highway 1 variously placed at improvements as they're marked to 1/100 of a mile.
You need a long enough cruise with no pedal pushing to get the true picture.
 
Workingdog1 said:
Go for a real drive. Top off tank in Malibu South of Pepperdine and drive to Neptune's Net or beyond. Check your odometer by CalTrans markers on Highway 1 variously placed at improvements as they're marked to 1/100 of a mile.
You need a long enough cruise with no pedal pushing to get the true picture.
Click to expand...
I have driven to Neptunes.

I filled up in San pedro and by the time i got to that first chevron in santa monica on pch i was already at half a tank. And i took the 110 to the 405 so i was at a consistent throttle. I drove to rock store. Then to neptunes. Then home and i used a whole tank. That was before we tuned it this past weekend. I will drive it up again.
 
AJ/FormS said:
Harbor city, CA
Elevation 49ft
CylinderPressure, unspecified
transmission, unspecified
stall speed, unspecified
cruise-timing, unspecified
IDK how anyone can give you accurate advice.

But yeah, as I said earlier, 67PMJs are gonna be lean, requiring extra throttle to get to 65mph, and possibly to maintain it.
Put some 70s in there and 78s in the back, and a 10.5 PV. Sync the Transfer ports, reset your pumps, Modify your VA and Mechanical Timing Curve to, together, generate at least 48* of Cruise timing.

Here's how to set your cruise timing exactly right.
1) check your timing at cruise-rpm
2) rev your engine up to cruise rpm, Set your cruise timing to 48*, then
3) keep it there for the rest of this test.
4) without regard to the actual timing number, advance the timing a small amount. If the rpm goes up, bring it back to the reference rpm. Then repeat until additional timing produces no additional rpm.
5) but if additional timing from 48* does not produce additional rpm, then go the other way, taking out timing, looking for the whatever timing makes the rpm to peak.
6) after the max cruise timing is found; determine if the AFR is rich or lean, at that rpm, and fix it.
7) finally, take out 3 degrees of advance, to compensate for the lack of cruise load. Read the timing; Whatever you get now, at cruise rpm, that is what your engine combo needs and wants, and that is your target.
8) reset your cruise-timing to what it was in step one above; then return the engine to idle and let it cool before shutting it off.
9) now you gotta figure out how to get to that target.


Notes.
1) what you are hunting for is the magic timing number required at cruise-rpm, at the smallest throttle opening, that the engine combo is able to produce. Then lean it out to the minimum amount of fuel to maintain that rpm, at that throttle opening.
This is so easy, and it works for any cruise-rpm.

2) I once had a combo that cruised 75@ 1840 rpm, in double-overdrive. I used this method, and she gave me back 32 mpgUSg. I'm certain that if I had been cruising in direct at 3300, the results would have been very different.

3) Another thing I did was to, at cruise rpm/speed, put the trans into neutral and see how much distance it took to slow down to about 20 mph.
Then I checked the cars mechanicals to see what could be done to increase this distance. Things like adjusting the wheelbearings , the brakes, installing new U-joints, adjusting the front-end height, the attack-angle of the rear spoiler, and of course, the tire pressures and the alignment.

4) I don't run that combo any more. That cam lost lobes, and I replaced it with the next bigger size from the same manufacturer. This new cam lost bottom-end, big-time, relatively speaking, leading to a different transmission, and the loss of Second overdrive.
I took the engine apart, and increased the Scr some more, with slight loss of Quench.
The new combo cruises at 65=2240, and forget about 32mpgs. But it's still pretty good. But she now likes 56* or more, of cruize-timing. and I leaned her out a bit more, lol.
5) At cruise rpm the engine doesn't care about how many accelerator pumps are on the carb, and it doesn't care if it has vacuum-secondaries nor what size MJs are in it unless the PMJs are just too small, to even get to the desired cruising speed. It doesn't even care about the Transfer slot sync. unless the idle-mixture screws are cranked right out.
6) at cruize rpm, the engine only cares about maximum cruise-timing and minimum fueling, for the load it is pulling, which can change quite a bit with the engine's running temperature.
Addition concerns are; the inlet air temp, and of course the air density and humidity.
Some things cannot be easily compensated for, like the amount and strength of the overlap cycle, and most especially with the amount of power extraction degrees.
In your case I grossed your cam up to guess at the zero-lash numbers and the formula spit out just 106 degrees. This makes your compression degrees and your extraction degrees nearly identical to mine, with the exception that you overlap is about 67* to my 61*.
I see almost no reason that your combo, being roughly 600 pounds lighter than mine, couldn't out-perform mine in the fuel-economy arena, if we both ran at the same rpm. At that point, the only advantages that I might have is the 3.58 stroke, maybe a slipperier body, and the fact that I run a minimum coolant temp of 207, with fresh cold, above-the-hood inlet air.
And BTW, I run an ancient 750DP Holley that I bought used in about 1977. Notta chance would I, if I had your carb, give it up, no way.

7) Just to give you food for thought;
My previous cam was
276int/115comp/112Power/276 exh/53*o-lap
As you can see the extraction was 112* to your estimated by me, 106*
This cam was 223/230 @050; and it was way more fun than the cam that followed, namely,
276/114/105/286/61* overlap 230/237@050

Your 234/244 has at least 4* more exhaust duration than it needs, and for the lightweight car probably 8 or 10 too much. which at WOT is a maybe a good thing, but those extra degrees are stolen from the extraction cycle, which means, that at cruise rpm, a lotta pressure is going right out the tailpipe.

If I had your cam, I would retime it to 2* retarded, in at 110; But, this will reduce your CCP, which is why I asked for your current compression test results. If you are in at 104 now, going to 110, that represents a pressure loss of perhaps as much as 12psi, which with 3.91s and a 3500TC you won't hardly notice. But with 3.23s and a manual trans, I know is gonna suck.
However the 110 degrees of resulting Power extraction versus my estmated 106, is gonna make a huge difference in the potential to make fuel-economy, after the carb and timing is cleaned up.
I'm pretty sure your combo can't ever make 32mpgs, but I'll bet 20 in steady-state at 65=2400 is doable, and with any 750, and more with a spreadbore with triple boosters.
Click to expand...
Thank you for this !
 
Wife's 383 x 4 gear for a 200 mile cruise yesterday. 14.1 miles per US Gallon and I never drive a 4 speed in economy mode.... makes me wonder about her 340 x auto getting 8.
 
AJ/FormS said:
Harbor city, CA
Elevation 49ft
CylinderPressure, unspecified
transmission, unspecified
stall speed, unspecified
cruise-timing, unspecified
IDK how anyone can give you accurate advice.

But yeah, as I said earlier, 67PMJs are gonna be lean, requiring extra throttle to get to 65mph, and possibly to maintain it.
Put some 70s in there and 78s in the back, and a 10.5 PV. Sync the Transfer ports, reset your pumps, Modify your VA and Mechanical Timing Curve to, together, generate at least 48* of Cruise timing.

Here's how to set your cruise timing exactly right.
1) check your timing at cruise-rpm
2) rev your engine up to cruise rpm, Set your cruise timing to 48*, then
3) keep it there for the rest of this test.
4) without regard to the actual timing number, advance the timing a small amount. If the rpm goes up, bring it back to the reference rpm. Then repeat until additional timing produces no additional rpm.
5) but if additional timing from 48* does not produce additional rpm, then go the other way, taking out timing, looking for the whatever timing makes the rpm to peak.
6) after the max cruise timing is found; determine if the AFR is rich or lean, at that rpm, and fix it.
7) finally, take out 3 degrees of advance, to compensate for the lack of cruise load. Read the timing; Whatever you get now, at cruise rpm, that is what your engine combo needs and wants, and that is your target.
8) reset your cruise-timing to what it was in step one above; then return the engine to idle and let it cool before shutting it off.
9) now you gotta figure out how to get to that target.


Notes.
1) what you are hunting for is the magic timing number required at cruise-rpm, at the smallest throttle opening, that the engine combo is able to produce. Then lean it out to the minimum amount of fuel to maintain that rpm, at that throttle opening.
This is so easy, and it works for any cruise-rpm.

2) I once had a combo that cruised 75@ 1840 rpm, in double-overdrive. I used this method, and she gave me back 32 mpgUSg. I'm certain that if I had been cruising in direct at 3300, the results would have been very different.

3) Another thing I did was to, at cruise rpm/speed, put the trans into neutral and see how much distance it took to slow down to about 20 mph.
Then I checked the cars mechanicals to see what could be done to increase this distance. Things like adjusting the wheelbearings , the brakes, installing new U-joints, adjusting the front-end height, the attack-angle of the rear spoiler, and of course, the tire pressures and the alignment.

4) I don't run that combo any more. That cam lost lobes, and I replaced it with the next bigger size from the same manufacturer. This new cam lost bottom-end, big-time, relatively speaking, leading to a different transmission, and the loss of Second overdrive.
I took the engine apart, and increased the Scr some more, with slight loss of Quench.
The new combo cruises at 65=2240, and forget about 32mpgs. But it's still pretty good. But she now likes 56* or more, of cruize-timing. and I leaned her out a bit more, lol.
5) At cruise rpm the engine doesn't care about how many accelerator pumps are on the carb, and it doesn't care if it has vacuum-secondaries nor what size MJs are in it unless the PMJs are just too small, to even get to the desired cruising speed. It doesn't even care about the Transfer slot sync. unless the idle-mixture screws are cranked right out.
6) at cruize rpm, the engine only cares about maximum cruise-timing and minimum fueling, for the load it is pulling, which can change quite a bit with the engine's running temperature.
Addition concerns are; the inlet air temp, and of course the air density and humidity.
Some things cannot be easily compensated for, like the amount and strength of the overlap cycle, and most especially with the amount of power extraction degrees.
In your case I grossed your cam up to guess at the zero-lash numbers and the formula spit out just 106 degrees. This makes your compression degrees and your extraction degrees nearly identical to mine, with the exception that you overlap is about 67* to my 61*.
I see almost no reason that your combo, being roughly 600 pounds lighter than mine, couldn't out-perform mine in the fuel-economy arena, if we both ran at the same rpm. At that point, the only advantages that I might have is the 3.58 stroke, maybe a slipperier body, and the fact that I run a minimum coolant temp of 207, with fresh cold, above-the-hood inlet air.
And BTW, I run an ancient 750DP Holley that I bought used in about 1977. Notta chance would I, if I had your carb, give it up, no way.

7) Just to give you food for thought;
My previous cam was
276int/115comp/112Power/276 exh/53*o-lap
As you can see the extraction was 112* to your estimated by me, 106*
This cam was 223/230 @050; and it was way more fun than the cam that followed, namely,
276/114/105/286/61* overlap 230/237@050

Your 234/244 has at least 4* more exhaust duration than it needs, and for the lightweight car probably 8 or 10 too much. which at WOT is a maybe a good thing, but those extra degrees are stolen from the extraction cycle, which means, that at cruise rpm, a lotta pressure is going right out the tailpipe.

If I had your cam, I would retime it to 2* retarded, in at 110; But, this will reduce your CCP, which is why I asked for your current compression test results. If you are in at 104 now, going to 110, that represents a pressure loss of perhaps as much as 12psi, which with 3.91s and a 3500TC you won't hardly notice. But with 3.23s and a manual trans, I know is gonna suck.
However the 110 degrees of resulting Power extraction versus my estmated 106, is gonna make a huge difference in the potential to make fuel-economy, after the carb and timing is cleaned up.
I'm pretty sure your combo can't ever make 32mpgs, but I'll bet 20 in steady-state at 65=2400 is doable, and with any 750, and more with a spreadbore with triple boosters.
Click to expand...
There is a typo in here, but my Edit button is gone
Under item 7 it starts out;
"my previous cam was
276....... "
That's not right.
The intake duration on that cam was 270*, lol. You can find it on the Hughes Website under discontinued cams, as HE2430AL. That was a heckuva sweet cam.
Knowing what I now know, I'd be tempted to slap a lil more overlap on it by closing up the LSA. but that's another story .......
 
Imperial gallons are .912 liter or 128ounces
Canadian gallons are 1.14 liters= 160 ounces
Thus a Canadian gallon is 125% as big as a Usg
Butum, the Canadian gallon is not supposed to exist anymore.
 
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Newbomb Turk said:
Isn’t your fuel dispensed in liters?
Click to expand...
Tell that to the government!
Up until recently, (IDK when the shift was made), any imported liquid product was labeled into equivalent metric, from whatever system was used in the country of origin.
So you know, most of our stuff comes from the US, so we're used to rip-off gallons.
>Paint now comes in USgallons and the tags are converted to metric; So we used to get, 160oz gallons in Canadian paint. But in the metric system we get 3.78 liters= 132 oz jugs = and we get to pay $80 bucks a jug, last time I checked. That's over 60cents an ounce! clean you rollers everybody.
>Engine oil used to comes in jugs marked 4.5 liters which is one gallon Canadian.
Now they come in 5 liter jugs.
Now a liter is ~28.44 ounces, and our ounces are same size as American ounces so
5 liters is ~176 ounces which is;
=1.09 gallon C = 4.4 qts , or
=1.375 gallons US =~5.5 qts US
So,
how much of that 5 liter jug do I put in my oilpan?
> but it gets better;
> Canadian suppliers hopped on the conversion train. What used to be a 160 oz/ 4qt jug of milk, became a 4liter jug at 114 ozs, which then became a jug of 3.78liter/107.5ounces, being 46 stinking ounces short of a proper gallon. and the price went up.
At the convenience store I recently paid 8.80 for a 3.78liter/ 107.5 oz jug. That's 8.2cents an oz. I used to drink that like water, easily a gallon a day.
Not no more.
I used to order milk at the restaurant,
not no more.
I used to push milk on the grandkids;
not no more.
I used to keep a jug of chocolate milk in the fridge for the grandkids,
not no more.
Oh it's so wonderful living in Canada. Everybody is all the time figuring out how to rip somebody else off.
Wanna buy an 40 pound bag of potatoes. They used to be ~$10. Now you gotta pay that for 5pounds. That's 800% since Covid. We are systematically being ushered into starvation. I'm dreading the day that the government claws back my Government Pension.
Oh Wait, I'm slipping off topic.
Can you tell I hate metric?
Our country is criss-crossed by mile roads so accurate you can calibrate your cruise-control by them. But all our speed'Os are in stinking Metric Who cares about how many liters it takes to go 100km. Regina is 365 miles from my front door. If my car uses 14 liters to go 100 km, how much gas am I gonna need. What the 'ell is 14liters/100km? Cariminy. Just tell me, at which mile-road am I gonna run out.
 
Last edited:
Dan Georgino said:
Nothing about the Business, but I do know about gas it's self. I do know Chevron is the reason California gas prices are so high. And the gas is bad. Most if it is chemical cleaning additive.
Click to expand...


lol so Chevron is running the cost of fuel up in California by adding taxes to their gas??

WTF??? Wake up.
 
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