1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

what kind of mileage are you gettign with yoru swapped in v8s?

Discussion in '40- & 55-Series Tech' started by mancinator, Jul 31, 2003.

  1. mancinator

    mancinator

    Messages:
    235
    Likes Received:
    0
    Joined:
    Jul 27, 2003
    just curious...id imagine most of you that have the engine swapped are running 350s, and i know the milegae will be dismal....but id just like to know how many times ill be hitting up the chevron if i pick up a v8 350 cruiser.
    thanx!
     
  2. s79bj40

    s79bj40

    Messages:
    359
    Likes Received:
    0
    Joined:
    Feb 10, 2003
    Location:
    Brisbane
    i had a friend with a nice 60 on gas and petrol and 33' tyres. He had 1 50litre gas tank, 1 70litre gas tank and the standard petrol tank 70Litres??. and he generally got between 400 and 600k out of the lot. (thats what he told me at least) He had some kind of lightly worked 350 or something.

    so thats about 180litres - useable of about 30litres =150litres for average 500k, so he was using 30l/100k against my 10l/100k (4cyl diesel)

    the figures may have been upped slightly to impress me though, but it certainly put me off petrols for ever.

    sam
     
  3. 72cruiser

    72cruiser

    Messages:
    2,709
    Likes Received:
    0
    Joined:
    Dec 29, 2002
    Location:
    nashville, tn
    whoa dude,

    you're gonna have to un-canada that one for us. ???

    jonathan
     
  4. 72cruiser

    72cruiser

    Messages:
    2,709
    Likes Received:
    0
    Joined:
    Dec 29, 2002
    Location:
    nashville, tn
    whoops,

    my bad, un-australia.

    i figured just as good, since all you english and french types get along so peachy.
     
  5. hammerhead

    hammerhead

    Messages:
    1,995
    Likes Received:
    0
    Joined:
    Jul 5, 2003
    Location:
    Central, Utah
    It depends. My old engine w/2brl got about 9 MPG, w/4brl about 10MPG. My new eng (old one blew) gets a much improved 15 MPG w/same 4brl.
     
  6. roscoFJ73

    roscoFJ73

    Messages:
    13,084
    Media:
    3
    Likes Received:
    223
    Joined:
    Jul 22, 2003
    Location:
    Perth Western Australia
    That works out to about 9.48 mpg and thats Imperial gallons not US gallons.Which is disappointing as I was led to believe the 350 could be as economical or better than my 3F.
     
  7. mancinator

    mancinator

    Messages:
    235
    Likes Received:
    0
    Joined:
    Jul 27, 2003
    dang! 15 mpg...is that fi?
    id rather have a big deisel putting out 30 mpg and 300 ft lbs of torque, but those conversions are hard to come buy here....and in the states, diesel costs the same as gas, but you dont get the same milegae obviosuly. back in canada diesal was a good 10 cents a litre cheaper then gas so i know the diesal crusiers were very popular up there. it wasnt uncommon to see a diesal cruiser with 500 000 miles on the original engine...only problme is wiht all the salt they use on the roads up there by that thime they were mostly rusted to heck.
    anyways, id be looking at a 350 bored to 383, with a quadrajet carb and headers....4 speed tranny, 35s, and 4.10 gearing i beleive. i dont know much about carbs, so whats yoru best guess on the kind of milege ill be gettign with that combo? im expecting, if i drive conservativly (i do..now :p) 10 mpg....i hope that isnt too ambitious a goal
    what do you cruiserheads think?
     
  8. hammerhead

    hammerhead

    Messages:
    1,995
    Likes Received:
    0
    Joined:
    Jul 5, 2003
    Location:
    Central, Utah
    Like I said...depends. My 15 MPG is Quadra-jet and manifold from a '79 blazer. Rams horn exhaust manifolds from old chevy pick-up (I think). High performance HEI. The engine is the one piece of the equation I know little about. A friend found it for me. It came from a '74 3/4 ton 4x4 that was converted to a tow truck. It pulls like a tow truck. A stock 4spd and t-case, stock 4.10 gears and 35s.
     
  9. nuclearlemon

    nuclearlemon not an addict Moderator

    Messages:
    15,587
    Media:
    87
    Likes Received:
    404
    Joined:
    Jan 30, 2003
    Location:
    meh-ico, colorado
    about 16-17 in town...diddly squat when the secondaries open up
     
  10. mancinator

    mancinator

    Messages:
    235
    Likes Received:
    0
    Joined:
    Jul 27, 2003
    haha...i knew when i felt those secondaries open up that i coudl just see buckets of gas been poured into the carb. i have anotehr carb question....when they get at to much of an angle, they tend to want ot stall out since not enough gas is getting into the carb right? does the quadra jet help with that at all, and how off camber can you get before you start running into problems?
     
  11. hammerhead

    hammerhead

    Messages:
    1,995
    Likes Received:
    0
    Joined:
    Jul 5, 2003
    Location:
    Central, Utah
    It's funny you should ask. We have been playing with just that. Trying to find out which carbs work best in the thrash and at radical angles. Quadra-jet won for us just like it won the magazine shootout. We discovered that some Q-jets were better than others. So far the '79 Blazer Q-jet out angles and out bounces the rest. There have been a couple that have gotten better MPGs but we were only after offroad performance. In this test there have been 4 vehicles and a dozen or so carbs. It didn't start out as a test or we would have kept logs. What we don't know is why this particular model works so well. The guys want to tear it down to see but its on my rig and I like being top dog. Shes still running fine when its so steep I feel like I'm on my hitch. As for side tilt it was still running when my mirror got stuffed in my window by the ground. OOPS!! :eek:
     
  12. mancinator

    mancinator

    Messages:
    235
    Likes Received:
    0
    Joined:
    Jul 27, 2003
    WOW THATS DANG IMPRESSIVE! this actually reassures me....cause ill be honest, im not a horsepower freak, but i did want to step up to some v8 power since i was tired with my old 2.8 in my trooper and since it only got 12-15 mpg anyways, i figure if im not going to get go mielegae, i might as well have some fun.
    i have another question...its more of a theory that ive kicked around with a few other people i know running v8s....ok, if you put a 350 in a suburban or fullsize truck that weighs like 6000-8000 pounds or whatever , that engine will have to work hard to move that trucks weight, thus killing the mielage. but if you take that same 350 and put it into a truck that is half as heavy, does that mean the engine doenst have to work near as hard, thus imrpving the gas mileage greatly? i have always been curious of this...is that how it works?
     
  13. woody

    woody Internet Fireman Staff Member

    Messages:
    10,335
    Media:
    303
    Likes Received:
    1,094
    Joined:
    Jan 15, 2002
    Location:
    Toquerville UT
    based on the BHCC trip, I'm gonna make a guess....

    it was 30 miles each way to the trailhead...so that's 60 miles road time. Add in about 10 miles total trail time, all low range, lots of idle time...plus the road time included some major hillage too...

    I put in 6-7 gallons of fuel each day to top off the cell. No odo/speedo in the truck, just an hour meter.

    I'd guess "true" road mileage at 14-15 mpg...350 TBI, stock, 4.11 gears and 38.5 tires at 10# street pressure.
     
  14. Rice

    Rice SILVER Star

    Messages:
    3,277
    Media:
    10
    Likes Received:
    2,578
    Joined:
    May 2, 2003
    Location:
    GSO NC
    Have been keeping a close eye on it lately just for curiosity sake.
    350 with Edelbrock aluminum heads, shortie headers, medium cam, and a small vacuum secondary carb (600):
    In the city right at 11 MPG.
    On the open road it just over 14.
     
  15. Paul_A

    Paul_A

    Messages:
    186
    Likes Received:
    0
    Joined:
    Apr 1, 2003
    Location:
    Rosendale, NY
    With a Carter AFB 650cfm on a 305 I get 14mpg.
     
  16. hammerhead

    hammerhead

    Messages:
    1,995
    Likes Received:
    0
    Joined:
    Jul 5, 2003
    Location:
    Central, Utah
    Vehicle weight definately is a factor. Ignition is also a factor. When I switched to HEI I felt a power increase as well. Air pressure is too. Woody got me thinking about this so I aired-up way above my normal 18-20 PSI. At 34 PSI and an intentionally light throttle foot I squeezed over 18 MPG out of her. Now I'm going to try for 20. I figure a bit of tuning and tweaking might do it. As already pointed out by others, this means squat when in low range and banging on the throttle. Stand on the secondaries like dunes or mud, and it probably looks like someone flushed a toilet in there.
     
  17. Plowboy

    Plowboy

    Messages:
    798
    Likes Received:
    0
    Joined:
    Apr 21, 2002
    Location:
    On a hill overlooking a lake in Idaho
    balanced/blueprinted 327 with 800 cfm afb, 33 in tires 4:11 rear. around town 9-10 freeway (below 65) 14 to 16 (above 65 and on the trail) I can see the gas gauge moving down everytime I bump the throttle!
     
  18. hammerhead

    hammerhead

    Messages:
    1,995
    Likes Received:
    0
    Joined:
    Jul 5, 2003
    Location:
    Central, Utah
    [quote author=mancinator link=board=1;threadid=4044;start=0#msg29790 date=1059703649]
    anyways, id be looking at a 350 bored to 383, with a quadrajet carb and headers...
    [/quote]
    What you need is a 350 stroked to 383. That's a 350 block w/400 crank, rods, flywheel, and harmonic balancer.
    You've got the right idea with the Q-jet but when you get sick of header exhaust leaks go with the rams horn type exhaust manifold.
     
  19. hammerhead

    hammerhead

    Messages:
    1,995
    Likes Received:
    0
    Joined:
    Jul 5, 2003
    Location:
    Central, Utah
  20. mixmaster

    mixmaster

    Messages:
    99
    Likes Received:
    0
    Joined:
    Jan 26, 2003
    My fj55 has a 400 SBC with Q-jet, stock 4 speed, little over stock height and 32" BFG AT's. The last time I looked at mileage it was getting around 10-12 mpg. I could probably get better but I like to use the V8 power.