Chevy Van G20 (1984)

Discussion in 'GM' started by SI_Prius, Sep 17, 2014.

  1. SI_Prius

    SI_Prius Well-Known Member

    I have been looking in purchasing a 30 year old Van, it has small block V8 305 (5.0 L) 4 bbl carb., 4 speed AT transmission. It would be used for about 9,000 miles per year in environment where 1 litre of petrol costs €1.44 or ~ $7 per gallon. Is that crazy or what?

    - Does the transmission have TC lockup or how can I check this?
    - What cheap modifications would boost MPG (electric grill fan, flat underbody)?
    - What MPG would Wayne get out of this thing and what techniques to use? FAS is not an option.
  2. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    Yeah , what could go wrong ?
  3. phoebeisis

    phoebeisis Well-Known Member

    mpg for that vintage GM-small block V-8 with a carb
    would be poor
    Probably 12-14 mpg at 65mph
    In heavy city driving perhaps 10-11mpg

    No way you can find one about 1996-with better EFI??
    Or even about 1988 with crude throttle body FI

    The old one will suck you dry.
    Not sure when it lock up transmission
    One way to tell drive about 55mph- gently press accelerator while looking at the tachometer(does it have a tach)- if it locks up RPMS will barely increase
    If no lock up-then it will immediately just up 300 RPMS or so

    This vehicle will drink 50 cents per mile in fuel-or more!!

    PS Other than tire pressure and keeping speed down-hypermiling-no mods worth doing
  4. SI_Prius

    SI_Prius Well-Known Member

    Re : Chevy Van G20 (1984)

    It's a completely restored van (will not disclose the price because you will say I'm crazy ;)) and it has old-timer status, that means only €150 per year, If I go for 1996 model it will cost me €1,000 per year just to insure and pay taxes.

    I can cut fuel costs by converting it to LPG, that would mean around €2,400 per year for fuel, otherwise €3,400 for petrol.

    The big question is how it will retain it's price and how much in repairs it will cost me.

    Prius stays. It will do around 18,000 miles per year and I will try to use Van as little as possible, say less than 9,000 miles. So combined MPG of both vehicles would be around 37 MPG, not bad if you look it this way ;)

    And when questioning the costs, I'm estimating that Prius costed me €9,000 only in depreciation in 3 years, combined cost per km is at €0.25 or 50 cents per mile@12,500 miles driven per year.
  5. SI_Prius

    SI_Prius Well-Known Member

    Any idea what this thing consumes at idle in N? 1 gph? 2 gph?

    Can the carburetor adjust idle if for eg. AC is used, or is there any benefit to shift from D to N?
  6. RedylC94

    RedylC94 Well-Known Member

    Idle consumption will be high, but not THAT high! Whether it will use more fuel idling with AC on than off depends on whether it has some sort of idle-speed control (at least a simple idle-step-up solenoid) in functional condition. I think idle-speed controls were added to most cars by the early 1980s, but am not sure about trucks. With no control, the engine will idle needlessly fast with the AC off, wasting fuel---assuming the idle stop screw is adjusted properly with AC on.

    Does the AC even still function on a truck that old? Is it still using Freon 12? Are parts for old American vehicles readily available in Slovenia?
  7. phoebeisis

    phoebeisis Well-Known Member

    My 1998 5.7 with modern but 2 generations behind the latest
    consumes .6gph at idle
    Crude guess is .7gph-.8gph-
    as Redy said not 1-2 gph-heck maybe a FORD(Found On Road Dead) vintage van might suck that much at idle-but not a SBC(small block chevy)
    Carbs can be tuned to give ok fuel consumption at a steady idle
    so idle consumption shouldn't be too much more than EFI consumption.
  8. 08EscapeHybrid

    08EscapeHybrid Moderator

    GM had fast idle solenoids for the a/c for a long time. My 74 Chevy C10 pickup had one, my 81 Regal has one, and my 86 Chevy C10 has one. If you're driving and turn on the a/c there's nothing more to do. If you're stopped, and at low idle when you turn the a/c on, you need to slightly rev the accelerator. When you hit the throttle, the solenoid will extend, and when it is fully extended, it will lock into position. Same goes for when you turn the a/c off at idle. It will stay in the "high a/c" idle until you tap the accelerator. When there's no tension on the solenoid it will unlock and retract.

    The transmission should have a lockup torque converter, my 74 Chevy had one. Especially if it has a TH-700 transmission, which it sounds like if its a 4 speed automatic.

    I would not expect much in the way of fuel economy with a carbureted 305, HOWEVER, if it has a 4bbl carb running properly, and you don't drive it hard you can get up to about 20 MPG in it if you can keep the speeds between 45 and 55 MPH. Above 55, your fuel economy will fall quickly. Back in the time period it was made, the national US speed limit was 55 MPH, and Chevy didn't care much about economy or gearing that worked well over those speeds on their base model trucks. My 86 Chevy (305 and a TH-700) falls into that category. It is a chore to get that thing over 55.
  9. MaxxMPG

    MaxxMPG Hasta Lavista AAA-Vee Von't Be Bach

    The US EPA dyno test - rounded to the nearest whole number - was 16 city and 25 highway and 19 combined, in US MPG. You can use an online calculator to convert those figures to l/100km. The "highway" number is attainable driving easy in the 80-90 km/h range if the van is in good shape. The "city" number will be close to your average if you drive 50/50 city/highway.

    The old 305 is a good engine but the cams tended to go flat over time. If it idles smooth at 400rpm and doesn't climb hills so well, the cam is worn. You can drive a car with a worn cam, but you won't want to challenge anyone to a stoplight drag race. The transmission is a first-generation TH700R4. If it's not leaking, that's a good sign. They also had a weak input shaft and too few vanes in the pump to build a lot of pressure. So if it takes a while to engage when shifting from P to R or D, you will want to take it nice-n-easy driving it, especially when it's cold.
  10. SI_Prius

    SI_Prius Well-Known Member

    Re : Chevy Van G20 (1984)

    Thanks for all the info and warnings.

    If idle consumption is 0.8 gph, then a glide in neutral will only get 30 MPG at my average speed, would steady speed be better than P&G with ICE ON?

    EPA is not that optimistic:
    From that I will take 20 MPG as an absolute ceiling and 16 MPG as a goal for daily hypermiling on local commute.

    If the parts are available in US then they are also in Slovenia ;) the only problem is price (shipping, import duty, tax) and shipping duration. We also have some local enthusiasts and American service shops

    Next week I will post some pictures from American cars meeting, my potential Van will also be there.
  11. Nice. We love van pics!
  12. phoebeisis

    phoebeisis Well-Known Member

    Like I said my 1998 5.7 -350-shows .6gph no ac .7gph ac
    It is possible you will get pretty close to that
    since a carb can do almost as well as EFI with controls
    at steady known loads that GM would have jetted for.
    They GM- wouldn't want it to be too rich-for FE and "too much gas being burned by cat con" reasons.
    So your idle consumption might be nearly as "good" as mine .6-.7 gph
    but just at idle.
    My 1998 SUBURBAN 4 Speed AT is EPA 12/17 - it gets 21mpg at roughly 60mph
    and with motor on pulse and gliding it wil get 14-16 in pure city driving-without shutting off at red lights-I don't think your 305 can do quite as well-but I would
    it is roughly the size of your van- but might be heavier-5200 lbs-vans and pickups of that vintage could be pretty light-my 8 foot bed 1980 D100 Dodge pickup weighed just 3800 lbs
    but it was an absolute stripper-4 speed MT 318 V8-

    GMs of my vintage(1996 AND LATER)- GLIDE IN D as if they are in N
    Yeah lift completely off accelerator at any speed between 27-and maybe 45(not sure upper end speed)-and it glides as if the transmission is in N
    Absolutely ZERO engine braking -
    GM fans here-plenty of them(I came very late 2007 to GM small block "like"-so not so knowledgeable about them)
    can let you know if they have the ZERO ENGINE BRAKING IN D feature

    Now at higher speeds-50 or so-pretty sure it does seem to "stay in gear"

    You GM fans-MAXX REDY ESCAPE EDWIN- when did the glide in D as if in N feature arrive in GM 1/2 tons?? It is great-no fiddling with gear shifter-hoping you don't stick it in R(yeah maybe it won't shift to R-but I wouldn't want to test it)
    But is sure is nice to not have to fiddle wirth a shifter-takes your mind off the road-where your eyes and head should be

    Pictures pictures-what color-
    White is a good color-but I am kinda plain in my car/truck taste,so black red blue green tan yellow or even mustard(like my 383 CUDA) are ok

    PS I also have a Prius "Great minds think alike"
    makes family MPG over 35 mpg-since we only put 3000-4000 miles per year on Suburban-7 years 30,000 miles-and that includes two 3000 mile round trips to Arizona from New Orleans
    It does suck gas in the city-because of wife's driving it-average actual city tanks-1-12 mpg
    44 gallon tank-$150 fill up makes a hypermiler out of you
  13. SI_Prius

    SI_Prius Well-Known Member

  14. 08EscapeHybrid

    08EscapeHybrid Moderator

    I'm not sure when glide in Drive came out. My 86 C10 doesn't do it. It originally had a 3 speed TH350 which I replaced with a TH700R4 when the transmission died in the late 90's. If I were to guess, that probably came in when when they switched to OBDII, which was 1994 I think?

    Parts are plentiful and cheap. You can probably go on just about any US based auto parts site and order them.

    BTW, that is a really nice looking van...
  15. Wow. That looks great in the pic. My parents had bought an 83 with the 6.2 diesel
  16. phoebeisis

    phoebeisis Well-Known Member

    I prefer the black one
    but the white one has a raised roof-nice for car camping
    but the regular roof has lots of "sleeping clearance"
    We sleep in the back of the Suburban-accomodates a big mattress-enough for two adults and a leggy bed hogging greyhound.
    Are you planning car camping??
    A van is certainly the way to car camp-comfortable.
    Black is cool-

    What is a benchinski motor??
    and 9999 is that Euros?? meaning about $15,000 USA
    THE 7995 being about $12,000-not too bad for a nice vintage conversion van
    PS I vote the black GM
  17. 08EscapeHybrid

    08EscapeHybrid Moderator

    Google Translate says its "Petrol Motor"
  18. phoebeisis

    phoebeisis Well-Known Member

    My USA eyes were thinking it was some high performance aftermarket motor builder
    not that that made one bit of sense in a conversion van
    but being a reformed performance type......
    Must say I did like that black van-
    it would be a better choice than our 98 suburban for "road trips"
    but the suburban $2950-was sooo cheap-and seemingly owner proof
    and soo relatively easy to fix with parts being sooo easy to find

    And I did mention-1998 Suburban is paid for-and I am a cheapskate
    so guess we will stick with the Suburban-despite those conversion vans being such nice car camping vehicles

    SI PRIUS- GUESSING Slovenia isn't too hot in the summer-perhaps cold winters more a concern?? Black is a beautiful color but it is POISON in south Louisiana(near NEW ORLEANS AT MOUTH OF MISSISSIPPI RIVER)
    it is HOT here- 35+ degrees most summer days-high humidity-bright sun-so black not so great.Our Prius-unfortunately-is BLACK-

    Which one is cheapest the other two were 8000 and 10,000 how much was/is the black one??
    That is euros?? meaning $15,000 and $12,000 or so-not too bad for what look like redone vans in great shape
  19. 08EscapeHybrid

    08EscapeHybrid Moderator

    Old full size GM trucks and vans are cheap... That's why I've kept my 98 GMC K1500. I wasn't going to really get anything for selling it, and it still runs great. It is very cheap to insure and register, so it makes a great secondary vehicle.
  20. SI_Prius

    SI_Prius Well-Known Member

    Yeah the main purpose of this van would be camping, next year Corsica or Sardinia. I will take it easy since I have half a year to make up my mind if this is really a smart move. I don't really see it very useful in winter.

    I think black color is not a problem since the roof is white and interior is light.

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