Results 1 to 17 of 17

Thread: GM 4.2 Atlas inline six

  1. #1
    New Guy
    Join Date
    May 2020
    Location
    Monrovia California
    Posts
    4
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    GM 4.2 Atlas inline six

    has anyone put a late model inline six in a first gen? 2002 to 2009 GM inline 4.2 twin cam great engine. 4L60E trans.

  2. #2
    VCVC Member
    Join Date
    Jul 2004
    Location
    Sacramento, Ca, USA
    Posts
    2,910
    Mentioned
    5 Post(s)
    Tagged
    0 Thread(s)

    Welcome

    Welcome aboard.
    108VanGuy...
    1969 Chevy Panel, 250 CID, 3 ring 4 Spd. with OD, 2.73 "WedgieVan" Daily Driver
    1967 Chevy Panel, 230 CID, 3 Spd. 3.36 "UtiliVan" 292 TFI coming. Owned since 76
    1964 GMC Panel, 194 CID, 3 Spd. "CrunchoVan"
    1965 GMC HandiBus Custom, 194 CID, 3 Spd. "MilkVan" Seized Engine
    1965 Chevy Panel 350 CID, 3 Spd. "RustoRoof" Runs but wiring bad
    1969 Chevy 108 Display 307 CID THM 350 Power Brakes 3.73 Posi
    1965 Chevy Panel, V8, 3 Spd. "Gold Hills Van"
    1965 CamperVan, V8, 3 Spd.
    1969 G20 Shell

  3. #3
    VCVC Member SAVAGE's Avatar
    Join Date
    Feb 2004
    Location
    FT. WAYNE IN.U.S.A.
    Posts
    3,382
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Welcome
    My friend Tom(Millwright71) had talked about it.
    Seems like they don't put them in a lot of cars???
    Don't remember what they put them in???
    Tom

  4. #4
    VCVC Member jrinaman's Avatar
    Join Date
    Apr 2011
    Location
    zelienople, pa.
    Posts
    2,478
    Mentioned
    10 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by SAVAGE View Post
    Welcome
    My friend Tom(Millwright71) had talked about it.
    Seems like they don't put them in a lot of cars???
    Don't remember what they put them in???
    test drove an suv with one, think it was gmc envoy? lots of info on inliners international
    https://www.inliners.org/ubbthreads/...oard=17&page=1
    '64 chevy, 292 40 over, 206/526 cam, 2004r trans. 9.75:1, dual webbers, Langdon cast headers, 1.94 valves

  5. #5
    VCVC Charter Member Vanner68's Avatar
    Join Date
    May 2000
    Location
    Kimball MI USA
    Posts
    13,437
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    Biggest hurdle for most would be the wiring and ECM, the rest is nuts and bolts fabrication.
    Gregg Groff


    There's no place like 127.0.0.1

    1968 Chevy G20 108 panel Now with 454 power!

    1965 Chevy G10 panel- OHC Pontiac inline 6

  6. #6
    VCVC Member lvjjj's Avatar
    Join Date
    Sep 2007
    Location
    BLAINE WA USA
    Posts
    4,046
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    I had a 2005 Envoy for a while and it had the Atlas 6. Actually used it to pull our 5,000 travel trailer. Sure had to get the rpm's way up for it to do the job. No comparison with the 292. Didn't like it for trailering so sold it and got the 94 Suburban. Running solo it was a good engine.
    LARRY OF THE PACIFIC NW
    1965, 292, TH350
    purchased Nov. 22, 1970

  7. #7
    VCVC Member lvjjj's Avatar
    Join Date
    Sep 2007
    Location
    BLAINE WA USA
    Posts
    4,046
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    I had a 2005 Envoy for a while and it had the Atlas 6. Actually used it to pull our 5,000 travel trailer. Sure had to get the rpm's way up for it to do the job. No comparison with the 292. Didn't like it for trailering so sold it and got the 94 Suburban. Running solo it was a good engine.
    LARRY OF THE PACIFIC NW
    1965, 292, TH350
    purchased Nov. 22, 1970

  8. #8
    New Guy
    Join Date
    May 2020
    Location
    Monrovia California
    Posts
    4
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    i was wondering if the front of the 4.2 is too tall for the dog house cover. the ECM is built into the engine, its one of the easier engines to put in an old vehicle, i think i could get 20+ MPG with this engine, the 292 would get me about 12 on a good day.

  9. #9
    VCVC Member lvjjj's Avatar
    Join Date
    Sep 2007
    Location
    BLAINE WA USA
    Posts
    4,046
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by danthemadlocksmith View Post
    i was wondering if the front of the 4.2 is too tall for the dog house cover. the ECM is built into the engine, its one of the easier engines to put in an old vehicle, i think i could get 20+ MPG with this engine, the 292 would get me about 12 on a good day.
    Heck no (12 mpg), I get 13 mpg on a really good day. Problem is I can't keep my foot out of it. Actually I installed the 292 so I could tow a trailer, gets 10 mpg which is wonderful when towing. Quite frankly, I have totally quit worrying about gas mileage, if you're going to be an RV'er, worryiing about mileage ruins the fun. All I care about is that gas stays in good supply. To me gas is freedom and its a large part of my daily budget.
    LARRY OF THE PACIFIC NW
    1965, 292, TH350
    purchased Nov. 22, 1970

  10. #10
    VCVC Charter Member Vanner68's Avatar
    Join Date
    May 2000
    Location
    Kimball MI USA
    Posts
    13,437
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by danthemadlocksmith View Post
    i was wondering if the front of the 4.2 is too tall for the dog house cover. the ECM is built into the engine, its one of the easier engines to put in an old vehicle, i think i could get 20+ MPG with this engine, the 292 would get me about 12 on a good day.
    I put a 67 Pontiac OHC engine in a 65 Chevy van, I had to drop the engine 2" for clearance, and may still need to do doghouse lid mods- so, yeah, it's probably going to be taller than the stock six.

    There are people hitting that magical 20 mpg with the stock 230 or 250 six. It takes a lot of self control, and accepting that everyone will be passing you since with stock gearing the highest efficiency is going to be around 60mph.

    You have to look at the drivetrain as a system, the overall gear ratio needs to be in the same range as the donor vehicle. Even with that, it's not going to be as efficient because even an Envoy is a far more aerodynamically efficient vehicle than an early van.

    The most efficient stock early I had was my 69 with a 307 and three speed manual, with 3.73 gears. At the time, the speed limit was 55 mph nationwide, and I usually cruised the highway at 65mph. It would return 18-19mpg if there were no steep grades. My 68 has 4.11 gears and when it had the 250 in it the best I could get was 15mpg @ 55mph, because frankly it was scary to wind that six out any higher. Replacing with a 350 got about the same mileage, but I built the engine for higher rpm than stock. It now has a 454, haven't had it on the road yet, but even with a 4L80E behind it I'm not expecting miracles, LOL.
    Gregg Groff


    There's no place like 127.0.0.1

    1968 Chevy G20 108 panel Now with 454 power!

    1965 Chevy G10 panel- OHC Pontiac inline 6

  11. #11
    VCVC Member jrinaman's Avatar
    Join Date
    Apr 2011
    Location
    zelienople, pa.
    Posts
    2,478
    Mentioned
    10 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Vanner68 View Post
    You have to look at the drivetrain as a system, the overall gear ratio needs to be in the same range as the donor vehicle. Even with that, it's not going to be as efficient because even an Envoy is a far more aerodynamically efficient vehicle than an early van.
    i would take weight and aerodynamics into account and probably lower gearing slightly. 100% agree you have to look at the entire drivetrain as a system. not only are modern vehicles more efficient due to computerized fuel injection, the trannies have more gears and are designed to shift with fuel mileage in mind with the torque curve of that motor. having owned many (more than 50) carberated work trucks, i can tell you a similar truck, driven in a similar manner and similar loads, they all get about the same mileage, straight six or big block. a bigger motor turns less rpm's to produce the same torque as a smaller engine. getting back to vans, a 292 has gobs of torque compared to a 250 but drinks gas. it drinks more gas because your using power you didnt have before! gear the 250 to match the 292 and it will drink just as much. now the atlas has all the modern efficiencies so it will do better. it will do best when gearing/shift points are matched to the vehicle and its usage. by the way, i get 12-14 with my 292. 4.11 gears and a few go fast parts.
    '64 chevy, 292 40 over, 206/526 cam, 2004r trans. 9.75:1, dual webbers, Langdon cast headers, 1.94 valves

  12. #12
    Van Addict
    Join Date
    Feb 2002
    Location
    Lake Havasu, Az
    Posts
    59
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    My wife's car is a trailblazer with a 4.2...... It has NEVER gotten 20MPG (gets 12 around town 15-16 hwy).......It runs good, but would be a disappointment for the amount of work required to put it in a van.... It's long and almost as wide as a dressed v8.... The accessories are all placed in awkward locations and you will have to reconfigure the accessory drive if you aren't gonna have power steering.... You will hate it before you love it..... If you want to be rewarded for a cutting-edge swap, do an LS...

  13. #13
    VCVC Member jrinaman's Avatar
    Join Date
    Apr 2011
    Location
    zelienople, pa.
    Posts
    2,478
    Mentioned
    10 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by AzDon View Post
    My wife's car is a trailblazer with a 4.2...... It has NEVER gotten 20MPG (gets 12 around town 15-16 hwy).......It runs good, but would be a disappointment for the amount of work required to put it in a van.... It's long and almost as wide as a dressed v8.... The accessories are all placed in awkward locations and you will have to reconfigure the accessory drive if you aren't gonna have power steering.... You will hate it before you love it..... If you want to be rewarded for a cutting-edge swap, do an LS...
    how does it run/power? the one i test drove ran good but not nearly as well as the 4.7 durango i had at the time. the durango got similar/slightly better mileage and was driven hard.
    '64 chevy, 292 40 over, 206/526 cam, 2004r trans. 9.75:1, dual webbers, Langdon cast headers, 1.94 valves

  14. #14
    Van Addict
    Join Date
    Feb 2002
    Location
    Lake Havasu, Az
    Posts
    59
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    4.2 runs okay, better than the last 4.3 v6 I had....
    Just not worth the hassle IMO, versus the original straight six
    The Atlas six is obese and complex and offers no real improvement over the stock six...
    It's designed to run 210 degrees, which is a problem in an early van, and the engine's size and shape would restrict airflow...
    Don't do it!

  15. #15
    VCVC Member panelmanrd's Avatar
    Join Date
    Oct 2009
    Location
    KC MO
    Posts
    1,979
    Mentioned
    6 Post(s)
    Tagged
    0 Thread(s)
    they used this engine in only 2 vehicles built by gm, finding a good used one
    is very challenging, they are very complex engines, almost a 6 cyl version of the quad 4
    and we all know what a money pit that engine was.
    54 chevy panel truck 355 tpi 700r4 325/9in
    64 chevy 90 5.7 tpi 700r4 336 8.2
    69 chevy panel van 5.7 tbi 700r4 336 8.2

  16. #16
    Van Addict
    Join Date
    Feb 2002
    Location
    Lake Havasu, Az
    Posts
    59
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The Atlas engine was available as a six in the Trailblazer, Envoy, Bravada, and I believe Buick and Saturn had a version of this SUV as well...... As a Five cylinder, these engines were standard in the Hummer H3 and may have been an option in the Colorado pickup... Also available as a 4 cylinder in the Colorado......The Trailblazer platform was around from 2003 to 2012 and many were 2wd, so there probably is no shortage of suitable donors......My wife's TB has 3.42 gears and 4L60 trans

  17. #17
    VCVC Member panelmanrd's Avatar
    Join Date
    Oct 2009
    Location
    KC MO
    Posts
    1,979
    Mentioned
    6 Post(s)
    Tagged
    0 Thread(s)
    Go on car-parts.com and see if you can find a good reasonable priced one,
    car lot I used to work for would trash them after an engine failure because of
    the price of the engine
    54 chevy panel truck 355 tpi 700r4 325/9in
    64 chevy 90 5.7 tpi 700r4 336 8.2
    69 chevy panel van 5.7 tbi 700r4 336 8.2

User Tag List

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •