New Truck Mysteries!

Discussion in 'Engine & Performance' started by SafetyHelmet, Sep 25, 2013.

  1. SafetyHelmet

    SafetyHelmet Junior Member

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    Location:
    Minneapolis, MN
    First Name:
    S
    Truck Year:
    1982
    Truck Model:
    GMC Jimmy
    Engine Size:
    454/TH350 (Built)
    Hi guys,

    First off, I'm new to working on trucks entirely, so this is going to be an awesome adventure for me.. hopefully! You guys have already helped me fix my doors (the slamming sticky) and I've been reading a ton of good info here, so thanks!

    I picked up a 1982 Jimmy that's been modified a bit. This thing runs like hell, but it was love at first sight, so now it's in my driveway.

    http://i.imgur.com/9NRbl9g.jpg

    Engine: 454 with a TH350 (built for it), Edelbrock 1406 carb. I haven't ID'd the motor yet, cant find any numbers on it. Dana 60 axles, 4.10 ratio. 36" Tires, haven't measured the lift but the hood sits about level with my girls' Rav-4 roof. Bottom of the bumpers sits around 30" from the ground. The floor from the edge of the front seats to the very back is 1/4" diamond plate steel, the PO didn't think the OEM floor pans were thick enough.

    At any rate, I had to remove the glass packs since they are illegal here in MN, and I wanted to reduce the sizeable fine I'd get if I get nicked for other violations. So the Jimmy has stock mufflers on now. I'm not sure if the Jimmy did it before the muffler install, but I get a nasty stumble if I punch it off idle. With the choke on full, it's not as bad, but still there a little. I've tried adjusting the pump for a better squirt, didn't seem to make a difference either direction. I have not checked to see if I can see fuel squirting into the carb, can I do that with just the air cleaner removed?

    Below are some things I have bigger questions on, and pictures of!! Sorry that they are huge in size. Also you might have to turn your head on some of them.. stupid phone cameras.

    #1: I noticed this thing seemed a little loose, when I gave it a wiggle I found I can easily just pull it right out, with no resistance. Is this bad?

    http://i.imgur.com/BSsov2V.jpg



    #2: First, I'm thinking this is not a proper vacuum port cap/plug, it also shows some drying/cracking on the sides of it. Do you guys with a 1406 run on the manifold, or port vacuum connection? I read some things about guys swearing by the manifold vacuum hookup being the best option, but you might need to adjust timing.

    http://i.imgur.com/5hD6n4i.jpg

    #3: I was going to ask about where the linkage for adjusting the pump shot was, but discovered that right after taking this. Anyway, let me know if you see other problems to address here please!

    http://i.imgur.com/WgbyKLv.jpg

    #4: The PO liked yellow. A LOT. Anyways, can someone tell me some info about that distributor? I saw the HEI 65k ebay one people here seem to be a fan of. Would that be a smart upgrade?

    http://i.imgur.com/2Xn6i9p.jpg
    http://i.imgur.com/pw3mp2E.jpg
    http://i.imgur.com/s6HyEvE.jpg

    #5: I'm not so sure about this fuel filter. I can also see grains of sand or something in it. I believe I got a replacement for it from LMC. Anything to be careful about when I change it, or can I just pop it off and swap it out? Also, the fuel line currently runs right up the front of the motor and rests real close to the block and passenger side valve cover, not sure if that is a concern.

    http://i.imgur.com/8OXFHCu.jpg

    #6: I've cleaned small engine carbs about a million times. This looks kinda dirty to me. Should I rebuild? Is a 1406 (600cfm) worth rebuilding for a 454, versus picking up a 650/750? I was considering the Edelbrock thunder 1805, 650cfm.

    http://i.imgur.com/rjIRlOO.jpg
    http://i.imgur.com/mMg5PiU.jpg

    #7: I've tried a bunch of times to find a number on this motor to ID it. Can anyone tell me at least what model it likely is from this pic? Mark IV?

    http://i.imgur.com/FJZgTm1.jpg

    Okay, that's all my questions for tonight. Thanks to anyone who feels like responding!
     
  2. lee0123567

    lee0123567 Full Access Member

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    First Name:
    Lee
    Truck Year:
    1987
    Truck Model:
    K10
    Engine Size:
    ZZ4 350
    Excuse my language, but holy shit is that one badass motherfucking blazer... :headbang:
     
  3. MrMarty51

    MrMarty51 Full Access Member

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    First Name:
    Martin
    Truck Year:
    1978
    Truck Model:
    K20
    Engine Size:
    400
    Yeah, badddd for sure.
    Got a timing light ??? get one, check the timing with the vac. hose disconnected from the carb and plugged, engine idling about 5 or 600 rpms.
    Making sure it is at least 10* advanced, then rev the engine to about 2500 rpms, check timing, if the light has an advance timing feature, set the mark alignment to whatever You had initial timing set at. not sure how many degrees advance You should be getting, guessing at about 25*, now hook the vac. hose to distributor back up, see where the timing is now, then rev the engine back to about 2500 rpms, the timing should now advance further, I think about to 50*, someone`ll help Me out with this please. LOL
    If the ignitions timing is slow, it will cause it to stumble.
    Them plug wires looks good.
    Check inside of distributor cap for carbon tracking, check rotor for the same, if they look burnt, change out plugs and plug wires.
     
  4. SafetyHelmet

    SafetyHelmet Junior Member

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    Truck Year:
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    Truck Model:
    GMC Jimmy
    Engine Size:
    454/TH350 (Built)
    Thanks guys! I'm picking up a light this weekend, along with a vac gauge and tachometer. I'll take a look inside the distributo, too.

    In another thread HotRodPC said some stuff about the accel pump on the carb, and its real dirty around it.. I suspect it's shot and is why punching the gas just about kills the Jimmy!
     
  5. SafetyHelmet

    SafetyHelmet Junior Member

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    S
    Truck Year:
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    Truck Model:
    GMC Jimmy
    Engine Size:
    454/TH350 (Built)
    I have a shop in northern MN looking at the timing, carb and alignment for the next few days. I want to set a good baseline so I can drive the Jimmy daily, and so far have been super helpful... still really curious if you guys have any thoughts on the other questions above though.

    Long term, I am hoping to make this a show truck, get the interior cleaned up, and get a crapload of power out of the motor, provided it's up to the task.

    Is a 1406 too small for a 454? If it turns out to need a rebuild, and I plan on upgrading engine components in the near future, should I just buy a new carb with more cfm?
     
  6. 89Suburban

    89Suburban Full Access Member

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    Truck Year:
    1990 Chevy Suburban
    Truck Model:
    R-1500
    Engine Size:
    5.7L TBI/700R4/3.73 10 Bolt Auburn L-S /Cat-Back
    That's a damn nice Blazer
     
  7. SafetyHelmet

    SafetyHelmet Junior Member

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    Truck Model:
    GMC Jimmy
    Engine Size:
    454/TH350 (Built)
    Hey guys,

    Thanks for the comments. I got her back from the shop today finally. She runs like a dream now on the manifold vacuum port, and got an overall inspection done. Accelerator pump was shot, and I will need to do some ball joints and tie rods up front. The front axle is actually a 3/4 ton D44, not a D60.

    We found some numbers on the engine, too. Anyone know if this is a good year for a 454, if I want to modify it? Apparently it's a 250hp 1978 out of a truck with a manual tranny.

    Numbers are: T1029TST..... CRF1499556
     
  8. jux

    jux Full Access Member

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    Truck Year:
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    Truck Model:
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    Engine Size:
    350
    Questions 1 and 2, the answers are yes, they are fine. Number 1 is a PCV valve, should just slide in and out of the valve cover grommet. If you shake it and hear it rattle then it should be fine.

    The hard questions will need to be answered by someone else.

    Other than that.....DAAAMMNNN nice engine/truck for sure.


    Edit: the 1406 Eddy should be enough for that engine. I didn't look at the pic of how dirty it was, but I would keep it and possibly rebuild it in the future if it's not too bad. I definitely love mine on my 350. But it should have no problem feeding your beast. They tend to hold a tune well and are leak/maintenance free.

    Down the road, if you feel like you would like slightly better gas mileage, you could always swap in a quadra jet. They take some learning to dial in correctly, but they are good carbs.
     
    Last edited: Oct 8, 2013
  9. cblohm350

    cblohm350 Junior Member

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    Truck Year:
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    Truck Model:
    c10
    Engine Size:
    350
    Looks like air horn around primarys is cracked makes me think the carb was dropped
    not really helping any just what i noticed
     
  10. Jims86

    Jims86 Full Access Member

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    Engine Size:
    5.7 TBI
    Stay away from Edelbrock carburetors, they have a fuel capacity defficiency, and fuel washes away from the jets if you corner too hard, the only fix for it is to re-design the float bowl with a dremel.
    The only good metering rod type carb is a Q Jet, other than that, Holley and Demon are the best aftermarket. Edelbrock Does have a Q Jet available which is a remaned Rochester unit.
     
  11. SafetyHelmet

    SafetyHelmet Junior Member

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    Truck Year:
    1982
    Truck Model:
    GMC Jimmy
    Engine Size:
    454/TH350 (Built)
    Thanks Jim. I am saving up for upgrades this winter, what would be a good CFM rate to look at, considering I eventually want to get this motor making 600hp/600ft-lb? Or will it run like crap at a high CFM if the motor is mostly stock otherwise?

    I was looking at a 750cfm Demon.. they seem to run about $340-375
     

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