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  1. 75gmck25

    C20 - Trailering vs. Camper Special

    Not sure about your year of truck, but for my ‘75, the Camper Specials have a Teepee emblem in the trim on the side of the cab. I have the deluxe package with Elimi-Pitch and it's impossible to miss. - Brackets bolted to the back of the cab extend through holes in the bed front, where they...
  2. 75gmck25

    Idle timing

    6 is factory spec, but that was a smog era setting that was very conservative. Most stock engines work better at about 12, or even up to 16 if you have aluminum heads. Still runs fine on 87 octane.
  3. 75gmck25

    350 or LS

    Based on your experience level, and the expertise of your crew, a mild 350 build would seem to make the most sense. Lots of info and all kinds of parts available to fit any budget. The weakest points of the early GM 350 are poor flowing smog-era cylinder heads, low compression, and old design...
  4. 75gmck25

    1999 454 carb swap. best street carb, 600? 650? 750? CFM

    On some newer engines they have gone one step further and used Gasoline Direct Injection (GDI) to inject the gas directly into the cylinder - which means only the air stream is moving past the valves. However, one downside of GDI is that the gas/air mixture is no longer passing around/through...
  5. 75gmck25

    Question on upgrading gauges

    An original cluster with tach would put a fuel gauge in the lower left and a tach where you now have your fuel gauge. Looks very balanced, and there is no clock to go bad.
  6. 75gmck25

    1999 454 carb swap. best street carb, 600? 650? 750? CFM

    The Edelbrock AVS2 seems to be a reliable solution that will probably only need some minor tweaking with springs and rods if you buy the 750 cfm version. A Quadrajet has the potential to be an even better solution, but it’s usually hard to find someone to set it up right.
  7. 75gmck25

    Fuel return diy

    You could also just change your sending unit to one with 3 ports. My ‘75 already had one, and when I replaced it I found they were stocked at some AutoZone stores. I don’t recall the price.
  8. 75gmck25

    Fuel cell to stock gauge

    GM fuel sending units are 0-90 ohms. If you can get a sending unit with similar specs, it should work fine. Wire from gauge cluster goes to the sending unit positive, and sending unit should be grounded to the frame.
  9. 75gmck25

    Symptoms of a bad mechanical fuel pump

    I think Ricko1996 has the right answer; the filter should really be down in the rubber line that feeds into the fuel pump. However, I've never seen anyone do it that way, maybe because it seems to be easier to reach when you put it up near the carburetor. I bought a fuel line T at the auto...
  10. 75gmck25

    Timing Tab Installation

    My Goodwrench 350 crate came with with 2 o’clock position timing tabs for two balancer diameters. They just bolt on using two bolts on the timing cover. The holes in the tab are elongated so that you can slide it to get TDC exactly right. Use a piston stop to find TDC. A PIA unless you take...
  11. 75gmck25

    Blower motor draining battery

    The blower motor relay has a direct (fused) power lead that runs from the junction near the brake booster, across the top of the firewall to the relay. That relay is only activated when the blower is on high speed or the A/C is on max. However, if the relay was bad, it might draw power when...
  12. 75gmck25

    late GMT400 interior lights wont shut off like a door is open.

    Sounds like an unintended ground at a light housing may be the culprit. The switched ground for the lights can be confusing if someone is used to other circuits that switch the power side.
  13. 75gmck25

    late GMT400 interior lights wont shut off like a door is open.

    Interior lights should have a constant power orange wire running to them, and there is also a white ground wire (but its not grounded). The light sockets and housings must be isolated from ground, so they have small spacers to keep them from grounding to the body. Basically it's a light socket...
  14. 75gmck25

    Aux battery for audio

    Check the wiring diagram for your truck. My ‘75 Camper Special has a simple (stock) setup with a relay and charge wire for the 2nd battery that runs to the junction near the brake booster. - when the truck is running and you have ignition-on power, the relay energizes and the battery positive...
  15. 75gmck25

    LMC C20 Exhaust

    I bought mine from Summit Racing, and I think it was made by Flowtech. Everything fit fine, but it was a slow job to get it all lined up. Also, none of the pipes are marked, so you have to look at diagrams and try to figure out exactly which on goes in which place. I did it all with the front...
  16. 75gmck25

    Help cant get heater box out

    It’s been a long time since I replaced mine, but I don’t think the AC box had to come out. However there is one stud hidden by the inner fender. You need to unbolt the inner fender and pull it out of the way, or some folks manage to get a universal joint and socket in there. Attached is the...
  17. 75gmck25

    Where does this go???

    Cigarette lighter wiring should be orange, since it provides constant power to the plug.
  18. 75gmck25

    T-Fitting for Oil Pressure Gauge and Switch

    They used to sell them at the auto parts store in the same place they had gauges, but it's been a long time since I've seen that square-shape block fitting. I do have a similar block fitting that is used for adding a fuel pressure gauge, but the port size is much larger. Home Depot has a...
  19. 75gmck25

    Help locating shift indicator part

    I replaced the string on mine with nylon fishing line that is tied to the metal retainer. It’s worked fine for years.
  20. 75gmck25

    Engine Paint Color Question

    My original ‘75 engine was probably orange, but I’ve never really liked that color. However, sometimes its because I see a picture where the owner goes crazy and paints everything orange (balancer, water pump, etc. A madman with a spray can. I think that if you are going to use orange, then...
  21. 75gmck25

    Building a new motor for my 79 C10 - would love some advice!

    Some general guidance- start out with better heads and higher compression. - Original smog heads are very poor flow. Better flowing heads will make everything work better. Lots of good choices out there, including the L31 Vortec iron heads. Don't bite on the idea of using somebody's used...
  22. 75gmck25

    HVAC Vacuum setup

    The small diameter vacuum line is sold in two sizes, and it’s often referred to as GM hard vacuum line. Parts stores used to stock it, but I’m not sure they still do. Dorman 47417 1/8” line is an example. https://www.dormanproducts.com/p-27841-47417.aspx It’s easy to use small sections of...
  23. 75gmck25

    HVAC Vacuum Controls

    Sounds like they integrated the functions of the vacuum reservoir more in the later years. For my ‘75, I think that was the first year cruise control was offered, so there was no reason for a vacuum canister on the driver side until they started offering cruise control.
  24. 75gmck25

    Carb Swap?

    The Edelbrock AVS2 is an improved design over the old 1406, and it is supposed to have better performance parameters. Annular boosters in the Venturi improve the low end fuel distribution for a better snap off the line, and the secondary opening rate is adjustable like the Quadrajet. Basic...
  25. 75gmck25

    HVAC Vacuum Controls

    The reservoir on the drivers side is usually for the cruise control. The HVAC reservoir is on the passenger side, very close to the blower motor. It might be ball-shaped, or some are more like a cylinder (mine looks like a short, black plastic 3 lb coffee can).

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