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  1. 75gmck25

    Finding the Correct Vacuum Balance

    I have had bad luck with diagnostic equipment bought at Harbor Freight. The electronic meters have been unreliable and their return policy for electronics means you pay a restocking fee even if the meter is bad. I gave up after two faulty dial-back timing lights, and bought an Innova instead...
  2. 75gmck25

    Engine Stalling - Bad EVAP/Charcoal Canister?

    My canister is an old 2 port that connects to a dedicated port on the ‘75 Quadrajet. However, since I’m no longer using that carburetor, I just left the end of the hose to the carburetor open, and it works fine. I also pulled vacuum on it to verify the tank vent line is open, so it does serve...
  3. 75gmck25

    First Square body pickup Chevy K10 350/700r4

    On a ‘86 the left side tank is the main and right side the aux. Pull the short rubber line off the carburetor and replace it with a long rubber line that will reach a container for gas. Then turn the truck over with the starter and see if you get fuel out from the fuel pump. If you get...
  4. 75gmck25

    What do these wires do?

    The 4th picture with the rubber boot and two wires looks like the A/C low pressure switch on my ‘75. The switch is mounted in the line to the evaporator, and that boot pulls off the switch quite easily.
  5. 75gmck25

    HEI ignition module relocation

    Thermal paste is very commonly used when you build a PC and install a CPU cooler. If the auto parts store doesn’t have it, try an electronics store.
  6. 75gmck25

    Newbie from France

    My ‘75 K25 also has the M40 transmission option listed, and it has a TH350. GM used the TH350 with the SBC in ‘75, even in the 3/4 ton with the heaviest GVW.
  7. 75gmck25

    Afrermarket fuel tank for 1973 k20 with dual fuel tanks

    The most common swap is to use a Suburban gas tank mounted up under the rear of the truck. There are multiple articles on the net that explain how to make that work, and at least 3 sizes of tank. The old saddle tanks may be rusty inside, and the sending units are probably so corroded that...
  8. 75gmck25

    Header hell

    I checked the Blueprint site, and they do have recommended brands. For Hedman Husler they recommend calling the Georgia office, since it has the experience with Blueprint.
  9. 75gmck25

    Intake plenum gaskets

    Sorry for being unclear. I was just suggesting a quick and dirty check to see if you can get the accelerator pump to squirt properly. That and a choke adjustment might solve the hard starting problem You will have to unbolt and lift the top to replace the accelerator pump, so there are still...
  10. 75gmck25

    Header hell

    If you check the blueprint site, I think they have a couple header brands they recommend. I have only blueprint heads, and I recall Sanderson and some other choices being on their list. I think it has to do with the port shape and height, so that some headers seal up better than others.
  11. 75gmck25

    Quadrajet accelerator pump part number

    Just give them a call. I think the longer ones are supposed to provide more volume, but I may be wrong. The silicone seal is what you need, versus the original rubber seal.
  12. 75gmck25

    Intake plenum gaskets

    I suggest only checking the Quadrajet for vacuum leaks, and replace the accelerator pump. Once you start to take the rest apart you are on a potentially long road to get it back together and adjusted correctly. Even verifying float level means you have to remove the top, and there are clips...
  13. 75gmck25

    Jack ideas?

    I carry a bottle jack just in case. With the piston adjusted up, it fits under the axle tube and lifts high enough to change a tire. To lift from the frame I have a hydraulic floor jack from HD, and it lifts high enough when I put it under frame in the area of the drivers door. I also built...
  14. 75gmck25

    Good, body parts

    I have a simpler flat hood brace from LMC and it was not effective in preventing a bend. I had to straighten the hood again and add thicker metal. The brace in the post above looks like a better design.
  15. 75gmck25

    Intake plenum gaskets

    I have a ‘75 K25 350 with an 80’s vintage Quadrajet that is similar to yours. Some suggestions. - if you can’t see fuel squirting in, you definitely need a new accelerator pump assembly. Get one that has seals designed for new ethanol mix fuel. Old pumps had rubber gasket that do not hold up...
  16. 75gmck25

    Won’t Turn Over

    Neutral safety switch is up on the column near the dash. Find the purple wire and use a jumper across it. Remote starter First run 12 volts to the HEI bat terminal so the ignition is powered. Then you go to the solenoid on the starter and use a wire between the large terminal where the battery...
  17. 75gmck25

    Transmission line locations

    Once it warmed up it doesn’t really make any difference. Some folks recommend the radiator cooler being the last before it goes back to the transmission, since it may add a little heat to the fluid during warmup and it will flow better when the vehicle is really cold. However, I don’t think...
  18. 75gmck25

    Cig lighter phone holder issue

    I have mounted one under the dash. I also ran a fused line (25 amp rating) through the firewall and directly to the power junction, so i don’t have to worry about overloading the fuse box.
  19. 75gmck25

    Bypass hose

    On many squarebody trucks the heater return hose runs to a fitting on the radiator instead of the water pump. When I remove my radiator cap I can look in and see that this hose is really flowing a lot of water. You can buy a thermostat with a hole in it, or just drill yourself, but this is...
  20. 75gmck25

    AC redo after sitting disconnected for a long time

    Are all the hoses still connected? Any idea why it quite working? Do you know what refrigerant and oil was used the last time it was working? Most folks convert to R134a and PAG oil, since it’s what all stores carry. However, R12 (Freon) and mineral oil are still available. I have used a...
  21. 75gmck25

    hei vacuum advance stop plate

    Base timing on a stock SBC was usually set to about 4-8 degrees BTDC (measured at about 650 rpm idle, vacuum advance line disconnected and plugged). You can get more performance from a stock engine by setting it to about 12, and maybe even a little higher. I have used up to about 15 BTDC with...
  22. 75gmck25

    AC control vacuum lines

    They usually sell it at the parts store in two sizes - GM hard vacuum line. You can splice it with small sections of rubber vacuum line. Dorman 47419 or 47417...
  23. 75gmck25

    dash pad

    Sounds like Chevy used the same color scheme as my ‘75 GMC. Interior color is mostly saddle (tan), but the dash pad is dark brown.
  24. 75gmck25

    Problematic Starting - rotate crank before starter engages?

    Also make sure it’s installed with real Chevy starter bolts. They have a knurled section that helps everything to align properly. Similar length bolts might fit, but don’t keep the right alignment.
  25. 75gmck25

    Unable to identify steering column piece

    They sell replacements in a kit to repair a GM ignition rack. Check yours carefully for cracks, and replace it if any part of it seems weak. It’s a common breakage item in the column. If the rack does not move the rod correctly, the key will turn but will not slide the ignition switch...

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