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  1. 75gmck25

    86 K20 Front Leaf Springs

    The Army stenciled the CUCV fender with a max speed limit, but AFAIK this is only a driver safety limit set by the Army. With proper tires they are safe at normal highway speeds. Blazer body CUCVs are relatively comfortable at normal highway speeds, but the high GVW pickups have a lower axle...
  2. 75gmck25

    86 K20 Front Leaf Springs

    My '75 K20 has the 8400 lb GVW package, with a FF rear axle, etc., and the front HD springs look the same as yours.
  3. 75gmck25

    AC Clutch Cycling Switch

    Let me try this again. My truck is a late '75, and by that time they had switched to a CCOT system. I assume your '76 is the same. Go to Rockauto.com and pick your vehicle then "Electrical Switch and Relay" then "Refrigerant Pressure Switch" There are multiple choices for the switch.
  4. 75gmck25

    Decided on a 350 engine, still deciding on stroking it out or not.

    I agree that a 96-99 Vortec 350 is the best starting point for a good midrange build, but a carburetor build may be a simpler solution. Just make sure the heads are good first (no cracks). Then pick a cam in the range of about 220-225 duration at .050. If the cam lift is too high you will...
  5. 75gmck25

    Did they mess up belts?

    Alternator belt looks fine. For the PS belt there were two OEM solutions - short belt goes around the PS pulley and the crankshaft pulley. This was the stock non-A/C belt - or there is a longer belt that goes around the PS, crankshaft and the water pump. This was usually used on A/C or HD...
  6. 75gmck25

    Rough Idle and Stalling

    16” is pretty low vacuum for an engine with a stock cam. I would have Firestone check for vacuum leaks around the entire intake, using a leak detector (propane, etc.). Also, how did you manage to switch from a Quadrajet (spreadbore) to an Edelbrock (squarebore) without changing the intake...
  7. 75gmck25

    Shakey Gauge

    Once you find the sending unit ground on the side of the frame rail, you will understand how it gets corroded and makes a bad connection. It’s fully exposed to road dirt, oil, etc. Remove the bolt, sand the frame and wire connector down to bare metal, and screw everything back down tightly...
  8. 75gmck25

    17-in rims

    AFAIK, squarebody wheels are lug centric, not hub centric ( like many newer vehicles).
  9. 75gmck25

    A/C only works when driving!?

    First check to make - with the vehicle running, put the HVAC on heat or vent. Turn the blower on high - does air come out in the right locations? This tests the blower motor and the high speed relay and the fuse for high speed. Turn the blower on next click down from high - does air come...
  10. 75gmck25

    Cooling Questions and Concerns

    If the temp is accurate, you don’t have any issues. Stock thermostat is a 195, and the engine temp may run a little above that. During a cool down cycle after a long highway run, or sitting in traffic it may spike to 210, which is also not a problem. Running at about 195-200 keeps your engine...
  11. 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...
  12. 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...
  13. 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...
  14. 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.
  15. 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.
  16. 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.
  17. 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...
  18. 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.
  19. 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...
  20. 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.
  21. 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.
  22. 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...
  23. 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...
  24. 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.
  25. 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...

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