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  1. 75gmck25

    Wire terminal ID

    See if you can match it to one that these guys sell. https://www.eficonnection.com/home/category/harnesses-and-connectors/automotive-connectors/terminals-and-pins
  2. 75gmck25

    Nasty gas tank

    On Roadkill TV show they always put at least two of the large diameter metal-body fuel filters inline before the fuel pump when they pull a junked car out of the yard. If the engine starts to starve for fuel they remove the filter closest to the tank and replace it with a section of hose. If it...
  3. 75gmck25

    1981 C30 cluster issue

    Did you make sure you connected the cluster ground? It’s usually a black wire connected to a post on the emergency brake mechanism, or on newer trucks they added a ground bar up under the dash.
  4. 75gmck25

    74 C20 Ammeter

    The stock ammeter uses the resistance of the wiring harness as a shunt. There are two fuses under the hood where it connects to the wiring harness. This is good from a safety standpoint, since high amperage does not go through wiring up to the dash. However, as the wiring gets old it’s...
  5. 75gmck25

    Rear end

    It is possible that your truck has 4.56 gears, since it’s a one ton. Changing from 16” to 17” rims is not the key measurement. You need to look at tire height, not rim size. In most cases a 33” tire will fit with no mods (originals tires were about 31”), and 35” will fit with only a 2” lift...
  6. 75gmck25

    Steering Gear

    I used the Borgeson on my ‘75 GMC, and it seems to be well made. Haven’t had it that long, but it seems to track really well on the highway. Shaft is relatively easy to install, but with splines on both ends you have to measure to make sure your steering box and steering wheel are centered on...
  7. 75gmck25

    OEM Breather replacement

    Trivia for you - did you know that most of the Edelbrock air cleaners will also not fit on an Edelbrock 1406 carburetor unless you use a spacer? The stock 1406 fuel fitting and choke are too high and they hit the bottom of the air cleaner. You need either a spacer, and/or the fuel line with...
  8. 75gmck25

    OEM Breather replacement

    If you go to a GM-related classic car show there will be vendors with various air cleaners to fit the Quadrajet. Some are even dual a snorkel design that allow you to use both cold air intakes in your truck (there should be a 2nd hole in the support on the driver’s side, but it is only used for...
  9. 75gmck25

    Tires for Stock Rims '79 K20

    Also check the GVW of your truck, and if it’s the high GVW (8400 or 8600 lb) decide if you want to buy the correct E load rating tires. Standard light truck tires will fit the wheels, but they are load rated for 1/2 tons and some 3/4 tons. It just depends on how you plan to use the truck...
  10. 75gmck25

    327 vs 350 for a daily driver

    The best starting point for a simple swap is a crate 350 with Vortec heads (or similar aftermarket aluminum). and a roller cam. It will have better compression, better flowing heads, and the roller cam setup will be much more reliable overall. Very easy 325-350 horsepower with a mid range...
  11. 75gmck25

    C20 Camper Special 454 Engine Starter Wiring

    If it’s like mine, the gunk will not come off. It’s like the steering wheel plastic is oozing out some type of goo and making it sticky. I added a lace-on steering wheel cover so I wouldn’t get the goo on my hands, and have ignored the spokes and horn button. Cleaning did not seem to help.
  12. 75gmck25

    Help me solve a cooling issue. Pic's inside.

    For my ‘75 350 I used a Stewart Stage One water pump (iron body, higher flow than stock) and a Stewart high flow 195 degree thermostat. Thermostat has about a 1/8” hole in it, with a poppet in the middle that provides a little flow even if the thermostat is closed. My heater hoses come from...
  13. 75gmck25

    Vintage Air Gen V (5) or replace existing compressor, etc., for 1987 R20 Suburban?

    Anyone know how much that HD6 weighs, compared to the old boat anchor A6? The brackets for my original A6 were thick iron, It was bolted down in two places to the intake, and had at least two supports that used the exhaust manifold bolts. One of the exhaust brackets also supported the PS...
  14. 75gmck25

    No power at temp gauge

    Did you use Teflon tape on the sending unit threads? That can prevent getting a good ground to the head. Check resistance between the sending unit body and the engine and it should be zero.
  15. 75gmck25

    Fuel spitting out spark plug hole?!?

    If you have a problem with a rocker or pushrod on that cylinder, fuel may be accumulating and not getting burned. It’s amazing how smooth a stock 350 can be even when one cylinder is not contributing. If you have the time, I would pull that valve cover, leave the fuel pump off, and watch the...
  16. 75gmck25

    Cruise control inop

    The diagram for my '75 is not really clear, but seems to show the regulator mounted very close to the place where the throttle cable goes through your bracket. The regulator must be able to measure speed. It should have one speedometer cable running from transmission to regulator, then a 2nd...
  17. 75gmck25

    R12 Replacement

    Alternative refrigerants can be made to work effectively, but now you have a system that nobody else can work on. You are forever your own A/C repair guy because local commercial stores and shops will only have R134, or maybe a machine that works with R12. Just think of how much fun you have...
  18. 75gmck25

    AC noise under throttle

    The A/C controls run off engine vacuum, and the vacuum reservoir under the hood should keep the controls vacuum relatively constant. Maybe your vacuum reservoir is not keeping up (leading?) and maintaining vacuum, and the controls cannot hold the vacuum pods in position. This would cause the...
  19. 75gmck25

    What is this hole for?

    The metal bracket behind that hole is attached to the HVAC duct that goes to the driver's side vent. In the LMC catalog it is the Vent-Assembly - LH, part number 38-5250, but the metal bracket is only implied (not really visible) by the nut and screw.
  20. 75gmck25

    Fluid Changes

    Simplest choice is to use 5 quarts of 10w30 full synthetic for an SBC. Even 10w30 Dino oil will work fine, but it will need to be changed more often. Cheapest source is usually the 5 quart jugs at Walmart. Since you probably have a flat tappet cam, it really should have added ZDDP in the oil...
  21. 75gmck25

    Ferd for my Granddaughter

    Quadrajet was not used on the 428 Cobrajet. I had a 1969 Torino/Fairlane Cobra with a 428 Cobrajet and it definitely had a Holley carburetor (weird size, 730 CFM, IIRC). I got mine in '71, and I know the previous owner. It always had a Holley, and I have never seen an article that mentioned...
  22. 75gmck25

    What locker shall I go for?

    Some of the choices are "lockers", while others are termed a "limited slip differential". Limited slip often has internal clutches, or some other mechanism that makes the locking come in more gradually. It sounds like a selectable locker might be your best choice, but they are usually...
  23. 75gmck25

    Edelbrock accelerator pump

    If you get a piston stop, and then find the balancer is one that puts TDC at the 2:00 position, use an aftermarket timing pointer that attaches to two of the timing cover bolts.
  24. 75gmck25

    Door Jamb switch housing

    I think Rivnuts or Nutserts would also work, as long as you find one with the right threads. You might have to drill out the hole a little for clearance, but then you do the installation from the front. The tool threads through and into the back threaded half of the Nutsert, and then you...
  25. 75gmck25

    Door Jamb switch housing

    My door frame has a hole with threads and it had very rusty factory door switches. I tried using the LMC switches on my K25 and they were too small to thread in correctly. I then bought some Dorman switches and found they were the right diameter. However, they screwed in so far that they...

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