Search results

  1. 75gmck25

    No Defrost

    You can use a hand vacuum pump to pull vacuum on the actuator and see if it works. If it still works, then it’s probably the lines to the controls. Do the rest of the actuators work when you change hvac positions. For example, if you put it in max a/c you should see the flap open in the...
  2. 75gmck25

    Belt squeal (while accelerating)/alternator question

    I have used the same 15445 Belt with a 12si on my ‘75 350 for many years. The only time I get a short belt squeal is if the battery is low (left lights on, etc.) and I rev the engine up quickly. I assume the alternator starts to charge more to recover the battery and the belt slips a little.
  3. 75gmck25

    2.5” exhaust kit for 85 suburban?

    If you have a relatively stock vintage 454, slightly smaller exhaust will not make much difference. Just make sure you get good flowing mufflers and an H or X pipe so you make the best out of 2 1/4” exhaust. There are flow limits in the older heads, limits to stock iron intakes, low...
  4. 75gmck25

    2.5” exhaust kit for 85 suburban?

    There are many 2 1/4” kits, so they are reasonably priced and easy to find. There is only one off the shelf 2 1/2” kit for 2WD vehicles that I’ve seen, and I think the brand was Pypes. It was at least double the price of the 2 1/4” kits, but it was also higher quality tubing. How deep are...
  5. 75gmck25

    Fitech efi on 350 question

    The FiTech “wet manifold” design is similar to many other aftermarket EFI systems. Individual port injection is better overall, but there is nothing wrong with throttle body injection. The newer systems are usually self-tuning up to a point, and then allow individual adjustments to improve...
  6. 75gmck25

    Taller tires for my 1976 K20

    Was there ever an OEM “lighter” version of the 8 lug steel wheels? All major manufacturers used the same 8 lug pattern for a while, and I assumed it was only on 3/4 ton and higher GVW. Aftermarket did offer some 8 lug alloys, but I don’t know much about them.
  7. 75gmck25

    Fusible Link?

    I used a TS-6 sending unit on my ‘75 and it is a pretty close match to proper temperature reading. The correct ‘75 vintage GM sending unit is only available as NOS, so it’s usually expensive. My gauge has no numbers, but fully warmed up to about 185 degrees it shows between 3/8 and 1/2 with the...
  8. 75gmck25

    new to me 75 turn signal issue hlp

    When I replaced the turn signal switch on my ‘75 the switch they gave me did not plug into my wiring correctly. The spacing of the flat plug’s terminals was a little off. I ended up using crimp connectors to put the old plug on the new switch and it worked fine.
  9. 75gmck25

    Fuel Tank Replacement

    For an ‘86 you probably need a 3 port sending unit (feed from pump, return to pump, and vent). Get the right one now so you can set the truck up correctly with a fuel return line (prevents vapor lock and other hot weather issues), and venting.
  10. 75gmck25

    Another Question!!

    The easiest choice for a simple install with original brackets is the 94 amp 12si alternator. It bolts on just like the original (which may have been a 10si). Alternators have Lester exchange numbers on them to make it easier to figure out which one you have (since the cases are very...
  11. 75gmck25

    Dual tank wiring

    How long since that passenger tank has been used routinely? The sending unit resistance sweep is a very simple mechanism, with a piece of copper bar/wire that sweeps up and down another piece of metal with varying resistance. When there is no gas in the tank most of the metal sweep...
  12. 75gmck25

    Charcoal / vapor / evap canister, how it should be set up and other information

    Sounds like a good alternative to try. My engine runs about 19-20" of vacuum at idle (fairly mild cam), so it will definitely have enough vacuum to signal and close the purge line at idle. I don't have a vacuum gauge inside the truck, so I'm not sure what the vacuum is at cruise. I run my...
  13. 75gmck25

    Charcoal / vapor / evap canister, how it should be set up and other information

    For Sir RobynO - my ‘75 K25 still has the original two port canister, and with the original Quadrajet there was a dedicated port for the canister vent line. When I switched to a newer carburetor I first just put a T in the PCV line to the carburetor and connected the canister vent there, but...
  14. 75gmck25

    Taller tires for my 1976 K20

    My ‘75 K25 Camper Special came originally with 9.50x16.5 tires and split rims. When I switched to 16” tires I went to the pick and pull and found a newer GM squarebody (IIRC it was a 3+3 one ton) with 16” 8 lug rims and tubeless tires, and bought the set for $25 each. Then I bought new...
  15. 75gmck25

    distributor removal

    You can use a marker on the edge of the distributor housing to mark exactly where the rotor points after you remove the cap. Then line up the same mark when you reinstall. This will put it back on the same timing when you reinstall and clamp down the distributor.
  16. 75gmck25

    edelbrock avs2 650

    When you do a cold start there is no fuel in the intake manifold, and if it’s been sitting for several days there may be no fuel (or very little) in the float bowl). It needs some fuel to get going. Cold - My procedure is to first pump the throttle 2-3 times and then crank the ignition with my...
  17. 75gmck25

    Qjet to Edelbrock 1400 vacuum line puzzle- I need help

    It looks like your Quadrajet must be set up like my original ‘75 carburetor, where there is a dedicated port for the vacuum canister. When I swapped to a 1980+ Quadrajet it did not have that port. I have not been able to find an original vacuum diagram for my ‘75 350 with HD emissions. I’ve...
  18. 75gmck25

    Instrument gauge problem, can’t find much info

    My best guess is you have a hot wire grounded somewhere, but instead of blowing a fuse it is providing a ground path for gauges and other devices. My suggestions is to take a picture of the fuse block so you know exactly where each fuse is. Then pull all the fuses out, turn on the ignition...
  19. 75gmck25

    K20 vs. K30 Difference

    My ‘75 Camper Special with 8400 lb GVW has the Camper Special option listed on the label inside the glove box door, but it also has a metal plate with loading information (max rear axle load, etc.) riveted on the inside of the drivers side door frame. Does your truck have any similar data plate?
  20. 75gmck25

    A/C Control Panel

    The only cable operated control is for the blend door that controls the amount of heat or cooling. All the vacuum motors are controlled by the other slider, and that is how you get the “heat” position.
  21. 75gmck25

    Thermostat

    Several year ago I started using the Stewart high flow 195 degree thermostat, and they have worked really well. However, it’s hard to believe how much the price has gone up the last few years.
  22. 75gmck25

    Thermostat

    195 is the best overall. Engines run more efficiently and last longer when they get up to temperature in the 195-200 degree range. Using a lower temp thermostat will not cure overheating or other cooling system issues.
  23. 75gmck25

    Single tank to dual tank FIX!

    A ‘76 dual tank setup is relatively simple, but you just have to follow the wiring diagram and not try to reengineer it too much. First get the right fuel valve If you have a fuel pump with a return line, you need the six port switching valve. The 3 port valve is used if you do not have a...
  24. 75gmck25

    Black Fuse-like Electrical Connector?

    In the early squarebody trucks they used the wiring in the truck as a shunt with a known resistance, and an in-dash ammeter to “calculate” amperage. That avoided the risk of running full alternator amperage up to the dash and back to the engine compartment. The dash gauge has the voltage at...
  25. 75gmck25

    Exhaust pipe bracket

    I have a similar bracket setup at the front of my mufflers but used HD angle iron with pre-punched holes. It’s not that attractive, but it works.

Latest posts

Forum statistics

Threads
44,391
Posts
956,269
Members
36,681
Latest member
91k5user
Top