Search results

  1. 75gmck25

    LED headlight upgrade

    It also helps quite a bit to install a headlight relay kit that provides direct battery power to the headlights. It’s a simple plug and play harness and two relays, and the headlight brightness no longer depends on the old wiring running to your headlight switch. The kit I got from LMC had a...
  2. 75gmck25

    GM Delco CB Radio

    Just connect a CB antenna. CB needs a good antenna that matches the frequencies, but an AM/FM radio is so simple that it could get by with an antenna made of just about any wire you found around the garage.
  3. 75gmck25

    Better illumination of gauge cluster possible?

    I wasn’t sure the #168 bulbs would help that much. I decided to repaint the metal back of the cluster white, and then ordered new dimmable led bulbs from an online store (Super-bright LEDs, IIRC). They are dimmable, but not exactly like an incandescent. They dim to about 1/2 brightness, and...
  4. 75gmck25

    Steering Box Screw

    If you read the GM shop manual, it is definitely an adjustment point. However, there is at least one other adjustment you do before you touch that allen screw. It’s all explained in the repair manual. And when you adjust the Allen screw the steering box should be disconnected from the...
  5. 75gmck25

    Steering Box Screw

    It should have an Allen wrench fitting in the middle, and a locknut around the outside. You put the Allen wrench in to hold the adjuster, and then loosen the outer locknut. If you want to take a little play out of the steering you would turn the center adjuster portion clockwise a very...
  6. 75gmck25

    1977 C20 hd emissions vacuum lines

    GM didn’t put the emissions diagram and other info on the core support until sometime in the late 70’s. AFAIK, for my ‘75 the diagram was on the side of the air cleaner, and it’s long gone.
  7. 75gmck25

    Deleting emissions,read this article.

    Rules for compliance also differ for each state. My ‘75 GMC is 8400 lbs GVW, so it’s original HD emissions equipment was minimal , and it never had cats. It now has antique plates, but I considered getting full inspections and regular plates like I used to have. The guy at the inspecting...
  8. 75gmck25

    Auxiliary trans oil cooler

    If you buy a separate external cooler, look for a stacked plate design, not a serpentine tube if you want best cooling. Long Mfg Low Pressure Drop (LPD) and the B&M coolers use stacked plates, and I’m sure there are others.
  9. 75gmck25

    1977 C20 hd emissions vacuum lines

    I have a similar carburetor on my truck right now - a 17080213, so maybe you will find these pictures useful. - I use full manifold vacuum for the distributor, but you could use ported instead. Whichever you use, the other small port must be plugged. - The large threaded port on the back is...
  10. 75gmck25

    CNC machined emblems

    Great looking emblems! What CAD program did your student use? If you use something like SolidWorks, the initial file created is usually a common file type that many different machines can use. It’s translated by the machine software to a set of commands for the specific machine. With a...
  11. 75gmck25

    1980 C10 backfires through carb under load

    Also buy a spring kit for the carburetor and try swapping to higher rated springs. Stock step-up springs on a 1406 are 5”, so the carburetor goes from cruise to power mode when engine vacuum drops to 5”. The kit will also have 6”, 7” and 8” springs. For example, when you use a 7” spring it...
  12. 75gmck25

    Anyone use edelbrock universal EFI fuel sump Kit w 2 tanks

    I have looked at using an EFI sump for my dual tanks, and the only question I have is how to handle the fuel return lines. I already have return lines on my mechanical fuel pump, and a six port solenoid that switches them. It would still work as designed for the mechanical pump. If the...
  13. 75gmck25

    fuel tank swap

    The tanks all interchange (although 87+ are supposed to have internal baffles for EFI), but sending units and filler pipes differ from year to year. It would require some body work to add a filler door, so you might want to look for the fillers from an older truck. I’d get a bunch of...
  14. 75gmck25

    Dead battery

    When you find dual batteries in a gasoline squarebody, it’s because they have the camper special package, maybe trailer towing package, or have added a plow or winch. The main battery and the aux battery then have totally different uses, so they are seldom identical.
  15. 75gmck25

    Replacement Option Code Glove Box Label for my 86 GMC High Sierra

    For an ‘86 you might be able get original build info from the GM heritage center. Based on that info, and looking at some other examples of ‘86 glove box labels, you could fabricate one for your truck.
  16. 75gmck25

    Nasty parasitic draw from plow

    I’ve never measured voltage, but I know there are solenoids that are specifically rated for continuous duty, and some are not. For example, the common Ford external starter solenoid works fine for a starter (short engagement) , but will not last if used for something like switching a dual...
  17. 75gmck25

    Need advice on Tuning a Quad

    You can buy a piston stop from summit, or make your own from an old spark plug. General process ( from memory) for finding TDC is: - Remove plugs and turn the engine over until you are a little short of where you think TDC is. Check rotor to make sure you are on #1, not #6. - screw piston stop...
  18. 75gmck25

    Need advice on Tuning a Quad

    Every engine is different, but a common guideline is that base plus mechanical should not exceed about 34-36 degrees for a mild build, usually measured at about 3000 rpm. However, this is just a guideline. It’s common for mechanical advance mechanisms to add about 20 degrees, so 12 degrees base...
  19. 75gmck25

    Under dash air box hvac.

    That actuator on the back is hard to reach with your hand, and IIRC, the plenum has to come out to remove it. However, you should be able to reach the lines after you remove the glove compartment and the vertical plastic plenum piece behind it. I also think that on my truck it’s the one...
  20. 75gmck25

    1986 Engine Wiring Question

    I don’t mind reading the diagrams. However, unless I understand what the functions are for each component, it hard to know what to disconnect or bypass. For example, if the AIR pump has been removed, what is the AIR module trying to do with the feed to distributor?
  21. 75gmck25

    Disappearing coolant

    Also check the bolts for the intake manifold . I used the bolts from my iron intake on a new aluminum intake, and never noticed that at least one bolt bottomed in out in the hole before the intake was tight. It was leaking slightly in the back passenger side corner between the intake and the...
  22. 75gmck25

    Broken hearted kid and fuel system

    Please start a new thread with your question . This one is already 7 pages long.
  23. 75gmck25

    Need advice on Tuning a Quad

    Good point about every engine being different. My aluminum heads seem to tolerate my timing setup on regular gas with no issues, but I also know that my compression ratio is probably no more than 9.2-9.4. I believe my GM 350 crate with 74 cc smog heads probably had only 8-8.2 compression when...
  24. 75gmck25

    Need advice on Tuning a Quad

    I also rebuilt and tuned my Quadrajet with a kit from Cliff Ruggles. Mine shows similar AFR readings as yours, and it seems to run fine. Not sure why it goes so lean at cruise. I’ll have to disagree on 4 degrees being enough base timing. 4 degrees made my engine really lethargic. When I had...
  25. 75gmck25

    Defroster not working

    In my experience, that 3/16” rubber line works well for splicing the old hard line. It pulling vacuum, so it doesn’t take a lot to seal if the fit is tight.

Latest posts

Forum statistics

Threads
44,391
Posts
956,269
Members
36,680
Latest member
4x4rick
Top