75 GMC 6000 truck - timing adjustment

[grain trucker]

This truck has 366 v8 engine. I have a timing lite but don't know how to use it.
I just replaced the points and condensor and now think the timing should be adjusted as it doesn't start easily.
Can anyone help with this?

Also if anyone had a wiring diagram for this truck, I sure could use it.

[maxwedge]

Welcome to AF, you do not know how to use a timing lite? Literally? A basic tune up book is suggested here, especially for the point dwell checks dist advance checks, carb settings and basic timing, all are specific to a given engine.

[grain trucker]

Ok, I've never adjust the timing before. So I guess you're saying go and read a book. I guess i was just looking for some online help.

[2000CAYukon]

http://www.hotrodder.com/kwkride/timing.html

[Chloe501]

you don't have to read the whole book, just the section on timing. it's got pictures which help tremendously and only a couple of paragraphs explaining the proceedure.

[sector95]

Before you begin this, the engine needs to be at normal operating tempurature. You need to make sure the points are set correctly using a dwell meter, the idle mixture is up to snuff and that the curb idle is set correctly. You'll need a socket with an extension to loosen/tighten the distributor clamp bolt (located down at the base of the distributor in the valley between the cylinder banks). You'll need to have a golf tee or something to plug the vacuum line going to the vacuum advance canister. Most importantly you'll need to get the timing specs for your engine.

Timing lights...okay, can you tell what kind you have? Not the name brand but how the little beastie is hooked up. The more modern lights have an induction hookup...it'll have one lead with what looks like a squarish clamp with a little square hole in the middle of it...that would be your pickup lead. It should also have a connection to the vehicles battery (a lead with red and black clamps). Hook up is easy: take the square clamp (the induction lead), open it up by squeezing the "jaws" and place the #1 cylinder spark plug wire (the right front plug lead as you face the engine...if memory serves correct) into the square hole of the clamp and release the jaws. The #1 plug wire should now be trapped inside the induction lead and the clamp should slide freely along the plug wire. Connect the power leads to their respective poles on the battery (red to "+" and black to "-"). Look down on the crank pulley and find the timing plate...it'll have numbers stamped into it and you'll need to clean it so you can read it. It will have a "zero" indication (or Top Dead Center/TDC) and numbers above and below it (representing degrees before or after TDC. Check the timing specs and look for the correct degree marking on the plate....use a little "White Out" typewriter correction fluid to mark the degree setting on the plate. You'll need to pull the vacuum line off the advance canister on the side of the distributor and plug it with a golf tee or pencil.*MAKE SURE ALL THE LEADS FROM THE TIMING LIGHT ARE CLEAR OF THE FAN AND BELTS BEFORE YOU START THE EINGINE*.

Start the engine, grab the light and aim it at the timing plate while pulling the trigger. You should see a strobe effect on the timing plate and see the timing index on the crank pulley aligning itself with one of the index marks on the plate. If the crank index lines up with your correctly marked degree setting, then you're all set. If things aren't quite right, you'll need to shut down the engine and loosen the distributor clamp bolt just enough so you can rotate the distributor back and forth. Fire up the engine and while aiming at the timing plate with one hand use the other to rotate the distributor to move the crank index so it lines up with the marked setting. Once the timing is set, retighten the distributor clamp while watching the timing mark to make sure it doesn't drift. Now, to check your mechanical/centrifugal advance, shine the light on the timing plate and rev the engine slightly...you should see the crank pully index mark move up the "advance" or BTDC (Before Top Dead Center) side of the plate and return to your initial timing setting as the engine winds down. Reconnect the vacuum advance hose and you should see the timing advance slightly....if not, your vacuum advance canister might have a leak in it. If all checks okay, you're done!

Shut down the engine, pull the timing light and remove the wrench from the distributor...make sure you've cleared the engine compartment of tools and that all connections are good.

Check eBay or do a Google search for factory service manuals for your truck...you should be able to score one for some easy money.

Good luck and have some fun....


Mike
'98Sierra

[grain trucker]

OK this sounds like some good information. I first need to find the manufacturer's specs for timing on that truck.......thanks for pointing me in the right direction as I think I see some manuals on ebay that might help me.

[grain trucker]

Thanks for this information. I'm on ebay trying to find a service manual with the specs for that truck as I guess I need to start there.