73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: swilliams on September 21, 2014, 12:18:19 pm
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I have a 1986 C10 that i have done a head change on. I have got the timing set around 12deg BTDC. I am getting fuel at the carb and spark to the plugs I checked the #1 and #2 for fire #1 got a good blue spark with a new plug #2 more yellow orange with an old plug. I have a good ground strap from frame to head where it was before the swap. It doesn't even act like it wants to start. I have no idea unless the timing is some how off. I have been told that if the timing is 20deg off the engine will not start. Any ideas???
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Sounds out of time or like carb problems. How do you know what the timing is set at if it's not running and hooking up a timing light?
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Remove the #1 spark plug and bump the engine to TDC compression. Align the timing marks to 0°. Is the distributor rotor pointing at the #1 plug wire?
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I have the balancer mark at 12deg before 0 and the rotor is pointing at #1.
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Just checked compression on #! and it has more compression than my cheapo tester can measure
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I'm trying to verify that the distributor isn't 180° out. So, the rotor is pointing to the #1 distributor terminal when the # 1 cylinder is 12° BTDC compression?
Spray a little starting fluid down the carburetor while cranking. Does it start or try to?
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I have pulled the plug and put a straw in the hole and the piston is right there. I am out of starting fluid so i have been using gas with no results. I read that the starter may not be turning engine fast enough so i just now went and put the charger on it turned it to 35 amps turned the engine over and got 1 backfire(the loudest i have ever heard neighbors came out and everything). Now nothing again. Very confused.
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the backfire makes it sound like a timing issue HOWEVER I just went through the same thing with my 74, thought i was getting fuel cause it would squirt out the accelerator pump jet when i gave it gas but the problem with mine ended up being that the fuel pump was bad pushing less than 1 psi, enough to get a little gas to the carb but not enough to even try to start. $18 fuel pump and it fired right up. I would verify timing is correct, then buy a cheapo fuel pressure guage and verify youre getting fuel.
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I think bd has it. The distributor is probably 180 degrees out.
You should know that there are two TDC positions in the engine cycle: intake stroke, BDC #1, compression stroke, TDC #1, power stroke, BDC #2, exhaust stroke, TDC #2. You want the spark firing on TDC #1 in this sequence. I think it is at TDC #2, which will give you no no running and the occasional kaboom backfire through the carb.
On the TDC #1, compression stroke, the engine will push your thumb off the spark plug hole when cranking; on TDC #2 it won't. Another way to check is to remove the valve cover: at TDC #1, both valves will be closed, and at TDC #2, they will both be partway open.
The solution is to remove the distributor cap, mark where the back of the rotor is, pull the distributor up a couple inches, rotate the rotor 180 degrees, and set it back down. The oil pump pawl will reseat as it is because it is slotted like a screw head. The rotor will rotate some as you pull the distributor out due to the helical gears, and it will rotate back the same amount when you drop the distributor back in. That's OK as long as the front of the rotor ends up on the mark you made for where the back of it is.
Just had one of these on another forum. It's easy to do.
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I have pulled the plug and put a straw in the hole and the piston is right there. I am out of starting fluid so i have been using gas with no results. I read that the starter may not be turning engine fast enough so i just now went and put the charger on it turned it to 35 amps turned the engine over and got 1 backfire(the loudest i have ever heard neighbors came out and everything). Now nothing again. Very confused.
Use your compression gauge or press your thumb over the #1 spark plug hole and bump the engine over until you see/feel compression building in the #1 cylinder. Then align the timing marks and see where the rotor is pointing.
Here's why: The #1 piston is at TDC twice for each distributor revolution. In other words, the piston comes to TDC two times for every one time the rotor points toward the #1 plug wire.
It sounds like the distributor is 180° out of time.
If you determine the distributor is properly stabbed, then remove and dry the spark plugs before continuing. Be methodical and eliminate ignition timing as the cause before jumping to something else.
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Yeah, betcha if you find TDC under compression, when you open the distributor the rotor will be pointing at #6.
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Ok i have checked for the compression stroke on #1 then use wrench to finish turning to 12BTDC and rotor is pointing at #1. I wonder if i should take the rotor off and turn it around to #6 just to see?
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...If you determine the distributor is properly stabbed, then remove and dry the spark plugs before continuing....
Once you've done this ^^^^^, try the starter fluid trick.
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The outer ring on the harmonic balancer has been known to slip. This will throw off the timing mark. Prior to doing the heads, when was the last time you had a timing light on it? There is also a chance that the timing chain jumped a few teeth.
As others have said, pull the #1 plug and place your finger over the hole. Have someone bump the motor over until your finger feels the compression (it may take a few tries to get the feel of it). Now pull the dist cap and verify that the rotor is pointing to the #1 plug wire
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I had a timing light on it recently. It may be a degree or 2 off but nothing significant. I went ahead and pulled the dist and turned it 180 and have the same results (no start).
The only results i have had was the backfire when i had the 32 amp battery charger hooked up.
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Hope the link works. It is to show that i am getting good spark.
goodspark.shutterfly.com/videos (http://goodspark.shutterfly.com/videos)
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once again....if you have verified that you dropped the distributor in and timed correctly, check your fuel pressure. just because a little squirts out doesnt mean youve got enough.
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That is true but with starting fluid i should at least get a small resopnse.
I am going to get a guage also.
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When we swapped over to TBI. We couldn't get the dizzy in right
We wound up taking an old distributor cap and using a dremel cut the center out so we could actually SEE where the rotor was pointing
That made it easy
Buy a new cap and cut a hole in the top of your old one
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That will help I have an old one to use thanks
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It was the only thing that would work for us
You think the rotor is pointed a certain way but it's usually off a little. Or a lot
I just used a dremel with a cutoff wheel and zipped out the entire center of the cap
Set the crank pulley to zero degrees
And stab the dizzy in
It doesn't matter which electrode the rotor is pointing at
As long as you use that electrode as number one
You can also stab it in 180* off
No way to know since the crank rotates twice as much as the cam
When setting the timing. I use a vacuum gauge
When the engine is warm and idling move the dizzy around until you get the highest vacuum
And then set it by ear doing test drives if it's a manual or bY power braking if its an automatic
Just stand on the brakes and put a load on the engine while an assistant slowly advances the dizzy till it knocks then back off a little
If its a manual find a hill where you can floor it in second gear lugging the engine a little
Keep advancing the timing till it pings when you lug It under full throttle
I don't pay any attn to the actual numbers
I have a 90 mustang engine EFI in my 73 Bronco
It runs good with 32* advance
About double what it's supposed to be
But that's where it runs best
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FInally sucess!! I took a few day(had to work anyway) started back in today and finally hot it to fire and start. Still needs tuning but i have a TINK noise randemly whyle ideling have not tried to rev it up. Is this just lifters that need adjusting or is it the ping of it being out of time? I went through at install and checked all 16 and have them at 1 turn past 0 lash. How would i go about readjusting them? Thanks for all the help getting it started.
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Why don't you explain how you adjusted the valves to us....
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I would spin the rods between my fingers untill i had slight resistance and no lifter to rocker arm play then tighten the nut 1 complete turn then lock down set screw. Since the original post i have gone back and added another 1/4 turn and backed timing to 8 or 9 deg BTDC. It has helped but it seems like i still have lifter tick or headers are leaking.
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What you are describing is probably what we used to call "header slap". Headers are thin walled compared to heavy cast-iron manifolds. You are actually hearing exhaust pulses hitting the header tubes. The Hooker 2453, for example, has tubes 3 and 4 bending back at right angles along the engine. Google "header noise" and you will see you are not alone.
Anyway, some headers do it, some don't, and it also depends on the cam and the heads. Fast-ramp cams and high-flow heads are more prone to it.
I hadn't heard headers up close and personal in decades, and I thought it was a header leak, but my speed shop guys reminded me that that's just the way some headers sound. They checked for a leak anyway, and for lifter issues, but all was good.
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You need to adjust the valves while the lifter is sitting on the base circle of the cam.
There is a sequence where you can adjust a few of the valves while the engine is on #1 firing, then rotate to #6 firing and adjust the remaining valves.
One other method is to adjust only #1 on #1 firing then rotate the crankshaft 90° adjust #8, then crank 90° then #4, and continue in the firing order until all 8 are adjusted.
When you tested for compression did you check all 8? Or just 1. If you have compression on all 8 then I would suspect the valve adjustment is not your issue.
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Just like Rich said, header tick. It can be confusing until you realize what it is. I have high flow heads, headers and dual exhuast. I noticed that after I used header wrap on the pipes under the cab it has quieted down a lot and with cooling fans running it's not super loud. Between my exhuast, sound of engine running, fans and the stereo jacked up haha I rarely hear it now, even when I'm starring right at the headers.
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Thanks for that. Knowing its not just me and mine makes me feel better.
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You need to adjust the valves while the lifter is sitting on the base circle of the cam.
This....
So are you saying you just randomly adjusted them and not in the proper sequence? You'll be bending push rods and burning valves in no time if you haven't already.
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No I went through and just after the intake valve closed on each cylinder where there was no pressure on each valve then adjusted
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Ha ha my headers ting with the 12-235-2 cam
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glad you got her figured out. ;)