More Complications..

[bbchevy]

I have an 86 K10 which im trying to build. im in the process of getting the motor to run right and stuff. the problem i have is that the motor will start but runs rough. i think its the timing. the distributor is lose and has moved. the motor is not original. how do i find out the year of it so i can time it. also, the column shift lever has no return to it. it just feels loose. how do i fix this. thanks alot guys!
-Scott

[72 CustomCamper]

I'd time the motor to the 86 specs...

[JonnyTechMech]

Mortec.com needs to be a reference link on your browser.

1) Check on the front of the engine block (usually under the alternator or AC compressor) for a bare flat protrusion in which there will be stamped number and letters. This will give you a suffix to in which to search on.
2) Have you checked the plugs, wires, cap and rotor for aging or damage?
3) Does the engine backfire when advancing the throttle?
4) Does it have a TBI or Carb?
5) Is the distributor a HEI or Points setup?

I’d mark the current position on the distributor with a bright chalk type pencil in a place that’s easy to access and observe. (The maker would have to be the type that leaves a thick residue, so it can be easily seen.) Mark in a straight line from the distributor base to the engine block. This way you can have a reference point and can always go back to a working point.

Then move the distributor (only one direction to start with) to the left or right (3-4 centimeters and start the engine and monitor any change in idle. Then move it a little more to see if it improves in behavior. (Best to move it while it’s running and while in drive if you can get some help to keep the brake on.) This way you are either advancing or decreasing the timing and checking if it improves in operation or gets a weaker idle.

Best to have a Timing Gun for something like this and know what type of engine you’re dealing with first, of course. It’s going to be really important that the components in my question above 2 and 4,5) are sound, to get a good judgment on the engine idle. All can affect the response.

JonnyTM

[piecesparts]

You know the cost of a timing light is minimal, pick up a decent one from Sears and set the timing on the motor at around 10 degrees before TDC and then work from there. I use a Sears timing light with the advance dial on it. I adjust my engines to where there is 35 degrees of total advance and there appears to be no problems. Most Chevy engines are timed the same, the use of a TBI and computer programmed distributor does affect the way it is timed. Most engines run good at 12 to 15 degrees advanced (initial timing) , but the computer will want the engine timed at the factory set point. If you are using a motor and an HEI distributor that is NOT from the 86 chevy, then you can adjust to get performance. The computer will not need the HEI to be adjusted for it.

[bbchevy]

the motor has an edelbrock what i think to be a 600cfm) and HEI. the cap, rotor, wires and plugs have been replaced.oh, and there is an edelbrock intake. so whoever put the intake on had to have taken the distributer out. i bought the truck not running. now it runs but backfires at idle and on advanced throttle it spudders, backfires, and hesitates . oh and its open header right now and some crazy flames come out when revving it up. does that help? because im really lost.

[piecesparts]

Take some time to align the timing mark with TDC ( 0 ) and look at the #1 cylinder (Take the plug out and rotate the motor as you approach the TDC mark put your finger over the plug hole---If the cylinder is on a compression stroke it will push air out of the plug hole (both valves closed --that is what you want). Once the TDC is found, look at where your distributor rotor is pointing. It should be aimed at the point on the cap where the #1 plug wire is. If it isn't then you will need to align the wires to that point. The next thing is to follow the firing order and make sure all wires are where they should be. Once that is done, you should be able to start the motor and get it to run (may have to rotate the distributor slightly to get it to start). Once running set the timing. The open headers don't help it either, this will make a cylinder run rich and cause it to not run right. The fact there is no resistance on the cylinders will evacuate the cylinders faster than they can fill with air. The guys that race will tune for this setup. My bet is that you have a couple wires crossed in your spark plugs. Check the plugs also, the fact that they have been replaced is not always acceptable that they will work right, one may be cracked and misfiring. The spark plug wires could have a bad one also, even though you have had them changed. If there is a cylinder not firing it will run colder than the other cylinders.

[1FaastC10]

set it at 8-10 degrees, and tinker with it from there, moving up or down 1-2 degrees at a time til its where you like it.