Cranks but does not start????

[Ghost]

I know there have been lots of threads about this but I'm swimming in new waters. I finally got enough of the details done to try and start the new old motor. 94 2.5L in my 84. She turns over but does not start. bucks some while turning over too. She has fuel in the rail I know that. And spark at the wire. On these fancy smancy engines where do I start? I really dont have the $$$ to throw at it so any advice or pointers would be appreciated.

[Eagle]

Didn't we just do this?

What you describe seems to be a common problem for people who build stroker motors. The usual problem is that the distributor isn't indexed correctly. The ignition generates spark, but the spark doesn't go off when the cylinder has gas and compression.

Double check to be sure the rotor points to #1 turret on the distrbutor cap when the #1 piston is at top dead center (TDC) on the compression stroke.

I don't mean to insult your intelligence, but it's amazing how many guys will actually build and install an engine without understanding how a 4-cycle engine functions. They have no clue that the engine goes around twice for every one revolution of the camshaft and distributor.

[Ghost]

I'm not sure exactly how to do that but I think I can figure it out. Get #1 to TDC then see if the Dist. is pointing to the #1 pole on the dist. I also forgot to mention that the map is hooked up to the intake but the rest of the vacume bungs are capped right now. Would that cause a not start condition?

[Eagle]

Originally posted by Ghost
I'm not sure exactly how to do that but I think I can figure it out. Get #1 to TDC then see if the Dist. is pointing to the #1 pole on the dist.

See, you're doing it, too.

A 4-cycle (4-stroke, not 4-cylinder) engine has each cylinder come up to TDC twice for each full cycle of the engine ... which is actually two revolutions. It comes up once on the compression stroke (which is when it wants/needs to fire), but it comes back to TDC again on the exhaust stroke ... at which time the exhaust valve is open, there is no fuel, and there is no compression.

So just getting #1 to TDC isn't enough. You have to confirm that it's at TDC on the compression stroke. You can do this by removing the spark plug while you crank, until you feel pressure pushing your finger off the hole, or you can remove the valve cover and look to see that both valves for #1 are seated. Make the final adjustment using a socket on the vibration damper bolt, and align the timing marks on the front timing cover with the mark on the harmonic balacer rim.

Then set the distributor to point at #1 terminal.

[Ghost]

Ok I think I can handle that. and actually my engine knowledge is very basic.

[Ghost]

Are they the hashes cut across the top of the Harmonic balancer? Or are they the holes drilled in the front of it? If its the Hash on the balancer then the timing is way off.

[Bender]

It's a small little slice on the top of the balancer. It will line up right below the timing degree markings.

It's not the holes in the front of the balancer.

[Eagle]

It's the single "hash" in the outer rim of the harmonic damper. That should be at the timing mark on the scale when the #1 piston is at TDC. Note that the harmonic damper is attached to the crankshaft, so the hash will align twice for each complete cycle of the engine -- the hash will align with the timing mark when #1 is at TDC on the compression stroke, and again when #1 is at TDC on the exhaust stroke.

Don't use the hash to determine which stroke you are on. Do that by pulling a plug and feeling for compression, or by removing the valve cover and watching the vales for #1 cylinder. Once you know you are near TDC on the compression stroke, use the hash mark to make the final adjustment to TDC (align the hash mark with the zero mark on the timing scale).

[Ghost]

Turned it over and blew finger off #1. Put timming hash at 0deg. Pull cap and loosen dist. bolt and rotated to where It looked close. Did this twice. Got it to run a little but only if I put my foot on the acc. pedal. So am I looking at a Fuel issue or timing?

[Eagle]

Considering the problems caused by distributor indexing, I don't think "looks close" is close enough. There's an old saying that "Close only counts in horseshoes and hand grenades."

For the 6-cyl engines, with the timing mark aligned as you have it the tip of the rotor is supposed to be just beyond the contact in the distributor cap, with an air gap of 0.020". That's how sensitive the setting is. I don't know if that same 0.020" gap is optimum for the 4-cyl, but it's a starting point.

There was an old tech bulletin explaining how to set this for the 4.0L. You take a "sacrificial" distributor cap and grind/cut away the side around the #1 contact turret. This gives you access for a feeler gauge. Install that cap with the rotor in place, and adjust the distributor until you get that gap. Remember, the rotor tirns clockwise, and you want the tip to be beyond the contact in the cap, so the gap is at the trailing edge of the rotor.

[Ghost]

Or would I be better off sacrificing my cap and getting a new one?

[billbobagns]

Eagle mentions a tech detale on aligning my distributor. Can anyone reproduc that bulieton?

I suspect I could do the following;

1) determin the least "advance" the motor will ever operate with (0 TDC)
2) determin the max "advance" the motor will ever need (25 TDC ? 30?)
3) devide by two and set the timing mark to this "center" measurment
4) adjust the distributor to point exactly at the turit at this point.

Does anyone have a better proceedure than this?

Bill Johnson