68 mgb won't fire

I put my 68 engine in my 72 because the clutch went out on the 72 and I couldn't afford to keep both cars running so I was parting out my 68. Everything went fine but now when I try to start it it won't fire. I've replaced points, condensor, rotor, plugs. I've been trying to set the static timing but I can't seem to figure out why it won't start. I try to find TDC and place the number one plug in the corresponding location on the distributor but can't get it to fire. Sometimes it sounds like it want to but once I let go of the key it stops. :banghead: Any suggestions would be greatly appreciated.

Have you made sure you are getting spark to the spark plugs while cranking?
Many of the old point systems have a power to coil by-pass while cranking
circut to give full voltage to the coil and then switches back to a resistor
once started and the key is released.
If this system is not working correctly,you may not have power to ignition
while cranking.

I do have spark to the plugs. I laid a plug on the engine and turned it over and saw spark on the electrode of the plug.

make sure your point gap is close.
Turn the eng. to TDC #1,make sure its on compression stroke!
Make sure the firing order is correct.Take the #1 plug wire,hook it to a spark
plug and lay it on a good engine ground.Next loosen the distributor, and turn on the ignition switch.Now slowly turn the dist.in either direction until you get
the plug to spark.Once this happens, you should be able to twist it back and
forth, sparking the grounded plug.The timing should now be close enough to
start the engine.

Just so I know; once the intake valve closes, the next time the piston comes up is the compression stroke right?

Ok, I've got the engine running and idles nice. However, when I took it out for a test drive it didn't have any power and seemed like it wasn't running right. Also, when I tried setting the timing with a strobe light the timing mark on the pulley seemed 180 degrees off and I couldn't even get close to a proper setting without the engine stalling. So back to the drawing board. I started the engine and pulled the plug wire from cylinder 4 (firing order 1,3,4,2) engine started running rough, pulled the wire from cylinder 2 same thing. Took the wire from cylinder 3 engine idle smooth, same thing with cylinder 1. Am I still 180 out? moving the wires around to compensate for the 180 and engine won't start. I'm thinking about pulling the pin on the drive dog and rotating it 180 but will that solve the problem or be the same as changing the wires? I'm miffed!!!!!

That should be correct,but to make sure,you should screw in a compression
test gauge,turn the engine over by hand while watching the gauge.When the needle comes up,you will know for sure.
If you dont have a gauge,you can probably hold your finger over the plug
hole and have someone turn the engine for you until you feel the compression.
Let me know when you get it running.Im curious to know what the actual
problem was. converter45

Are you going clockwise or counter-clockwise on the distributer cap when determining plug order? Pulling the pin on the drive dog for the distributer should not make a difference. To help find TDC on the number one cylinder, remove the spark plug and put your finger or a pencil into the spark plug hole, while slowly rotating the motor, feel to see or watch the pencil (don't let the pencil fall completely into the cylinder) when the piston is at its highest point. Now look at the valves, both valves for #1 should be closed. If not, rotate the engine 360 degrees. When the motor is at TDC for #1, look to see where the rotor is pointing. It will be pointing at #1. Go counter-clockwise on the distributor cap and put the other wires on, 1,3,4,2

What was wrong with the '72 motor?

The clutch went out on the 72, due to limited funds I figured I would take the clutch from the 68 and put it on the 72. So I pulled both engines (easier to me than dropping the trans in the garage, no hoist). As I started to loosen the bolts of the clutch on the 72 the engine turned making me think the compression was weak on this engine. I knew that the 68 was strong as it only had about 15k on it since I rebuilt it last and when I tried loosening a bolt on that clutch the engine was solid. So I decided to swap engines.

I've tried and found TDC on the 68 and when I had it at TDC the rotor was pointing to the bottom left location on the distributor so I put that on #1 and went 1,3,4,2 counterclockwise, engine wont' start. Did this process several times. Frustrated I moved the wires around on the distributor until it did start and #1 was on the top left of the distributor. Engine starts, idles great but is only running on 4 and 2. I removed the wires from 1 and 3 and the engine idle doesn't change but it does when I remove them from 2 and 4. Also, when I put a strobe light on it the timing mark is at 10 o'clock instead of 6. What am I missing or doing wrong? I've been messing with this issue for a week now.

So,did you get everything running smooth yet?
The last problem sounds like the firing order may still be off. Make sure you are setting it up in the correct rotation.

Have you used a guage to do a compression check on the '68 motor? A motor can be hard to turn if the bearings are binding or tight, if the bores have rust.

Have you tried putting the '72 distributor in the '68 motor?

I must thank everyone for all the help. The car is up and running!!! :) Just need some fine tuning for the vacuum advance. I can't believe what it turned out to be. I feel totally stupid. Let me explain. First I must say that I've had my 68 for 26 years and have rebuilt the engine 3 times for various reasons so I know this vehicle quite well. Anyway, here's my blindness; Firing order is 1,3,4,2 and found TDC on #1 more times than I can count. However, the cylinder order from radiator to firewall is 1,2,3,4. See where this is going? I setup the wires on the distributor for 1,3,4,2 but didn't do that on the cylinders. One plugged into cylinder 1, 3 plugged into cylinder 2, 4 plugged into cylinder 3, 2 plugged into cylinder 4. What an idiot, I can't believe I did that :screwy: . So, once that was figured out and after a tweak on two valve clearances the car is running. Thank you again for the help.

We all make mistakes, good to hear you have it running.

Clifton