Timing issue

[Scott21]

When I get to TDC on the number 1 cylinder, the rotor is pointing to the #2 plug. Shouldn't it be pointing at #1? I did not set the motor up. Can I just back the distributor out and retime the motor?

Any input would help.

Thanks

Scott

[Ryan_Miller]

Scott,

This is Wes's territory, so I will briefly answer until he comes along.

You can back the distributor out and retime it, but you have to coordinate it with the oil pump (at least on the L head engine).

Proper oil pump timing on the L head engine will keep you from having to turn the distributor up into the crossover pipe to get the engine timed.

Wes, where are you?

Also check out the downloads section under M38A1, there are two documents on timing the engine.

[wesk]

Scott,
If you are telling us you are 100% certain you have #1 cylinder TDC ON COMPRESSION and the points are just about to open and the timing marks you are using are properly aligned and correct for your engine then you have a situation where either the oil pump was not correctly indexed or the wires are not installed in their correct positions on the cap.

Since the distributor is driven by the oil pump which has an offset flat the distributor can only be installed one way.

The most simple solution here is to match #1 wire to the rotor's position. Then install the remaining three wires in their correct order in their correct direction of rotation.

The correct remedy is to index the oil pump correctly.

The above data applies equally to both the L134 and F134 engines.

[Scott21]

Thanks Guys, How do I index the oil pump.

Scott

[wesk]

The service manuals and TM's explain it in great detail.

The condensed version is to install the pump so it's offset tang aligns correctly with the offset tang on the distributor shaft with the rotor pointing at #1 wire while the engine itself is in #1 TDC firing position.

The problem is with the engine in the jeep you cannot sight up the oil pump shaft opening. So you must temp install the distributor and set the rotor where it should point. Now without allowing the rotor to move pull the distributor out and look closely at how the tang offset faces. Now put the pump in so it's tang will end up matching the distributor. Remember that since the pump shaft has the helical driven gear on it it will have a tendency to rotate slightly as it travels upwards the last inch towards the block. Take this rotation into consideration when determining how to start the pump up into the hole. This is all a lot easier with two people.

[Scott21]

Wes,
Thanks and yes I am doing everything myself. I have 2 girls, a wife and a female lab. The girls, at least like to sit in the jeep while I work on it.

Can I align the distributor and pull the pump and align it that way?



Scott

[wesk]

Yep, Just tie the distributor down so it can only lift up about an inch or so when you push against it with the pump shaft. Remember the last inch or so of travel the pump shaft will rotate in the direction of the helical gear on it so start an appropriate distance ahead of that rotation so it will end up correct. It will take a few tries the first time. You'll feel the distributor lift up and then when you have it right the distributor will drop back down in place ALMOST because there is a small anti-rattle spring clip at the bottom of the distributor shaft that will need you to push it another 1/2" down.

[Scott21]

Wes

Thanks a million

Scott

[TomM]

Scott,
Dont forget to put your patience hat on before taking this job on. It took a number of tries for me to get it right (at least I think its right and will find out when I try to start). There is nothing complex about this but it takes a bit of trying so that you can finally visualize which way the gears will move and how much.
Once you get indexed properly you can get closer to correctly timing by using an ohmmeter or test lite to watch the point gap opening as you use the normal distributor adjustment. If you are one tooth off with the pump you will not be able to time to 5degrees btdc even if the locations of the wires look correct.
Tom

[Ryan_Miller]

Tom is so right. It took me several times. I first did it while the engine was out, but ended up being off a tooth due to the rotation Wes mention. I did not realize it until I had the engine installed and ran it for the first time. I could not get it times until I turned the distributor way up to the cross over intake pipe. Then I new I was off.

I then did the installed engine version Wes gave here earlier.

[wesk]

The error and interference issue being discussed can happen if you are off a little in one direction. The small round civilian distributors can swing almost 360 degrees without any interference problems but the large oval shaped military distributor will hit the block or breather tubes before it can be adjusted enough when timing with a timing light.

The real problem is after the engine is assembled finding TDC is always a vague act since the crank will move several degrees in the TDC range with no perceivable movement in the piston. If you are not very experienced with this feel for TDC thing you could end up say 3 or 4 degrees after TDC. Now if you add more error by missing a gear tooth when installing the oil pump and that additional error is in the after TDC direction you will find it impossible to get enough swing on the distributor housing to adjust it to 5 degrees BTDC.

This is why it is so important to get it right during engine assembly. When done correctly during engine assembly the cam and crank gear timing marks are aligned and the vagueness of finding TDC by piston movement is avoided.

If all the engine rebuilding shops would use the darn book when building your engines this would not be overlooked.