Need some timing help-way off the mark
#1
Le Mans Master
Thread Starter
Need some timing help-way off the mark
Just got my rebuilt L48 running. Having issues setting the timing. To get it run right, the timing mark is at about 12 o'clock or about 35-40 * away from where it should be (no vacuum advance hooked up). I set the timing using a vacuum gauge set to highest reading which was only 13-14". No wild cams, just a XE-262. When I connect the vacuum advance to manifold vacuum, the engine dies. The dampener is the same one I took off, and when I assembled the engine, the timing mark lined up with #1 TDC. Seems like I might have a vacuum leak. Disconnected every vacuum line=no change. Sprayed WD-40 around the intake manifold=no change.
I did a compression check before I started it and all cylinders were 160-165 PSI
Where should I look next?
I did a compression check before I started it and all cylinders were 160-165 PSI
Where should I look next?
#3
Race Director
Pull the left valve cover. Manually rotate the engine until both #1 cylinder valves are closed and the timing mark is at 0 ( Top dead center).
The distributor is now pointing to the #1 spark plug wire. Put the wires on as indicated (proper order) starting with the #1 wire.
If everything else is correct that should solve the issue.
The distributor is now pointing to the #1 spark plug wire. Put the wires on as indicated (proper order) starting with the #1 wire.
If everything else is correct that should solve the issue.
#6
Race Director
Did you try rotating distributor and watch the mark move?
#7
Le Mans Master
Thread Starter
#8
Le Mans Master
Thread Starter
#9
Your distributor is probably off a cog. Not unusual. As stated above, you can find to dead center by pulling the #1 plug, stuff a rag or your thumb against the hole, and have someone turn it over until your thumb blows out the hole. Now pull disti cap and see where the rotor is pointed. Should be approx at #1. If not, move your wires one position.
#10
Le Mans Master
Thread Starter
Your distributor is probably off a cog. Not unusual. As stated above, you can find to dead center by pulling the #1 plug, stuff a rag or your thumb against the hole, and have someone turn it over until your thumb blows out the hole. Now pull disti cap and see where the rotor is pointed. Should be approx at #1. If not, move your wires one position.
#11
Sorry I edited and it didn’t save. As suggested, your wires may be off one position. Double check those - I think No.1 should be at the right edge of the little door on the cap.
#12
Le Mans Master
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Sounds as though it runs well enough, but timing marks are off the chart.
WAGs
Regardless of what it seems ... maybe your damper's outer ring has slipped.
Maybe dial-back feature of timing light has failed and is way out of calibration ... won't be the first one to do so. (my WAG top pick for cause)
Maybe timing tab is incorrect or located improperly.
As you assembled motor ... did you verify Piston @ TDC with Damper's Timing Mark @ TDC?
WAGs
Regardless of what it seems ... maybe your damper's outer ring has slipped.
Maybe dial-back feature of timing light has failed and is way out of calibration ... won't be the first one to do so. (my WAG top pick for cause)
Maybe timing tab is incorrect or located improperly.
As you assembled motor ... did you verify Piston @ TDC with Damper's Timing Mark @ TDC?
#13
Le Mans Master
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Points caps have a door/window to adjust gap/dwell ... HEI is not adjustable and no door for use as point-of-reference to locate wires.
#14
Le Mans Master
Thread Starter
Sounds as though it runs well enough, but timing marks are off the chart.
WAGs
Regardless of what it seems ... maybe your damper's outer ring has slipped.
Maybe dial-back feature of timing light has failed and is way out of calibration ... won't be the first one to do so. (my WAG top pick for cause)
Maybe timing tab is incorrect or located improperly.
As you assembled motor ... did you verify Piston @ TDC with Damper's Timing Mark @ TDC?
WAGs
Regardless of what it seems ... maybe your damper's outer ring has slipped.
Maybe dial-back feature of timing light has failed and is way out of calibration ... won't be the first one to do so. (my WAG top pick for cause)
Maybe timing tab is incorrect or located improperly.
As you assembled motor ... did you verify Piston @ TDC with Damper's Timing Mark @ TDC?
Yes, when I assembled the motor, I verified TDC with the dampener. Right now, it's a little too far advanced since it was slow to crank over cold. I timed it using a vacuum gauge to get highest reading but the most I could get was 13-14" which seems rather low.
#15
Le Mans Master
Thread Starter
Correct, HEI dizzy. The #1 wire is where it's suppose to be based on the wire retainer that goes on top the cap. It has the wire numbers molded in.
#16
Pro
I don't believe the problem lies within the distributor. As the OP says, "to get it to run right", the timing mark is way off. Moving the wires on the cap makes no difference unless the cap cannot rotate anymore due to the vac canister hitting something. So, assuming there is no vacuum leak, either the mark on the balancer has moved or the timing gears are off. Set the #1 piston at TDC by using a dial indicator thru the spark plug hole, or using some sort of piston stop and rotating the engine both ways and marking the balancer where it stops. The middle of these two marks is TDC. This will tell you if the balancer has moved. If not, then I would suspect something is off with the timing gears, BTW, its much easier to rotate the engine with all the plugs out.
#19
Le Mans Master
Member Since: Oct 2002
Location: Las Vegas - Just stop perpetuating myths please.
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I'm sure you are aware those timing gear marks are for TDC on #6 while for TDC on #1 is with the cam sprocket mark @ 12:00 position.
So let's look at low vacuum. Vacuum is a function of valve overlap while compression pressure is a function of the intake valve closing. Low vacuum could be valves over adjusted that don't fully close. You would see this as a lowered compression pressure from the intake valve closing late as a compression loss and a leak into the intake manifold. If the exhaust valve doesn't seat compression pressure would be lowered as it becomes a leak into the exhaust manifold. You can hear this if you pressurize the cylinder as in a leak down test. You can also tape over your intake entries and use soapy water to observe leaks all the way from a pressurized cylinder.
Last resort you could loosen the intake valve rocker arms and pressurize with a sealed carb (taped) checking for leaks with soapy water. Or you could loosen all the rocker arms and check each cylinder for leaks one at a time. But I would refrain from doing this on a new rebuild motor until fully broken in.
That's enough for now. Good luck and please post your results.
Last edited by cardo0; 05-27-2019 at 02:11 PM. Reason: Stupid auto correct!
#20
Le Mans Master
Thread Starter