Timing the 4.9L engine
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Mountain Pass
Joined: Apr 2012
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Timing the 4.9L engine
Hi, I have a 1986 E 150 4.9L . I replaced the timing gears and now in the process of putting it back together. I want to make sure I get the timing right. I lined up the marks on the cam and crankshaft gears. Set the timing mark on the crank pulley to top dead center then reset the distributor with the rotor pointing to #1 plug. I checked the hood sticker and it calls for a setting of 10 degrees before top dead center. Should the engine start with it set at top dead center and then I need to use a timing light to set it to 10 degrees before top dead center?
Cargo Master
Joined: Sep 2012
Posts: 2,112
Likes: 286
From: Eastern TN
AFAIK you can only eyeball the distributor at #1 TDC, unless you marked the distributor against the block. So, yes, start the engine then use the timing light. If it seems difficult to crank, nudge the distributor towards less advance. The engine is easier to crank with less advance. Check the manual for whether there are wires to jump or ground and/or vacuum hoses to plug while setting ignition timing.
Sixto
07 E350 5.4 178K miles
Sixto
07 E350 5.4 178K miles
Logistics Pro
Joined: Oct 2014
Posts: 3,677
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Can you plug the #1 spark plug hole with your finger while you turn the crank pulley?
Maybe you already did that... At TDC on the crank pulley with the timing marker lined up doesn't necessarily mean you are TDC on the compression stroke.
Since it's a 4 stroke engine, TDC on the crank pulley timing marks lines up twice in each cycle. once on the intake stroke and again on the compression stroke so you have to make sure you are on the compression stroke when you set the distributor to the #1 wire.... You probably already knew that but if not then I hope this makes sense..
Maybe you already did that... At TDC on the crank pulley with the timing marker lined up doesn't necessarily mean you are TDC on the compression stroke.
Since it's a 4 stroke engine, TDC on the crank pulley timing marks lines up twice in each cycle. once on the intake stroke and again on the compression stroke so you have to make sure you are on the compression stroke when you set the distributor to the #1 wire.... You probably already knew that but if not then I hope this makes sense..
Logistics Pro
Joined: Oct 2014
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A problem I had when I replaced the distributor win my 85 with a 5.0 was that I was off one tooth on the distributor gear. The engine would start and run but I couldn't turn the distributor enough to adjust it correctly because the ICM module was hitting the intake or thermostat housing I believe.. I had to go back and carefully lift the distributor up and drop it back down after feeling for it to move one tooth! After that I was able to set the timing.
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Mountain Pass
Joined: Apr 2012
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I did make sure it was on the compression stroke, then moved the pulley mark to 0 (TDC). I marked the distributor base where the #1 wire is on the distributor cap, moved the rotor to that mark and put it back in. I'll have to check what the procedure is for timing the engine, if I have to plug anything or not. I was wondering if the engine would start with timing mark on TDC. Which way would I move the distributor for less advance?
Cargo Master
Joined: Sep 2012
Posts: 2,112
Likes: 286
From: Eastern TN
The engine will start with timing close to TDC. The chance of you eyeballing TDC spot on is small. I’d guess it’ll start from 20 BTDC to 10 ATDC so there’s a lot of leeway. As mentioned, it’ll start with the distributor a tooth off. If you’re too far BTDC and fuel delivery is good, the starter will struggle.
There might be an arrow on the distributor cap indicating which way the rotor spins, or the posts are numbered in sequence of the firing order. If not, nudge the crank clockwise and see which way the rotor turns. Or just start the engine and use the timing light to tell you which way turning the distributor is advance vs retard.
Have confidence in yourself. Lots of people who can set ignition timing can’t replace timing gears
Sixto
07 E350 5.4 178K miles
There might be an arrow on the distributor cap indicating which way the rotor spins, or the posts are numbered in sequence of the firing order. If not, nudge the crank clockwise and see which way the rotor turns. Or just start the engine and use the timing light to tell you which way turning the distributor is advance vs retard.
Have confidence in yourself. Lots of people who can set ignition timing can’t replace timing gears
Sixto
07 E350 5.4 178K miles
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