302 Timing for best performance ???
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Senior User
Joined: Feb 2005
Posts: 200
Likes: 1
From: Chester County PA
302 Timing for best performance ???
I have a 91 F150 302 with a very recently rebuilt engine. I was wondering what the timing (crankshaft position) should be set at for best perfomance/ fuel mileage with out tooo much pinging. What do some of you guys have your set at if you know?? I know the emisions label says 10 degrees BTDC but that dosent mean its the best. Any help is appreciated. thanks
Junior User
Joined: Nov 2005
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I have a 1996 with a 302cid. I have mine set at 15 degrees BTDC. I set it at 20 degrees BTDC and had the engine light come on. I have not had any problems since I set it back down to 15 degrees. The fuel milage did not change much at all and I seem to have just a bit more pep. This definitely helped with the 140,000 on the engine and no rebuild.
Senior User
Joined: Oct 2004
Posts: 371
Likes: 1
From: Wetaskiwin, Alberta
I would be cautious about advancing the timing much more than 12 degrees on your fresh rebuild. You need to drive the vehicle over a wide range of operating parameters before you can say that "it's all good" at 15deg. My engine ran fine at 15 deg. until I put a load behind it and started to ping like crazy. I set it back to 11 degrees and haven't had any problems at all. One degree advance dosen't souond like much however I did notice an increase in crispness of engine response so I haven't made any further adjustments. YMMV.
Cheers!
Mike
Cheers!
Mike
Mountain Pass
Joined: Aug 2005
Posts: 211
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From: Newark, Ohio
wouldn't it be good to run it a 10 while the computer gets its memeory back? I had comp issues and ran my truck at 10 for about 100 miles and then adjusted for my taste. I think it is around 12.
I know very little but ask way too many questions so don't take my word for gospel.
rob
I know very little but ask way too many questions so don't take my word for gospel.
rob
FTE Legend
Joined: Jun 2006
Posts: 31,930
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From: Ottawa, Ontario
I have my 5.8 at about 18deg now... but.. and this is a big one. This is an engine I personally rebuilt from the ground up with ported heads. I took pains to smooth the combustion chambers and remove all sharp edges and nodes in the castings. The stock castings range from decently clean to really bad, so without this type of rework many engines will not tolerate much ignition advance. The 5.0 I replaced would not take more than 13deg initial advance before pinging was audible, for example.
Lead Driver
Joined: Nov 2002
Posts: 9,557
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From: Concord, NC
The computer will never fight any timing changes. It gets all timing information from the distributor with no other reference for engine crank or cam position. If you turn the distributor the timing will change no matter if the spout connector is in or if the spout connector is out.
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Mountain Pass
Joined: Aug 2005
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From: Newark, Ohio
Originally Posted by EPNCSU2006
The computer will never fight any timing changes. It gets all timing information from the distributor with no other reference for engine crank or cam position. If you turn the distributor the timing will change no matter if the spout connector is in or if the spout connector is out.
Unfortunatly I found that out the hard way when I replaced my computer. They have to have their way on everything. I swear with these computers they go goofy if the cigarette lighter needs changed. Lets go back to the good old days of cubic inches and raw power.
Lead Driver
Joined: Nov 2002
Posts: 9,557
Likes: 44
From: Concord, NC
The reason behind pulling the SPOUT is so that you get an unmodified view of where the distributor is sending the signal to spark - it takes all the computer advance out of the picture. The computer will advance from base timing, yes. I never disputed that. Again, the computer only knows the signal it is getting from the distributor. The computer advances from the base timing a specific amount for every engine load/operating condition, programmed by Ford; it doesn't magically find the optimum timing advance value on its own. The computer doesn't adapt to a new distributor position. If it did, there would be no point in setting the timing at all.
Mountain Pass
Joined: Aug 2005
Posts: 211
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From: Newark, Ohio
It was my understanding that the knock sensors would detect knock and the comp would start to retard timing til it didn't detect knock. Therefore it would be tuning to each specific engine since no two engines are the same. Am I way off here? I spent WAY too much time under my hood last winter testing and trying to trace down all the issues it had when I had a no run situation. It ended up being the computer and a whole ton of sensors.
Senior User
Joined: Mar 2005
Posts: 341
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From: Newark
The 5.0 mustang "ten minute tune up" for the 5.0 was to advance the timing until you hear detonation under load then back it off until gone. Put in 93 octane and advance timing the same way. The motor makes the most power at the edge of detonation. The higher octane will allow for more timing advance without detonation. As far as knock sensors and ill affects, not my area.
Lead Driver
Joined: Nov 2002
Posts: 9,557
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From: Concord, NC
My understanding is that when knock is detected, the computer pulls out a set amount of timing, say 4 degrees for a specified time. The newer EFI stuff is able to constantly run at the edge of knock, but I don't believe that these truck computers are that advanced. The mustang didn't use a knock sensor, and the 302 (and 300?) were the only truck engines to use knock sensors. I have a 302 with a knock sensor, and if I advance the timing too much, it will ping. I left it that way to see if the computer would eventually adjust the maximum advance down a bit to eliminate pinging but the pinging never went away.
New User
Joined: Jul 2005
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Knock Sensor
Has any one of you had a problem with your knock sensor? I have a knock that comes and goes at idle. I also have a problem of the engine stalling at idle when warm. I have replaced computer, idle air bypass value, Map sensor, temp sensor, rotor and cap.