351w EFI performance upgrades?
Cargo Master
Joined: Mar 2010
Posts: 3,342
Likes: 294
From: Laramie, WY
Did you remove the SPOUT connector? 97' is likely SD, assuming it's in an f250 or f350. Is there a MAF sensor in the intake tube? Is it OBDI (EEC-IV) or OBDII (EEC-V)?
Cargo Master
Joined: Mar 2010
Posts: 3,342
Likes: 294
From: Laramie, WY
Which cam did you use. Sorry if I missed it. SD is sensitive to LSA.
I don't have a ton of experience I've just read a lot recently, and have been asking questions that might help one of the experts help you.
It's possible the sensor isn't working correctly. Does the exhaust smell rich? What do the plugs look like?
I don't have a ton of experience I've just read a lot recently, and have been asking questions that might help one of the experts help you.
It's possible the sensor isn't working correctly. Does the exhaust smell rich? What do the plugs look like?
Junior User
Joined: Jul 2016
Posts: 53
Likes: 0
Motor is a stock 97 5.8. Mods are pro comp gt40 heads,5.8 lower intake ported to match 5.0 upper intake, 1.7 roller rockers with longer pushrods to center on valve stems, hotter ignition from coil to plugs, shorty headers and new exhaust. Cam is factory roller.
Junior User
Joined: Jul 2016
Posts: 53
Likes: 0
Snap on is all I can say it's the neighbor whose helping me. I'll see if he can check fuel trim
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Junior User
Joined: Jul 2016
Posts: 53
Likes: 0
Yes played with timing today. Pulled spout out reved motor by hand and turned distributor , set it by ear but got more power and motor revs better. Feels like I'm just now back to the power I had before doing any upgrades.
Lead Driver
Joined: Jul 2007
Posts: 7,868
Likes: 9
From: Rhode Island
You need a timing light to set the timing, period.
The computer has only one way to control the timing of the engine, and that is through the SPOUT wire. The computer also has no way to verify the timing - all of its timing information comes from assuming the distributor is perfectly set to 10* BTDC.
If you unplug the SPOUT connector, the computer has absolutely no control of the timing. The read out on the scanner is just what the computer is trying to command the timing to be.
The computer has only one way to control the timing of the engine, and that is through the SPOUT wire. The computer also has no way to verify the timing - all of its timing information comes from assuming the distributor is perfectly set to 10* BTDC.
If you unplug the SPOUT connector, the computer has absolutely no control of the timing. The read out on the scanner is just what the computer is trying to command the timing to be.
Cargo Master
Joined: Mar 2010
Posts: 3,342
Likes: 294
From: Laramie, WY
I would start with 10 degrees and go drive it. Six liter tune up just calls for advancing the base timing as much as you can get away with, without pinging under load. I tried it with plugs at 0.055" and found 11 degrees was all my truck (96' F150) would tolerate.