351w EFI performance upgrades?
Logistics Pro
Joined: Jul 2009
Posts: 3,635
Likes: 3
From: Lansdale, PA
Because you're putting vacuum to one side of the engine(with pcv), unless you have a breather style oil fill cap, it will create that suction. There's no way for the engine to get the vapors out if it can't get fresh air in.
My truck will build suction if I plug off the vent on drivers side.
Logistics Pro
Joined: Jul 2009
Posts: 3,635
Likes: 3
From: Lansdale, PA
It's a pain, but check drivers side rocker adjustment. You installed the rockers when it hadn't been run much, double check that the rockers in case they are too much preload and holding a valve open a little.
Junior User
Joined: Jul 2016
Posts: 53
Likes: 0
Ok been through rockers twice 0 lash and 1/4 turn helped some checked firing order numerous times put 460 pcv in with breather oil fill cap. Tried to bump timing using scanner but it. Keeps jumping around I set it shut truck off restart it changes it. Motor still won't rev.
Logistics Pro
Joined: Jul 2009
Posts: 3,635
Likes: 3
From: Lansdale, PA
When you pull the spout to set timing, I usually rev engine up to 1000-1200 to help keep the timing marks from jumping as much.
Do you have an adjustable timing light, or are you using timing marks on balancer?
Make sure you marked btdc on balancer if you have a fixed timing light. And passenger front is number 1. Firing order starts with 1-3 and not 1-5 correct?
Is this a new engine also, or just the intake? Is cam installed at 0?
Do you have an adjustable timing light, or are you using timing marks on balancer?
Make sure you marked btdc on balancer if you have a fixed timing light. And passenger front is number 1. Firing order starts with 1-3 and not 1-5 correct?
Is this a new engine also, or just the intake? Is cam installed at 0?
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Cargo Master
Joined: Mar 2010
Posts: 3,342
Likes: 294
From: Laramie, WY
When setting base timing with the timing light and turning the distributor, you need to unplug a jumper to disable the advance.
Logistics Pro
Joined: Jul 2009
Posts: 3,635
Likes: 3
From: Lansdale, PA
Lost my message due to crapy phone. Short answer now.
You need to find the little grey plug by the tfi module to unplug. This will lock the computer at it's base timing, then you can adjust/set the timing where it needs to be.
You need to find the little grey plug by the tfi module to unplug. This will lock the computer at it's base timing, then you can adjust/set the timing where it needs to be.
Cargo Master
Joined: Mar 2010
Posts: 3,342
Likes: 294
From: Laramie, WY
How did you set base timing? It can't be done with the scanner.
Do you mean 0.620 volts to 0.760 volts? It should oscillate between low to high, 0.1V or so up to around 0.8V. This would indicate it's cycling rich/lean as designed. If it's constantly over 0.45V it's rich, if it's under 0.45 its lean. Edit: that assumes the sensor is working correctly.
Is your truck MAF or SD?
Do you mean 0.620 volts to 0.760 volts? It should oscillate between low to high, 0.1V or so up to around 0.8V. This would indicate it's cycling rich/lean as designed. If it's constantly over 0.45V it's rich, if it's under 0.45 its lean. Edit: that assumes the sensor is working correctly.
Is your truck MAF or SD?