351w Idle problems
Thread Starter
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Mountain Pass
Joined: Mar 2018
Posts: 233
Likes: 2
From: Puyallup, WA
I didn't disconnect the vacuum from the distributor when I set timing the first time.
I just followed the procedure you laid out and I tried getting the distributor advance vacuum line to 0 but I was only able to get it to 3-4. The engine runs at about 650-800 RPM with it set this way and really doesn't want to stay running. I had to spin the distributor clockwise to get it to this setting, and the #1 plug is pointing off towards the 1-2 o'clock direction.
A guide online says if my EGR won't hold vacuum applied it needs replaced, should I replace it too?
I just followed the procedure you laid out and I tried getting the distributor advance vacuum line to 0 but I was only able to get it to 3-4. The engine runs at about 650-800 RPM with it set this way and really doesn't want to stay running. I had to spin the distributor clockwise to get it to this setting, and the #1 plug is pointing off towards the 1-2 o'clock direction.
A guide online says if my EGR won't hold vacuum applied it needs replaced, should I replace it too?
Moderator
Joined: Jan 2001
Posts: 56,965
Likes: 2,725
From: Virginia
Forget the EGR. No wait, take the EGR off, get a pop can or thin piece of aluminum and make a solid block off gasket for it, and put it back on there blocked off. There is a lot of junk on these engines that can cause problems, the EGR is one of them and it would be good to take it out of the equation. You are worried about it working, that is what you don't want right now. You need to be worried about it leaking, which they are famous for. That would mess up your idle.
Your main problem right now is your idle speed. That is messing everything else up. You can't set the carb up if it's open too far.
Your main problem right now is your idle speed. That is messing everything else up. You can't set the carb up if it's open too far.
Postmaster
Joined: Mar 2011
Posts: 2,698
Likes: 7
From: Taxachusetts
Mebbe you've got other things going on that need to be addressed first but the video of the vacuum gauge going bonkers strikes me as a leaky head gasket......compression test or leak down test in order?
Cargo Master
Joined: Dec 2004
Posts: 3,362
Likes: 22
From: Florence, SC
Plug your vacuum gauge into a manifold vacuum source, and slowly turn the distributor clockwise to get the highest vacuum reading. This method is very similar to setting the idle mixture screws. When the engine stops gaining vacuum, back it off very slightly and lock it down.
I didn't disconnect the vacuum from the distributor when I set timing the first time.
I just followed the procedure you laid out and I tried getting the distributor advance vacuum line to 0 but I was only able to get it to 3-4. The engine runs at about 650-800 RPM with it set this way and really doesn't want to stay running. I had to spin the distributor clockwise to get it to this setting, and the #1 plug is pointing off towards the 1-2 o'clock direction.
I just followed the procedure you laid out and I tried getting the distributor advance vacuum line to 0 but I was only able to get it to 3-4. The engine runs at about 650-800 RPM with it set this way and really doesn't want to stay running. I had to spin the distributor clockwise to get it to this setting, and the #1 plug is pointing off towards the 1-2 o'clock direction.
Moderator
Joined: Jan 2001
Posts: 56,965
Likes: 2,725
From: Virginia
Good. Put the block-off piece back on there. If you have pinging problems, we can work on that later. But that is one thing out of the equation that could possibly cause idle problems.
Lariat 85 is suggestion what I suggest you do. Just twist the dist around till the engine speeds up some and then re-adjust everything. You need to close that carb up.
Lariat 85 is suggestion what I suggest you do. Just twist the dist around till the engine speeds up some and then re-adjust everything. You need to close that carb up.
Post Fiend
Joined: Feb 2008
Posts: 5,831
Likes: 121
From: St Albert, Alberta
I second that one. Leaking between cylinders it looks like. I think a compression test is order. Be sure to pull all the plugs when you are doing it. Especially since you are looking for a leak between cylinders.
Moderator
Joined: Nov 2007
Posts: 22,415
Likes: 92
From: Denver Metro Area, CO
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Postmaster
Joined: Mar 2011
Posts: 2,698
Likes: 7
From: Taxachusetts
Not that steady, constant flopping of the pointer. A bent valve or a loose/worn guide, would show up as an intermittent fluctuation of the pointer....as in whenever the cam tells that particular lifter to "do its thing" to that particular valve, the fluctuation would show up.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Originally Posted by Jghake
Hey guys,
I have a 351W with Motocraft 2100/2150 carb, auto choke, and Duraspark. It ran like absolute crap when I got it...
[.........]
...Any ideas where I should look next?
I have a 351W with Motocraft 2100/2150 carb, auto choke, and Duraspark. It ran like absolute crap when I got it...
[.........]
...Any ideas where I should look next?
It is tough to troubleshoot remotely and sometimes the skill level or experience of the forum poster is unknown. Not trying to beat up on anybody, and include myself here - but this stuff was hashed out long ago. Every repair manual since about 1910 has, on the very first page 1 paragraph 1, a recommendation that says perform a compression test. Not jump into carburetor adjustment, ignition timing, or tibetan prayer magnets on the fuel line.
The reasoning is sound, if there is internal engine damage or excessive wear a tune up is pointless and a waste of time & money. A mechanic's vacuum gauge will also reveal much the same information and is easier to use but in any case there is no substitute for a methodical approach. RTFM!!
Thread Starter
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Mountain Pass
Joined: Mar 2018
Posts: 233
Likes: 2
From: Puyallup, WA
Well..........
Tightened the carb down and it's running like a champ. All 4 bolts holding the carb down were barely finger tight. Then I tuned it to max vacuum, 0 in the vacuum advance at idle, it will idle as low as 500 if I want it. I have it set at 750 right now but occasionally it will bounce 20-30 RPM or so. Drove it around a bit and it is acting a hell of a lot better. I think I can still get it to run a little better with the mixture screws. Tomorrow I'm going to pull the carb and spacer off to replace both gaskets. Then I'll tune it again. Thank you all for trying so hard to help me get this running. I've reached my frustration levels several times already with this truck and it's nice to know there are others out there so willing to help.
If I were to head to the junkyard first, what vehicles should I be looking for to score a non-EGR spacer? Maybe NumberDummy might know!
Tightened the carb down and it's running like a champ. All 4 bolts holding the carb down were barely finger tight. Then I tuned it to max vacuum, 0 in the vacuum advance at idle, it will idle as low as 500 if I want it. I have it set at 750 right now but occasionally it will bounce 20-30 RPM or so. Drove it around a bit and it is acting a hell of a lot better. I think I can still get it to run a little better with the mixture screws. Tomorrow I'm going to pull the carb and spacer off to replace both gaskets. Then I'll tune it again. Thank you all for trying so hard to help me get this running. I've reached my frustration levels several times already with this truck and it's nice to know there are others out there so willing to help.
If I were to head to the junkyard first, what vehicles should I be looking for to score a non-EGR spacer? Maybe NumberDummy might know!
Moderator
Joined: Jan 2001
Posts: 56,965
Likes: 2,725
From: Virginia
Here's a Ford one on ebay. I think they make aftermarket also. I would try to get one like the Ford with that large hose connection in the back. That is for your PCV valve, the PCV valve works best when it is hooked very close to the carb so it gets mixed to all the cylinders. Some carbs have the large PCV connection on the carb itself, so this may not matter in your case.
https://www.ebay.com/itm/2-Barrel-Ca...4383.l4275.c10