86 351W HO Timing
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New User
Joined: Jul 2005
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86 351W HO Timing
On my truck I had someone do the head gaskets and a new timing chain and when I start my truck it runs at very high idle then stalls out and the carb catches fire what causes this and why does it idle so high cause now it runs for about 1 minute than stalls!
Postmaster
Joined: Mar 2003
Posts: 4,038
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From: Spokane WA
If fire makes it into the intake manifold and or carb, then it is firing too early and it is usually timing, and its WAY off
Have you timed it? whats it at?
Im not familiar with the 351, but Id guess 6,7,8,9 degrees BTDC???????
It sounds like you could have a combination of problems...... Id start with the timing, its supposed to be warm when you time it though, tell us more about your setup.....
Have you timed it? whats it at?
Im not familiar with the 351, but Id guess 6,7,8,9 degrees BTDC???????
It sounds like you could have a combination of problems...... Id start with the timing, its supposed to be warm when you time it though, tell us more about your setup.....
New User
Joined: Nov 2005
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Remove #1 spark plug and bring to top of stroke using a whistle stop or probe of some sort (best if you rotate motor by hand with coil unplugged), when it's at top of it's travel remove distributor cap to see where rotor is, s/b just past #1 tower of cap since that motor fires about 10 degrees btdc.
Fleet Mechanic
Joined: Nov 2003
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Make sure your firing order is correcct...5.8's and 5.0's hjave a different firing order...there should be a sticker on your radiator support panael telling you what the timing should be (10 before, I think) as well as the firing order.
Elder User
Joined: Jun 2004
Posts: 747
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From: Pelahatchie, MS
The 86 351HO is supposed to be set at 10 BTDC with the vacuum advance disconnected. It's carbureted, Holley 4180, which is most likely leaking from the accelerator pump, bottom right hand side of front bowl. Fuel on the intake could cause the fire, old carburetor begging for a rebuild could explain a LOT of problems. I had so much trouble with mine I just replaced it with an Edelbrock. Best thing I ever did. Mine idled REALLY high when I first got it and started tuning it up. Carb turned out to be the culprit for 90% of my troubles.....
Junior User
Joined: Oct 2002
Posts: 95
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From: Southeastern , Illinois
Sounds like vacuum leak to me. Possibly intake manifold gaskets, to check for leaks, I spray carb cleaner (with the straw) next to the heads and alongside the carb gasket. The motor's rpm will change if there is a leak. Also , my '86 Ho carb, had so many vacuum lines that I replaced it with a universal 4160 (Holley # 80457)and an aluminum intake. I got lucky and found those parts on E-bay or I would not have been able to afford them. I would also check the firing order, may have an ignition wire crossed.
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Post Fiend
Joined: Jan 2004
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From: Northwest, Arkansas
Thread moved to " 221, 260, 289, 5.0/302, 5.8/351W V8" Tech forum. Should find more resources here to help with the problem.
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