351C missing
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From: west michigan
351C missing
Hey guys. I have a Cleveland in my 82 Bronco that I rebuilt a few years ago. I just put it on the road a couple of weeks ago after sitting (body job) for about 6 months. Now when I start it, it has a constant miss. After it warms up it seems to fire on all eight except when I bring the RPMs up in neutral. Then it really misses but under a load it doesn't (or so it seems). Not long before I parked it I put a new distributor (351M electronic) cap, rotor, wires, and plugs so I wouldn't think it would be ignition, but... and when I rebuilt the engine I had the valves done so they should be OK (I know, don't assume). I did use the original cam and lifters so I'm kind of leaning towards that but I thought It might be wise to ask the smart people first and get some input. So, any ideas? thanks
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Joined: Aug 2001
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From: Delaware
Look inside the cap for signs of moisture, or tracking, or crossfire. Check your plug wire terminals for moisture, dirt. Wipe your wires with a clean rag. I am betting on contamination from moisture or dirt, especially inside the cap.
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From: chicago burbs
if it sat for a long time without the engine being spun at all, a valvespring or two could be all squeezed out? or something got down the carb while the body was getting done? wouldn't be the first time, check the plugs for fouling and damage.
Last edited by grclark351; Dec 13, 2005 at 12:34 AM.
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From: west michigan
Thanks for the replies so far. This website is by far the best I've found.
I'm pretty sure it's not the plug wires or cap. I just put new ones on last week and that changed nothing. I put a 650 DP holley on it right after the paint job and it ran good then. Now that I think about, when I was working on the body (over the course of about 6 months) I would move the truck in and out of the shop every so often and it fouled the plugs out. When I got ready to drive it I sand blasted the plugs (they were fairly new at that point) and it ran pretty good for a while.
I guess my next check will be on the plugs and maybe a compression test.
I did pour some stuff called 'valvemedic' in the crankcase yesterday. It's supposed to free up sticky valves or so the guy said. It almost seemed like it ran a little better when it was cold but it still wasn't right.
Well thanks again guys, I'll report back when/if I find something.
I'm pretty sure it's not the plug wires or cap. I just put new ones on last week and that changed nothing. I put a 650 DP holley on it right after the paint job and it ran good then. Now that I think about, when I was working on the body (over the course of about 6 months) I would move the truck in and out of the shop every so often and it fouled the plugs out. When I got ready to drive it I sand blasted the plugs (they were fairly new at that point) and it ran pretty good for a while.
I guess my next check will be on the plugs and maybe a compression test.
I did pour some stuff called 'valvemedic' in the crankcase yesterday. It's supposed to free up sticky valves or so the guy said. It almost seemed like it ran a little better when it was cold but it still wasn't right.
Well thanks again guys, I'll report back when/if I find something.
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From: west michigan
OK I put in a hotter set of plugs. I took a guess on the gap. The Cleveland calls for .035. I replaced the distributor this summer with an M dist with electronic ignition. The gap for the M was .044 so I went with that. It runs about the same but won't idle when its cold (its 20 degrees outside) and still missed bad for a while. But like before, once it warms up it hits on all eight. I think my next step will be to start it when its cold and let it run for a few minutes (while its missing)and then check the plugs and hopefully tell which ones are firing and which ones aren't. Any thoughts on what plug gap I should be using? I appreciate the input so far.
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From: chicago burbs
the .035" gap is for a point/condenser ignition. i use a spray bottle and squirt the exhaust manifolds or headers right where they attach to the head to see if i have a "cold" cylinder. just about anything in the spray bottle will work, but you might want to use window washer so your bottle won't freeze up. what kind of choke set-up do you have?
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From: west michigan
OK I'll try that tonight. It has an electric choke. It doesn't seem to have any effect even if I wire the choke open.
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From: west michigan
Update-It still runs like crap when its cold. I did notice though that when I first start the engine it hits on all eight but just for a few seconds. I'm starting to wonder if I have a valve that works twice then sticks in the guide until the heat of the engine expands the guide and loosens itself up. Maybe a weak valvespring as well, as grclark351 mentioned earlier. If that is the case, does anyone have cure for that (hopefully that doesn't involve major surgery)
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From: chicago burbs
does the choke appear to be working properly? when you come to the cold truck it should snap fully closed when you tap the gas pedal twice. then when you turn the key and the engine starts, the choke should "pull off" (open) just slightly. it should be running off of the fast idle cam, the regular idle screw should not be touching its adjustment stop. as the engine comes up to temp the choke blade should be slowly opening up, and when the idle seems to be climbing higher a little tap on the gas pedal will release the fast idle cam if it's ready. does any of this happen?
Last edited by grclark351; Dec 16, 2005 at 11:47 PM.
