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351M wonít rev past 1,000

  #16  
Old 10-16-2018, 09:11 PM
jtagge86
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I think I may have finally figured out the issue. After checking valve lash numerous times, a new carb, new distributor, new Duraspark box, and new plugs.... I had the idea to look at the emissions sticker on the stock valve cover (I put new Ford Racing covers on), recommend initial ignition timing is 14 degrees BTDC. It now revs up! Unfortunately itís a bit late to attempt cam break in being that I live right on top of my neighbors. Hopefully tomorrow after work I can give it a go. Iíll keep everyone posted! Thanks for all the help!!!
 
  #17  
Old 10-18-2018, 10:22 AM
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So, it's recommended to be at 14į initial? What did you have it set at? I can't see that limiting it from revving up past 1000 RPMs.

Either way, have you broken in the cam yet? How'd everything go?
 
  #18  
Old 10-18-2018, 01:10 PM
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Initially I had it at 10 degrees. I ran it last night in an attempt to break it in but unfortunately it didnít seem like it really wanted to run that well. It will rev well past 2,000rpms but it just doesnít seem smooth. The engine temperature also seems very hot, so much so that my temporary flexible exhaust pipe was glowing red. The temp gauge stayed in the middle but I wasnít feeling too confident. The engine would also diesel after I shut it down.

Im really at a loss. It just doesnít seem like it runs like it should.
 
  #19  
Old 10-18-2018, 01:12 PM
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Yikes, yeah, glowing red hot is usually something to do with timing.

Are you certain that your crankshaft and camshaft gears are lined up properly?
If they're a tooth off, that can really upset your valve timing. There's no way to fix it without taking your timing chain off and setting it right.
 
  #20  
Old 10-18-2018, 03:09 PM
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Iíve been thinking that Iím going to have to do that, as much as I donít want to. I installed a brand new comp timing set with the cam, I took my time but itís my first build so anything is possible.

It still back fires through the carb periodically so I still have a timing gremlin somewhere. I appreciate all your help!
 
  #21  
Old 10-18-2018, 03:44 PM
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If you can't rev it and you're getting a back fire, even with your static timing set correctly, you almost certainly have an alignment issue between your cam and crank.
It sounds like your valves are opening and closing incorrectly in relation to the position of the piston, which unfortunately you simply can't fix without pulling the timing cover off.

This is why I take a picture of my timing gears (the 300 doesn't have a chain) when I put them together, so if I have any doubt, I can refer to it and assure myself it's right (or know that it's wrong).



It sucks to pull something back apart that you just finished putting together, but unless someone else has some other theories, that sounds like that's what you're up against.
 
  #22  
Old 10-18-2018, 07:38 PM
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Youíre right. That is the only logical step at this time. Iím hoping I do find timing a tooth off, that will at least explain what has been happening. Iíll keep you posted.
 
  #23  
Old 10-20-2018, 11:37 AM
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disconnect the vacuum hose to the vacuum advance before trying to set the timing. depending on the port its connected to or how high the idle is set it might be getting vacuum and that advancing the timing affecting your initial setting.
 
  #24  
Old 10-21-2018, 07:36 AM
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Iíve actually been running it with vac advance disconnected and all ports capped.

I removed the timing cover and everything looks good as far as cam/crank timing. I havenít been able to check timing with a light because Iíve been so consumed with making sure I donít damage the cam but I think at this point Iím just spinning my wheels.

Im also wondering if I have a manifold vacuum issue but I donít have a gauge to test. I hope I can get to the bottom of this soon!
 
  #25  
Old 10-22-2018, 08:59 AM
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For the most part you still need to actually set the timing before cam break in as it doesn't take very long to do. If you haven't checked it then it could be way off.
 
  #26  
Old 10-22-2018, 12:38 PM
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what carb are you running? if its a Holley, could the PowerValve be shot? is the cam stock?
 
  #27  
Old 10-22-2018, 01:23 PM
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Carb is a new Edelbrock 1406 600cfm carb.

This is might be a dumb question but setting timing before cam break in requires me to set at idle correct? Youíre saying the few seconds it should take to set at idle shouldnít have a negative impact?

Also, any tips on how to get throttle response quicker when initially starting? What I mean is the electric choke will obviously be choking the carb since itís relativeky cold out, applying throttle is flooding the engine.

Sorry to seem like such a newbie but this is my first engine build.
 
  #28  
Old 10-23-2018, 01:43 PM
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with vacuum advance plugged the motor wont rev very high because the timing isnt advancing. so get timing set, then plug vac advance in and see how things go.
 
  #29  
Old 10-24-2018, 05:09 PM
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turn on the key and wait a little before starting it and it wont be so rich. if you leave it on the high idle cam for the choke and adjust the timing while its running without a light get it to smooth out and see if you can get it up to about 1500 and leave it like that for 15-20 mins. just keep an eye on the water temp and let it finish breaking in. if you can get it closer to 2000 than that's better. after that your done and then you can figure out the other problems. make sure the electric choke has power when you turn on the key to run.
 
  #30  
Old 10-24-2018, 05:28 PM
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Well, at least you know it's not your cam/crank timing.


You're right in that you want to be extra careful with the cam until its broken in.

What ignition system do you have? Depending on the system, you can set the base timing with the engine off.
Generally, you just rotate the engine until the timing mark points at the advance you want. Like 10į advance. Then pull the distributor cap and make sure everything's lined up correctly with the #1 spark plug post. This'll start your engine up at 10į base timing.

Don't worry about the vacuum advance for now. Unplug it and cap it off if you need to. Many engines don't even have vacuum advance, and it's really only for gas mileage. It will not affect your engine at idle in any noticeable way.

When I broke my cam in last year, I had a helper fire it up, and then I turned the idle adjustment screw in until it rested at 2000 RPMs. Then, for the next 15 - 20 minutes, I sat in the cab and just feathered the throttle around to bounce between 2000 and 2500. But, having the idle screw turned in made it so that I could never drop below 2000.

There isn't sufficient oil flow below 2000 RPMs to properly break in a cam.

What is your choke wire hooked to? If it's the stock position on the alternator, then it won't start opening until the engine is actually running (desired). If its' just a 12v source then yeah, you can turn on the key and wait a few and let it open up a bit. You can also leave the key on for a while to double check that your choke is working and opens up all the way.

Either way, if your timing is at least close (anywhere between 5 and 15 advance base timing is going to be fine for breaking it in), and your choke opens, there should be no reason you shouldn't be able to get it over 2000 RPMs if you keep giving it throttle.

Last but not least..... Are you sure that when you press the gas pedal to the floor that it's opening your carb all the way? It's possible that if you have an issue with your linkage that pushing on the gas pedal is only giving it just a little bit of throttle.
 

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