1970 Ford 390
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1970 Ford 390
I just built a 390 for my 1970 F-100 PU. I had the heads ported and a Crane 343901 cam put it. The cam has a much higher lift than stock. The truck really runs great, but I have a miss at 1600 RPM when the engine is not under a load. I have timed and retimed and cannot seem to get rid of it. Everything from the coil to the plugs is brand new. My point gap is set at the stock non-emmission setting of .017 and the plugs are at .032. Do I need to change these settings because of the cam? Also, there are only 500 miles on this engine and it has a mild lifter tick that is loudest from 1500 to 2000 rpm. Should I have shimmed the rocker arm assemblies to make up for the tall lift of the cam? This is my first rebuild project and could use some input.
Sam
Sam
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Joined: Jun 1999
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1970 Ford 390
Make sure your collapsed valve lifter lash (off lobe)is somewhere between .060 and .090 inch. If it is more you will have to get a longer pushrod. They are available in plus or minus .060 sizes. Another alternative for more $ is to get an adjustable pushrod or rockerarm. You can locate the noisy lifter by taking off your valve cover and listening with a length of tube at each rocker. Not real sophisticated but it works well. Good Luck
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1970 Ford 390
I had an FE engine in a T-bird years ago that developed a vibration that I thought was a miss. Investigation found I was getting too much timing advance at midrange on and that was setting up a strange vibration. Good luck,
ray
ray
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1970 Ford 390
Sam,
....and I had a (what sounded/felt like) an engine miss at low RPM,and it was noticeable enough to prompt me to search for the problem over and over again, to no avail. It wasn't until I pulled off the dist. cap and turned over the engine with a wrench and socket (ignition off, please, trans in neutral!!) It wasn't until I had the crank pulley position at TDC and the rotor pointing at #1 firing position that I realized just how out of phase the rotor was with the distributor cap! 6 to 8 degrees BTDC timing setting doesn't have the rotor pointing *that far* away from the center of the cap post for #1, and my problem turned out to be cross-firing. Once I set the rotor right in relation to the dist. cap post, everything has been running fantastic since.
CW
....and I had a (what sounded/felt like) an engine miss at low RPM,and it was noticeable enough to prompt me to search for the problem over and over again, to no avail. It wasn't until I pulled off the dist. cap and turned over the engine with a wrench and socket (ignition off, please, trans in neutral!!) It wasn't until I had the crank pulley position at TDC and the rotor pointing at #1 firing position that I realized just how out of phase the rotor was with the distributor cap! 6 to 8 degrees BTDC timing setting doesn't have the rotor pointing *that far* away from the center of the cap post for #1, and my problem turned out to be cross-firing. Once I set the rotor right in relation to the dist. cap post, everything has been running fantastic since.
CW
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