Debating on buying a used 390 for my 74 F100 Project

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  #16  
Old 06-25-2018, 03:59 PM
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So, one thing I thought about today at lunch... I do not own a compression tester.

No big deal, I still have lots of time before I get home from work. Searching on Amazon, I see many kits ranging from $25 - $75. What is everyone else using?
I have no problem spending money on a quality tool, but I also understand not always spending top dollar on something that will not see much use.

Looking for input, what are your thoughts?

Thanks in advance.
 
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Old 06-25-2018, 08:25 PM
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The big parts chain stores down here rent that stuff out. Might look into that.
 
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Old 06-25-2018, 09:29 PM
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It's not just a compression test you need to do, you need to run a 'leak down' test to make sure your not leaking through a valves (intake or exhaust). Where is the popping noise coming from, EFI or exhaust? The idea of pulling one plug wire at a time and replacing it each time before you move on to the next one,,, is a good start. Than you know its popping under ignition. At least you'll know where to focus on when doing the 'leak down' test.
 
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Old 06-25-2018, 10:29 PM
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I was reading about the leak down test today. Seems like the compression and leak down test are pretty good diagnostic tools.

Most of the popping comes through the exhaust, but every now and then it will come through the intake.
 
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Old 06-27-2018, 12:34 PM
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I watched a mechanic pull the wires off one at a time to find where the miss was. I had a miss in my 69 SS350 Camaro, and I tried that pull the wire off and it sounded like some one fired a 30-06 in my ears, my fingers were num and blacken and the neighbors came out to see what happened and all they saw was me holding my hand and teaching them all some new language.
 
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Old 06-27-2018, 01:29 PM
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Originally Posted by Tex51
I watched a mechanic pull the wires off one at a time to find where the miss was. I had a miss in my 69 SS350 Camaro, and I tried that pull the wire off and it sounded like some one fired a 30-06 in my ears, my fingers were num and blacken and the neighbors came out to see what happened and all they saw was me holding my hand and teaching them all some new language.
I have had a bad experience with distributors and plug wires. I know it may be a tried and true method of diagnostic, but it will not be one that I perform. I will find other ways to figure it out.
No disrespect for those folks it works for, it's just not for me...
 
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Old 06-27-2018, 02:21 PM
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They made a set of insulated spark plug wire pliers for that years ago.
The newer electronic ignitions are hotter with the spark jumping farther increasing the chances of getting bit when pulling the wires by hand.
Was working on a brothers HEI Chevy once, told him to get me a screw drive I could use to lift the wires with, didn't notice he'd handed me one with the steel shank extending thru the handle
Man that thing lite me up when he started the engine.
 
  #23  
Old 06-27-2018, 02:24 PM
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Originally Posted by Destroked 450
They made a set of insulated spark plug wire pliers for that years ago.
The newer electronic ignitions are hotter with the spark jumping farther increasing the chances of getting bit when pulling the wires by hand.
Was working on a brothers HEI Chevy once, told him to get me a screw drive I could use to lift the wires with, didn't notice he'd handed me one with the steel shank extending thru the handle
Man that thing lite me up when he started the engine.
The secret is to make sure none of the rest of your body is touching the car (grounded) And not be standing on a wet floor.
 
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Old 06-27-2018, 02:58 PM
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Originally Posted by baddad457
The secret is to make sure none of the rest of your body is touching the car (grounded) And not be standing on a wet floor.
Figured there was a secret...

I was bit hard enough when I was younger, that I adjust timing with a wooden dowel, I refuse to touch the distributor when the engine is running. Yep, chicken I are...
 
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Old 06-27-2018, 07:42 PM
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Originally Posted by AK FORD GUY
Figured there was a secret...

I was bit hard enough when I was younger, that I adjust timing with a wooden dowel, I refuse to touch the distributor when the engine is running. Yep, chicken I are...
You and me both ! I won't touch one unless absolutely necessary while running. Especially a Duraspark setup. I've seen them throw a spark 3-4 feet.
 
  #26  
Old 06-27-2018, 08:50 PM
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It's all in how you do it. You first pull the plug wires off and stick them back on so just the boots hold the wires in place but still make sure they are pushed on far enough so the wire is touching the plug tip. Do this with the motor OFF. The tool you need is a long handle spark plug plyers. You can get them at your local Harbor Freight. If your still a little shy, use a pair of those long rubber gloves like the ones you use for your parts cleaning tank.
And YES I've been zappppped a few times but I quickly learned over the years what works.
 
  #27  
Old 07-11-2018, 05:16 PM
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I just got my younger brother and he did it once for me and then I had to find another volunteer. I do not remove any plug wires unless the motor is off and I have the keys in my hand.
 
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