chasing down a miss

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Nov 9, 2003 | 12:52 PM

HiDesertRat

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Mountain Pass

Joined: Aug 2003

Posts: 143

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chasing down a miss

For all you gutter heads, this is a miss in the engine; not a miss as in young lady!

I have a 460 which we just rebuilt and is seems to have a small miss during idle. I also noticed it when going down the road at normal speed.

In my searching, I removed one wire at a time to see if I could notice any differance in the idle of the engine. With this big engine, I wasn't able to really tell much of a differance, so decided to try two wires at a time. I just found it interesting that I could remove every other wire on the dist. cap and the thing would still run without much of a differance in the idle!

What is a good way to determine if one of the sparkplugs is not firing? I am thinking of removing four (everyother one) and than one at a time for the other four. Once that is done, remove the other four (every other one) and check the remaining ones. Just thought there may be an easier way. Getting tired of getting zapped by stray sparks from the dist. posts!

Nov 9, 2003 | 01:39 PM

locknkey

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Joined: Sep 2003

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From: Right Next to U

Use a Timing light on each plug...you'll find the miss easy.

Nov 9, 2003 | 01:58 PM

HiDesertRat

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Mountain Pass

Joined: Aug 2003

Posts: 143

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See there, I knew there was an easy way to do this! I am going to assume, if the miss is on that plug I will not have any light on the timing light. No current flow, no inductive pickup....no light.

Is it normal for this engine to run well on four plugs?

Nov 9, 2003 | 02:12 PM

plowpusher

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From: lino lakes, mn

try loading it in gear with four plugs diconnectedthe killing part is normal check idle mix to ythat will show as aslow speed/idle miss to the best way to check pug wires is under load have a partner hold the brake stand off to the side and pull plug wires look for a vacum leak to

Nov 9, 2003 | 02:49 PM

locknkey

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From: Right Next to U

It will miss even while its in park with the motor rev up....its a real good way to find a bad plug or wire....

Nov 9, 2003 | 10:41 PM

motorheadmach1

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Joined: Apr 2003

Posts: 159

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From: nowhere town nj

i had amiss in my 302 efi that i couldnt find doing an elimination test at idle because of how the motor ran. my service manager at work told me to put it in gear and put a little gas to it to put aload on the engine, thre was a big difference with every wire and one of them didnt make a diference at all. that was the miss. to check plugs just switch plugs out.

Nov 10, 2003 | 12:12 PM

HiDesertRat

Thread Starter

Mountain Pass

Joined: Aug 2003

Posts: 143

Likes: 2

Thanks guys, I should have the truck back in the yard later this week... the owner has it now. I will take a shot at the timing light method. It is a standard, so applying a load will be a bit more complicated, but I am sure we can do it...If I can trust the owner with clutch control!!!

I am beginning to think it may be a misadjusted carb. Is there any good method to adjusting the carb? It has a four barrel with two mixture screws at the base. I adjusted them by going back and forth until the engine sounded good, but maybe there is a better way. I seem to remember there was a way of doing this with a vac. meter hooked up, but can't find anything in the books I have. Any ideas here?