i got a 351w with brand new edelbrock 600 cfm..got year old plugs and wires..new coil...it had been running fine till the other week develop a miss..but sometimes it dont miss..not a bad miss but it is there ..could it be the rotor or cap?..they dont look bad...bad plugs foul out?...i hope it is not that new carb...thanks for any help

 

pull a plug and take a look at it, maybe your carb needs a slight mixture adjustment. Also, check for leaks around carb-to-intake. I spray starting fluid around the carb base to check for those hard to find leaks; if the engine revs up when you spray the fluid, you have a slight leak. A small leak may have appeared due to the expansion, and break in of new parts/gaskets. One more thing, check for any vacuum lines that may have come off, or are cracked and leaking.

 

Test your ignition module at the parts store, it's free!

 

....well already have got that covered owning a ford like this..got a new on the truck and a spare one i keep with me..so i am pretty sure it is not that...

 

Then try swapping the spare in. Have you had the spare module tested?

I always use MotorCraft modules, the aftermarket parts store modules can/do fail at a moments notice, so new or not, it may be bad.

 

My 77 400 kept missing on and off. The pick up in the dizzy was loose.

 

...yes i have done swap them..must be something else

 

ok let me see if someone might would know what might be wrong..it is 77 ford 351w engine..i just put a new edelbrock carb on there a few weeks ago..but after that is was running fine..i have checked and replaced the ignition module,new plugs and wires,new distrib cap and rotor,new coil,...but it started off like a miss a little here and there..now it is missing worst..especially uphill or in load..i have no idea what else to do ..

 

maybe assumed, but new fuel filter with carb?

 

I changed the title.
The "truck isn't missing"...... the Engine still has a miss in it.

How many miles on it?
Perhaps is has:

1) A Vacuum Leak

2) A Worn Push Rod(s) & Rocker arm (s)

3) Bad Wire

4) Mis-firing Plug

There are many mechanical components to consider.

 

Take the dist. cap off and see if the pick-up is loose.

 

ok i am no mecahnic ..but i took the distr. cap off and looked i dont see where nothing could be loose in there..the pickup that you talk about that is the little blue box on the side of the cap has two wires coming from it?..it all seems tight...new rotor and cap installed..plugs..wires..fuel filter and air cleaner..

 

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.well i have new wires on it..replaced them one by one to see if that was it..new plugs also..the plugs is really what i thought was it..but was not..i put a new air cleaner and fuel filter..on guy on here said the pickup inside the distrib cap to check if it was loose..i looked inside it but could not see or feel anything loose ..i really dont know..


..oh yeah one thing i did notice like this morning when i change the wires..on it i drove it to see if it would miss..it drove fine..but went up the road like a mile or so..then coming back going up the hill it started to miss again...it kinda was doing this a little every now and again..not it has got a lot worst



Originally posted by 79 posi
maybe assumed, but new fuel filter with carb?
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..yeah installed new fuel filter and air cleaner..like when i crank it up this morning it ran fine..went up the road about a mile or so..turn around come back and started to miss..seems got home mess with some stuff check wires stuff like that..then drove it a little more less than a mile..it started to miss so much did not thing it was going to go up the hill..when i got home and put it in park it runs fine..

 

I think you missed what I was meaning.

Just because something is NEW, doesn't mean it can't be faulty.

I have seen many spark plugs that were faulty.
Way too many people assume that because they just came out of a box that they are great.

Wires can go faulty too.

Did you buy a cap that has aluminium contact or Brass ?

Brass are more rare, but they are better than Alum.


Have you tried looking under the hood at night?

Have you used a spray bottle (a mister) and sprayed water to see if there are sparks going to ground?

 

..well you are right about faulty new stuff..but the distrib cap is the good kind with brass ...guess it is just a lot of replacing stuff