missing at part throttle

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jivemother33

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having some problems ,i got a miss at part throttle , thought it was a carb problem ,tryed new one not it ... this is what i got

69 340
msd 6 box
new wires new plugs
mopar electric dist.
new cap and roter
headers
eddy air gap
holly 750 vac sec.
904 4.10 in the rear
electric fuel pump timing at 15 inital

my problem just happen it stumples at first quarter of pedal at wot it seem to be fine it get with it but at crusing speed it misses. in park holding it at a steady rpm like 2500 u can hear the miss and feel it ,kind like a flutting. any one got any ideas ?????
 
Does it maybe have a cracked plug?(but you said you replaced the plugs) Is you charging system working good? I have seen MSD's fail with a weak charging system? Sure sounds electrical maybe a faulty MSD box too. Do you have a standard distributor you can check it with?

jivemother33 said:
having some problems ,i got a miss at part throttle , thought it was a carb problem ,tryed new one not it ... this is what i got

69 340
msd 6 box
new wires new plugs
mopar electric dist.
new cap and roter
headers
eddy air gap
holly 750 vac sec.
904 4.10 in the rear
electric fuel pump timing at 15 inital

my problem just happen it stumples at first quarter of pedal at wot it seem to be fine it get with it but at crusing speed it misses. in park holding it at a steady rpm like 2500 u can hear the miss and feel it ,kind like a flutting. any one got any ideas ?????
Click to expand...
 
Poor engine or MSD box ground maybe. Yep I've cracked a plug before too (shh...don't tell anyone). What's your fuel pump regulator pressure set at? Should be no more than 7 psi, 6.5 is perfect for a Holley. I only run 7 if I'm running N20. 5 psi is too low.

What coil are you running? Are you using a ballast resistor? Shouldn't need one with the MSD. You didn't weld anything on the car with the MSD installed did you?

Are the basics good? Compression even across the cylinders?

Hope this helps.
 
never had a regulater never had a problem till now .i got a blaster 2 coil . i will check compression tommorow but if there was an problem how come at WOT it pulls hard thats what has me stumped ? and my charging system is working great
 
If the fuel pressure is set too high, you may be running rich under no load/light load conditions, but at WOT you're engine is getting the fuel it needs with no chance of overriding the needles and seats. Know someone with a fuel pressure gauge? What electric pump are you running?
 
Are you seeing black somke when it's missing? One more thing, have you checked the reluctor to pick up clearance on the distributor? It may not be correct even if the distributor is new.
 
Blaster2 coil is fine. You do have it mounted vertically right? They rely on oil to cool them and can't withstand horizontal mounting for very long unless you are using the "vibration proof potted" style Blaster.

Pardon the "multiple post whoring" but I think in chains.
 
coil is vert. trry to check fuel pressure today never check the pick up in the dist. what should the gap be set to on the pic up?

i like the multiple post i got a short attention span anyways lol....
 
.006" - .008" and use a brass feeler gauge. You should be able to pick up a brass one for a couple bucks at a Chokers or Auto Bone.
 
found out what my problem was .... gap on my spark plugs lol never checked them they were set at .oo28 put them to .0040 runs like a champ!!!! thanks for all the info
 
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