1974 D100 440 misfiring at 4500 rpm
#1291229
08/25/12 04:43 PM
08/25/12 04:43 PM
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Joined: Jun 2012
Posts: 35
karmakritters
OP
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OP
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Joined: Jun 2012
Posts: 35
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Hello, I am new here and really need some help. The truck has a 1971 440 with flat top forged pistons,forged crank,LY rods, lunati 509 lift cam,516 heads ported with 2.14/1.74 valves, edelbrock performer intake and a holley 800 mechanical secondaries carb.
So far I have changed plugs,wires,distributor,cap,rotor, fuel pump,carb, still starts popping at 4500 rpm no matter what I try. I have also disconnected the gas tank and ran the fuel pump from a clean container hoping it was a tank issue to no avail. The timing is at 10 degrees advance at idle and pulling to about 35 degrees total at 3200 rpm. Thanks in advance, Sam
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Re: 1974 D100 440 misfiring at 4500 rpm
[Re: karmakritters]
#1291232
08/25/12 06:59 PM
08/25/12 06:59 PM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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Either rotor phasing or fuel delivery. Caps and rotors are carbon copies and will not change rotor phasing. Having no vac adv makes it easier to sort out. Generally running the car up thru the gears if it is ign it will miss in all 3 gears at the same LOAD and RPM. If it's good at 4500 in 1st and 2nd then acts up in 3rd that points to fuel delivery as it takes time for the need to outstrip the delivery unless the fuel delivery system is EXTREMELY inadequate which I do not think is the case here. Whereas an ign miss will happen at the same load/rpm no matter what gear you are in. I'm thinking fuel but if need be drill the hole in the cap & check rotor phasing at idle. Ign sub issues; MAY need a rotor with a .060" longer blade NAPA Echlin MO3000 which helps some with phasing issues(& we can fix phasing directly) and check ECU ground and pickup gap but first let's pin it down to ign or fuel
live every 24 hour block of time like it's your last day on earth
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Re: 1974 D100 440 misfiring at 4500 rpm
[Re: karmakritters]
#1291234
08/25/12 07:53 PM
08/25/12 07:53 PM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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Yours must have a vent hole. Not sure where it is located. You want a seperate drilled hole in the roof flat 2/3 of the way between the center terminal and the #1 plug wire terminal so you can look down & see if the rotor metal blade is pointed too far in front of or behind being dead even with the metal cap terminal around the circumference while running using the timing light
live every 24 hour block of time like it's your last day on earth
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Re: 1974 D100 440 misfiring at 4500 rpm
[Re: karmakritters]
#1291235
08/26/12 08:30 AM
08/26/12 08:30 AM
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Joined: Jan 2003
Posts: 5,894 Florida
Locomotion
master
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master
Joined: Jan 2003
Posts: 5,894
Florida
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You didn't say which ignition system you are using. If it's the Mopar style with an ignition box (OEM/Orange/Chrome), try another "known" good one. I've seen a couple of the Chrysler style boxes act like rev limiters.
Not sure if other brand boxes can malfunction in a similar manner.
Do you recall if it started after you changed anything? Always run 35* timing? Different brand fuel? Change plugs? (Oops, nevermind on the plugs!)
Last edited by Locomotion; 08/26/12 08:43 AM.
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Re: 1974 D100 440 misfiring at 4500 rpm
[Re: karmakritters]
#1291239
08/27/12 09:29 PM
08/27/12 09:29 PM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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To the right (clockwise) of #1 would be the #2 terminal & we're still missing something as it would not run if it was that far off & if the drilled hole is between the center & #1 you would not be able to see the rotor blade that far off & tell that it's in the middle unless I'm missing something.
live every 24 hour block of time like it's your last day on earth
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Re: 1974 D100 440 misfiring at 4500 rpm
[Re: karmakritters]
#1291256
12/05/12 08:52 PM
12/05/12 08:52 PM
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Joined: Nov 2003
Posts: 36,040 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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10/35 is conservative timing more so the 10 especially with no vacuum advance. Make a mark on your dampener at 2&7/32" clockwise from the TDC slit to verify you are at 35 total. If good there I'd get the TDC tool & install it in the #1 plug hole & verify that the TDC slit is correct but I imagine it will be as dampener slippage is rare. Sure sounds like too much timing though. EDIT I reread the posts & it WAS running OK at one point with this timing correct? I was thinking the cam could be machined wrong but that is rare & I always want to k.i.s.s. but same deal it ran OK prior with this cam/timing. Something ain't adding up
Last edited by RapidRobert; 12/05/12 09:09 PM.
live every 24 hour block of time like it's your last day on earth
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Re: 1974 D100 440 misfiring at 4500 rpm
[Re: karmakritters]
#1291258
12/05/12 10:46 PM
12/05/12 10:46 PM
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Joined: Jun 2003
Posts: 4,872 connecticut
pnypwr
master
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master
Joined: Jun 2003
Posts: 4,872
connecticut
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did you change the ignition box? I had a pertronix that did that to me. i run msd in everything and can count all the problems on oh wait ive never had a problem with an msd!
"Are you gonna bark all day lil doggy? Or are you gonna bite?"
05 ram 2500 ctd 74 gremlin x 360 65 mustang 347 70 coronet R/T 440 03 Mach 1
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