Engine Missing Above 5K RPM

[jackboxxx]

Did you check your fuel filter?

Ive got the clear glass filter, that has a replacable element inside, which i like for seeing whats coming from the tank, and yea once they start clogging you get a similiar miss. I just replaced the element a couple hundred miles ago

shortly after this problem started thinking the same thing you did.

thanks,

JacK

[jackboxxx]

Next time you try it with sub standard componets

email me at smokingwheels@yahoo.com

well because i ended up with 2 flat batteries in 2 cars

the time frame is too close

PS I have a 40 amp charger home made hmmm 2000 va transformer

was rated 20 volt 20 amp until i removed a few windings

hmmm 2000 va @10 volts ~199.2 amps is this correct?

no wonder i can arc weld the jumper leads

however blows the rectifiers up, out of sum old altnator

Was your Flux Capacitor fully charged at the time? and what rating resistors

were you using? most people screwup and use the 720 ohm.

JacK

[jackboxxx]

Unless I misread you dident say what carbs you are using . I tried a RX-7 fuel pump on a stroker with tripples, Mikunis , no regulater needed and it supplied with no problem all the way to redline. I am running the same pump on my Z running a pair of SUs again no regulater. Also the pump is quiet and pumps 4psi. Have you checked the float levels , if you are running SUs. For other carbs I can't be of any help. Shooting ducks at 5K and above could be caused by running lean , however if he float levels check out , see if any of your friends have a '79-80 ZXdist and coil . I have one and have never experienced any missfire at speed . In my openion counting on a 30+ dist having a true running shaft is expecting a lot , at the Rs you are turning . Thats my 5c . Gary It was 2c but with the cost of gas I have to charge more.

Sorry, Im using 50mm SU's, stock pump at the moment, what does a stock fuel pump put out in pressure anyway? no I havent checked the floats,

I did just richen the carbs a couple days ago by 1/2 turn because it did seem to be running a bit lean. as for my distributor its been professionally re curved

and is nice and tight maybe moves 10 1000ths. its pretty straight.

But besides all that stuff, I went out yesterday, and found out this misfiring is only happening when my headlights are turned on....see I usually only drive my car late in the day, becasue its so dammed hot out here..im about 40 miles or so from palm springs. point is, half the time im out driving, it gets dark enough for lights, and it never occured to me turning the lights on was related till yesterday. So,, I tired tearing out all my front lighting, refurbished all the harness's looking for maybe some wire intermittinly grounding or something. once all was reinstalled, the same thing was happening,the instant i turn the lights on above 5k rpm. feels like the lighting is robbing the ignition system of needed power to fire properly. what do you think?

[beandip]

When you ask about the stock pump , are you talking of the electric or manual ? No matter they pump under 5psi. Question , are you still running seald beam head lights or H-4 s ? What condition is the battery in , full charged , some what discharged ? This may sound like stupid questions but we need to eliminate a few things here. Check the tention on the v-belt to the alt. If loose it could be slipping under load . Where I live the daylight hours are deminishing to the point that more and more driving is with the lights on. A loose belt could cause the battery to be discharged to the point that the miss could be from a weak spark. You did say that you had the ignition coil tested , right? O , I started to ask about the h-4 s . If you havent up graded the wireing to the head lights and are running H-4 s this could be part of the problem . But not likely all of it. Just for the heck of it , if you have a batt charger , hook it up and let it charge for a few hours or over night . Then drive it and turn on the lights and see what happens . No more shooting ducks ! then you found the problem . Still does it , we keep checking. Doing this is free so try it before throwing money at it. Another thing if the float chambers run dry or just starting to . This also will cause this high end missing. Did you feel the quakes today ? I received notices of 9 seprate shakers since yesterday in your area. all around 4.5 Gary

[ezzzzzzz]

Interesting the the problem seems to be headlight related. Sounds like a simple drain on the ignition system. H4 or not, I'd look at every connection and ground ...every one! Remove, clean and replace. To test, prior to this PMS (preventative maintenance service), you could run a wire, with a switch, between the ballast resistor and battery (disconnect the hot lead to the ballast, from the ignition, and tape it off the prevent a short). Double check the wiring to the coil and distributor (clean these connections good). Ensure the chassis to ground and/or battery - to engine block is clean and tight. Turn the switch to 'on' and start the car. Take it for a spin with the lights on and pushing the rpm's. If the miss is gone then you've got your answer. You'll have to use the switch to kill the engine after the run. The plugs wires breaking down could cause this as well but you'd probably feel this at lower rpm'stoo. On that note, open the hood in pitch darkness and look for the blue aura down the spark plug wires. If you see a glow anywhere but at the base of the plugs the insulation is failing causing crossfire or reduced spark at the given plug(s). If so, replace the wires.

[jackboxxx]

When you ask about the stock pump , are you talking of the electric or manual ? No matter they pump under 5psi. Question , are you still running seald beam head lights or H-4 s ? What condition is the battery in , full charged , some what discharged ? This may sound like stupid questions but we need to eliminate a few things here. Check the tention on the v-belt to the alt. If loose it could be slipping under load . Where I live the daylight hours are deminishing to the point that more and more driving is with the lights on. A loose belt could cause the battery to be discharged to the point that the miss could be from a weak spark. You did say that you had the ignition coil tested , right? O , I started to ask about the h-4 s . If you havent up graded the wireing to the head lights and are running H-4 s this could be part of the problem . But not likely all of it. Just for the heck of it , if you have a batt charger , hook it up and let it charge for a few hours or over night . Then drive it and turn on the lights and see what happens . No more shooting ducks ! then you found the problem . Still does it , we keep checking. Doing this is free so try it before throwing money at it. Another thing if the float chambers run dry or just starting to . This also will cause this high end missing. Did you feel the quakes today ? I received notices of 9 seprate shakers since yesterday in your area. all around 4.5 Gary

*I meant the mechanical one.

*Im running sealed beams sylvania "performance" from kragen auto.

*the battery is about a year old, its a die hard, its never stranded me, always cranks strong has never given me any reason to think its not holding a charge I drive the car 10-20 miles daily.

*new cables as well.

* 1500 miles ago, i replaced the belt, then this week i replaced the alternator

which required me to readjust the belt, and i did check it today, its nice and tight.

*I replaced the ign coil because the one i had is not rated for over 6500 rpm

so i bought a MSD blaster coil. its only a couple weeks old.

*I dont think its the float chambers only because of the uphill testing I did,

I sprinted up a long grade of at least 2 miles, the car pulls hard all the way to 5k rpm, then sputters...but if i keep it under 5k, itll go up hill all day. ((i was told by a good mechanic that if you are not getting enough fuel once it begins to sputter or die from lack of fuel itll keep doing it through the gears

i can race up to 5k, shift race up to 5k...etc etc no problem. the uphill part creates much more load on the engine thus using more gas.

im going to focus on the headlight issue i think..perhaps ill do the rewiring

thing so they get thier power directly from the battery...

[jackboxxx]

Interesting the the problem seems to be headlight related. Sounds like a simple drain on the ignition system. H4 or not, I'd look at every connection and ground ...every one! Remove, clean and replace. To test, prior to this PMS (preventative maintenance service), you could run a wire, with a switch, between the ballast resistor and battery (disconnect the hot lead to the ballast, from the ignition, and tape it off the prevent a short). Double check the wiring to the coil and distributor (clean these connections good). Ensure the chassis to ground and/or battery - to engine block is clean and tight. Turn the switch to 'on' and start the car. Take it for a spin with the lights on and pushing the rpm's. If the miss is gone then you've got your answer. You'll have to use the switch to kill the engine after the run. The plugs wires breaking down could cause this as well but you'd probably feel this at lower rpm'stoo. On that note, open the hood in pitch darkness and look for the blue aura down the spark plug wires. If you see a glow anywhere but at the base of the plugs the insulation is failing causing crossfire or reduced spark at the given plug(s). If so, replace the wires.

Ahhh i like this test good idea. but i started doing the headlight rewire thing tonight before I read this so...i gotta finish that up 1st.

[beandip]

when you find the cause please let us know . I think it would be a good idea to check the float leavels This is simple and costs nothing , just increase the volume just a little and see it the problem is better .

[jackboxxx]

yep i will indeed, hopefully ill figure it out over the weekend and let you all know.