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Ignition Or Fuel ?breaking Up Car???

S

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Feb 14, 2009
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IM HAVING PROBLEMS WITH MY TIMING JUMPING AROUND WHEN I REV UP THE ENG.IT ONLY BREAKS UP UPSTAIRS IN HIGH GEAR NOT IN 1ST .I HEAT TIRES AT 7,000 NO PROB LEAVE ON BRAKE AT 7000 NO PROB PULLFROM 1ST@8500RPM TO DRIVE NO PROB... ITS A GLIDE JUST AS I REACH THREE QUARTERS DOWN THE 1/8 MILE MARK AT ABOUT400 TO 500FT AT 7900RPM IT STUMBLES REALLY BAD?EVEN WHEN I BACKDOWN ON THROTTLE TO SEE IF ITS A FUEL PROBLEM, STILLSTUMBLIN.. CHECKED ROTOR PHASE ITS FINE ,PUT NEW PLUGS SAMETHING.ITS A CRANK TRIGGER WHEN CHECKING TIMING MOVED CLAMP AWAY FROM CAP AND WIRES STILL RETARDS. CHECKED ALL VALVE SPRINGS STILL THE SAME..MOTOR HAS 15 PASSES ON FRESHEN UP ITS DRIVING ME CRAZY, ITS A 7AL2 .COULD IT BE A COIL OR MAGNETIC PICKUP FOR CRANK TRIGGER??THE WIRES I NEED TO CHANGE NEXT. THEY BEEN ON AWHILE BUT NO SIGNS OF ANYBURNT UP.1050 DOMINATOR W/ 95 JET Q 16 FUEL ITS A 420 CI 18 DEGREE 14 CR SBC.MY FUEL PRESS IS AT 8LBS ON GAUGE UNDER THE HOOD I NEED TO MOUNT A GAUGE ON THE HOOD TO SEE.. PLEASE ANY ADVICE BEFORE I BURN IT.:mad:
 
Coil Wire??

If the coil wire is the same age as the plugs wires, the first thing I would do is Ohm the coil wire because it get 8 time the use as the plug wires. MSD says 40 to 50 Ohms per foot.
 
thuston thats funny you say that before all this shit started the old wire that was going thru the firewall was bad. it was arching out on the fire wall an i changed it thinking it was over, but its not after i changed it, it stopped sparking under dash.so as for the coil wire i did change it and stopped it from sparking but mabe it hurt somthing else could it be coil or pick up still see timing moving around?? i guess i need to put fresh wires on and hope for the best thank you ...
 
Make sure your grounds are good. MSD might still have a schematic on recommended ground paths.
 
Make sure you have a ground wire going from the MSD box DIRECTLY to the engine--NOT to the frame or the firewall or anywhere else but DIRECTLY to the engine (preferably the head but the block will do to). Make sure you use AT LEAST #10/12 wire & solder the connector to the wire!!!! Make sure you clean the block or head GOOD !!!! NO rust ,paint,grease nothing but bare metal where the connector lug contacts the head!!!-Run a ground wire from the battery DIRECTLY to the engine TOO---MSD's get real touchy when you get into the upper RPM's like over 7000-7500 RPM---A good ground is of paramount importance--Next replace ALL your plug & coil wires EVERY season even if you only make 40-50 passes--The voltage these things kick out is phenominal!!!! You should be using at the bare minimum a 8MM wire NOTHING less can handle the resistance an give you enough voltage --Probably should have 11MM wire in there!!!! Too much of a chance for crossfireing--Keep the plug wires away from each other if you can that will help too--- Check the gaps in your plugs too---Nothing over .035!!! MSD's do not like large plug gaps either...Try it and see what happens--My .02 cents Comp 387
 
Speedy, after reading your post, you might want to invest in one of MSD's Firewall Feed-Thru. About $15.00 from Jegs. Even though it's a new wire you could still be losing voltage at the fire wall. The energy will take the path of least resistance and at higher RPM the cylinder preasure creates a lot of resistance, making it hard for the energy to jump the spark plug gap, which inturn makes it easier for engery to find a different place to seek a ground. I also agree with Dick, make sure your plug gap is .035 or less, I have never seen any performance gains using a wider gap. Good luck.
 
Guys i really appreciate all your help. for 1 i guess my gap is to much its at 48" but thats what ive always ran #2 i have to replace my old wires to 10mms also, i have no grounds even from block to frame and batterie is in the back.,also its a brand new 12 vt batt w/t no alternator. i had a 16 vt also w/o alt and didnt not even run any faster same speed.and a rubber grromet for firewall will be replaced should i try to change my magnetic pickup on cranktrigger? and cap oh 1 more thing my msd is mounted in my glove box could it be that it is not screwed to the floor? but i ran like this before i dont under stand. ill try everything you told me.still dont know why the timing is moving all over when i rev it up it retards..
 
You running a gear drive or a timing chain??? Timing chains will sometimes as they wear tend to retard the timing--even if they are new they miight stretch a degree or 2 and retard--When you set your timing do you rev the engine and hold it at say 5000-6000RPM and check it or do you set the timing at a lower RPM?---Comp387
 
Yep and hold it while you quickly check the timing DO NOT ZING the motor while checking the timing ----otherwise the timing WILL move on you-- retard as you accelerate the engine and advance as you let off the throttle!!! also check the advance plate in the distributor make sure nothing is loose that can mess your timing up too---Comp 387
 
Dick Ullrich said:
Yep and hold it while you quickly check the timing DO NOT ZING the motor while checking the timing ----otherwise the timing WILL move on you-- retard as you accelerate the engine and advance as you let off the throttle!!! also check the advance plate in the distributor make sure nothing is loose that can mess your timing up too---Comp 387
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i got ya. Going to put fresh wires/plugs on it tomorrow different coil,different mag pickup,cap rotor,also check the distributor gear. thank you very much on the help.ill let ya know how she runs this week.
 
Heres my .02...if the timing is moving all around, it is likely a misfire condition. With a crank trigger, any other wiring that is close to the wires from the crank trigger to the MSD box can cause a misfire, and that makes the timing jump around. I fought a similar problem for a year and solved it by isolating the crank trigger wires away from all other wiring and also using a shielded and grounded crank trigger cable that MSD sells. The 7al2 doesn't have any timing retard capability, so that should not be causing the retard, it may just be another misfire symptom.
 
Changed Cranktrigger Wire It Had A Burn On It . And Thr Blk Grnd From Box Was Stripped About An Inch Ifixed It And It Still Broke Up.so I Checked The Fuel Press It Was At 5lbs So I Increased It To 8 And The Track Was At The End Of Night Couldnt Mk Pass
 
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