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06-28-2014, 07:43 PM
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#1 |
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Registered User
Join Date: Nov 2013
Location: BC
Posts: 47
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Mid Range RPM miss
I recently put a 9:1 sbc race engine out of my circle track race car in my S10. Just working out the bugs, get it on the road and it runs good to 3500 then starts stumbling bad. Haven't seen what it will do past that range. This engine was built by a reputable builder at Tesar Engineering and has never missed a beat in my stock car. Once I get this figured out I can get back to the C10 build.
I am running a MSD 6al ignition that is relatively new but I am thinking this issue has to be ignition. I've played with timing, tried other Rev limiter chips, checked plugs to see if its running rich/lean (they look good), even thought I may not be getting enough power from alternator, grounds, etc. Anybody have experience with the 6al setup? Is there possibly a wiring issue to the box that is causing this? Or any other hints at what might be causing this. Pretty sure its not internal, just replaced valve springs and had it looked at as the guys who built it said it was time after a season racing with this engine. Thanks in advance.
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1967 Chevy short stepside 1982 S-10 1975 C-10 2wd Short box 2014 Silverado |
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06-28-2014, 09:08 PM
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#2 |
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Registered User
 
Join Date: Mar 2008
Location: tyler texas
Posts: 1,538
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Re: Mid Range RPM miss
Plug wires? Trash in a jet?
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NHRA Super Street 469C It only runs 10.90 at 156 mph |
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07-18-2014, 07:19 AM
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#3 |
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Registered User
Join Date: Dec 2010
Location: Arkansas
Posts: 608
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Re: Mid Range RPM miss
Valve spring broke?
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07-18-2014, 09:39 AM
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#4 |
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Registered Truck Offender
Join Date: May 2008
Location: hells training ground (aka Ariz)
Posts: 3,118
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Re: Mid Range RPM miss
It takes a lot of power to keep the coil happy at upper RPMs. You said there may be issue there,, it's a distinct possibility.
MSD will tell you first place to look for ANY ignition problem is GROUND, GROUND, GROUND!!!! Battery grounded to the engine block,, engine block grounded to the piece of metal that 6al is mounted on. It's kind-of a moot point if there isn't a solid 12v on the other side,, but always a good place to look.
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Still playin with trucks, even at my age! When you're dead, it's only a problem for the people around you, because you don't know you're dead. .....It's kinda the same when your STUPID. I just did my taxes and reviewed my SS statement. Thanks to the current administration it looks like I will only have to work till noon on the day of my funeral. |
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07-18-2014, 12:21 PM
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#5 |
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Registered User
Join Date: Nov 2013
Location: BC
Posts: 47
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Re: Mid Range RPM miss
I should have posted that I found the problem. My coil wire was arcing off the firewall. This is the second time a new coil wire has gone bad. Last time it was obvious because my pretty orange firewall had black marks on it. This time no such luck. Truck runs great now but it has broke another ujoint and this time the drive shaft was ruined.
Terry
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1967 Chevy short stepside 1982 S-10 1975 C-10 2wd Short box 2014 Silverado |
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07-18-2014, 10:08 PM
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#6 |
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Registered User
Join Date: Dec 2010
Location: Arkansas
Posts: 608
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Re: Mid Range RPM miss
Glad you sorted it out. Good luck with the drive shaft.
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07-19-2014, 12:33 AM
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#7 |
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At the body shop.
Join Date: Aug 2009
Location: Land of fruits and nuts.
Posts: 5,256
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Re: Mid Range RPM miss
Dad used to run an engine at night and look for for spark scatter.
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" That didnt make it any newer " " Dont antique the equipment " |
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