Posted: Sat Dec 10, 2016 12:09 pm Post subject: 911 SC - loosing power over 3k revs PROBLEM SOLVED
Car pulls very well up to 3k revs, then seems to loose power.
seemed to be great when first purchased in October 2016. But did have one ht lead snapped going into dizzy cap, which caused bad idle and bad running below 2.5k revs. Run really well in the high rev range though.
Replaced the leads with brand new beru type, although seem a loose fit on the new plugs. Would this be a problem?
Replaced spark plugs with iridium denso type
Replaced dizzy cap with beru type.
Replaced rotor arm
Replaced air filter.
Lower rocker covers are original type and are leaking, I haven't done a compression test yet. Only been doing a coupe of hours work to the car on weekends. Will be replacing the covers with turbo style ones soon and checking the valve clearances.
Could rocker covers cause high end power loss?
Other things I'm thinking of soon: replacement coil and ignition module. Other people seem to be going for MSD Not sure to buy the MSD 6al 2 programmable.
Any feedback will be greatly appreciated.
Last edited by Soundbud on Sun Jan 08, 2017 5:31 pm; edited 1 time in total
Soundbud Newbie
Joined: 29 Oct 2016 Posts: 19
Posted: Tue Dec 27, 2016 11:41 am Post subject: Update
Put new coil on the car, the car runs much better. It's powerful and very responsive up to 3k and then still got the power loss.
I'm looking into the electrics at the moment and thinking that it could be the earth strap. Will test later with a multimeter.
Palladium Indianapolis
Joined: 01 Nov 2015 Posts: 2469
Posted: Tue Dec 27, 2016 9:33 pm Post subject:
ive got '82 sc, I don't have this issue, could the problem be the engine?
mine has done 127k and the engine has never been opened. Very powerful right through the gears. I don't think it would be rocker covers.
hope you solve it.
Soundbud Newbie
Joined: 29 Oct 2016 Posts: 19
Posted: Sun Jan 08, 2017 5:30 pm Post subject: Problem solved - spark plugs wrong gap :-)
Solved the problem, I bought some cheap beru plugs which were recommended in my owners manual. Gap of .8mm
The iridium plugs bought from ebay cost 3.5 times as much and were the wrong gap. They were .6mm
This give amazing power up to 3k very very strong, crisp and responsive but lacked power high up in the range.
The new plugs seem to be smooth right through the rev range when warm but now seems to be idling too low on cold startup.
Next jobs to do will be refresh the WUR and fuel distrubutor diaphragms and gaskets, washers etc.. Car has a very slight mis fire.
Palladium Indianapolis
Joined: 01 Nov 2015 Posts: 2469
Posted: Sun Jan 08, 2017 5:36 pm Post subject:
surprised it was plugs, but there you go.
Soundbud Newbie
Joined: 29 Oct 2016 Posts: 19
Posted: Sun Jan 08, 2017 7:27 pm Post subject:
the plug leads also fit tightly on the new plugs, the iridium ones were a little shorter, maybe about 5mm and some leads seam be a loose fit. so i dont know if this was a contributing factor?
in the spring time, i plan to try the iridium plugs again with the correct gap. see what happens
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