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911 SC - loosing power over 3k revs PROBLEM SOLVED

Soundbud

Member
Joined
29 Oct 2016
Messages
19
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.
 
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.
 
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.
 
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.
 
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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