Hi, I was just wondering what would be the best plugs to use during the break-in period? Seeing as I'm not revving over 4000rpm or driving on boost a lot, would stock-type plugs (ie. 7's and 9's) be better? Right now I've got B9EGVs all around, and they seem to be a bit of a hard starter. I was thinking that a hotter plug would start slightly easier and generally be better to use during the break-in period.

I tried searching but nothing came up..

 

I use a hotter, BUR7EQ plug (in the leadings) for all of my rebuilds and break-in process. A not-so-broken-in engine needs all the help it can get.

B

 

The stock set up is good for the break-in period. Use the BUR9EQ for trailing and BUR7EQ for leading. Since the seals are not broken-in yet, they don't sell as well. The hotter spark plugs will not foul out as easy.
To properly break-in your engine, you should let the car idle for 10-15 minutes on the first start. This will insure the apex seals and the side seals seal well at low rpm/idle and which can help the car to start easier also.

 

Thanks for the advice...

I went ahead and bought 7's and 9's for the leadings and trailings.... the car starts quite a bit easier compared to having B9EGV's all around...

I've since done about 150kms (about 95 miles) and I'm finding it very hard not to drive on boost (I know I shouldn't)

One more question: could low vaccum at idle when first starting the car indicate leaky injectors? If the car hasn't been started in a while, the car takes a bit of cranking to get going (along with a fair bit of smoke), and the vacuum at idle sits at about 8in... the more the car is driven, the more the vaccum increases at idle (to about 15in). Any ideas???

 

since the combustion is not complete, the mixture cannot get fully ignited, which lowers the engine rotation speed and cause less vaccum.
8in is a little low... even for a non-broken-in engine, possibly due to a too-small apex seal to rotor groove clearance. The reason your engine runs better after warm up may be because when the engine gets warm, the groove on the rotor expends slightly due to the heat, plus the apex seal itself expends when its warmed up. The expension of the apex seal groove helps the apex seal to travel easier, and which might be the reason why the engine generates more vaccum after it is driven.