V8 rough running

[andybloggs260@ho]

bought a 350i project last year missfiring badly so suspected head gasket removed heads skimmed etc rebuilt still missfring compression on all 8 is 150+ cleaned plugs run on all 8 for 30 secs then missfiring again its had new airflow meter new plugs now im baffled any ideas welcome

[Barkychoc]

Have you tried a distributor cap?

[Campbell]

I dont think it the distributor cap, the chances are the dizy is buggerd, it could be a problem with the bobin weights inside the dizy may be fixed on advanced.
You could change the coil and module on the side of dizy as its the easyist ones to change and not to pricy.

Cambelt

[adam quantrill]

Yeah, check the timing at 800 rpm then at 2400, and that it advances, all with the vacuum advance off.

[GreenV8S]

Are you getting a good strong spark, at the right time? Confirm the timing marks are accurate before relying on them to check the timing. Is the fuel pressure right? Check that the rotor arm lines up with the posts correctly at TDC (I've heard of one that was firing between posts so each cylinder only got half a spark, had very similar symptoms).

[andybloggs260@ho]

will re check timing leads etc its had new dizzy cap and plugs so will check timing with light on tdc mark hopefully get it runing corectly soon

[Jonny weggie]

Make sure that the gaps in the plugs are all the same, i think there about 30thou would need to check..because one of my cars had between 5 - 15 thou difference and it ran like a pound off mince.. jonny.

[TVRleigh_BBWR]

andybloggs260@ho said:

will re check timing leads etc its had new dizzy cap and plugs so will check timing with light on tdc mark hopefully get it runing corectly soon

You also may want to check the TDC mark is correct, a lot of them are not.

Do a search for piston stop for how to do it correctly.