Manifold to Cat bolts

[Sam]

These bolts with the springs on. Is the spring just to stop the bolt un-doing?

Can I use another 8MM bolt with a locking nut to connect them together??

Thanks, Sam!

 

[JezzaMac]

Needs the springs IIRC because the engine and manifold moves there needs to be some flexibility about the mani - cat join.

 

[Steven103]

Another reason to use a sprung bolt is to account for thermal expansion, which is probably quite an issue on a cheaply made car.

On the "nut undoing" front - resonance seems to happen at about 2,500 to 3,000 RPM (slap bang in the middle of normal driving conditions!)

 

[Andyman]

I was always having problems with the mesh gasket wearing out (Genuine kits) and causing blowing so replaced the bolts for the biggest ones which would fit and bolting it up a lot tighter and have never had a problem in over 5 years since

Imo the stock bolts allow for too much movement and promote wear of the gasket