Looking for a 409 engine bonnet-compatibility?

[DODD]

Roger’s posting above reminds me of issues I had with my 410, as per one of my previous posts of June 25th 2021.

I had what I thought was a blown cylinder head gasket; unfortunately, on further investigation it turned out to be a crack in the cylinder head between two chambers.

As noted previously, the bimetallic coil which controlled the flap within the exhaust manifold had seized. The result was that an excessive amount of exhaust gases were diverted across the inlet manifold to the opposite exhaust. This also in my opinion was the cause of my exhaust manifold developing hairline cracks.

Additionally, whether related or not (I think it was related), the small metal plate which sits on the inside of the inlet manifold had accumulated large amounts of carbon buildup between the plate and the metal casting; in fact it was a solid block!

As a result of the above issues, I completely removed the flap in the exhaust manifold to alleviate future problems.

Additionally, Roger noted in the same thread that when he fitted the SLJ swept exhausts system, a small aperture maybe/was required in the wheel arch. I imagine that this aperture would also help disperse some of the heat buildup from under the bonnet. This is something I will seriously consider doing on my 410 this autumn; if anyone else has created vents in a similar position, I would be interested in their views.

Brian