Plenum gasket?

[rickprice]

Folks,

Have removed the plenum to fit new trumpets, which appears to be going well except for getting the old b*****s out.

The plenum did not have a gasket between it and the trumpet base, nor is there a gasket beneath this.

Should there be?

Thanks in advance,

Rich

[selnic]

No gasket on the plenum, just make sure the mating faces are true and apply a smear of Blue Hylomar.

[tonys]

selnic said:

No gasket on the plenum, just make sure the mating faces are true and apply a smear of Blue Hylomar.

Agree about the mating surfaces; I think there are differing views about the need for any sealant 'stuff'. Didn't use any on mine, and nothing had been there originally either.

[Pupp]

A thermal insulator under the trumpet base is a good addition - mylar sheet ones are available or some made from thinner space-age gasket material - keeps the plenum way cooler than the manifold etc

Some run a 10-15mm spacer between the base and the plenum top - (controversially) increases plenum volume and, probably more importantly, moves the plenum roof away from the trumpet ends - easy to make from a nylon chopping board

[pwd95]

Blue Hylomar is the stuff to use. Those surfaces must be completely sealed otherwise extra un metered air will get in causing a lean mixture & the engine will run rough as hell. Vital.

[rickprice]

Thanks everyone. Job done, used some silicone instant gasket in the end, sparingly so no intra-engine disaster. Running nicely now apart from the lead extender I discovered whilst there! (new post)

Rich