Two different inlet manifolds were used: one for 29G and 29GB engines (home market, most exports, and France) and one for 29GA engines (USA and later Canadian). Both are available on exchange with the customer's own unit reconditioned. Each incorporates two Welch plugs and a brake servo vacuum adaptor. The servo adaptor changed during production: early cars up to chassis 1153 used one type with a copper sealing washer, from chassis 1154 a revised adaptor with fibre washer.
Fifteen studs secure both inlet and exhaust manifolds to the cylinder head.
Hot-Spot and Heatshield
A hot-spot connector links the inlet manifold to the exhaust manifold at four bolt positions, transferring exhaust heat to the inlet tract to aid fuel vaporisation during warm-up. Two hot-spot gaskets seal the connections. The heatshield mounts above the hot-spot area protecting the float chambers from radiant exhaust heat that would otherwise cause fuel vaporisation, rough running, and hot-start difficulties. The heatshield differs between home market and North American specifications, as does the return spring anchor plate.
Six screws with spring and plain washers secure the heatshield.
Carburettor Mounting
Eight studs, eight nuts with spring and plain washers, and two insulating blocks with six gaskets complete the carburettor-to-manifold installation. The insulating blocks reduce heat transfer from the manifold to the carburettor bodies, important because the SU carburettor's fuel metering is sensitive to float chamber temperature changes.