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Twin cam carburettor cross over pipes plus other noob questions.

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berni29:
Hi There Guys

Apologies for the noob question, but did all Fedral Twincams originally have those crossover pipes that run from the exhaust to the Stromberg manifold? I presume this is to combat carb icing? I have only ever seen one photo of a car with them, namely Fourloti's car 3826R, which is what got me thinking about them.

Why do people remove them? Do originality nuts put them back when missing? Whats the story?

Other noob questions, on a TCS, what is the standard cam cover colour, and all TCS's apart from the JPS were available with black or oatmeal interiors right?

Many thanks in advance

Berni

Kendo:
The crossover pipes were an emissions solution, I think to warm air entering the engine so gas wouldn't condense. They make a long air passage, reducing engine responsiveness. If you wanted to fake originality, you could retain them, but block off the ends with a thin patch of aluminum. There are also a second set of butterflies that would have to be removed.

My 1974 TCS cam cover is black.

I don't remember when the oatmeal interiors came in. But mine had that color.

4129R:
I have never seen any other colour on a "Big Valve" Twin Cam engine other than black, with the BIG VALVE lettering on that cover.

I have only seen red on small valve twin cam engines.

berni29:
Hi Guys,

Thank you for the answers.

With regards to the "Big Valve" legend, I have seen it misquoted as "Big Value" and "Bio Valve". It does quite often look like "Bio Valve" I must say.

All the best

Berni

BDA:
The crossover pipes are commonly deleted. When I bought my car at the distributor, they were deleted for me without asking me (which was fine with me). Also, headers are a common mod that shouldn’t affect the originality since headers were a Lotus option. Although I have seen a picture of headers that support the crossover pipes, most don’t, notably the original Lotus headers (which are probably very difficult to find - newer headers are quite common).

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