Federal CrossOver Pipes

[terryp]

Hello to all!
My new car has the original cross over pipes. What do we all think I should do with them?
Keep them?
Block Off?
Do they really effect performance?

Thanks
Terry

[RogerFrench]

Removing them, or blocking them, alone won't affect much. You can remove them, block the holes in the inlet manifold, remove the extra set of throttle butterflies and block the holes, and rearrange the throttle linkage so you use only the butterflies in the carburetters.
Then you probably need to fiddle with your choke linkage - it'll work on only one carb after that but that's OK for starting.
Then throw away the vacuum retard and reset the distributor to about 11deg advance, static, and retune the carbs.
That'll make a difference. Well, it did to my Federal TC Europa and I think all the stuff is the same.

P.S. My son lives in France, Cote d'Azur, and also has a Caterham. Maybe you'll come across him som etime.

[1964 S1]

Hi Terry, I'd follow Roger's advice. (With a last name like that, how wrong could he be?)
I worked at a Lotus dealership in the early seventies and removing the pipes along with eliminating "smog pumps" on other British cars was frequently done by the car owners.

Then, just as now, the federal government thought it knew what was best for all of us. Although I must agree with the lowered pollutent/emission idea and am glad the USA led the way, I'm not sure this design accomplished anything other than to comply with regulations.

My '69 +2 still has them installed and it's a very "poppy" engine, runs better than the Webered S1.

Eric

[terryp]

Thanks for that, the problem is that I quite like them as they are a bit quirky

Whats the overall difference in driving experience? and approx BHP loss?

Thanks
Terry

[alan.barker]

Terry,
imho it's best to rest quirky like the car I wonder how many are still running with the crossover pipes. Keep it original and the BHP are not even important Dare to keep it original and to hell with modifications
Alan B

[terryp]

Any other opinions on this. I can't even get my head round quite what they do and why?

Terry

[billwill]

They use heat from the exhaust manifold to warm up the inlet air at low revs.

Quite why that reduces pollution I dunno.

[terryp]

Make it run more efficiently?

Terry

[billwill]

Make it run more efficiently?

Terry

First thoughts are the opposite. Warm Air, less dense, less mass of oxygen, incomplete combustion.

[terryp]

Bill
But that would make the emissions worse?

Thanks
Terry

[billwill]

Bill
But that would make the emissions worse?

Thanks
Terry

Yeah, that's what I said.


I don't know why heating the air reduces pollution, because at my first thoughts it would make it worse.

[terryp]

I took it too pieces today, its all a hell of a mechanism!

[RogerFrench]

They use heat from the exhaust manifold to warm up the inlet air at low revs.

Quite why that reduces pollution I dunno.

It helps to reduce the amount of unburnt fuel passing through the engine at low revs, by helping to evaporate droplets and making the mixture easier to burn. Not necessary at high revs.
Or so I've been told.