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Tell me about X Flows


Red SLR

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Think you're going to need to be more specific, Simon - what kind of advice on what aspect of the Cross-Flow?

 

From my own experience, 40's need to be well balanced and getting a 'good' pair is a pretty hit and miss affair. I've been told that Caterham-supplied 40's have in the past been modified to suit the characteristics of an easier-breathing x/f - & sometimes less than succesfully (info. ex. James Whiting). Mine don't go out of balance &/or tune too often, but I'm also told I'm lucky - others find this a big issue. They must all be choked and jetted by someone who really knows what they're doing to get the best from the Carbs. and the engine.

 

The 'standard' 135bhp Supersprint ex. Caterham doesn't seem to last longer than 15-20k miles before needing attention, but is still basically a sound engine. For all the in's and out's on the x/f, I'd always recommend Roger King (he's often on this board) - what he doesn't know about this engine 'aint worth knowing. With a thick-wall 711M block and a properly-built (steel internals) x/f + all the best bits like double valve springs, Cosworth crank, forged pistons, 244 or 254 cam, bronze valve guides, etc., etc. the x/f, for all the jibes about it's age, can still easilly manage 7,500rpm and 170(+?)bhp without being 'peaky' or needing to be constantly driven on the cam. Add 3-D mapping and it'll return 28-30mpg, too, I'm told, complete with much better partial-throttle response and increased performance.

 

OK, it's not the lightest engine - but Roger can fix that too, with an alloy block (HOW MUCH, Rog?!) - and it's perceived as old, smokey, noisy and smelly. But it's a doddle to work on, cheap(-ish) to repair and a good one still manages to cane the K's [dons Nomex.....]!!

 

The head can be modified to accept hardened seats, allowing the engine to run safely on unleaded (even ones with large inserts - ask Roger) + IMHO, the Ford heritage maintains a Caterham/Lotus link to the past. Maybe you don't care about this, other do.

 

Bottom line - speak with Roger. He's forgotten more than I'll ever know about the x/f.

 

Pierson

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I recently bought a new pair of Webers for my Twin Cam Seven 45DCOE152 and I am quite disappointed by the overall fit and finish.

 

The chokes are very badly made and have a very poor surface finish and are a rattle fit in the body, the auxilliary venturis are even worse. The choke/ventuti does not centralise in the body correctly and I understand from a few people that the number of progression drillings have been reduced.

 

Del Orto carbs seem to be better finished and Contact Developments seem to be very helpful.

 

I know the DHLA works well on the Twin Cam and the BDA but has anyone tried them on a crossflow. I believe that they keep their tune longer than the Weber even though they may be more difficult on initial set up. The standard of fit and finish is certainly better and I think I have made a mistake with Webers.

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This is the engine I am talking about.

 

New in 1998. Develops 150bhp at back wheels

Ford crossflow 711M block 90 thou overbore Rods

Lotus short stroke Fully lightened flywheel

Balanced with Crank Rods fully balanced

Head fully ported, with maximum size valves Duplex timing chain 244 Cam with

steel rocker shaft

Dry sumped with Pace 5 port pump Electronic ignition Twin

40 Webbers with matched ported inlet manifold

Custom exhaust manifold

 

Not been raced and only had about 400 road miles since the head was re-built in 1999.

 

Does this type of engine stay reliable?

 

 

 

X777CAT

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Simon

 

I would be very suprised if you are really seeing 150 at the wheels...one thing I have learnt is that people make all sorts of claims about BHP but the truth is it is usually exagerated, and it comes at a price. 40 DCOES and the level of tune you mentioned is more likely to produce 150 at the flywheel, very different figure to the wheels.

 

The engine should be reliable providing the rolling road has been done properly (correct jetting etc). Reliability will also depend upon how you use the car, if it is being bounced off the redline constantly around tracks then it may go 'bang' a lot sooner than 'normal use'. Still, should be good for several years with some TLC.

 

Hope this helps.

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I can't comment on long term reliability of items, but some of the faults that I have had have been due to bolts working loose such as on the exhaust manifold, the alternator and the starter. With use of nylocs or loctite cured these problems.

I have generally found the alternator to be a source for a number of problems (all cureable). At high rpm I found that the alternator broke either the waterpump bolt, the waterpump or the adjustment strap, by using a nylon adjustment strap from a specialist in Hinkley these problems have disappeared. The Magnetti Marelli alternator also has a terrible main power lead connection, this was fixed by welding a nut onto the back of the connection after it had again fatigued to stop the connection post from wobbling.

 

 

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