Mark H Posted December 10, 2002 Share Posted December 10, 2002 Hav,in recently been offered a good twincam at the right price i am keen to know if there are any complications to this converstion. So anybody done this or have any idea if its feasable , or not .so over to you guys Link to comment Share on other sites More sharing options...
Tight fart Posted December 10, 2002 Share Posted December 10, 2002 I was advised against this, unless it was on cosmetic grounds that I wanted it. If you are looking for more power, they are more fragile than a crossflow. With only a single cam chain. Link to comment Share on other sites More sharing options...
Lawrence_Z Posted December 10, 2002 Share Posted December 10, 2002 IIRC you'll need a special Caterham inlet manifold to raise the carbs above the chassis side and possibly a new cut out in the bonnet (or new bonnet) Lawrence Link to comment Share on other sites More sharing options...
Graham Sewell Posted December 11, 2002 Share Posted December 11, 2002 Have you considered the VeganTune conversion? Low tech luddite - xflow and proud! Link to comment Share on other sites More sharing options...
R2D2 Posted December 11, 2002 Share Posted December 11, 2002 The Twin Cam engine doesn't have a seperate inlet manifold. The "manifold" is integral with the cylinder head casting. There is a slight problem with height and Weber clearance over the side of the space frame and you will need about a 5 mm spacer fitting between the nearside engine bracket and the engine mounting bobbin that is fitted onto the chassis. The engine was always canted over slightly in Escort Twin Cam applications and doesn't cause any problems. The bonnet cut out for a crossflow lines up with the Webers on a Twin Cam but the carbs "stick out" about 50-60mm further as the inlet tract is longer than a typical crossflow inlet manifold. If you have clam shell wings this is a problem and you will need to fit Air Filters that are a maximum of 55mm deep or they will foul the wings. You will also need to modify the bonnet if you have clams as the gap between the bottom of the air filter and the wing will only be about 12mm. You need to take the "return" off the lower portion of the air cleaner cut out. If you fit 55mm deep filter you will also need to fit short "trumpets" on the carbs. 20-25mm is the maximum length. I think K&N have some that are 19mm long. You will also need to fit the thermostat housing off the Caterham crossflow. The Twin Cam, as standard has a sealed housing so you could not fill the engine with water unless you fit some kind of header. Depending on the exhaust you choose the cut out in the nearside body may need re-shaping. I think you would also need a new top hose. Twin Cam timing chains have never been a real source of unreliability with this engine providing you use a one-piece chain and un-reliability wasn't that much of a problem if power outputs are kept to around 150-160 BHP. The real problem now is due to cylinder head porosity. Most of the engines around are 30 + years old, have maybe stood around with either plain water or insufficient anti-freeze. The quality of early castings wasn't great and they do have a tendancy to have become porous. I had one that pressurised the water system when running at full load but didn't show any problem with compression loss at idle. The replacement head I found has been fine. It is worth having the head pressure tested by someone such as Nick Stagg Engineering in Chipping Norton. Great engine, makes a great noise. Edited by - chris flavell on 11 Dec 2002 08:42:31 Link to comment Share on other sites More sharing options...
R2D2 Posted December 11, 2002 Share Posted December 11, 2002 Graham, The Vegantune engine was fitted as standard by Caterham in about 1989 and I have been trying to buy one from Vegantune for about 5 years now. They seem to sell for about £4-8K depending on spec. but I have phoned regularly without success. Link to comment Share on other sites More sharing options...
Old Septimus Posted December 11, 2002 Share Posted December 11, 2002 From my experience many years ago with a Mk 1 Lotus Cortina, when the twink is good it's very good and when it's bad it's awful - not much middle ground. Link to comment Share on other sites More sharing options...
Michael Peterson Posted December 11, 2002 Share Posted December 11, 2002 Would a BDR be a better choice? Would it be less expensive or more? Link to comment Share on other sites More sharing options...
Peter T Posted December 11, 2002 Share Posted December 11, 2002 A BD series engine would cost farrrrr more! And would produce more power! C7 PWT X-Flow all Steel Link to comment Share on other sites More sharing options...
Nigel Riches Posted December 13, 2002 Share Posted December 13, 2002 Water pumps are a major head ache when they fail, for more info on the Twin cam motor Miles Wilkins book, "Lotus Twin cam Engines" (isbn 0-85045-676-2) is an absolute "all you want to know, and some stuff you'd rather not know" read. Regards Nigel. Link to comment Share on other sites More sharing options...
deanteam Posted December 13, 2002 Share Posted December 13, 2002 We run Twin cams and Chris's info is good. We have found that there is sometimes a problem of getting the water hose to the pump around the steering shaft, especially if dry sump. A front /water pump casting from the Europa helps. Make sure that the head is higher than 115mms, std is around 117mm, less than 115mm will lead to flexing of the combustion chambers and gasket failure if power much above std 125bhp. We like them, when you have a Lotus 7 that is the engine to have. Link to comment Share on other sites More sharing options...
terry b Posted December 14, 2002 Share Posted December 14, 2002 Marc, buy it and have a proper car! t.buss Link to comment Share on other sites More sharing options...
gramey Posted December 14, 2002 Share Posted December 14, 2002 I have a '90 Caterham (left hand drive) with an early TwinCam which, when I ordered bought the kit suitable for the TwinCam so my info may not be applicable for a right hand drive. The right side motor mount (72032) is for the x-flow and TwinCam. The left side motor mount (72069) is for the TwinCam and BDR. This may tilt the engine so that the air filters align with the bonnet opening. The x-flow uses a 72033 left side mount. Instead of short Weber horns, I use the "stub stack" which is just a hemisphrical inlet shape with 47mm thick K&N filters which protrude 10mm outside of the forward side of the bonnet opening (forward carburettor). Since I am one of the fortunate few to have a build sheet, I can supply part numbers for the thermostat housing and hoses. I also have part numbers for the Caterham 4-1 exhaust system, including "silencer" (I use that term bemusedly) for the Twin Cam as well. My engine compartment chassis diagonal tubes are the fixed, welded in, not bolt ins, but I have no clearance problems although I did have to "relieve" ( make a slight indentation) the no. 1 exhaust pipe. Also had to use a small Nippon Denso alternator and fab my own mounting brackets (I have drawings) but this was to clear the left hand steering shaft. You may not have this problem although the alternator comes close to the left side chassis diagonal tube. I could go on with a plethora of minor details but this covers the majority of issues. I can supply my bonnet part number but I suspect that the newer bonnets are different part number because of the extra set of louvers which were added with the newer plastic shrouded heater. If you need additional info, you can e-mail me off list if you like George gramey@cmc.net Link to comment Share on other sites More sharing options...
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