ashaughnessy Posted July 21, 2002 Share Posted July 21, 2002 Just got my engine back from the builders yesterday. Beautiful and shiny and new! I need a new fuel pump - the old one is too worn. I had the original mechanical pump. My preference is for another mechanical one because of a) simplicity of installation and b) too many stories about electric pumps breaking down. What would people's preference be? Stick with an OE mechanical pump or get an electric one or something else? Engine is 1700 supersprint uprated with 244 cam and extra porting on the head and inlet and exhaust manifolds. 40DCOE carbs, probably will fit 36 mm chokes. Rev limit of about 7200rpm. I don't think I need extra fuel supply capability over what the mechanical pump would have given me, but I don't know for sure. Anthony Link to comment Share on other sites More sharing options...
cdg Posted July 21, 2002 Share Posted July 21, 2002 Anthony, Don't use 36mm chokes in a 40 body. They flow no more air than a 34mm, and perform worse at low engine speeds as you're losing the venturi effect. I would go to 45 Webers with a 36mm choke on your X-Flow. This is a good compromise between having a gas speed high enough for low down/midrange torque, and a big enough choke for high engine speed power. You'll need a good electric pump though. Chris. Link to comment Share on other sites More sharing options...
stevefoster Posted July 21, 2002 Share Posted July 21, 2002 Electric every time. You fill the floats before start up... Easier start Vroom... go for a Webcon one. So far (touch wood) all the ones I know of have proved totally reliable. Good for 200+ BHP. More bhp than that & the choice narrows. Facet Redtop... or more exotic. James Whiting does them the Webcon ones. Cheaper than the Facet's too. Facet (Silver tops) have had a terrible reliability record. I have had 3 fail.... Similar reliability story for others I know. Steve My racing pics hereid=red> Hants (North) and Berkshire area club site hereid=red> Link to comment Share on other sites More sharing options...
Peter T Posted July 21, 2002 Share Posted July 21, 2002 Second what steve says , go for an electric pump, the webcon units are very reliable. C7 PWT X-Flow all Steel Life begins at 40(00rpm) Link to comment Share on other sites More sharing options...
Casbar Posted July 22, 2002 Share Posted July 22, 2002 I've had a red top for 3 years now, and its still going strong. Link to comment Share on other sites More sharing options...
Graham Perry Posted July 22, 2002 Share Posted July 22, 2002 SSSSSShhhhhhhhhhh it will hear you ! Graham (3 broken facets & always carry a spare) Perry Link to comment Share on other sites More sharing options...
ashaughnessy Posted July 22, 2002 Author Share Posted July 22, 2002 Thanks for the advice, I'll ask about the price of the webcon one vs. a new mechanical one and see if I can afford it. cdg - interesting advice about the choke sizes. I don't want to go to 45DCOE carbs because that would be too expensive. I'll check with my engine builder about the 36mm vs 34mm choke issue and see what he thinks. He originally mentioned 36mm chokes when we first discussed the rebuild but that wasn't his considered opinion, just a remark. I'll be giving the car to him to be rechoked and rejetted and set up on his rolling road, so I'll probably go with his recommendation. He knows I want the engine to be tractable. Anthony Link to comment Share on other sites More sharing options...
Phil P Posted July 22, 2002 Share Posted July 22, 2002 Anthony FWIW, I'm running a Webcon pump from James Whiting and its been very good. Much, much quieter than the previous facet interrupter type and builds fuel pressure quicker prior to starting too. As i remember, it was about £30. If you're going down the electric pump route, then a fuel pressure regulator might also be a good idea - I have a purolator chrome dial type which was about £15 Phil Link to comment Share on other sites More sharing options...
eric Posted July 22, 2002 Share Posted July 22, 2002 If you don't need 45 Weber, if I was you I will stay with your mecanical pump it is so reliable that you will be sure to go where you want with your Caterham. I have twin Weber 40 with a mecanical pump and I don't need electrical item to supply fuel. I like to much to drive without thinking to another thing that the pleasure of driving the thing. Link to comment Share on other sites More sharing options...
Graham Sewell Posted July 22, 2002 Share Posted July 22, 2002 For carbs (From Dave Andrew's program): For power: Weber 45 DCOEs with 37 chokes (150 mains) For flexibility: Weber 40 or 45 DCOEs with 35 chokes (140 mains) Low tech luddite - xflow and proud! Link to comment Share on other sites More sharing options...
cdg Posted July 22, 2002 Share Posted July 22, 2002 Anthony, If you're sticking with 40s I must re-emphasise that a34mm choke is all you will require. Choke sizes for body size is an issue that has been exhaustively tested by such luminaries as David Vizard and Dave Walker using a flowbench. if you want to fit 35(rare) or 36mm chokes you need 45s. It's black and white! Hope the new engine is great! Chris. ps. If you want to see David Vizard' published graphs of airflow through 40 and 45 Webers they are in his "Tuning BL A Series Engine" bible. Edited by - cdg on 22 Jul 2002 11:46:33 Edited by - cdg on 22 Jul 2002 11:48:47 Link to comment Share on other sites More sharing options...
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