unclepete Posted November 20, 2020 Report Share Posted November 20, 2020 Delving into the dark art of fitting triple Webers to the 6 Pot TRs reveals a huge combination of set ups! I have 3 x 40 DCOEs 151s with 30mm Main venturi, 4.5 Auxiliary Venturi, 40 Pump Jets and F9/45 Idle Jets and standard progression holes, What combination of the following would give me a good start for tuning? Touring and Local Show stuff, definitely not Racing (although the odd track day might be fun). I have deliberately not put down what I have fitted already but have got the tick over slow running working nicely. Needle Valve size Air Corrector Jet size Main Jet size Emulsion Tube size/pattern. Quote Link to post Share on other sites
M. Pied Lourd Posted November 20, 2020 Report Share Posted November 20, 2020 Hi Peter, What other mods do you have? Cam? Headwork? Exhaust etc. Cheers Tush Quote Link to post Share on other sites
Tom Fremont Posted November 20, 2020 Report Share Posted November 20, 2020 I was told there are 4 billion permutations for the DCOE . If you have the CP cam and c/r per original the setup I have in my driver '250 with CP cam and wide port head can be a guide: 125 main 175 air F7 emulsion tube closed pump bypass 45 pump jet 175 needle valve 30 chokes 60F4 idle ( these may be scarce - 50F9, 55F8 are similar ). This recipe has given joy for 95,000 miles and counting! If you have a true extractor manifold like a GOODPARTS the main jet may need downsizing from the above. Tom Quote Link to post Share on other sites
M. Pied Lourd Posted November 20, 2020 Report Share Posted November 20, 2020 I was hoping you would jump in here Tom Good to see you. Cheers Tush Quote Link to post Share on other sites
Tom Fremont Posted November 20, 2020 Report Share Posted November 20, 2020 Hi Dave, Looking forward to your fire up someday; there are several others going this way I'm in touch with. Might not be a wave yet but the trend is good! For Uncle Pete: Float level is critical; for the 40DCOE151 I believe the setting should be 12mm by the book method. For sure the height of the fuel below the top of the well ( where the main stack screws in ) should be 27-28mm, all equal. A makeshift dipstick is used to gauge this. Tom Quote Link to post Share on other sites
unclepete Posted November 20, 2020 Author Report Share Posted November 20, 2020 Thanks Tom and Tush Bit more spec for you; 1969 CC engine with wide port 2500S head. Original CAM. Extractor Manifold. Fuel level 29 - 30mm below collar of access cap. 175 needle, 115 main, 200 air corrector, F9/45 idle jet, F11 Emulsion - anything there make you raise your eyebrows? The inlet manifold is a Bastuck with solid rod throttle linkage bar. I have installed adjustable rose jointed linkages to each carb, although this would seem to me, to make the connection solid between each carb! Is it advisable to have a little slack at fully closed throttle? Quote Link to post Share on other sites
unclepete Posted November 21, 2020 Author Report Share Posted November 21, 2020 17 hours ago, Tom Fremont said: closed pump bypass Hi Tom Closed Pump Bypass? Did you mean the Air Bypass? Quote Link to post Share on other sites
John L Posted November 21, 2020 Report Share Posted November 21, 2020 I presume you have this document? Weber_DCOE_Tuning_White_Paper (1).pdf Quote Link to post Share on other sites
unclepete Posted November 21, 2020 Author Report Share Posted November 21, 2020 7 hours ago, John L said: I presume you have this document? Weber_DCOE_Tuning_White_Paper (1).pdf 96.98 kB · 6 downloads Yes John. Nowhere near as much fun as chatting on the Forum... Quote Link to post Share on other sites
roy53 Posted November 21, 2020 Report Share Posted November 21, 2020 1969cc ????????????????????? Quote Link to post Share on other sites
unclepete Posted November 22, 2020 Author Report Share Posted November 22, 2020 16 hours ago, roy53 said: 1969cc ????????????????????? Hi Roy 1969 TR6 CC USA car fitted with carbs. as against a CP, CF or CR. I popped an endoscope down the inlet track of the manifold and all checked out OK by the way. Quote Link to post Share on other sites
Tom Fremont Posted November 22, 2020 Report Share Posted November 22, 2020 Hi Peter, The CC engine with its 8.5:1 c/r and 10/50/50/10 cam is a poor candidate for triple Webers; the best that can be achieved is parity with the stock carbs. Sorry to be the bearer of... If it were mine I'd get the head shaved to 9.400" thick and fit a CP cam or comparable. Then the Webers can do their thing and deliver full on CP performance once dialed in. All the jets etc. you list are for the LOTUS ELAN engine; only the 30mm chokes are applicable in my experience and may need to drop to 28mm. I haven't dialed in Webers for the stock emissions engines though I drove one which was and it ran fine albeit was no faster than my stock '250. I don't know what its jets were. Fuel level height should be measured from the top of the well where the main stack screws in. I don't have a reference dimension for the collar you mention. Cheers, Tom Quote Link to post Share on other sites
foster461 Posted November 22, 2020 Report Share Posted November 22, 2020 Have have not touched my dcoe configuration since 2012. This is how they are set up: Chokes 30mm Aux 4.5 Main 140 Air 160 Emulsion F11 Idle 55F9 Accelerator pump 50 Pump exhaust closed (made a big difference) Float height (Spanish carbs, plastic floats) 7mm/15mm Idle mixture screws 2 turns out from fully closed Goodparts GP2 cam, 9.6:1 compression Quote Link to post Share on other sites
unclepete Posted November 24, 2020 Author Report Share Posted November 24, 2020 On 11/22/2020 at 6:19 PM, Tom Fremont said: If it were mine I'd get the head shaved to 9.400" thick Hi Tom I might not have mentioned earlier that it has a higher compression head fitted (219015 TR6 PI CR) with a Compression ratio of 9.5:1. I'll work with the existing Cam for the moment. Reading all your recommendations and various Journals I have put together the following set-up from the bits I have. 30mm main venturi, 4.5 Aux Vent, 125 Main jet, F9/50 Idle Jet, 180 Air Corrector Jet, F7 Emulsion tubes. I have managed to source and am waiting for F4/60 idle jets. After checking all the fuel levels and screw settings, I ran her up yesterday. She started OK with plenty of popping, so I initially wound all the idle screws out a 1/4 turn which calmed things down a bit! After warming her up, I then adjusted the idle screws on each cylinder by 'feel', once happy with this - and the air flow between carbs - and the tickover, I then put a Colourtune on each cylinder in turn. I was quite pleased how my 'Feel' setting and the Colourtune indication matched up at Idle. I took her for a run and was pleased with the progression and flat out phases, although I would say it's work in progress! Quote Link to post Share on other sites
unclepete Posted November 24, 2020 Author Report Share Posted November 24, 2020 On 11/20/2020 at 3:59 PM, Tom Fremont said: closed pump bypass On 11/22/2020 at 7:50 PM, foster461 said: Pump exhaust closed (made a big difference) Guys Is this the same thing? I cannot find reference in any literature I have? Quote Link to post Share on other sites
foster461 Posted November 25, 2020 Report Share Posted November 25, 2020 (edited) 3 hours ago, unclepete said: Guys Is this the same thing? I cannot find reference in any literature I have? Yes, it is the same thing. There is a jet in the bottom of the accelerator pump circuit (one per dcoe) that bleeds fuel off back to the float chamber. It comes in various sizes including a blank jet (no hole) that bleeds no fuel so everything from the pump gets inhaled. Listed as a pump spill on some dcoe diagrams. Stan Edited November 25, 2020 by foster461 Quote Link to post Share on other sites
unclepete Posted November 25, 2020 Author Report Share Posted November 25, 2020 Thanks Stan. I'll try some of those. Quote Link to post Share on other sites
unclepete Posted November 28, 2020 Author Report Share Posted November 28, 2020 Situation so Far - Mk 2 PI head, Extractor Manifold, CP Camshaft 35,65,65,35, 30mm Venturi, Needle 175, Main 125, Air Cor 180, Emulsion F16 (tried the F7), Idle F4/60, Pump 40, Bleed nil. Very pleased with running and about where I want to be. Gentle to brisk increase in Throttle, provides smooth response right up to 4500 rpm.(as far as I want to take it). However if I stamp on the throttle there is a lot of hesitancy? I am thinking about increasing the Pump Jet? or reducing the Air Correction Jet? Quote Link to post Share on other sites
John L Posted November 28, 2020 Report Share Posted November 28, 2020 Could be too much or too little on the pump jet, if all else is ok I would go for pump jet. Just check that the outlet of the spray hole in the pump jet is facing the right way squirting into the engine, I had one that was on the wrong side, squiring into the aircleaner! John Quote Link to post Share on other sites
unclepete Posted November 30, 2020 Author Report Share Posted November 30, 2020 What about ignition timing? Book says at idle 4 deg ATDC with a strobe or 12 deg BTDC static. I have an electronic Power Spark ignition Dizzy with Vacuum Advance, the manufacturers have said that leaving the Vacuum Advance disconnected is not a problem. There is no vacuum take off with triple Webers, so what are your thoughts? Quote Link to post Share on other sites
ntc Posted November 30, 2020 Report Share Posted November 30, 2020 With your setup you need 11 strobe btdc at 800rpm Quote Link to post Share on other sites
unclepete Posted November 30, 2020 Author Report Share Posted November 30, 2020 (edited) 10 minutes ago, ntc said: With your setup you need 11 strobe btdc at 800rpm Vacuum connected/disconnected? I do not have a Vacuum take off with the Webers! Edited November 30, 2020 by unclepete Quote Link to post Share on other sites
ntc Posted November 30, 2020 Report Share Posted November 30, 2020 16 minutes ago, unclepete said: Vacuum connected/disconnected? I do not have a Vacuum take off with the Webers! I know so n\a , you must get this right or you will never set them up right. Quote Link to post Share on other sites
Tom Fremont Posted November 30, 2020 Report Share Posted November 30, 2020 Hi Peter, My pump inlet valves have closed bypasses. Try this to resolve your " stamping " hesitancy. All else is on par with the setup I have on my driver with the same cam and c/r. I never had any luck with the F16 emulsion tubes; with these mine would fall flat on their face at WOT. What happened with the F7s? Tom Quote Link to post Share on other sites
unclepete Posted November 30, 2020 Author Report Share Posted November 30, 2020 4 hours ago, ntc said: I know so n\a , you must get this right or you will never set them up right. Hi NTC To clarify - I forget the Vacuum advance and Strobe set up at 800 rpm to 11 deg BTDC? 4 hours ago, Tom Fremont said: My pump inlet valves have closed bypasses. Try this to resolve your " stamping " hesitancy. All else is on par with the setup I have on my driver with the same cam and c/r. I never had any luck with the F16 emulsion tubes; with these mine would fall flat on their face at WOT. What happened with the F7s? Hi Tom - The F7s gave a similar result (hesitancy at full throttle) so I put the F16s in to see if there was any improvement. I have fitted Pump Bypasses that are rated nil/0 bleed-back. You will probably see from my recent posts, that I need to establish that the ignition timing is correct? I have been running the car at spec timing of 4 ATDC at idle, you will see in this post that NTC recommends, with the Vacuum advance disconnected, 11 deg BTDC. That is a big difference?? Quote Link to post Share on other sites
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