Cold Start problems with a V8 & Edlebrock Perofrmer 500

Nov 28, 2003 1 Replies

Hi,



I am getting cold start/run issues with my 90. Its got a genuine 3.5l V8 with a Edlebrock 500 carb and manifold and original 35D8LM dizzy/ ignition. It starts ok on choke but after letting it warm for a few mins it starts to run rough (rich). If I press the throttle and release the choke it runs fine but dies if I then let go of the throttle.



I can get it to idle fairly smooth if I play with the choke but then it won't driver properly as the mixture is too rich when I accelerate



- lumpy and hesitant (keeping the choke out to stop it dieing at idle).



I have changed the leads, rotor, cap recently and will change the plugs soon too. Oil was changed recently. Fuel pressure is ok.



I spoke to a chap at RPI who said I need to upgrade the ignition as it isn't powerfull enough to burn all the fuel when the choke is out. he suggested their A&R power amp. Has anyone tried it? Is it worth the money?



it runs ok in warmer weather.



What else can I check?



Thanks


Simon


thats a load of crap from RPI , no way do you need more ignition amplification for that .

you are probably running too lean rather than rich, especially if you have to keep choke out, by just doing this it means you are trying to compensate for a lean mixture .

have you got a big enough fuel pump for acceleration , you probaly need an electric carter or holley pump, rotary type as opposed to the facet pulsed type .

have you got enough manifold vacuum , ie what cam do you have and does it give enough vacuum at idle to draw fuel through the idle circuit .

do you have just a vacuum advance distributor or is it vacuum ratard also . check the ignition timing is set correctly .

have you got an accelerator pump on the carb , if so does this work and discharge fuel into the venturi upon throttle movement from idle .

you may need to run a vacuum pipe to the carb base [ does carb have pipe inlet at base of carb ] from one of the rocker covers, via a PCV valve , ie as ford

3 litre v6 engines have , and also chevy v-8 .

maybe get some MOROSO rocker covers and a PCV valve to fit , try SUMMIT RACING EQPT akron ohio .

you would have been better using a 390cfm or 600cfm vacuum secondary holley 4 barrel carb , but if you have extremely low manifold vacuum due to radical cam selection then you may need an anular discharge carb , something like a holley

660 centre squirter which are designed for low manifold vacuum racing engines, but they have no choke and drink fuel like no tommorrow .

try looking for BILL MITCHELL racing engines in usa for holley carbs and parts for racing engines .

even if youre manifold is the spreadbore type you can still use adapter plate to go from one make carb to other .

you may only need to richen up the idle mixture though on youre carter carb , there should be screws for adjustment of idle mixture .

make sure that the float level is correct in carb and that it isnt stuck open and leaking neat fuel straight in under pressure . if fuel pressure is too high from pump ,you can buy adjustable fuel pressure regulators from summit racing , or in uk try REAL STEEL [- if theyre still going ] .

if engine dies when under hard sustained accelerating then you may need higher volume fuel pump .

just a few thoughts although probably a lot simpler to sort out than reverting to changing carbs and parts .

hope you get it sorted .

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