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		| Leyland P76 Owners 2004 | Question Holley carbys   |  |  
 Question
  Sunday, November 06, 2005Right oh , i just found the problem (I think).I had a go at retuning the holley 600 carb and found that when i turned idle screws back in and only turned them out half a turn   the motor started to run smoother and now theres no smoke out the pipes.Now the question is i thought that these carbs had a one and a half turn idle ajustment?? could there be another prob?(leak?)cheers niko.Reply
  
  Monday, November 07, 2005 5:06 PMHi NikoOne question, why are you running such a high CFM Carby when their is no way in the world that your 4.4can flow that much ???If you want it to boogie down low and up high,don't go larger than a 465 Holley.So many people think bigger is better and end up driving a fuel guzzling pig instead of a torquey street sleeper.I have the figures here to work out your CFM requirements if you provide me with some details about your motor..Cheers Anton...Reply
  Monday, November 07, 2005 8:44 PMHi Anton, i think from memory i had been told that the 600 would work fine, but im not sure by who its been in the car for a while.When i had the motor recoed they (speedpro) did do a fair bit to it.It was bored out to 4.8ltrs and flattop pistons were fitted.The heads have been ported/shaved and the manifold is a custom number (4barrel)Other mods includejethot coated extractors, electronic distributor,and a cranecams sparkamplifier.Im not sure of the power out put but the biggest problem has been the transmission its blown up three times( one time really blowing up!!)Its all going to change as im going to fuel inject the motor sooner than later.cheers niko.Reply
  Mon, 7 Nov 2005Sounds good in the motor department Nico, but i would still like to see a 465 holley set up properly for the motormods, recon you would think twice about fuel injection then. I would imagine that the 600 holley you have on atthe moment would be running a heavier spring on the vacuum secondarys to negative any of the ill effects of thelarge carby, opening the secondarys too quick which would play havoc with your airspeed.The formula for working out your CFM is-----   Engine CID X  Maximun RPM   Divided by 3456 .......This formula assumes 100% Volumetric efficiency, which off course you will only have if your motor is blown. \Yours is probably working at around 80 to 85%  realistically.For example a 350 chev X 8000 rpm  Divided by 3456  = 810cfm at 100% VEWhere at 85%  VE its CFM is 689 quite a difference.So your motor would roughly come out at  290cu X 5000rpm  divided by 3456 = 420cfm at 100% VE........Hope this helps & Happy Peeing.................cheers Anton.Reply
  Tue, 8 Nov 2005Your Holly 600 isn’t too big for the capacity (4.4) but the P76 ports in the heads are too restrictive to allowthe flow rate the 600 needs, hence try using a smaller CFM size and it will probably go better and use less fuel .You can enlargen the ports for more flow and fit bigger valves , cam etc and the horsepower will go up but low down toque will suffer , also don’t expect it to be a cheap option .By the way – Holly lies about the CFM rate on  their carbies (they have a creative way of measuring their CFM rates to get higher figures)Hope all this helps , now where was that coma .......RickReply
  Mon, 7 Nov 2005With a mild cam, extractors and few head mods  a 390cfm would do nicely, I reckon.Mick.
 
		
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