Isaachunt4u
Part of things
God I Hate Idiots !!.
Posts: 142
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Jun 27, 2011 17:36:13 GMT
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Hi all, I have a Rover 4.6 V8 engine, Fast Road Cam, (but unsure which one ),  & looks like Mildly Ported Heads, which is powered by a Holley 600 cfm Carb, (Vac 2nd`s), sitting on an Offy 360 Manifold. I bought the Carb "as new" straight from the States, (Bargain!!),  and it is in fact fine. But, it was previously fitted to a Chevy 350 ci Motor, and although seemingly OK on the Road, (in fact Acceleration is Brutal !!),  on Tick Over, when Fully Warmed Up, its obviously running too Rich. (Already backed all the way off on Adj. Screws). Can anyone please advise me of what Size Jets to use to suit the 4.6 V8 Lump ??!!. Thanks.  |
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Old Petrol Head. Owned and Driven most "Classic" & "Customised/Rodded" things from Mk2 Zodiacs, to "Daily Modern Drivers". Now own 2009 Fiat Bravo 165bhp Multi Jet Diesel, (Great Engine), and 1985 Bedford CF2 4.6 V8 Custom Van !!.
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burns
Part of things
Posts: 373
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Jun 27, 2011 18:17:41 GMT
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The jets shouldn't really be doing anything at idle. Why do you say it is running rich?
Could be something is up on the secondary side, if you have the idle mixture screws would all the way in the I would have thought it must be idling on what it is drawing through the secondaries. So maybe adjusting the stop on them so there is less air getting through there will give you more control back through the primaries?
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Isaachunt4u
Part of things
God I Hate Idiots !!.
Posts: 142
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Jun 27, 2011 18:36:42 GMT
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The jets shouldn't really be doing anything at idle. Why do you say it is running rich? Could be something is up on the secondary side, if you have the idle mixture screws would all the way in the I would have thought it must be idling on what it is drawing through the secondaries. So maybe adjusting the stop on them so there is less air getting through there will give you more control back through the primaries? Thanks for that, I`ll get it checked out. When hot, it starts to gradually Tick Over "Unsettled", Revs Slowly Decrease, and it just sounds "Choked Up". Exhaust Tips are Sooty, and Plugs are Sooted up a little too. (Not Fuel or Oil). Just gives the appearance of using far too much fuel at Idle. Runs great on the road, and pulls like a Train, with no Misfiring, or Flat Spots etc, and feels like it would rev forever if you let it !!. Cheers, Dave. |
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Old Petrol Head. Owned and Driven most "Classic" & "Customised/Rodded" things from Mk2 Zodiacs, to "Daily Modern Drivers". Now own 2009 Fiat Bravo 165bhp Multi Jet Diesel, (Great Engine), and 1985 Bedford CF2 4.6 V8 Custom Van !!.
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Jun 27, 2011 21:19:58 GMT
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unless you are running the engine to around 8k a 600cfm carb is on the large side for a 4.6 you ideally need around a 500cfm for the type of tune your running . a 600cfm will always be a little rich on idle but you could try jetting it down say around .64 primary's and .73 secondary's this would normally be a little lower than the stock jetting for these carbs but to low to cause it to run lean
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Isaachunt4u
Part of things
God I Hate Idiots !!.
Posts: 142
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Jun 27, 2011 21:39:17 GMT
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unless you are running the engine to around 8k a 600cfm carb is on the large side for a 4.6 you ideally need around a 500cfm for the type of tune your running . a 600cfm will always be a little rich on idle but you could try jetting it down say around .64 primary's and .73 secondary's this would normally be a little lower than the stock jetting for these carbs but to low to cause it to run lean Hi, Thanks for that. I bought the Holley 600 cfm, as it was basically a Bargain, direct from the USA. It was fully Rebuilt, looked new, and only cost around £130`ish including International Postage !!. Mind you the Customs boys charged me 17.5 % VAT on this at the time, but it still worked out cheap. I did actually have a Holley 390 cfm, but sold it, as I thought it wouldn`t be up to the job on the 4.6 V8. I would have liked to have tried an Edelbrock 1404 500 cfm, as I know they aren`t "too fussy" Jet Wise, but I couldnt/cant find a used one at the right money, and I`m not paying £350 or what ever for a new one !!. I`ll have the Idling Mixture looked at on the Holley 600, and look at getting the Jets that you suggested. Where do you buy from ?. There is a place called Stateside Autoparts in Atherstone, Warwick, just "down the road" from where my van is at present ; - www.statesideautoparts.co.uk/ContactUs.htmI was down that way today, so dropped by, but just as per my usual luck, they don't open on Mondays !!. All the best, Dave. |
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Old Petrol Head. Owned and Driven most "Classic" & "Customised/Rodded" things from Mk2 Zodiacs, to "Daily Modern Drivers". Now own 2009 Fiat Bravo 165bhp Multi Jet Diesel, (Great Engine), and 1985 Bedford CF2 4.6 V8 Custom Van !!.
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30psi
Posted a lot
Posts: 1,024
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Jun 27, 2011 22:36:06 GMT
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Check the float levels. If it's running high on the floats (e.g. from a stuck needle) it can drip out the jets.
You will have a metering plate on the secondary's unless someones fitted a metering block and a longer transfer tube, so you'll only be able to re-jet the primaries.
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1962 Ford Thunderbird 6.4L
1981 Datsun Bluebird SSS CA18DET
1981 Datsun Bluebird SSS SR20DE
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Jun 28, 2011 19:27:37 GMT
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you should only need to rejet the primaries. Idle circuit operation is only going to be on the primaries if its genuinely just the idle which is rich as the secondaries will be shut?
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1941 Wolseley Not Rod - 1956 Humber Hawk - 1957 Daimler Conquest - 1966 Buick LeSabre - 1968 Plymouth Sport Fury - 1968 Ford Galaxie - 1969 Ford Country Squire - 1969 Mercury Marquis - 1970 Morris Minor - 1970 Buick Skylark - 1970 Ford Galaxie - 1971 Ford Galaxie - 1976 Continental Mark IV - 1976 Ford Capri - 1994 Ford Fiesta
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Isaachunt4u
Part of things
God I Hate Idiots !!.
Posts: 142
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I`ve been looking at different options regarding how to solve my little Dilemma, as I`m just not happy with the Holley 600 cfm on my Rover 4.6 V8 lump, no matter how its adjusted, and I`m sure I can do much better Fuel Economy wise too. So, I was looking at swapping over to an Edelbrock 1404 500 cfm Carb, for which I`ve placed an Ad in the "Stuff Wanted" section. BUT, having delved a bit deeper, I`ve now realized that the Flow Rates on Holley`s & Edelbrock`s/Weber`s are Calculated in very different ways, i;e - Holley 600 cfm = As near as F#ck it 600 cfm. Edelbrock/Weber 500 cfm = More like only 400 cfm, hence much more suited to the Rover 3.5 V8 lump, in either Standard or Mild Tune, as is the Holley 390, as a Standard 3.5 V8 requires around 365 cfm.
I have now found for sale a Holley 450 cfm 4 Barrel, with Vac 2nd`s, which by my reckoning, "Should" actually fall nicely in between the Holley 390 & 600 cfm models, and be pretty near the mark for what my 4.6 V8 lump "ideally" needs, but before I go jumping in with my Size 11`s, your Comments & Opinion`s are as always much appreciated !!.
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Old Petrol Head. Owned and Driven most "Classic" & "Customised/Rodded" things from Mk2 Zodiacs, to "Daily Modern Drivers". Now own 2009 Fiat Bravo 165bhp Multi Jet Diesel, (Great Engine), and 1985 Bedford CF2 4.6 V8 Custom Van !!.
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It's certainly closer to what you need. For a street drivencar you are often better with one a little small than one too big...
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1941 Wolseley Not Rod - 1956 Humber Hawk - 1957 Daimler Conquest - 1966 Buick LeSabre - 1968 Plymouth Sport Fury - 1968 Ford Galaxie - 1969 Ford Country Squire - 1969 Mercury Marquis - 1970 Morris Minor - 1970 Buick Skylark - 1970 Ford Galaxie - 1971 Ford Galaxie - 1976 Continental Mark IV - 1976 Ford Capri - 1994 Ford Fiesta
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Isaachunt4u
Part of things
God I Hate Idiots !!.
Posts: 142
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It's certainly closer to what you need. For a street drivencar you are often better with one a little small than one too big... Yes, this is my way of thinking too. The Holley 450 I have seen is a VERY strong contender now, I`ve just emailed back the Seller, as I want to know what it was fitted to previously, and also if he knows what Primary Jets are fitted. Once I know this, I "should" be able to make a decision. What ever the case, the existing Holley 600 will now be replaced, and will also be for sale before too much longer !!. |
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Old Petrol Head. Owned and Driven most "Classic" & "Customised/Rodded" things from Mk2 Zodiacs, to "Daily Modern Drivers". Now own 2009 Fiat Bravo 165bhp Multi Jet Diesel, (Great Engine), and 1985 Bedford CF2 4.6 V8 Custom Van !!.
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Isaachunt4u
Part of things
God I Hate Idiots !!.
Posts: 142
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Jul 22, 2011 18:45:36 GMT
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Very pleased to report that after a little fettling time, adjusting the Float Levels, (way too high !!), and the Idle Mixture, & Curb Idle, the Engine is running MUCH better.  This carb really is a Corker, with Instant W.O.T Response, no delay, or popping and farting at all !!. BUT, its still too big for the 4.6 V8 that its on, and who can really afford to Waste Fuel at todays Prices ??!!.  So, I`ve advertised for a Good Used Edelbrock 1404 500 cfm carb, but have also been offered a Holley 390 cfm at the right money, so I`m back where I started from, as I have already sold a Cracking Holley 390 !!. Personally, I think that the 390 may be a little too small, as just to recap, I have a R/Rover P38 4.6 V8 Lump, Crane Fireball Cam, (I think !!),  stock P38 Tubular Headers, a little Porting Work to the Heads, but standard 4.6 Valves, and of course, an Offy 360 Manifold. As always, your opinions would be more than welcome as to whether this Holley 390 will be suitable, or if I should hold out for the "Eddie" 1404 !!. I will also be selling the Holley 600 cfm soon, and have already promised someone first dibs, but if they don't want it, I`ll advertise it for sale soon !!. |
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Old Petrol Head. Owned and Driven most "Classic" & "Customised/Rodded" things from Mk2 Zodiacs, to "Daily Modern Drivers". Now own 2009 Fiat Bravo 165bhp Multi Jet Diesel, (Great Engine), and 1985 Bedford CF2 4.6 V8 Custom Van !!.
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30psi
Posted a lot
Posts: 1,024
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Jul 22, 2011 20:13:45 GMT
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Fit the 390 and plumb up a vacuum gauge. Go for a blast and see what vacuum it pulls at high rpm
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1962 Ford Thunderbird 6.4L
1981 Datsun Bluebird SSS CA18DET
1981 Datsun Bluebird SSS SR20DE
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& looks like Mildly Ported Heads, which is powered by a Holley 600 cfm Carb, (Vac 2nd`s), sitting on an Offy 360 Manifold. I bought the Carb "as new" straight from the States, (Bargain!!), 
and it is in fact fine. But, it was previously fitted to a Chevy 350 ci Motor, and although seemingly OK on the Road, (in fact Acceleration is Brutal !!), 
on Tick Over, when Fully Warmed Up, its obviously running too Rich. (Already backed all the way off on Adj. Screws). Can anyone please advise me of what Size Jets to use to suit the 4.6 V8 Lump ??!!.
This carb really is a Corker, with Instant W.O.T Response, no delay, or popping and farting at all !!. BUT, its still too big for the 4.6 V8 that its on, and who can really afford to Waste Fuel at todays Prices ??!!. 
So, I`ve advertised for a Good Used Edelbrock 1404 500 cfm carb, but have also been offered a Holley 390 cfm at the right money, so I`m back where I started from, as I have already sold a Cracking Holley 390 !!. 
stock P38 Tubular Headers, a little Porting Work to the Heads, but standard 4.6 Valves, and of course, an Offy 360 Manifold. As always, your opinions would be more than welcome as to whether this Holley 390 will be suitable, or if I should hold out for the "Eddie" 1404 !!. I will also be selling the Holley 600 cfm soon, and have already promised someone first dibs, but if they don't want it, I`ll advertise it for sale soon !!.