Edumacate me on 650 holley Carbs

[hendrixhc 10,921]

So i am looking at carbies and noticed you can buy the 650 double pumpers with or without chokes.

 

If you dont have a choke are they a bastard to start or doesnt it make a difference?

 

I noticed the ones without the chokes have a more contoured set of venturies which i assume is to increase air velocity.

 

Can anyone enlighten me on the subject?

 

 

 

[revhead 1,392]

best 650 to buy is a double pumper with choke housings machined off ,to start is easy 3x full pumps to the floor ,lift foot off and turn key ,let idle for 5 minutes before driving ,

 

i like the holley 750 centre squirter my self ,but thats another story,lol

 

in the end most manual electric chokes play up better off without one.

[hendrixhc 10,921]

Thanks Pete!

[revhead 1,392]

anytime ,just think wallet with a 650 double pumper ,if your feeling rich give it the berries ,if your a little poor the following week but still want a drive ,dont crack the seconderies as youl watch the fuel guage move,lol my last build was a 383 stroker in an EA sedan with a 750 centre squirter ,omg ,it was fast ,i remember hahaha driving 22 ks a day return  for 5 days a week to work and home ,a full tank cost me $99 buck ,well after the 5 days the tank was dry,lol but fuck it was fast fun,lol 68 litres for 110ks wow but is was fun.

[hendrixhc 10,921]

Hey its only fuel, plenty to go round and we might as well burn it up while we still can!

[KRUPTOR 929]

Go for a squarebore 600dp,those spreadbore 650's are crap.

[Trev Vaa 1,185]

depends how serious your motor is.... look a choke is always handy, especially when your in a cold area.

 

ive seen motors with 550hp that still have a choke, in saying that i dont use one, two pumps then crank it and hold my foot lightly on the throttle and play with it till it clears out, then hold the revs up before i drive off... of course at 5am my neighbours did not like the idea of me doing that.... especially with an exhaust that was 127db and set off every car alarm as i went past....

 

i prefer the way a double pumper feels on the throttle, i like a mechanical connection between my foot and the engines performance.

as for spreadbore vs squarebore... just depends on the applications and how punchy you like the secondaries.... i like the feeling of a squarebore, i like to get booted up the ass when the secondaries come into play...

[hendrixhc 10,921]

I was talking to a mechanic mate yesterday and he suggested that i go 650 holley squarebore DP with no choke and mech secondaries. So recon that will be the right direction to go. Just wasnt sure about the no choke thing.

 

Yes i do like the idea of giving it a boot full and being kicked in the arse to Trev!

[revhead 1,392]

nothing like the feeling of being planted in your seat when the seconderies kick open,or the feeling of wheel spin under heavy acceration

[Trev Vaa 1,185]

so long as you've got the time to wait to warm it up and good manifold vaccum you'll be fine without it

 

 

that thing doesnt have a choke and you can drive it within 5minutes of first firing it up, and move it out into the driveway within a minute.... and that thing is SAVAGE (cam is around 270 @50thou) it runs twin 600s and its 532 cubes.

[slydog 7,873]

This is a very open ended question with answers that can be taken in many ways with out many specifics.I use a 650 ST HP DP on my ute ATM.So it's a Street (ST) HP double pumper (DP).All DP's are mechanical secondary's.If it's not move on.

I give my ute one full pump and it will key start within half a turn usually but it will never idle under 1300rpm and any splash oiled camshaft should not be left to idle in any case as it speeds up cam/lifter wear.So basically after it's started and running for like 30secs drive off like normal but just be smart and don't rev it till it comes up to temp.

 

As for a choke...IMO they are not needed unless your wife will be using it as a daily driver.

 

So my suggestion for a carb on your engine is a squarebore 650 DP on a HP design but NOT a new style Ultra.They are poo...The real Holley DP's do not have chokes but these new Ultras do and they don't have a awesome reputation.The street HP needs idle circuit tweaks to work well and have adjustable air bleeds and 4 corner idle.Again IMO not needed in your case so I would go for the basic HP DP...

 

Use this and delete or just don't use the choke and your happy for years...  http://www.summitracing.com/parts/hly-0-4777c/overview/

 

If your thinking performance then go for this bad boy...http://www.summitracing.com/parts/hly-0-80541-1/overview/

[PRO250 1,506]

A DP is not for everyone my ute had a 750 pumper and i pulled it off, i pull a 2 ton trailer with mine and it had issues bumping it on the 2nd barrels so i just removed it, and never think a vac carbys not as fast as a pumper my corty runs a vac on its clevo and it still heaps fast

 

i now run a HP 750 vac the one your talking about with no choke horn just 3 pumps of the throttle and turn the key and its a live even sitting out side on a -3 morning it just fires up. you do have to dab the trottle a bit to keep the old girl alive but my cams on the large side of things you may not have that issue

 

my pick would be the 2nd one on robs list it may cost more but a better carby by far

 

but remember pumpers are for light cars with short gears a XE is not light althow i dont know what gears you plan to run but 3.9s or 4.11s would not work well with a small camshaft a vac would be better IMO as it will not bog the seconderrys open at low revs cause the car is going to slow or the engine speeds to low it will open when it needs to

[gerg 10,871]

If you're going for all-out performance, then the 650 DP is a no-brainer. Getting the most out of it is what will have you tearing your hair out. It takes 10 minutes to bolt one on, but may take months to get it right. I found this out with my EBay 600 vac I bolted on.

 

It turned out to be a bit of a Frankenstein made up of mongrel parts that didnt match. Very quickly, an old, worn-out $80 carby turned into a $200 kitted, manual choked, worn out carby. The car goes ok but I do wonder how much better a 600 Edelbrock would go, particularly with economy.

 

I personally like the idea of spreadbores. It's business up front, party out the back. Dont be scared of looking into a reco Quadrajet or Thermoquad, they're both up around 750 cfm but are superior in economy to any equivalent Holley. Yes it's possible to get performance with efficiency, just look at the GM LS1, etc.

 

Horsepower is easy, but horsepower with efficiency is the challenge.

[slydog 7,873]

Maybe if you bought a new one you wouldn't have struggled to tune it.Can't use a part thats been thru who knows how many hands and your lack of tuning ability as a sole blame on tuning Holleys.A simple AFR gauge doe's wonders here or a trip to a mechanic with AFR probe would have saved any issues in sorting it or atleast gave you ideas how to tune it.Mine was found to need idle circuit changes from factory settings plus I had the butterflys open to far that was showing the transfer slot and idle circuit air and fuel which made it a tad dowey and used ALOT of fuel and very rich.It was sorted easy via the AFR gauge and 11.7 compression.Problem gone...  

 

Spread bore carbys were solely designed for BB V8 in the US and there use on small cube engines is always a tuning issue as throttle response due to having two small holes open then 2 extra large one coming open the amount of air difference is extreme.A Q jet was used to get LP and victory or 2 but they were by no means close to stock.I also question anyone on the planet who wants a V8 and economy? Like owning a Harley but you want it quiet and don't want to raise attention or get noticed? You can not compare any modern EFI V8 with a 30 year old carbied V8 for fuel efficiency either.The new car has superior ignition burn and timing control,precise fuel metering and a much better designed heads to flow more power easier plus much better matched gearing to improve economy via multi speed transmissions.I'd imagine there a lighter engine too but just stuck in a fat over weight car.       

 

I hear what your saying to Webby but what is a light car these days? I reckon anything under 1500kg's is doing well based on new Commodores and Falcons tipping the scales at around 1900kg's loaded.Our FG XR6 is not that much but a base model is still 1700kg's but the V8's and the luxury models are barges.All of the sudden a 1400kg Falcon is no over weight sow which is why Ants Wagon is gunna tame ALOT of big $$$ late model V8's turbo's and such.It's 400-500kg's lighter which is 3-4 politicians in weight.

 

My ute is 1380kg with me in it (after a hefty diet) so yes It will be on the lighter side but Cortys are not that much lighter really and my ute carby got sized by Pro Systems as needing a 740 CFM DP for it's intended purpose but for methanol it would be smaller.Showing how far out the CFM calculator can be.None of the fast x-flows run smaller than 650 CFM but I have seen many many fast V8's run 650-750's on a extra 50-100 cube combo's that makes you wonder how it works?

 

I still rate the DP over the vac units due to only using a poxy thermo quad that was poo from day dot but a newer 600-650 may be fine if tuned right to start with??? 

[hendrixhc 10,921]

Thanks for all the comments and advise guys. Ill definitely be going for a 650DP, no choke and new out of the box. I Put evrything else no into this engine so might as well finish with a new carby.

 

Was thinking one of these here

 

http://www.ebay.com.au/itm/Holley-650-CFM-HP-Series-Four-Barrel-Street-Strip-Carburetor-D-Pumper-82651-/190734714429?pt=AU_Car_Parts_Accessories&hash=item2c68acc63d&_uhb=1

 

Do you have to use the kickdown linkage and what is an AOD Transmission?

[slydog 7,873]

AOD is a US 4 speed auto that there a few over here but not many.We use electronically controlled autos they used the good hyd units...

 

That carb is EXACTLY what mine is and will have to be tuned rich at idle or you need to get the idle circuit tuned to suit your needs.You can get them rather close via tuning the air bleeds and any real shop could sort that for you I'm sure.Thats why the HP based standard DP is better for more cruiser type users straight out of the box.Still the ST HP is years ahead of the new ultras bro and hard to go past for the price. 

 

As for your linkage the box has to be built to handle it's own shifts if not using the kick down.I have never had one on any C4 I have owned but there all shift kitted or full manual C4's.

[hendrixhc 10,921]

Cheers Rob!

[Trev Vaa 1,185]

dont buy one of ebay, buy one from VPW or the like, you may have to wait for it but they have good customer service, ive spent over 30K there all up.

if you have any issues they will help you, and the boys know there shit.

 

personally id just buy straight from Pro Systems now, theyre so affordable its not funny.

[gerg 10,871]

 

Maybe if you bought a new one you wouldn't have struggled to tune it.Can't use a part thats been thru who knows how many hands and your lack of tuning ability as a sole blame on tuning Holleys.A simple AFR gauge doe's wonders here or a trip to a mechanic with AFR probe would have saved any issues in sorting it or atleast gave you ideas how to tune it.Mine was found to need idle circuit changes from factory settings plus I had the butterflys open to far that was showing the transfer slot and idle circuit air and fuel which made it a tad dowey and used ALOT of fuel and very rich.It was sorted easy via the AFR gauge and 11.7 compression.Problem gone... /quote]

 

You just said you had dramas with your brand new carby, so it's not all beer and skittles either. It's never a bolt-on proposition, especially with hotter engines that need expensive dyno time to sort. I'm nearly satisfied with my 600 vac on my mild 302C now, if I want to squeeze a few more MPG out of my car then good luck to me. As for my "lack of tuning ability", well I've learnt a lot in the process, and you can't knock someone for having a go.

 

Like many folks on here, I havent got the dough to throw at brand-new, $600 carbys or wideband O2 meters and the like, only seat of the pants and a bit of trial-and-error, you know, like in the old days. And just because an engine happens to have 8 cylinders doesn't mean you need to see half your weekly wage disappearing out the exhaust pipes.

 

I guess we all have differing opinions on what is a reasonable figure for a V8's fuel consumption, but 20 mpg (11.7 l/100km) on the open road is not out of the question on a carby-fed smallblock. I'd certainly be happy with that.

 

Of course EFI is better in all areas except cost. Mostly better in emissions, or more importantly, making less emissions for similar power. Carbys do an amazing job considering they only have two input parameters: throttle position and air flow.

 

Big blocks aren't the only ones to benefit from spreadbores. Brocky dunnydores had Rochesters too, and made good power at the time. They even came on later 253s.

 

Good thermoquads are getting hard to find, but in their day were considered a great carby apart from the warpage issues. Also, the metering rod vacuum piston bore wears out and to fix that, you throw the carby in the bin. They are mech secondary but have a variable Venturi so come on nice and soft.

 

"Performance" Holleys come tuned hell rich, especially at idle/transfer. Lots of stories abound of people getting the shits and modifying them for removable air bleeds and idle restrictors, even going to a Proform body for this reason. They're jetted pretty fat too, you could often drop a size or two and gain power.

 

It's horses for courses really, and comes down to what carby you can make work for you. For me, Holleys are more performance-oriented and economy is less of a priority for them.

[SJG351 6]

Innovative Motorsport tuners forum has a ton of holley tuning info, some absolute carb magicians post on there, I have seen guys tune 500hp carbied small blocks and get 26mpg at cruise, now thats tuned!

[Butcha 111]

I've run 650DP 750DP HP and even my current 950 e85 carby i have never felt the need for a choke. Maybe its a factor of running lower compression 8 or 9:1? they all fire the engine before a full turn with the exception of the 950 sometimes but thats a different ball game. DP not the best choice if fuel eco is your concern but a second spring on the seconaries to give that pedal stop feel works a treat keeping off em unless you really wanna go..

[hendrixhc 10,921]

Dont think fuel economy is a concern!  Bit of fun is the goal!

[Butcha 111]

dont worry about the second spring then lol.