Carburator question
 

I have a holley 750 DP on my 351W. It is a used model that i have been having some problems with. I am going to buy a new carb, I just dont know what to get. The Holley I have, really seems to put off a lot of exhaust fumes. Which the co-owner of this car is not that fond of (wife). I was wondering does an edelbrock performer carb make any less fumes? (maybe a stupid question I dont know). Also I would like the most reliable carb without a lot of fidaling to make run, I would like to do initial install and forget, but not sacrifice any performance. My choices are, new Holley, Demon, or an Edelbrock, which is the best for what i am looking for? HELP PLEASE. Bly.

Everyone knowledgable about carbs I have spoken to says stick with a Holley...I have heard the 850 with annular boosters is the way to go...

Bly,
The Holley 750 DP (double pumper) is really too much carb for a 351W unless you have heads that will really flow. The DP is designed for the track, not the street. I had one on my 351C (that had the 4V heads with massive ports) and I was always adjusting it, trying to make it more streetable.

I would suggest a Holley 650 with vacumn secondaries. This carb is designed for street use and will probably give you much better performance and reliablity.

Cheers
Jim

Hi,
I would suggest an edelbrock 750 carb. The edelbrock carbs have a bottom feed system so they never leak. Also they have much better low speed transition from idle to mid range and there is an air flap in the secondaries that will meter the gas according to air flow. I run 2 600 carbs on my 460 with very good response. It is too much cfm but with the secondary metering the air I never bog or stumble,it just pulls hard.A double pumper holley is a good carb for the track only,it will just puke gas and actually slow down on a mild street engine.
Perry.:cool:

You just need to tune your carb. It probubly has #80 jets at all four corners, god knows what # power valve, etc. I bet you are just running too rich, and a carefull tune of all the circuits on your holley would fix it. 850 DP is a little on the big side if your motor doesn't make an honest 500 hp, a 750 would give you better low end throttle response. If you decide holley's are junk, send me the one you are running now, I'll give it a good home.

I second Fixit opinion, I run Holley on all my cars with same type of engines. You need to get to a good shop that has a dyno that will check your fuel air ratio. Run in the area of 13 to 1 and you will love your carb. Buy some books and read about Holley's they are very adjustable, and easy to understand. But.... if you still want to junk your Holley carb, I'll pay shipping plus some beer money.

You don't need a dyno to tune carbs, just new sparkplugs, a road you use to run it through the gears, and a bunch of jets, squirters, pump cams, and patience. Getting one of the many books written about tuning, rebuilding and modifying holleys is a cheap way to learn a bunch of stuff you want to know.

Has anyone tried one of the new Holley Street Avenger carbs?
They are priced higher than some of the other Holley street type carbs and I'm wondering if they are worth they exta money.

I'm currently using 670CFM Street Avenger. I swapped it out for an older Holley 650 with mechanical secondarys. I to bought the 650 used. It was in need of major work as the previous owner plugged the secondary power valve circuit.

I changed to the Street Avenger and could not be happier. It does run a little rich out of the box but not to bad. Gets good marks on performance and reliability.

This sits on top of a 302 motor.

Mike

Mr. Fixit's right....
 

Most probably your 750 just needs some tuning. You didn't mention which 750 you have, but I just swapped a Holley 4160 series 750 DP for a 4150 series 750 -HP. The difference in the 4160 and 4150 is the 4160's do not have replaceable secondary jets - they have a metering block. 4150's are more like the original everything's adjustable Holley's, and are really more to my liking.

My 4160 had vacuum secondaries, electric choke, and non-replaceable secondary jets. My new 4150 has mechanical secondaries, no choke and fully replaceable jets, power valve, accelerator pump, squirters, etc. etc. The difference is the 4160 is about $260, while the 4150 is $600....big difference, indeed, but the 4150 is bar far the better carb.

Used to run too rich with the 4160, but since I couldn't make adjustments I had to live with the fumes. WIth the 4150 series, I'm running #70 primaries, and #72 secondary jets. The 'fumes' you mentioned are all but gone...and the car really comes on like gangbusters! Everyone said my gas mileage would go to hell with the mechanical secondaries, but I figured what the hell, this ain't no Corolla and I really don't give a flyin' flip about gas mileage in a Cobra...who does? So far, I've been very pleased with the changeover and wonder why more folks don't just go to the 750-HP right on the front end. Sure, it's more expensive, but if you're looking to not spend a lot of money, brother are YOU in the wrong hobby.

The Holley 750-HP seems perfect for my stroked 351... Tastes great, less filling....what more could I ask for?
:3DSMILE:

I would definately not suggest the Edelbrock for out of the box performance. It is a decent carb once it is tuned in but it may take quite a bit of tinkering to get you there. I had one on a big block for a while. It took me a good couple months to get it tuned in to where I liked it. After that it ran fine until the acc. pump decided to act up.

Your other choices are Holley & Demon.

Holley 4150= It's really hard to go wrong here. They are set out of the box to run. You will of course have to set you idle mixture & choke.

A friend of mine is & has been running a street demon for about the last year on a SmBlock Chevy. He loves it. We set the Idle mixture, the choke on the first day & he has had no problems since. I also had a Speed Demon for a time. Really nice but IMO don't really look right in a Cobra.

The most important thing I have found is getting the correct size carb to begin with. If you do an internet search on Carburetor Size Calculator you might find this handy tool. I would post it but I don't have it with me right now. If you can't find it & are are interested PM me & I will look it up tonight when I get home.

Holley and Brasswell developed the HP together. It it designed to be a ready-to-run mass produced race carb with the performance of a hand built race carb. $600 is cheap considering it often out-performs its competion which cost $1200-$1600.

Since I've never run one on a mild street engine, I would question the "ready-to-run" aspect for that application, but when dialed in, the part throttle to full throttle transition is second only to a VERY good custom carb.

Careful, nothing damages rings faster than black smoke (rich)coming out the pipes at idle.
Scott

Just a tip:
You can modify the 4160's to have removable/replaceable rear jets, without spending any money. Plug the pickup holes on the metering plate with locktite quick set epoxy, and then drill and tap those passages to accept jets. Or just buy the conversion metering block kit for about $40 and have a 4150 when finished.

I just switched fro a Carter (same as Edelbrock) The Carter had a little better bottom end, but there is NO comparison on the top end, the Holley is much better. Idle quality was about the same on both, but I had to fatten up the idle mixture on the Carter.

I ain't going back.

Once again, Mr Fixit's right....
 

Holley sells a block with replaceable jets to replace the fixed-jet metering blokc in 4160's....when you get done, you've essentially got a 4150....replaceable jets, etc. I think the kit is about $44.95 from Summit, plus jets, of course. Jets were $4.95 a set when I ordered mine last month. I got an assortment after talking with Dennis Olthoff of Olthoff Racing....he suggested #70 primaries and #72 secondaries for my stoked 351 (392 cubes) w/ Edlebrock Victor Jr heads (2.02 intakes/1.85 exhausts), Comp Cam. Stock out of the box the carb came with #74's....primaries and secondaries. A little too rich in our opinion. Leaned out a little with the 70/72's and seems to be right for my set up. I wound up with a set of #68's, #70's, #72's and #74's...saved the #68's, and removed the #74's from the stock carb. I'm using the 30cc accelerator pump and the stock squirter jets...so far, so good.

One thing to note....the 750-HP carb does not have a choke and therefore, no choke tower to hold the choke butterfly. Because all that hardware is gone from the top of the primary side, there's a much cleaner air flow down the primary venturis. But, it's a little but of a bugger to keep going when it's cool...just gotta learn to feather the throttle a little to keep the revs up until it warms up. But, once it does, the engine runs and accelerates MUCH smoother with the 4150 series carb over my former 4160 model. No flat spots, no 'trigger' throttle....the power comes on smooth and quick, with a steady pull from idle all the way to 7K....YEEEEEE-HAAAAAAAAA! It'll jerk your fillings out...! Or, you can just ease around town on the primaries only, like you're driving a Nissan....

Yeah.....sure you can....

.....NAWT!

Just a note:
Do not confuse the 4150HP with the 4150, they're completely different carbs. The 4150HP has much better fuel metering. Whether it's used on the street or the track it will deliver fuel more precisely than the 4150 and as a result deliver crisper throttle response. For me the lack of a choke is a very small trade off.

Another note:
You can convert the 4160 to a 4150 with the metering block, but not to a 4150HP

Hey bly:
I'm running a Holley 750 on my 351W with no problems and no fumes. It's an 80508 (4160). This carburetor has vacuum secondaries and an electric choke. I'm very happy with it. If I were doing it again I might go to a 650CFM.

Bob

Sorry to disagree with your comment about not using a dyno with fuel /air & EGT measurement mr. fixit, but I wonder how one can read a plug at every rpm range from idle to redline ??

Of the various Holley books, does anyone have a preference??

what type of manifolds are all you holley boys running??