What size Carb?

[UpRise_5.0]

And how big of a carb would you need for approx 300 Flywheel Hp, and mabye later a 75-150 Shot of Nitrous.

Thanks

 

[Michael Yount]

650 is plenty; just be sure you have enough fuel pump to handle the carb and the wet shot.

 

[green]

ya a 650 should be the very best.

 

[Musclecarfan88]

650 is good, its what i have on my car, but some people feel the 750 really wakes up a modified 5.0, now weather or not it really does or they are just feeling things is a different story. Id like to get my car on a dyno and see what kind of numbers it makes with a 650 and hten again with a 750 to see if their is any performance gain or loss.

 

[UpRise_5.0]

Would a Edelbrock 600 4 Barrel be to little? Just because I might be able to get one for a very good price.

 

[dude5l]

I'm not a big fan of the Edelbrocks myself. I would go with either a Holley or A Barry Grant.

 

[85GTlover]

Would a Edelbrock 600 4 Barrel be to little? Just because I might be able to get one for a very good price.

I imagine the edelbrock 600 would do a fine job, and they are good carbs as well. The differences between that and a 650cfm are going to be minor. Unless you are talking tenths in the 1/4 mile.....I doubt you would really feel the difference driving.

 

[Michael Yount]

I agree with 85GT (hey there!) -- the Edelbrock 600 makes a good street carb and should be plenty for your 5.0L. BG makes a nice piece too.....just more $$$.

 

[thumper460]

Sorry... the holley 750 ( list 3310) vac. secondary!! it will pull past any 600 or 650 !! and for the street strip stay away from the double pumps!! Cool?? as for the NOS, it will use any size as it is a chemical supercharger...cool?? fuel pressure? keep 6-7 at the carb and 5 at the juice!! all I can say is " Been there , done that!! Bought the Tee shirt!!"

Just me................

Thumper

 

[Michael Yount]

I guess we see it differently Mike - in 35 years, I think I've yet to see any Holley that wasn't leaking somewhere after it's been in service for more than a couple of months. The larger carb is only helpful if you've got enough motor to utilize it. Most streetable 302's don't require anymore than 650cfm of carb -- in other words, the carb cfm isn't the bottleneck to better performance. And the larger carb if it's not needed for the top end, hurts bottom end (read - street) performance. I'd guess most small blocks out there on the street are over-carbed. Even a vacuum secondary 750 is too much for most 302's - run's little if any better on top, and hurts the bottom, not to mention drivability, throttle response and fuel mileage. It's a lose-lose most of the time in my mind.

 

[SmockDoiley]

You can run either the vac or the mechanical but the vac. will be more forgiving on the street because it adapts to climate and weather better. I really wouldnt go past a 650 though because although a 750 will make more power at the topend, it will have a tendency to bog your off idle. As for Edelbrock, screw that crap. They are garbage and not suitable for NOS and racing. The Holley is very adaptable and tunable and the Demons are a cleaner version of the Holley so either one will do. DP's run just fine on the street and mine gets 15 mpg with 625 horses at the flywheel. There is a reason you can get that Edelbrock cheap, lol. If you think you need a 750, look at it this way. I'm only using a 700 DP with 625 at the flywheel, so why would you need anything bigger than me? Just a thought.

 

[thumper460]

I would agree if I hadn't bolted on a 780 holley on my 302 and went faster ( 750 cfm now, list 3310) I have been proving that to everyone where I have lived for the past 35 years!! yes the more the cam, the better the heads and the higher rpm of the engine will like more cfm, but most street strip 5.0s will go FASTER with the vac secondary 750 holley than the 600/650 carb!! and that is with NO low end bog.. the bog is the tuner not the CFM!! you can tune the secondarys with a spring kit and have the carb open where you want it, and pull thru the entire RPM range!! There have been many posts on the boards on the 600/750 thing.. and all that did upgrade went FASTER!! Mike 35 years ago the guys ( who ever they are) said 600 cfm!! It was right for the stock camed 2.70 geared 289 mustang then, but not the mild head, camed, 3.73s of today!! Try this take the 600/650 carbed to the track.. try and borrow a 750 ( list 3310 Holley) and take that with you.. make a few runs on the 600 and then the 750... you will be amazed on the increase power!!

I did this.. I have a POS pick up ( the Fl. thing...lol) it weighs in at 3900 lbs, 5.0 solid cam and C4 with a 3500 stall.. on the 750 Holley it cuts a 1.9 60 ft ( street tires) and trips the lites at 13.70 !! all I did was have my grandson gain experiance changing the intake to an old Dual quad intake!! Two 625 cfm carters off a few old cry. 440s ( hell yes they are reworked!! LOL) the truck droped 2 and 1/2 tenths!! 13.70 to 13.48s !!
and that IS 1250 CFM... go figure..... !! Try the 750 vac secondary, learn to tune it and you'll be handing the boys with the 600 cfm... their doors!!

just me............................

Thumper

 

[BillaMustang]

stock 302's- 600 should be fine.
modified- 650 dp.
i run a demon 750 on my street car- it works great [email protected]
a lot of it has to do with carb tuning.

 

[85GTlover]

This thread has yielded some great, great information.

 

[UpRise_5.0]

Hey great info! What do you mean by Vac do you mean Vaccum Secondary? Im new to Carbs!

And how hard would it be to get a 1989 5.0 through emmissions with a Carb?

Its in Canada so theres no visual check except for cats, and they do an idle and WOT test.

And im looking at the 650 Speed Demons and Edelbrocks, but not sure which one,which one though for a for 1989 5.0

http://www.barrygrant.com/demon/default.aspx?page=11

 

[maverick0716]

650 DP or a 750 vaccum secondary carb. But you can easily get 300 hp even with a 600 cfm carburetor.

 

[UpRise_5.0]

So does Vac mean Vaccum Secondary? And what about Electric or Mechanical for the choke for a carb swap on a 1989 5.0?

 

[UpRise_5.0]

Bump

 

[Musclecarfan88]

So does Vac mean Vaccum Secondary? And what about Electric or Mechanical for the choke for a carb swap on a 1989 5.0?

You only need a choke if you plan on driving it in cold weather. I have a mechanical choke on my holley, you have to pull the choke, its in hte interior though so its not too bad. Electric would be more convenient but i wouldnt pay more for something i could do on my own. Electric adjusts the choke on its own, which is nice if you do alot of winter driving.

 

[thumper460]

vac is vac. secondary! the list 1850 and the 3310 ( 600 and 750 cfm holleys). The opening rate of the secondary is controled by manifold pressure and a "spring " in the Vac diaphram !! I remove the check ball in the vac dia. usually use the silver or the purple spring for opening events, and rock!! the smaller the cam, the more vac pressure and the stronger the spring, the later opening the stronger the spring, there is a short yellow spring that almost opens the secondary instantly!! SO, buy the spring kit.. and experiment on your car and mods!! for a Killer performance street/strip car.. the vac. secondary carb is always the better ( after tuning) as it will open WHEN the engine wants it, instead of mechinically like the Dpr's causing a mild flat spot off idle!!As for CFM... try that you'd like , but the faster car will have the modified vac secondary 750 CFM holley!! cool??

Electric chokes.... If you need chokes ( kinda rare here in sunny Fl ) then the electric is the best for consistancy and working most of the time!! Just another learning curve...cool??

Just me................................

Thumper