4door!cutlass

Hello an thanks for your time,i have a 455,400 trans,mild cam and will be going with 3.55 rear . i was told to go with a 650 double pumper.
i will be going with edelbrock rpm.i was told to start. with 650 so i wont over gas .so if i need more gas i can jet it.
so what do you think will be the best carb.

Shanghai Smith

I think a Q-Jet would be a better choice. Here is a link to SMI I have one of their carbs on my 403 and it works very well for the street and at the strip with a 150 shot of nitrous.
http://www.smicarburetor.com/product...D2/9/sfID3/100

tmaleck

Sound like too much carb to me. I would stay with vacuum secondary single pump on a manifold like that. Too many folks over-carb. I'd look at a Holley 650 street avenger. Also, look for a book by David Vizard on tuning Holley carbs. Lots of great info on carb selection and tuning. If you're not into carbs, a 1406 Edelbrock might be a good choice.
Tim

chadman

You didn't give a whole lot of information on the rest of your combo so I am going to assume it to be a basic 455 with stock heads and a very mild cam that will be going into your 4 door in your avitar and will just be cruised around on the street. If so I would not suggest a double pumper carb of any size for that application. I would either run a Q-jet or a Holley model 3310 which is a 750cfm vacuum secondary.

Beob

Ive been running a Holley 750DP for 25 uears and I love it. I had it on a 455 G head solid lifter mild cam 9:1 comp 3.31 gears. when the secondaries open up it just screams. If you're looking to roast you're tires and do donuts you'll be very disappointed with a vacuum sec.

Run to Rund

I agree with Chadman.

Fun71

That has not been my experience. I have done lots of tire roasting and dounts with a vacuum secondary carb.

rjohnson442

If not worried about gas mileage I'd go with the Holley 750DP. You'll be very happy if you add an intake and a spacer down the road. I'm running an 850 DP on a 461 and almost flinch when the secondary open up.

droptopron

Another variable is torque converter. If you have a higher stall speed it will be much more forgiving of a double pumper.

chadman

That's why they make the vacuum secondary sytem tuneable. For the record I have a 850 DP on my '65 but I think it is a bit more radical than what the OP has and it spends a fair amount of time at the dragstrip.

70cutty

I agree with chadman too, 750 vac. secondary will do the job on a stock or near stock 455.

billmerbach

I agree as well if everything is gonna be mostly stock why sacrifice gas mileage if you have nothing to back it up with. I mean go dp if you are gonna go with upgrades in other areas but don't waste time and money both now and later on gas for something that won't add much power I hope I stated that right lol

Keegan

One of my buddies has one of these on his '79 Camaro, and it seems like it's a pain to get tuned right. Maybe it's just his lack of experience and trying it "trial-and-error" on his own, but the thing stalls out in revere and seems to dump WAY too much, trying to flood the engine.

rjohnson442

Pumps are adjustable with kits and yes a DP can be a pain to get it in tune. But once you do

4door!cutlass

Ok,so many different options,my 455 has stock heads,bored over 40,mild cam.will be getting edelbrock rpm air gap intake upgrade. probably going with 3.55 gears .i have g heads,the moter comes from a 71 delta 88.
i like the holley avenger 4150 750manual. i never even herd of vacume.i plan on driving the car daily .i do like decent gas milage.so I'm just not shure what carb is the right one.

4door!cutlass

QUOTE=chadman;673441]You didn't give a whole lot of information on the rest of your combo so I am going to assume it to be a basic 455 with stock heads and a very mild cam that will be going into your 4 door in your avitar and will just be cruised around on the street. If so I would not suggest a double pumper carb of any size for that application. I would either run a Q-jet or a Holley model 3310 which is a 750cfm vacuum secondary.[/QUOTE]
Ok,so many different options,my 455 has stock heads,bored over 40,mild cam.will be getting edelbrock rpm air gap intake upgrade. probably going with 3.55 gears .i have g heads,the moter comes from a 71 delta 88.
i like the holley avenger 4150 750manual. i never even herd of vacume.i plan on driving the car daily .i do like decent gas milage.so I'm just not shure what carb is the right one.

4door!cutlass

The avenger was my firsts choice,what size do u recomend

4door!cutlass

I see that chadman got the most votes.i herd that vac.secondary tends to stall when trying dump the petal.which system is less likely to bogg when dumping.

drjr56

You'll get the best of both with a properly set up QJ on that car. I run a 750 vac secondary Holley on my 455 no problems.And break the tires loose at 25mph in drive.Gas milage is so so....until I get on it. QJ gives you decent mpg and performance on what you have.My 400 with a mild rebuild has a QJ and runs just fine.

dmullin

The vacuum secondary will never bog out if adjusted correctly. It provides smooth power delivery when transitioning from 2 to 4 barrels. Excellent design for the street, especially with an auto and tight converter.
A 650, really! The cubic inch/volumetric efficiency and rpm band would dictate a need for a 750 if you plan to see power up to 5500. IMO.


Too much carb is bad, I agree... Don't discount a well built quadrajet.

oldcutlass

Even by Holley's standards it's recommended you use a vac secondary 750cfm carb. You can play with their recommendations yourself below.


http://holley.com/applications/Carbu...bSelection.asp

Fun71

You probably heard that from someone who doesn't know how to properly adjust the vacuum secondary operation. As dmullin posted, when properly set up there is a smooth transition with no bogging. Lots of us with vacuum secondary carbs can attest to that.

z11375ss

I like my setup. Holley 780 DP. Manual trans, 3.73s. Perfect. Your setup? Sounds like a QJet is the way to go. Some economy and a lot of get up and go.

jag1886

No dp!

4door!cutlass

4door!cutlass

They ask for engine size an max rpm.i don't know the max rpm.and thanks for yur time

billmerbach

Max rpm shouldn't be more that about 5500 am I right

4door!cutlass

4door!cutlass

The avenger was my firsts choice.even though i will be driving the car i plan on doung a head upgrade and start playing at the track, i want speed but still keep it street .the guy that will be working on the car is highly respected and builds race cars. he told me the double pumper is what I'm looking for so I'm stuck between the avenger an the dp.
my head is spinning .

oldcutlass

I deleted your other thread as a duplicate. Your not going to get different answers.


Your engine size is a 455 and your rpm should be 5000. Mild build, street use, pay attn. to the notes about the DP vs vac secondary.


http://holley.com/applications/Carbu...bSelection.asp

4door!cutlass

Ok,I'm new to all this stuff so i know nothing about rpms.so what is your openion on the dp vs.vac secondary .and i take it that u are saying the 455 rpms are 5000 or that the goal is 5000 rpms?.

4door!cutlass

I'm not understanding what people mean about rpms. I have a 455 and need the right carb,so when someone. sais u need 5000 rpms. is that the goal rpms that i need with the carb or is that what the 455 produces?.
o yea stop giggling I'm new to this.lol

MDchanic

I'm not understanding what you're asking.

- Eric

4door!cutlass

The reply was this:Your engine size is a 455 and your rpm should be 5000. Mild build, street use, pay attn. to the notes about the DP vs vac secondary.
So I'm asking what does he mean,your rpm should be 5000.

TripDeuces

My two cents:

1) QJet
2) Holley vacuum secondary or an Edelbrock

You mention you're going with an Air Gap manifold. That's tall and will require AC bracket modifications to fit if you have AC. It's also rated for 1500-6500 RPM which you're never going to see with your set-up. If that is the Cutlass in your sig that you're putting all this into then I'll bet it's too tall with that manifold and will require cutting the hood. You need a nice low rise dual plane and a new mechanic or at least stop taking his advice. Stick with the QJet and stock for now.

z11375ss

The Air Gap fits on my setup. It's tight, but it does fit.

Alex72cutty

I was thinking about using the air gap for my 72 cutlass.

rustyroger

The rpms (revolutions per minute) you need from your engine will depend upon what you want it to do.
If you want horsepower for screaming down a drag strip you will want lots more rpm than if you want stump pulling torque for towing a heavy trailer.


So what are you going to use the engine for?, bear In mind the higher the rpms tou want the more strain there is on moving parts, particularly pistons and rods. To build a 455 Olds engine to run at 5000 rpm for any length of time will be expensive, either because to build one to handle it will require strengthened quality parts, or because the engine won't last long if you leave it as standard.
The carb you require is also dependant on what cam you use, compression ratio, exhaust system and other factors.
Let us know what modifications your engine has and what you want to use it for and you will find plenty of well informed help and advice here from people who have lots of experience building engines successfully.


Roger.

4door!cutlass

No major modifications other than a rebuild,bored 40 over and a mild cam upgrade.I'm just wanting to be able to smoke any average car if someone tries me at the stoplight!.

4door!cutlass