Carb for 408

[flyfish]

Then you don't know what you are missing, unless you are damn good at tuning a carb.....

I am closer to the latter. My street car has an off the shelf cam, a cobbled together carb and runs low 10's....I must be doing something wrong

.......Must just be morons who have people like Braswell and BLP build their carbs. Or Mark Whitener to Dom. Just plain morons, when they can buy an off the shelf carb, which is calibrated for who know what and have it be perfect...........

Not saying anyone is a moron for using their services, but seriously....you can get a 750 proform for ~$530...that is $1000 less than a Braswell....its not rocket science. By the way, Thumper (Dom) is a good guy, if I were to use a carb specialist I would use someone like him WAY before the overpriced other guys.

 

[zsn0w]

Cost is definitely a big factor in this that I may have left out so far, as well. At nearly $600, the 750 ultra double pumper is about $230 more than the other two carbs I'm looking at. I feel like it might be hard to justify this price if the only difference is 10 HP extra at the top end and worse fuel economy. But again, I don't know enough to know if this is actually true. I've seen people say the edelbrock style carbs are more fuel efficient without sacrificing power at the low-mid range, but is that true?

 

[furrystump]

I have run a mighty demon 825 and currently running an 800 thunder avs. On my 410, I would go with the 750 holley. You aren’t chasing every hp and the avs has a slight transition issue that I believe the AVS 2 is supposed to address. Don’t get me wrong, I like the avs, no fuel spill when changing jets, ease of changing rods, but you sound like you won’t be in there after it's set. You don’t need anything bigger than 750. Throttle response will be much better with a slightly to small carb.

 

[zsn0w]

I have run a mighty demon 825 and currently running an 800 thunder avs. On my 410, I would go with the 750 holley. You aren’t chasing every hp and the avs has a slight transition issue that I believe the AVS 2 is supposed to address. Don’t get me wrong, I like the avs, no fuel spill when changing jets, ease of changing rods, but you sound like you won’t be in there after it's set. You don’t need anything bigger than 750. Throttle response will be much better with a slightly to small carb.

Which Holley would you recommend is worth it for me? Is the ultra double pumper really worth over 1.5X the AVS2? or is a there a cheaper holley that is better for this kind of build?

 

[furrystump]

Which Holley would you recommend is worth it for me? Is the ultra double pumper really worth over 1.5X the AVS2? or is a there a cheaper holley that is better for this kind of build?

My take on it has more to do with you. You are not chasing every hp. So the big dollar carbs and the big dollar tuner carbs are not really you. They most certainly have their place and if I could run a holley based carb I would be talking to thumperdart ect, because I am chasing hp. $900-1000 for 10-15 hp gain,sign me up, as long as the wife doesn’t find out! I would guess a good holley vacuum sec carb would suit you nicely. I don’t have model numbers.

 

[Wyrmrider]

U said way up front mostly street car
think about that real hard

 

[yellow rose]

Cost is definitely a big factor in this that I may have left out so far, as well. At nearly $600, the 750 ultra double pumper is about $230 more than the other two carbs I'm looking at. I feel like it might be hard to justify this price if the only difference is 10 HP extra at the top end and worse fuel economy. But again, I don't know enough to know if this is actually true. I've seen people say the edelbrock style carbs are more fuel efficient without sacrificing power at the low-mid range, but is that true?

No, it's not true. Those people either didn't want to PAY for a carb that was tuned or cant or won't tune a carb. A Holley is easily a 100 MPG carb. Easily. All day long. Just like any other carb.

 

[yellow rose]

Which Holley would you recommend is worth it for me? Is the ultra double pumper really worth over 1.5X the AVS2? or is a there a cheaper holley that is better for this kind of build?

Here's my BEST advice. Don't buy ANYTHING that is in any way related to Holley. It's not worth it. That includes Quick Fuel which is now owned by Holley.

If you won't spend the money, or can't, or won't buy something you can tune, buy an Edelbrock, bolt it on and live with it.



EDIT: by Holley I don't mean a carb that looks like a Holley, I mean any carb that Holley has its name on, or QF name on it. Holley is so dumb, they still teach people the wrong way to select power valve opening, so why would you want to buy anything they calibrated????

 

[68Dart500]

I run a Quickfuel SS750 on my 408 with similar specs as you and I've been pretty happy with it. I had it dyno tuned and we had to change out the jets but otherwise it's been great. Last weekend before Mopars in the Park my battery took a **** so I got it running with a jumper but then couldn't shut it off so I had it idling for an hour and it never fouled a plug or anything. Lots of adjustability with that carb and it's been good to me so far. I think any carb you go with you should have it tuned on a dyno to make sure it's running well. You put all that money into the rest of the engine, why not make sure the A/F ratio is correct and it's running as good as it possibly can.

In the past I ran an Edelbrock and it was fine for an off the shelf piece but my car has never started as good as it does with my current QF. I barely hear the starter before its running. Also I got rid of the choke and from cold it will idle without throttle input after 15-30 seconds with the QF and the Edelbrock needed the choke. That's with a 244/248 @050 575 108 LSA cam too.

Just my personal experience.

 

[rumblefish360]

Which Holley would you recommend is worth it for me? Is the ultra double pumper really worth over 1.5X the AVS2? or is a there a cheaper holley that is better for this kind of build?

How much do you want to pay for HP?

Cost is definitely a big factor in this that I may have left out so far, as well. At nearly $600, the 750 ultra double pumper is about $230 more than the other two carbs I'm looking at. I feel like it might be hard to justify this price if the only difference is 10 HP extra at the top end and worse fuel economy. But again, I don't know enough to know if this is actually true. I've seen people say the edelbrock style carbs are more fuel efficient without sacrificing power at the low-mid range, but is that true?

Is 10 hp worth $230 to you?

U said way up front mostly street car
think about that real hard

Stupendously outrageous GREAT advice!

Each and every carb blows chunks until it is tuned.
Can you tune a carb?
Can you install an 02 sensor?
Can you read a book?

Have fun bro. Live and learn. Start with don’t get it right, just get it running. Then from there you can start learning.

I had a very mild 318 that I tried a Holley 4160/600 cfm vs a Edelbrock 600 AFB.
Absolutely the same on the track and with the mileage.

Go pay and go play.

 

[BrianT]

I was going to ask him to post some pictures of his plugs but then I thought why bother.

What I think is dead rich most guys think is perfect. And they'd be wrong.

I'm sure my carb could be tuned better, but it's working fine for me. It's a little rich at idle but I have chassis dyno sheets somewhere that show that my AFR is acceptable throughout the whole pull. This is stock out of the box.

On a related note, I had a Edelbrock 600 on the worn out 340 that was in my car before the 408. Never did anything but set the idle mixture on it for seven years. When we pulled the engine, we pulled a plug just for giggles. The plugs looked so good, my buddy said "Save those for your new engine!"

My point is, these carbs can and do function well straight out of the box for someone who doesn't like to constantly tune and tweek their carbs. Am I leaving a couple of horsepower on the table? Probably, but that is okay with me. I haven't touched my engine in two years since it was installed and that's the way I like it.

 

[zsn0w]

How much do you want to pay for HP?
Is 10 hp worth $230 to you?
Each and every carb blows chunks until it is tuned.
Can you tune a carb?
Can you install an 02 sensor?
Can you read a book?

Thanks, this is really the kind of information I was getting at wanting. 10 HP isn't worth that much money to me here, so I'd much rather put that money into somewhere else. I'm looking forward to figuring out the tuning. Think I'm probably gonna go with the AVS2.

 

[justinp61]

My 408 ran a Bigs 950HP that I bought of e bay for $400. After some tuning it was a great carb, my Dart ran 6.57 @ 104 on pump 93 with it.

I've never owned a aftermarket carb that didn't need tuning, some a little, some a lot.

 

[gzig5]

Thanks, this is really the kind of information I was getting at wanting. 10 HP isn't worth that much money to me here, so I'd much rather put that money into somewhere else. I'm looking forward to figuring out the tuning. Think I'm probably gonna go with the AVS2.

Last night I fired up the new AVS2 650 I installed last week. Need to fix a fuel leak at the pump so didn't run much, but initial impression is good. Idles much smoother than the rebuilt Holley 650 DP that was removed and fires almost instantly.

 

[512Stroker]

I'm doing the final parts selection for a 408 build I've been planning for awhile, and I'm wondering about my choice of carb. This is going to be a street engine that I want to do well at low to mid rpm. I'm more concerned with keeping performance there good than I am with maximizing the top-end. I was originally thinking I was going to go with a Holley 750 CFM ultra double pumper, but now I'm wondering if a different carb like an Edelbrock 800 CFM AVS2 or a 750 CFM street demon would be better. Open to any suggestions at all, these are just the ones that have caught my eye so far. This is also going to be going into a B-body, I've just had much more engagement about engine questions over here in the past than on FBBO. Thanks!

I run a Edelbrock 1407 on my ported iron head 340 roller engine - 452 hp on dyno, all street.
I got the carb off ebay for $100 and had it professional rebuilt for another $150 parts and labor.
Engine runs very well, super easy to tune, fair fuel mileage.
IMO the Edelbrock line of carbs do very well for street applications on mild engines. It would not be my first choice wild race set up
Good luck with your build keep us all informed