Edelbrock Performer or AVS carbs for 318 dual quad?

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glockr

glockr

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Looking for carb recommendation for a dual quad 318. Intake is the Offy hi-rise, cam will be a Howard's hydraulic roller (Lift: .525 / .530, Duration @ .050: 227 / 235, LSA 109), shooting for 10.5-11 static compression ratio with Speedmaster "as cast" heads. Going into a 66 Barracuda with manual transmission. Rear gear can be set to whatever fits the engine combo. The ones I see on the web all seem to run the Performer 600 cfm carbs, but Edelbrock makes an AVS that they claim is tuned for running in a dual quad setup. I'm kind of leaning towards the AVS b/c from what I've read the AVS is easier to adjust for secondary opening, but I don't know a lot (i.e. absolutely nothing) about carbs.
 
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The AVS will be more forgiving and have more adjustability. JMO
 
I'm running 2 AVS2 800 cfms on my 440. If you are buying new carbs, buy the AVS2 series. They have annualar boosters on the primary side. Very nice for throttle response.

Tunnel ram Cuda.jpg
 
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Go back to that post and on the bottom left corner click on report. It opens up and says edit, then erase the 88 and put in 66. Then click save.
 
Vertex_Jeff said:
I'm running 2 AVS2 800 cfms on my 440. If you are buying new carbs, buy the AVS2 series. They have annual boosters on the primary side. Very nice for throttle response.

View attachment 1716008412
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This ^^^^^^^^^^^^

(Nice car!)

For a dual quad 318, the 500’s would work just fine though I’d run a pair of 600’s. Your set up is not very radical. You could do 500’s if you desired. The carb choice would be the AVS 2. They have an advantage over the earlier AFB style with the primary annular boosters which are really nice on throttle response & fuel distribution. The adjustable secondary air door is very nice as well.
 
rumblefish360 said:
This ^^^^^^^^^^^^

(Nice car!)

For a dual quad 318, the 500’s would work just fine though I’d run a pair of 600’s. Your set up is not very radical. You could do 500’s if you desired. The carb choice would be the AVS 2. They have an advantage over the earlier AFB style with the primary annular boosters which are really nice on throttle response & fuel distribution. The adjustable secondary air door is very nice as well.
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Tune the carbs right for WOT and it'll be a screamer. You have the shorter stroke 3.31" to wind it up, then you use that cam? How high do you plan on winding this with that hydraulic roller?
On my 360 build and it's 3.58" stroke, with 4.10 gears. I haven't even considered my converter yet, my Offy is the low rise version so the plenum will be smaller and my cam is a slightly bigger SFT.
Here are the carbs I plan on using: Edelbrock 19049 Edelbrock AVS2 Series Carburetors | Summit Racing
I think you'll be fine with 2x500cfm and mechanical secondaries.

I suspect your issues will lie elsewhere... You may want to consider some STOUT valve springs.
 
Ottmundr said:
Tune the carbs right for WOT and it'll be a screamer. You have the shorter stroke 3.31" to wind it up, then you use that cam? How high do you plan on winding this with that hydraulic roller?
On my 360 build and it's 3.58" stroke, with 4.10 gears. I haven't even considered my converter yet, my Offy is the low rise version so the plenum will be smaller and my cam is a slightly bigger SFT.
Here are the carbs I plan on using: Edelbrock 19049 Edelbrock AVS2 Series Carburetors | Summit Racing
I think you'll be fine with 2x500cfm and mechanical secondaries.

I suspect your issues will lie elsewhere... You may want to consider some STOUT valve springs.
Click to expand...
That's what Howard's recommended when I filled out their "cam recommendation form". I spent a lot of time reading David Vizard's book and looking at cam specs, I'd have probably picked this cam but I know even less about cams than I do about carbs :) I don't know how high I can wind it and keep it reliable. The block is a 1976 LA block that will be bored .030 over and I'm probably going to run KB 399 pistons to get the compression I want and they're grooved for Total Seal gapless. If the hyper's aren't a good idea I'll run Icon domed.
 
Go buy two QF 650 sized carbs and be done with it. Then learn to tune them. It’s not hard once you understand how they work.
 
Ottmundr said:
Tune the carbs right for WOT and it'll be a screamer. You have the shorter stroke 3.31" to wind it up, then you use that cam? How high do you plan on winding this with that hydraulic roller?
On my 360 build and it's 3.58" stroke, with 4.10 gears. I haven't even considered my converter yet, my Offy is the low rise version so the plenum will be smaller and my cam is a slightly bigger SFT.
Here are the carbs I plan on using: Edelbrock 19049 Edelbrock AVS2 Series Carburetors | Summit Racing
I think you'll be fine with 2x500cfm and mechanical secondaries.

I suspect your issues will lie elsewhere... You may want to consider some STOUT valve springs.
Click to expand...
I was running a 650 AVS2 on my 340 before I tore the engine down. In the meantime, I picked up an Edelbrock TR5 dual quad tunnel ram and I think I might just pick up a second 650 AVS2 when I give the TR intake a try, once the car is back on the road. Cheapest way to get it up and running. Should be an interesting tuning experience.
 
gzig5 said:
I was running a 650 AVS2 on my 340 before I tore the engine down. In the meantime, I picked up an Edelbrock TR5 dual quad tunnel ram and I think I might just pick up a second 650 AVS2 when I give the TR intake a try, once the car is back on the road. Cheapest way to get it up and running. Should be an interesting tuning experience.
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My 2 cents:

Run the carb linkage 1:1 - that makes tuning DEAD simple. I think people that have tuning problems with dual quads are mostly related to trying to use progressive linkages.

Also - with a tall tunnel ram, don't be afraid to advance your timing more than you think you should! The engine will like it.
An o2 sensor and AFR gauge is almost like cheating when getting these things set up........but still check your plugs.

Happy motoring!
 
An AFR gauge might be cheating rod someone here but if it gets you in the ball park to start, screw it! Use it.

However…..

On the strip, let the engine tell you what it wants.

1:1 is best IMO. If your going to run it progressively, that’s best done on a dual plane and not a TR ever.
 
rumblefish360 said:
An AFR gauge might be cheating rod someone here but if it gets you in the ball park to start, screw it! Use it.

However…..

On the strip, let the engine tell you what it wants.

1:1 is best IMO. If your going to run it progressively, that’s best done on a dual plane and not a TR ever.
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Agreed. I made the comment about the AFR gauge because I installed one in my car, and it really sped up the tuning process for me. Reading plugs is still a necessity - but you can get pretty darn close with a wideband quickly.
 
kdeboy said:
That's what Howard's recommended when I filled out their "cam recommendation form". I spent a lot of time reading David Vizard's book and looking at cam specs, I'd have probably picked this cam but I know even less about cams than I do about carbs :) I don't know how high I can wind it and keep it reliable. The block is a 1976 LA block that will be bored .030 over and I'm probably going to run KB 399 pistons to get the compression I want and they're grooved for Total Seal gapless. If the hyper's aren't a good idea I'll run Icon domed.
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That cam has a 110 LSA and if you run the formula he
(David Vizard) presents for the Chevy engine which is also a wedge head…..
IDK if there is any adjustment for the better valve angle of the Chrysler head.

But as I was about to point out the formula points to a 107.44 for a LSA. For a off the shelf cam? That would be a Thumper cam from Comp or maybe, not sure at the moment, maybe a Hughes engines cam. Research the Howard’s catalog and see if the cam is offered on a 108 or 106. I’d do a 106.
 
Vertex_Jeff said:
Agreed. I made the comment about the AFR gauge because I installed one in my car, and it really sped up the tuning process for me. Reading plugs is still a necessity - but you can get pretty darn close with a wideband quickly.
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Absolutely! I used a 02 on my sons truck to get the ball park idle/cruise ratio. It ran a hair rich 13.8-14.2 area with the Edel 600 AFB during the hot part of the summer here @ 95*’s. (F)

I’ll figure out WOT later. Which is used little at best to get on the Hwy or pass slower traffic. Mostly it’s a slow cruise around the area. That’s how Florida rolls, nice and slow.
 
rumblefish360 said:
That cam has a 110 LSA and if you run the formula he
(David Vizard) presents for the Chevy engine which is also a wedge head…..
IDK if there is any adjustment for the better valve angle of the Chrysler head.

But as I was about to point out the formula points to a 107.44 for a LSA. For a off the shelf cam? That would be a Thumper cam from Comp or maybe, not sure at the moment, maybe a Hughes engines cam. Research the Howard’s catalog and see if the cam is offered on a 108 or 106. I’d do a 106.
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I think that's for a 350. From the chart I'm looking at, for a 323 (.030 over 318) it looks like between 109 and 110. Kind of don't want to run a Comp Cams after reading about problems some people have with their hydraulic roller lifters. Leaning towards Howard's Cams or Hughes.
 
I'm putting dual quads on the 318 that I just got running. If you are running an underhood in line 2X4 manifold (as opposed to a cross ram or a tunnel ram which require the carbs to open simultaneously) then Edelbrock sells a match pair of AVSII carbs that work progressively. One has an electric choke (primary carb), the other manual (that you fix open). They are made to work in tandem. Edelbrock still makes in line 2X4 manifolds for small block Chevs and Fords and the carbs don't know what they are sitting on.
 
str12-340 said:
I'm putting dual quads on the 318 that I just got running. If you are running an underhood in line 2X4 manifold (as opposed to a cross ram or a tunnel ram which require the carbs to open simultaneously) then Edelbrock sells a match pair of AVSII carbs that work progressively. One has an electric choke (primary carb), the other manual (that you fix open). They are made to work in tandem. Edelbrock still makes in line 2X4 manifolds for small block Chevs and Fords and the carbs don't know what they are sitting on.
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That's the carb(s) I'm looking at, but I'm probably going to run manual chokes on both (with one wired open) and 1:1 instead of progressive linkage. Does anyone know if there is any difference between the 1903/1904 and 1901/1902 versions of this carb besides a .077" main secondary jet on the 1903/1904 and a .095" main secondary on the 1901/1902? Can't tell from the manual if there's any other differences in internal channels, etc. If the only difference is in the main secondary jet, it seems like I could run 650's (1905's) and just put a smaller main jet on the secondaries.
 
650s !?!?! EEK!!!! I've got 2 500 Eddie AFBs on the STR-12 on my 340. I can't imagine why you would use 650s. If you are going to open the carbs at the same time, no reason not to use the same carb front and back. By the way, I used Performers (AFBs) because they didn't make AVSIIs in 2005.
340 11-06 o.JPG


IMG_0010.JPG
 
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