ScottinSF
New Member
Any advice on a carburetor to replace my stock Carter CVS on a 1970 300? Not interested in anything more than stock reliability and ease of starting. The motor is bone stock except for a MSD box. Thank you for any ideas.
Carb choice for a 440
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SIPLOWGUY
Well-Known Member
Holly seems to have a range of carburetors available
With any aftermarket carb, just be aware that you'll almost certainly need to tune it. Not saying you can't take one out of the box and run it with decent results, tons of people do, but unless you tune it you'll be leaving some performance and fuel economy on the table. In some cases, the out of the box tune could be way off. I know it was on my Edelbrock AVS2 650 I have on my 77 440. It was way way too rich.
And having said that, the Carter/Edelbrock style carbs are a bit easier to tune than the Holley because you don't need to empty the fuel bowls to make jet changes -- except for the Holley Street Demon which has a similar design to the Carter/Edelbrock.
If you're not interested in tuning a carb, maybe just look into rebuilding the Carter that you have?
And having said that, the Carter/Edelbrock style carbs are a bit easier to tune than the Holley because you don't need to empty the fuel bowls to make jet changes -- except for the Holley Street Demon which has a similar design to the Carter/Edelbrock.
If you're not interested in tuning a carb, maybe just look into rebuilding the Carter that you have?
SportFury70
Senior Member
May I highly suggest an Edelbrock AVS2 1906? We got them on most of our cars and are happy. Easy to tune and run great… but be warned, they could be defective even if they are brand new in the box… we did have that happen and had to send it back, but they exchanged it with no problem.
SportFury70
Senior Member
If you want to keep the Carter though, try to see what woodruff carburetors says. Best of luck!
Edelbrock does sell "refurb" carburetors, which are probably re-checked warranty returns. Price is enough less than "brand new" that it might be worth it.
To me, the current Holley line-up of carburetors is too complicated and TOO UNIVERSAL.
As mentioned, the Street Demon carbs are Carter Thermoquad clones with some improvements. They are basically spreadbores, in their throttle sizing. Worth a look!
I like the AVS2 for its annular discharge venturis. Better fuel atomization than a normal venturi. Might be a bit better on fuel economy and some liken the throttle response to "EFI" (which should be better).
We are now in the SEASON OF SALES, so shop wisely for the best deal. Although if one re-seller has a sale, others do to.
Have fun!
CBODY67
To me, the current Holley line-up of carburetors is too complicated and TOO UNIVERSAL.
As mentioned, the Street Demon carbs are Carter Thermoquad clones with some improvements. They are basically spreadbores, in their throttle sizing. Worth a look!
I like the AVS2 for its annular discharge venturis. Better fuel atomization than a normal venturi. Might be a bit better on fuel economy and some liken the throttle response to "EFI" (which should be better).
We are now in the SEASON OF SALES, so shop wisely for the best deal. Although if one re-seller has a sale, others do to.
Have fun!
CBODY67
ScottinSF
New Member
That’s what I’m planning on doing. This will just be to get me going while I have someone who knows what they’re doing go through the old Carter. And always good to have a spare.
Fury1969WI
Member
if this is a temporary thing then a remanufactured Edelbrock (Carter based) carburetor is an economical choice and really easy swap - they are pretty much identical bodies/footprint. 650-750 Performer or AVS should work just fine for a driver.
i see there are off-shore versions available for super-duper cheap ... anyone try one?
FOR Edelbrock 1406 Performer 600 CFM 4 BBL Barrel Carburetor with Electric Choke | eBay
i see there are off-shore versions available for super-duper cheap ... anyone try one?
FOR Edelbrock 1406 Performer 600 CFM 4 BBL Barrel Carburetor with Electric Choke | eBay
ScottinSF
New Member
Thank you CBODY67. I have ordered that piece.
I run the 800cfm avs2 on my mild 440 in my SFGT. I had to richen it up significantly from what it was ootb. But once dialed it runs fantastic and starts right up. Very snappy too.
I will always recommend the 800cfm for big blocks. Save the 650s for small blocks..
I will always recommend the 800cfm for big blocks. Save the 650s for small blocks..
Fury1969WI
Member
@67valiant 100 - are you using an O2 sensor to determine AFR? I have a rebuilt 800 CFM AVS2 on my 440 that i've been trying to lean out to the point where i'm looking at needing to go beyond the Edelbrock tuning kit.
Carter AVS is the way to go. Rebuilding yours can be done by @woodruff carburetors. Another option is the Edelbrock 1406 w/ the carb linkage adapter. 600 cfm is all you need for a stock 440.
My experience with the AVS2 650 aligns with yours. I was able to get part throttle AFR decent using the leanest rods from the kit. But for the secondaries had to purchase jets smaller than what came with the tuning kit to get my WOT in a decent AFR range. I have a wideband O2 sensor so it wasn't just seat-of-the-pants tuning. I have a stock 1977 440 with dual exhaust and Performer intake.
Fury1969WI
Member
Thanks for this, I thought i was going nuts!
I'm also running a wideband O2, though the sensors aren't perfect (i assume). I am running HP exhaust manifolds and TTI 2.5" exhaust. I installed the sensor in the downpipe, within 11" of the manifold per the instructions. The instructions seem to assume sensor installation on a horizontal section, with emphasis/warning not to install the sensor below 90 degrees from the bottom of pipe (something like 135 maybe). However, i've seen lots of factory O2 installs in the downpipe and thought proximity to the manifold was more important. I have always wondered if my assumptions were correct or if the sensor location was part of the reason i couldn't seem to get near stoich efficiency.
Honestly, I'd be happy with upper 13s but still hanging in 12.x mostly, occasional 13.x. As a check on the gauge/sensor, I changed the plugs and have about 500 miles on current tune, I'll pull those over the winter to see how those read.
Car runs good, though if i let all the way off the throttle, like coasting, and then get back in it with other than feather light throttle, it has a dead spot/bog, that i can't get over. My 750 Performer did not behave like this.
I should say, this was a used carb I picked up that i (eventually) rebuilt that did NOT have the factory metering rods & jets, so i acquired those and starting from factory baseline I had to lean it out a lot, max in the kit really.
Also, I'm running an open air cleaner. I have a stock dual snorkel but it rubs on the hood. RB in 69 Fury and Mopar M1 intake (stockish height?) doesn't leave much room).
With apologies to to @ScottinSF for hijacking this post!
Old school, reading plugs and running it down the track. It was way lean and breaking up in the higher RPM. Every jet & rod change resulted in better/quicker et's. I think I went as far as I could with what comes in the edelbrock tuning kit. I even bought extra, larger jets then what comes in the tuning kit but I havent needed them yet.
o2 positioning is due to keeping condensation from potentially collecting in the tip of the sensor and ruining it. Generally the closer to 12 o'clock positioning you can place it the better.
ScottinSF
New Member
Hijack away! Always new things to learn. Thank you to everyone who replied to my post.
Fury1969WI
Member
I think "12 o'clock" positioning is for when doing a horizontal pipe run installation. Position doesn't matter so much in a downpipe, am I wrong?
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