how large of a carb can perform well on stock 273 commando ?

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This a little video of the dartcharger 273 running before the ld4b intake went on.
still working on the video of the ld4b intake manifold ..... coming soon.
 
Interesting thread. I'm wondering if a Carter 4 barrel, M6 9628S will work on my 273 with solid lifters. It's off of a 318. I rebuilt it for a 273 but haven't changed the jets or anything. Anyone know the cfm rating on this carb?
 
I have an App just for carb sizing. At 100% VE (volumetric Effeciency) and 6000RPM it calls for a 486cfm so the 500 is the choice.
 
many different opinions on carb size.i think original 340's where 485 cfm and the early 440's were 535 or 585 cfm.
..those cars ran very well back in the day!
 
65Val said:
650 is a bit too much for a 273. Also, is it 4 speed? If not, get rid of the dbl pump.
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67Dart273 said:
ANY small fairly stock engine should have a vacuum secondary carb and not a DP or other mechanical secondary design. That's one reason the old venerable Holley "780" was so popular, the vacuum secondaries let you throw it onto about anything.

The AFBs and AVSs are also much more forgiving in that regard

I would think a 600 AFB would be about the top of the max
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This is terrible advise.

First off you did no tuning on the eninge or carb so to blame it on the carb is just a scapegoat.

2nd a vac secondary carb is nothing but a mask for a problem(s) and thus creates one or them. Only run vac secondaries on a auto car? WTF? Learn how to tune an engine. If it doesn't work right with a mech sec carb you don't have it dialed in...period. I don't know any engine builders that recomend a vac sec carb. My engine builder doesn't even stock them. They are not a better carb they are more driver friendly as you control when the secondaries kick in.

Put the holley back on. Set the timing and then get your idle speed and idle mixture screws set. Get a vaccum reading. Now you are ready to begin digging deeper into the carb.
 
I've run a QJet off a 72 Chevelle 350 on a stock 273 Commando and it would take whatever cfm that is. I really like the factory AFB's also.
 
stroker402 said:


This a little video of the dartcharger 273 running before the ld4b intake went on.
still working on the video of the ld4b intake manifold ..... coming soon.
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Sounds great! You should mike the cam. It sounds bigger than a stock Charger 273 cam. tmm
 
roccodart440 said:
This is terrible advise.

First off you did no tuning on the eninge or carb so to blame it on the carb is just a scapegoat.

2nd a vac secondary carb is nothing but a mask for a problem(s) and thus creates one or them. Only run vac secondaries on a auto car? WTF? Learn how to tune an engine. If it doesn't work right with a mech sec carb you don't have it dialed in...period. I don't know any engine builders that recomend a vac sec carb. My engine builder doesn't even stock them. They are not a better carb they are more driver friendly as you control when the secondaries kick in.

Put the holley back on. Set the timing and then get your idle speed and idle mixture screws set. Get a vaccum reading. Now you are ready to begin digging deeper into the carb.
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You seem to be outnumbered.....
 
Give me the proper Holley,every time. I prefer consistent response.....
 
65Vart said:
Eddy 600 all day long.
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So 50cfm and brand is the make it or break it?

66fs said:
I've run a QJet off a 72 Chevelle 350 on a stock 273 Commando and it would take whatever cfm that is. I really like the factory AFB's also.
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Hmmm...

65Val said:
You seem to be outnumbered.....
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Just the way I like it.... i'm not a can'tbeat em' join em' guy. Keep running your vacum secondary only carbs only on automatic cars and make sure it isn't 50cfm too big. Oh, yeah and stay away from those poor performing Holleys. No one runs those with any success. :coffee:

Abodybomber said:
Give me the proper Holley,every time. I prefer consistent response.....
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Bingo:compress:
 
I've run my share of Holleys like me everyone else has. Just that when I bought my first edlebrock a few years ago, thru it on adjusted the air/fuel and the car was running great within five minutes. Very little adjustment. Time will tell with shitty gas though. The 600 is a good carb for these motors.
 
ok I know some are going to disagree with me but this is the way Holley decided to set their base jetting. Holley used a slightly better than stock Chebbie 350 to set base jetting. Your running a 273 which is 77 cubes smaller. I'm willing to bet that the 650dp is a little on the fat side of things. The 650 should work great on there just needs to be jetted right. Also, the accelerator pump squirters may need to be changed to a smaller shot if your getting too much fuel on acceleration or even run a smaller pump cam.
 
Pacific Carburetors mentioned that rejetting won't replace a proper cfm sized carb.

So, I'll look for a stock 273 4 barrel intake and a stock Carter 500 cfm carburetor for my '65 Dodge van automatic.

Thanks for the discussion.
 
65Vart said:
I've run my share of Holleys like me everyone else has. Just that when I bought my first edlebrock a few years ago, thru it on adjusted the air/fuel and the car was running great within five minutes. Very little adjustment. Time will tell with shitty gas though. The 600 is a good carb for these motors.
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eddy's are known for that and i'll admit i've run a couple. but dialed in i'll take the performacne of a holley all day.


clifftt said:
Doesn't Holley still make a 600 dp? Anybody try one of those?
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Never run a DP carb with an auto transmission.
 
A Quadrajet is 750 cfm, Infinately adjustable secondary air valve, like an AVS or a TQ. Thermoquads are definately my favorite. I Dorked with Holleys for a while. They are fine for a race car, but an everyday driver at temps from -20 to 100 degrees, you can have them. I sold all of mine. I'm not a Racer, but I have friends who are. I the end, it comes down to tuning and keeping it in tune for the street. A factory AFB is tuned very well for a 273 Commando. There are 3 steps for enrichment, idle, midrange and WOT. It has an air valve tailored to the little Commando so it doesn't bog when you floor it, but opens when the 273 revs up. The OP asked about a stock Commando. I definately agree that you don't need to limit cfm by cubic inches and rpm. I proved that wrong a long time ago.
 
66fs said:
A Quadrajet is 750 cfm, Infinately adjustable secondary air valve, like an AVS or a TQ. Thermoquads are definately my favorite. I Dorked with Holleys for a while. They are fine for a race car, but an everyday driver at temps from -20 to 100 degrees, you can have them. I sold all of mine. I'm not a Racer, but I have friends who are. I the end, it comes down to tuning and keeping it in tune for the street. A factory AFB is tuned very well for a 273 Commando. There are 3 steps for enrichment, idle, midrange and WOT. It has an air valve tailored to the little Commando so it doesn't bog when you floor it, but opens when the 273 revs up. The OP asked about a stock Commando.
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100% agree!!!
 
Any of you guys run a AVS on their Charger/Commando instead of a AFB? I have a 600 AFB on mine and it runs well. The AFB's do have a secondary air valve but it isn't adjustable. I have a 4 speed though and I'll bet the AVS would be better with a automatic. tmm
 
toolmanmike said:
Any of you guys run a AVS on their Charger/Commando instead of a AFB? I have a 600 AFB on mine and it runs well. The AFB's do have a secondary air valve but it isn't adjustable. I have a 4 speed though and I'll bet the AVS would be better with a automatic. tmm
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I have run them. They run pretty good. My "66" 273 is almost exactly like yours, maybe the heads are milled a bit more and I run stock 340 valvesprings. The AVS will fit but you may need to drill two extra mounting holes to use 4 mounting bolts or studs. You can use the factory AVS choke also. Try to find a 340 AVS, It would probably be pretty close jetting wise. What number AFB do you have on the car now?
 
We had a 1403? 500 cfm on my son's 318 with a small cam and 273 Commando intake. It ran good but I found an original 4295s, rebuilt it and it runs much better. If I remember right, your original Carb, 4119s, was in bad shape? Some of the Carter 600 cfm carbs would not open the secondaries on the original manifold... I measured a 4294s and it only has 1 9/16 secondary blades. Did you check to see if your secondaries are opening after you installed it? Also the secondary air valve is heavy on the Edelbrock compared to stock Commando.
 
66fs said:
We had a 1403? 500 cfm on my son's 318 with a small cam and 273 Commando intake. It ran good but I found an original 4295s, rebuilt it and it runs much better. If I remember right, your original Carb, 4119s, was in bad shape? Some of the Carter 600 cfm carbs would not open the secondaries on the original manifold... I measured a 4294s and it only has 1 9/16 secondary blades. Did you check to see if your secondaries are opening after you installed it? Also the secondary air valve is heavy on the Edelbrock compared to stock Commando.
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My original carb was shot. Being a stick car it had been opened and closed a million times in 100,000 miles. The throttle shafts were worn and I replaced them with ones from a automatic carb which were in good shape. The butterflies never seated in the bores very good and it doesn't idle very well. I put the Edelbrock on as a test carb and never took it off. My biggest idle quality problem was spark plug heat range. $ heat ranges hotter than the Autolites I had in and the problem was fixed. tmm
 
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