273 Carb Size

[67BELVSLEEPER]

Hi guys,

I have a 67 Belvedere II with a 273. The previous owner swapped out the two barrel carb/intake with a correct “Commando” intake and Holley carb. I got the two barrel intake and carb with the car. The Commando intake is marked with grease pen “273 Commando”. The heads have also been redone in 2009, they are marked as well. I’m not sure if there was a cam swap. The car has an MSD billet distributor and coil. When I researched the carb I believe it is a 700 CFM.

I haven’t driven this much yet. The engine sounds nice and quiet, no ticks or knocks. One issue is while idling it produces smoke from the exhaust. It’s not burnt oil, it’s running rich. I was able to adjust the carb somewhat but it stumbles under acceleration. I had to lean it out to get the smoke to go away but it’s still present. I don’t think it’s valve seals or rings. The car only has 98K and the heads were done.

I’m thinking this may be a timing and carb adjustment issue? Is the carb too big?

What should I be looking at for timing? If this carb will work I would like to keep it.

Thanks for any help.

 

[oldbee]

IMHO it's too big, thinking you shud be looking at a 600cfm if everything is stock. More comments will follow I'm sure.

 

[rumblefish360]

IIRC, the 700 cfm carb was on the “D dart,” that also came from the factory with a mechanical cam and Doug’s headers.

As far as what you have, assuming a stock 2bbl. cam, iron single plane intake, you could run a AFB/AVS 500 no problem.
It is a small engine, it just injest a lot of cfm with a 2bbl. Cam and the small valves. If you use a used 600 for the inexpensive nature, just tune accordingly and you’ll be ok fine.

 

[wyrmrider]

check and see if it really is a d dart carb and manifold
$$$$
small avs
I like TQ 1 3/8 primary and self adjusting secondary
(like avs)

 

[67BELVSLEEPER]

It definitely has the “Commando” intake installed with a 4160 series Holley 4 BBL. i have the original 2 BBL intake and carb in a box. Not sure what was done to the heads but they were reworked. I am running the cast manifold with Magnaflow 2.5 inch down pipes, to chambered mufflers to 2 1/4 Accurate Exhaust Tailpipes.

 

[67BELVSLEEPER]

273

 

[lewtot184]

I believe the D dart carb may have been a 3116 race hemi carb. if it were me i'd find the correct AFB for that manifold. the 500 & 600 edelbrocks will have secondary throttle bores too large for the intake.

 

[rumblefish360]

I’m not sure what the OE carb throttle bore/butterfly size was. On a Poly dualquad intake, the 600 AFB was to large to fit the 4 hole intake throttle bores.

Doe the AFB 500’s have a smaller butterfly?

 

[RJRENTON]

Gentlemen,
I had a 1967 Belevedere II, with first generation LA 318 and Stromberg WWC3 2 bbl carb. I fitted 273 HP (235 hp cam, manifold, heads etc) parts to the 318. I used the Carter 3854S carb (rejetted for best performance) and the recurvedPrestolite dual point distributor. The car had the 727A trans, 3:55 resr gear. The car ran extremely well, dusting off 327 Cameros and 289 HP Mustangs.
The Carter 3854S carb has velocity weighted secondary air valves (below the secondary booster venturi....this is NOT the Garter AVS design). Absolutely NO BOG or stumble upon hard acceleration. I later changed to a Carter 4294S for a little better midrange fuel distribution. Later, i then I replaced my originally conversion with 340 parts....manifold, heads, 1968 std trans cam, and switched to a Carter AVS for the 340 engine. An absolutely great street warrior....easily handling GM 350 Cameros, and giving Roadrunners something to think sbout. My opinion.....stay with Mopar stuff....because it works and is reliable. Do not listen to your next door neighbor's brother in law's cousin best buddy.....who knows NOTHING about Mopars. This is just my opinion.
Bob Renton

 

[wyrmrider]

EXCELLENT BOB
hard to find that 340 stick shift cam now- IDK anyone grinding it- but old school anyway, that 273 would be even rarer

 

[67BELVSLEEPER]

I’m pretty intrigued by the 273 D-Dart set up. I already have the commando intake, does anybody know a similar cam profile to use or the difference in the heads. I was going to build a 318 but I think this 4 Door Belvy would be pretty cool with the hotter 273 setup. I already have the motor and would like to keep it original.

 

[67BELVSLEEPER]

I’m pretty intrigued by the 273 D-Dart set up. I already have the commando intake, does anybody know a similar cam profile to use or the difference in the heads. I was going to build a 318 but I think it would be cool to have the hotter 273 in this Belvy to include some Doug’s Headers.

 

[lewtot184]

I’m not sure what the OE carb throttle bore/butterfly size was. On a Poly dualquad intake, the 600 AFB was to large to fit the 4 hole intake throttle bores.

Doe the AFB 500’s have a smaller butterfly?

the OEM carb had 1 7/16" primary and 1 9/16" secondary throttle bores, with 1 1/16" primary venturii/1 1/4" secondary venturii. throttle bore sizes are the same as big block 4bbl 1965.

the 500 edelbrock is a 600 with a restrictive primary cluster. in my opinion not good.

 

[lewtot184]

I’m pretty intrigued by the 273 D-Dart set up. I already have the commando intake, does anybody know a similar cam profile to use or the difference in the heads. I was going to build a 318 but I think it would be cool to have the hotter 273 in this Belvy to include some Doug’s Headers.

they used a Camcraft camshaft. not sure if it's still available. probably too much cam for a big car and little engine.

 

[67BELVSLEEPER]

I’m thinking the Belvedere II is about 3200-3300 according to my research. My Foxbody is about 3150. Stock Fox 302 is 225 hp 300 tq. If I could get the 273 close to those numbers that would be a fun car in my opinion and sound nice with a good cam.

 

[rumblefish360]

Build the 318 over the 273 unless you don’t have a 318 and have the 273. Nonsense in wasting money in that fashion.

The cam was rated at a 284/.484 IIRC.
What the duration @.050 would be I’m not sure. But if it were a purple cam, it would have a duration @.050 or 241.

That, would be a stout street cam.

 

[67BELVSLEEPER]

Build the 318 over the 273 unless you don’t have a 318 and have the 273. Nonsense in wasting money in that fashion.

The cam was rated at a 284/.484 IIRC.
What the duration @.050 would be I’m not sure. But if it were a purple cam, it would have a duration @.050 or 241.

That, would be a stout street cam.

The original 273 is in the car. I am going to run it for this year but was planning on building something next winter. I want something that’s fun and sounds good. My Fox has a built 302 as a street/strip car.

 

[67BELVSLEEPER]

The cam I run in the Fox is a .542”/.563”, it has really good street manners.

 

[lewtot184]

the 273 has small ports and valves. small bore doesn't help the heads. i'd be cautious. the D-darts weren't competitive.

 

[wyrmrider]

just start with a 360 magnum core