283 carb choice.

[Marty68]

I have (believed to be stock) 1964 283. It has a new rebuilt 2 jet. That works good. I have an Edelbrock c3bx manifold. And a 1405 and 1406 carbs.
Edelbrock told me those carbs are too big for a 283..
So the question is would I see any gain by installing manifold and using my 2 barrel?
I calculated mpg yesterday at 15.6.
I like the look of stock air cleaner and script covers...

[cadillac_al]

Back when I was a kid I couldn't get my 283 4 bbl conversion to outperform the old trusty 2 bbl. I might have better luck if I tried it in my old age. I used to rev that 283 to the moon in low gear with that little 2 bbl.

[Marty68]

What intakes were you using? Will I see gain by using 2bbl on dual plane aluminum intake?

[Ziegelsteinfaust]

A 500 cfm 4 barrel works great on a 283, and a 650 Vacuum secondary is not so bad either.

A 2 barrel has a tendency to run richer throughout the rpm band due to the 2 vs 4 barrels. I put a 500 cfm holley 2 barrel on a 289 I had to mess with people, and it didnt lay down more power that I could feel when I went to a 4 barrel. My mpg did go up a couple mpg on the highway due to better control of part throttle air fuel ratio.

Running large holley or edelbrock carbs on smaller motors. Such as a 800 cfm on a 350 or a 750 on a 283. Q-jets are different here due to the small primaries. But you have issues with progressive afr, and part throttle tip in feels softer. Correspondly if your constant turning 5000+++ rpm they work better since the engine can not pull more fuel then it needs allowing control of the afr. So if this was 1969, and your running a trans am race this gives you extra mpg. So you have to fuel less often.

[Marty68]

I dont have a 500 cfm.. I have 2 600 cfm. And stock rochester 2jet.

[cadillac_al]

Lots of 305's came with aluminum intakes and Qjets. I don't see any reason a qjet wouldn't work fine on a 283. My swap was with a used Holley so that was doomed from the start lol. I'd say try one of those 600's and see how it runs. I'm forgetting my Eddy carb numbers now, one of them is jetted lean for emissions and I always said it was jetted for a 305 or 5.0. I thought that was the 1405. If that's not the one you can always jet it leaner if it needs it.

[truckster]

To answer your question, you're probably not going to see any appreciable gain by installing the manifold with your 2 barrel.

[Marty68]

Originally Posted by truckster

To answer your question, you're probably not going to see any appreciable gain by installing the manifold with your 2 barrel.

Thank you...that was my thought

[Marty68]

I will be looking for a 500 cfm edelbrock.

[geezer#99]

Originally Posted by Marty68

I will be looking for a 500 cfm edelbrock.

Why?
A 600 will work fine.
You got two, use one.

500 and 600 have same primary and secondary sizes.
600 is jetted bigger.
Info here.

https://www.forabodiesonly.com/mopar...-sizes.285890/

[Marty68]

Originally Posted by geezer#99

Why?
A 600 will work fine.
You got two, use one.

500 and 600 have same primary and secondary sizes.
600 is jetted bigger.
Info here.

https://www.forabodiesonly.com/mopar...-sizes.285890/

Thank you..

[vince1]

When I was a kid I put a 4 barrel on a 58 Ford 272. It was a Holley square bore with small openings and vacuum secondaries. Performance and fuel economy went way up and the car ran great. I don't know what the cfm rating was but suspect maybe 500 to 600.

[geezer#99]

Originally Posted by vince1

When I was a kid I put a 4 barrel on a 58 Ford 272. It was a Holley square bore with small openings and vacuum secondaries. Performance and fuel economy went way up and the car ran great. I don't know what the cfm rating was but suspect maybe 500 to 600.

I think the smallest Holley was a 390 cfm. Could have been what you had.
57 fords came with this monstrosities.

https://www.hemmings.com/blog/articl...l-4000-teapot/

[vince1]

That was definitely not it. Looked somewhat like this.

https://www.speedwaymotors.com/Holle...retor,375.html

The carb looked very similar to the modern versions as in above link. Money was tight back then. A friend sold me the carb and manifold with a supplied broken lug for about $20. I brazed the lug back on in high school and bought a kit for the carb. I used to like the difference in sound when the secondaries opened. As I recall top speed was somewhere between 105 and 110 MPH. I don't know what engine or car the parts originally came from but just a common old Y block I guess. I would have put it on in about 1968.

[geezer#99]

Musta been 110 down Nose Creek hill after you escaped from Peters Drive In.
That style Holley has been sized from 390 cfm upwards. Many different cfm ratings.

[vince1]

http://4secondsflat.com/Carb_CFM_Calculator.html

I bought that car when I was 16 for $40 with a transmission in the trunk. I remember the guy's kids trying to ram it into place. I towed it home and found the torque converter knob too big to fit the end of the crank. Therefore I found out the engine was a 272 which used an air cooled torque converter but after having a machine shop cut the knob off and me welding in a another I was good to go. The engine was probably from a 55 or 56 and had Thunderbird written on the valve covers if that meant anything, I do not know.

There're lots of straight aways around Quesnel and it would do 105 any day of the week. Pretty scary though as it floated along and felt like it was going to go airborne. Probably it wasn't safe past 70.

Maybe I would have gotten into the Chevy V-8's sooner but my dad never bought any. He liked sixes and standards. Our 55 wagon had three on the tree and I believe a 261, although people say it would have been a 235. Our 216's in farm vehicles did get changed out to 235's

Good luck with the carbs Marty68.

[vince1]

I'd like to ask a question Geezer as to the suitability of a carb that has more than enough cfm rating. I can remember driving in cars that had the quadra jet and when they stepped on the pedal the car would bog, hence the nomer of bog jet. I suppose they were direct linked to the secondaries and no wonder they didn't work correctly. Do the carbs that Marty68 has have any provision for not bogging when the secondaries open?

Sorry for the rant previously. I guess we remember much more of when we were kids than from subsequent events.

[geezer#99]

Quadrajet had an air door that had an adjustable spring on it. Guys would set the spring looser and the door would flop open and bog city.
Eddy carbs also have an air door. Only adjustable by adding or removing weight of the counterweights on the door.
Both quadrajet and eddy carbs also had a secondary lockout feature. Linkage that only worked when the choke was fully or partly on during motor warmup. Once warmed up the choke would be completely off, the linkage would drop out of the way and the secondaries would work.
Secondary lockout was needed to stop wide open throttle operation on a cold engine.

[vince1]

So on a 283 at WOT and revs high the secondaries of a 500, 600 or 750 cfm carb will be open but only partially depending upon how much venturi effect is going on?

[geezer#99]

Yup!
If you don’t have the airflow they don’t open more than is needed.

[vince1]

If you're getting 15.6 US (19.5 Imp.) MPG I would leave whatever you have alone. If it is in a P/U I don't think you will ever see better than that.

[Marty68]

Originally Posted by vince1

If you're getting 15.6 US (19.5 Imp.) MPG I would leave whatever you have alone. If it is in a P/U I don't think you will ever see better than that.

My fear is 10 mpg. I have 3.42 gears and a 5 spd.


I am trading one of the 600 600s for a good 500. So I can play. My research reading indicates the 500 would have more velocity. Velocity = throttle response. Edelbrock says tuning down a larger carb does not make a smaller carb.


With one remaining 600 cfm (unsure if friend wants 1405 or 1406) and a 500 cfm. I would have the option of trying the 2bbl. The 500 and one of the 600.

I I am furloughed next week. I have never swapped intakes yet... wish me luck.

[geezer#99]

You might need a heat spacer too.

https://www.walmart.ca/en/ip/Edelbro...RD2QCRY047C5F5

And throttle linkage.

https://www.google.com/search?q=edel...ih=921&biw=991

And fuel regulator.

https://www.google.com/search?q=edel...ih=921&biw=991

[AcampoDave]

When you pull that stock 283 intake take a look at the size of the runners and ports, you will see that velocity not only comes from the smaller carb, but also the smaller runners of the oem manifold as well.

[Marty68]

Originally Posted by AcampoDave

When you pull that stock 283 intake take a look at the size of the runners and ports, you will see that velocity not only comes from the smaller carb, but also the smaller runners of the oem manifold as well.

So... not worth changing?...
Leave it as is?...
Hate to do work and make it worse.