Need carburetor suggestions for 283ci

[Alex V.]

Is the 4* timing the correct spec for your '67 engine? That sounds too low for a pre-smog engine but I may be wrong. I'd bump it to 8 or 10 before I did much more with the carb.

[palallin]

Originally Posted by El Dorado Jim

X2 if you want an easy carb to rebuild and tune, they work great right out of the box, I have three of the 1406 edelbrocks on trucks of mine, and planning on another when my qjet on my '74K20 goes south, the 1404 500cfm would be great on your 283

I have been running one for over ten years in my K10 on my 327. I have no complaints. I *prefer* a really good, well-tuned Q-jet, but I haven't the patience or the time do tune one or the money to have someone else do it.

[chefk85]

Yes 4*btdc is the correct spec from the book.

[oldchevynut]

I did a little research when I put the Q-jet on my 283 Malibu and as far as I could find no 283 ever came from the factory with a Q-jet. Apparently Q-jet production started within the last year or two of 283 production and the few 4 barrel 283's produced during that time frame all came with the 4G. As far as i could find the smallest small block that came with a Q-jet was the 305. That is why I had Cliff do my Q-jet, i figured if anyone could make it work, he could. I was looking for fuel efficiency since the Malibu is a daily driven commuter, but still a little power for towing. It has accomplished those objectives. The only indication that it is a large carb for the application is that even with the idle speed adjustment screw all the way out it still idles about 50 rpm higher than i would like. Apparently the idle circuit is too large to feed that little 283 at idle.

[chefk85]

Here is the intake number as far as I can tell 388 or 3980364. I can't find it anywhere on the net . I will take a wire wheel to it this week and get an updated picture up.

[RichardJ]

http://www.carbkitsource.com/carbs/t...jet-index.html

Read DESIGN on the left. .....The basic 750 cfm QJet casting is used from 231 CID to over 400 CID -

[Crabass]

Seems to me that you're not quite ready to pitch the QJ just yet--------here's a link to to a large chunk of info on 'em (didn't see it mentioned). Lars used to rebuild carbs for forum guys but stopped the practice quite some time ago. This article is a bit dated but still very informative:

http://www.corvette-restoration.com/...arb_Tuning.pdf

.......and another one that presents problems/issues:

http://www.corvette-restoration.com/...leshooting.pdf

[Alex V.]

Originally Posted by oldchevynut

I did a little research when I put the Q-jet on my 283 Malibu and as far as I could find no 283 ever came from the factory with a Q-jet. Apparently Q-jet production started within the last year or two of 283 production and the few 4 barrel 283's produced during that time frame all came with the 4G. As far as i could find the smallest small block that came with a Q-jet was the 305. That is why I had Cliff do my Q-jet, i figured if anyone could make it work, he could. I was looking for fuel efficiency since the Malibu is a daily driven commuter, but still a little power for towing. It has accomplished those objectives. The only indication that it is a large carb for the application is that even with the idle speed adjustment screw all the way out it still idles about 50 rpm higher than i would like. Apparently the idle circuit is too large to feed that little 283 at idle.

That sounds right. IIRC the first cars to come with Quadrajets were '66 275HP 327 passenger cars, continuing through '67 with the addition of the 350SS Camaro. 750 CFM may be a lot for a 283 but I seriously doubt it's legitimately too much.

[68Gold/white]

Originally Posted by oldchevynut

A few years ago I had Cliff rebuild and tune a Q-jet for my 1967 Malibu 283 engine. It has worked nearly flawlessly for over 40,000 miles now. The downside is at that time he had a 1 year waiting list. I think I may still have the records for the rod and jet size he used. May take me a while to find them tho...

If you could...measure how far open the secondary air flap opens on your 283 Q-Jet. just curious how Cliff set yours up. Just push down gently on the back of the flap, measure from top of flap to front and/or rear of body casting.
Thanks!

[oldchevynut]

Will do. May take me a day or two to get to it. Randy.

[oldchevynut]

68Gold,

The secondary air flaps on my Cliff-built Q-Jet easily open to the fully open position. Hope this helps...

Also, I found some of the specs for this carb;
Jets are 066
Primary Metering Rods are 39
Remember this is set up for an intermediate size car for fuel efficiency. Results likely will vary for trucks.

[68Gold/white]

Originally Posted by oldchevynut

68Gold,

The secondary air flaps on my Cliff-built Q-Jet easily open to the fully open position. Hope this helps...

Also, I found some of the specs for this carb;
Jets are 066
Primary Metering Rods are 39
Remember this is set up for an intermediate size car for fuel efficiency. Results likely will vary for trucks.

Thanks!
Cliff is the Q-Jet man!
I am putting the 283 from my 67 Bel Air into my 67 C-10 hopefully this summer. I had this engine professionally built in 1984, and dyno'd. It's just a daily driver. I didn't have the info back then to properly build a Q-Jet back then. Tried several, didn't do well.

[chefk85]

So it's been a while since I was on the thread. I've been messing around with the Ole qjet and have gotten it to run quite a bit better. I started noticing upon closer inspection that it has been frankensteined. 2 check balls for the accelerator pump passage. A modified power piston spring and a set of primary rods with no stamp. I replaced the spring with another I had laying around and put in a set of 39b rods as well as removing the extra check ball. It has no more part throttle hesitation or off idle stumble but still has wot hesitation. Overall it's a huge improvement but I'm getting about 6mpg now. I'm not sure the jet size but that's where I'm headed next. I would live to find a complete spec sheet for 283ci qjet setup i.e. jets, rods both primary and 2nd, springs hangers, etc..

[Alex V.]

I believe it's been determined there really isn't an established spec sheet for a 283 Quadrajet application. Oldchevynut's specs should be a good starting point, though I think jetting needs will more depend on the exact engine setup (head type, compression ratio, etc.) than what vehicle it's setting in.

If it was mine I'd get it set up real close to oldchevynut's specs and make any further adjustments based on the traditional methods - spark plug color, vacuum, throttle response, etc.

[chefk85]

Thanks. I'll look into it. Mines stock setup w power pak heads. Which I think came on it. I'll update when I get a little closer to where I want it.

[68Gold/white]

Cliff can give you what you need, parts or info. wise.Get his book, Hastings or Barnes and Noble usually has it on hand, he sells his book, also...
His tuning ability is huge, not just his Q-Jet knowledge, either...
Get the carb tailored to your engine, you'll be smiling!!!

[fwayne]

On your Q-jet. If it bogs on full throttle acceleration for a second but then kicks in, your vacuum secondaries are opening too fast. Usually really easy to fix. A Small allen screw to adjust the secondary's make them slightly tighter. it can stop that bog pretty much every time.

http://www.73-87.com/7387garage/driv...lock_screw.jpg

[chefk85]

The bog I'm talking about is more of a constant at wot. Like a skipping.