CUTLASS Buick V6 4bbl carb jetting/cfm
- Thread starter nycutlass
- Start date
That should be an interesting carb to use. You probably want to lean out the secondaries. Do you have dual exhaust on the car?
That is likely too much carb for what you seek.
The problem you will have is too many CFM, and too rich on the setup.
The turbo motor used compressed air charge via the plenum between carb and intake. Accordingly, the carb was set to dump LOTS more fuel in because with the compressed air the 231 acted more like a v8.
This does not solve the problem.
You could try asking Cliff Performance if they can tune the turbo carb down but he will likely have a waiting list.
the engine is not in any car its a spare, should i buy a car with no drivetrain or blow up my bigger ones. i can swap in this one in. it ran good enough to keep tucked in the corner of my shop. it still has the stock cast manifolds for exhaust with Y pipe. if i ever come across a set of cheap headers ill pick them up.
Most likely i will have to jet this carb down or lean it out a lot. it shouldn't dump no extra fuel with a open air filter ( meaning I'm not sticking this carb in a box to force the air, To do a Q-jet you have to build a "box" for it so the boost is constant ). i really don't think ill have that much of a issue.
Last edited:
The factory turbo wasn't a blow-thru setup, it was a draw-thru.
So, at the top you had a very high CFM carb - usually a throw back to 800 CFM. On the non-CCC it was set up to dump lots of fuel down below into a plenum.
The second level was the plenum. A turbocharger forced the extra air charge in at this point which mixed with all the extra fuel coming from above.
The third level was the intake manifold itself, where the entire mixture entered the engine.
There wasn't a 'box' the way you're talking about. The factory turbo had a colder air intake accomplished by a small 'hat' on top running a duct forward to the headlights, but, this wasn't related to the boost/turbo.
The 78-83 factory carb turbo stuff was set-up different than how guys build turbo setups themselves for swaps.
So, yes, you have a high cfm carb that is set up to dump lots of extra fuel beyond what a base 231 v6 needs. Displacement x rpm ÷ 3456. Peak hp on these was usually roughly 3800rpm, and valves start to float around 4500 rpm. So let's use 3800 rpm.
Your 231 x 3800 ÷3456 is only 254 cfm. 231 x 4500 ÷ 3456 is only 301 cfm.
When stock, the carb turbo cars left the factory around 10lbs boost. For every 14.7psi boost you double the original displacement effectively. So, (231 + (231 x[10/14.7])) x 3800 ÷ 3456 is 427. Or if you prefer around 450p, (231+(231x[10/14.7])) x 4500 ÷ 3456 is 506.
You bought a carb that was a throwback to the 750/800 cfm buick v8 setup days. It was factory set up to release WAAAAAY more fuel than appropriate for your stock 231 at any given percentage of throttle. It will need BIG changes to it.
You can take that info and use it, or choose to ignore it, your choice. But the factory setup introduced the boost BELOW/AFTER the carb. It didn't need the "box" you speak of, and, it will be pig rich
Does anybody know of a 4.1 4bbl intake for sale on this topic? I have an appropriate 350 cfm Q-jet for it. My t-stat housing on my Edelbrock is beyond corroded, will not keep a seal and hold coolant. I'd be willing to pay $150 for a the stock 4.1 intake.
Similar threads
