Stovebolt.com Forums The Shop Area The Engine Shop 235 (57-62) 4B Carb/Clifford Intk

In 1965 my dad decided to rebuild a 235 to go in a 1939 Chevrolet car that he had fixed-up. A racing friend talked him into pop-up pistons, cam, porting and polishing, dual exhaust and three BXOV-2. Back then those racing parts were a lot of money and I remember my mom giving him the "evil eye". Years later he told me it never ran to the performance level he was expecting, but don't tell your mother. When it was really cold outside, the engine would flood before he could get it started. It became a ritual with the battery charger, starting fluid and frozen fingers. Finally he got tired of messing with it and converted back to a standard intake with one carburetor so he would have less trouble.

Today there is a lot more Chevy I-6 information and insight available (basically facts), than what my father had in 65. He would have loved to have read about it, before he started on his venture.

Let me get this straight, and I don't mean to sound adversarial because I truelly enjoy reading and contributing here, but none of you have ever run a clifford manifold, let alone one with a 390, 450 or any other carb and you want to theoretically opine that no matter what, it will not work work or run well? I ran one with a 390 carb and it ran great. Could I have run a bigger carb, I guess but Jack Clifford (late 70s early 80s) told me that the 390 was the right carb for that manifold and that anything larger was too much. I used what he recommended and after a little bit of basic holley tuning, it was a very good set up.

How is it that those who have never actually run one of those intakes can be so insistant on poo pooing an induction system they have never ever used themselves?

I don’t see why the little Holley wouldn’t work fine on the primaries. And I appreciate that you can speak to it first hand.

Did it ever need the secondaries? And if so, how did you tune them?

Deagsix, we will give it our best shot and definitely keep everyone posted. Again, everyone has been super helpful and all this information is very much appreciated.

Were you running that Clifford manifold on a bone stock basic engine like the OP is? It seems like we're comparing apples to coconuts if other modifications are involved.
Jerry

Grandpas48 I made my own intake back in the sixties ran an AFB on it no heat ran good,be sure your accelerator pump is in good shape. My big objection to those Edelbrocks is not very good economy,I guess Vic Edelbrock figured you would always be on it anyway !!!

The small primaries (390) need only the right PV and MJ, the secondaries are as close as you will get to the right A/F curve.
As the CFM from bigger secondaries goes up (600), the mixture curve deviates more & more away from a small engine wants. You need an adjustable metering block or it will run lean at high rpm. No, a smaller HSAB or bigger MJ is not enough, but it's a start.

Haven't tried it, but a "universal" (JY V8) QuadraJet can be gotten pretty close by using all of the Sprint tuning parts. Great value for low $$. Bad: no manifolds for it, needs an adapter to Holley pattern.

The Q-Jet can be made to really run well on most applications, depending on the skill of the individual doing the tuning. MOST are 750 CFM, which is a fixed 150 on the primary side, and a "demand" 600 on the secondary side. So if the tuner understands what he/she is doing, the secondary will only supply what the engine asks for. Virtually impossible to overcarburate.

To anyone even considering using a Q-Jet, the paperback on tuning Q-Jets by Cliff Ruggles is absolutely required reading. One of the most user-friendly carburetor books I have ever read, and don't need a college degree in mathematics and physics to understand the book.

Jon

I think you're going to find you are over carbed for a 235. Did you consult edelbrock support on your application. I put that same carb on a 307 and it does well. But 70 less cubes its not going to meter fuel correctly.

How does the 230" Pontiac Sprint function with its original 750 QJ?
Very well.