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

Reading everyone's experience and stories is really cool. I'm shooting my shot with this set up. We gon see what happens and how it plays out.
Below is what the person I purchased the engine from said was done years back. After opening up the engine and checking the pistons, lifters, push rods, main and rod bearings etc. The parts are all brand new and it's amazing how well kept they stood after so many years. The engine was never turned over since the rebuild, so that in itself will be a test. Anyways for those who were wondering if the engine was bone stock or not, below is what he listed was done;

"Regardig is rebuild, as best as I remember, valve job, valve train, and lifters....bored 30 or 60 over with new pistons. Crank was turned +30 with new main and Rod bearings. I think I kept stock cam. And as I mentioned alum flywheel new clutch and pressure plate. Prior to the rebuild I was running this same set up with a 2 barrel Holley 500."

Buoymaker - you listed the venturi size for the Carter 9400s, but there are smaller Carter AFB carbs.

The smallest one I could remember without doing a bunch of research does have the dimensions I mentioned, same as the Holley 390.

As I stated earlier, I have not used the Carter on a 235, but did use the 9400s on a 300 CID Ford six replacing the original Holley 1-barrel.

There was a significant difference in power; but the biggest difference was fuel economy, especially on the highway. The AFB gave a HUGE increase in fuel economy over the Holley. However, I will admit to knowing more about tuning the AFB than the Holley. Possibly one reason I had no low RPM issues was a 4-speed with a "granny" low gear.

I won't post the fuel economy but this was in an extended wheelbase 1979 Econoline with a stock fuel tank. Loaded for a Swap Meet, we drove the speed limit, maybe a tad over (55~70 in Missouri, 75 in Oklahoma) from Eldon, Missouri to Chickasha, Oklahoma without stopping for gasoline, and I have a witness.

Again, this was a different six.

And if anyone wants to fabricate an intake so they can use the Pontiac Sprint Q-Jet, and cannot find one, give me a call I have about 2 dozen of them. But unless one is grounded in intake manifold design, I would not recommend one of these.

Best would be a slightly larger single barrel, on three MUCH SMALLER single barrels

Jon

Jon, I always enjoy reading your AFB fuel economy story. I calc'd it out the last time you mentioned it and it was roughly 24mpgs on that trip!

Does the Pontiac Q-Jet have the same bolt pattern as the other Q-Jets?

If I were to attempt a QJ-stovebolt manifold, beginning with the Clifford 4500, I would make the transition no merely a bolt pattern change but position the QJ closer to the OEM Sprint manifold. The secondaries are roughly centered in the manifold casting closest to the ports, but the primaries are outboard.
No, the manifold won't fit.

[img]https://i.ebayimg.com/images/g/N~AAAOSwJVRgIKuj/s-l400.jpg[/img]

Does the Sprint Q-Jet have the same bolt pattern as other Q-Jets? From photos I have seen it appears to.

Yes.

Jon.

17 years ago.

Re: 350 cfm Holley on Clifford 4 barrel intake - 28/02/05 08:44 AM posted by Tony, "I found there was nothing to gain beyond 400 CFM."

I did a lot of additional tests on a modified 261 ,3/4 cam, stock 848 head, about 9-1 compression, Fenton headers with either a Clifford heated 4bbl intake or an Offenhauser heated dual carb intake. Using various 4bbl carbs from 390 to 600 cfm, Holley, Edelbrock and a Carter AFB and dual Rochester and dual Holley Weber on the Offenhauser intake, I found there was nothing to gain beyond 400 CFM. All the tests were done with a stopwatch on a measured back road stretch, using full throttle in second gear from 2500 to 4500 rpm, about 65 MPH in my 37 truck. All carbs were jetted for best acceleration which was pretty close to the stock jetting in all except for the Edelbrock 500 4bbl which had to have the primaries leaned out a few sizes. My findings are very similar to the engine CFM carb requirement charts offered by Holley. These are my opinions, on the way my engine was tuned, but I think they would be true for most similarly tuned 235/261 engines. [i][/i]

Back in the mid-1960's there were a huge number of Chris-Craft wooden runabout boats on the lakes around Nashville. My father got quite a reputation for being the top tuner available to make those boats run well. The Hercules industrial engine was a flathead inline six, converted for marine use by Graymarine. If you think it's difficult to make a stovebolt a hotrod, try it on a side valve engine, sometimes one equipped with an updraft carburetor!

Dad would do all the "go fast" modifications the other boat wrench jockeys did, and then do one more thing- - - -have the tachometer recalibrated. It's amazing how much "faster" a boat feels like it's running when the tach is indicating 200 RPM faster than the crank is turning at full throttle!

LOL!
Jerry

Grandpa's 48 Try it may run fine.

Fixite7 thats the plan brotha.