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

What about the Rochester GC 4-jet carburetor, that was factory installed on 1961 thru 63 Pontiac Tempest 195, 4 cylinder engines. Exactly 1/2 of a 389 with the same bore and stroke,that produced 166 HP. An idea from auto industry icon John Z. DeLorean, Pontiac's chief engineer to utilize some existing parts. There is a few on eBay but quite expensive.

Panic, if we have a bone stock Chevy 235 inline-6:
What, in your opinion, is the best carburetor (of any carburetors ever made) and intake manifold combination for that engine? Assume normal everyday truck driving.

Suppose you are given a Sprint QJ, a AFB 9400s and a "390" (sorry, no picture):
1.) For the above engine, which one would work the best? "390", QJ, AFB or none?
2.) Which intake manifold would work the best?
3.) For the carburetor selected in 1) above, what could be done to optimize the carburetor to run best on that engine?

Question #4- - - - -Which one of the carburetors listed above will show a consistent power gain compared to a stock 1-BBL intake and a Carter, Zenith, or Stromberg carb that's optimized for a 235 stovebolt engine in good condition?

Qustion #5- - - - -Assuming there is a power increase that can be measured on a dyno, is the power gain worth the considerable effort and expense of installing the 4 BBL carb and manifold? Somehow, I believe that neither the hotrodders, nor the merchandisers who pick their pockets would want to answer those two questions honestly.
Jerry

Best for what purpose?
Adding CFM to a truck will only help at engine speeds you don't want to use.
You can't buy anything like a QJ bolt-on, the Sprint model bought new is $$$, there is no manifold, results are entirely the work of someone with experience and fabrication skills. The common QJ to Holley pattern adapters are notorious for bad vacuum sealing.
Some original Sprint QuadraJet carburetor numbers are 7026260, 7026261, 7041314, 7041315, 7027260, 7037260, 7027261, 7037261, 7027268, 7037268, 7027269, 7037269, 7028260, 7028261, 7029260, 7029261

The 390 is popular because it's available and it's been done. Clifford suggests an “85” (8.5) power valve and a .048” main jet as a starting point

I’d like to hear from DragSix on how well the baby Holley ran in comparison to the common one barrel setup. Genuinely curious, not baiting into some sort of argument. He’s the only one in this thread who seems to have first hand experience with the Clifford/Holley.

Also curious if this was for a regular driver or some sort of drag strip toy.

Let’s face it, these things are all toys, even if they are regular drivers. Nothing a stovebolt does that can’t be replaced by an engine a few decades newer.

I have my doubts that the Clifford/Holley could run a lot BETTER than the stock configuration. But I really have no way of knowing. And even it’s just parody to stock, and the owner has fun (it’s a toy) with it just to be different…..that’s cool.

Panic - I do not have one to look at, what size are the primary throttle bores/primary venturii on the Holley 390?

The small Carter AFB has a throttle bore of 1 7/16, and a primary venturi of 1 1/16 inches.

For comparison, the Pontiac Sprint Q-Jets (which are available) have the same 1 1/16 venturi, but the throttle bore is slightly smaller at 1 3/8 inches.

No argument, just would like to have the specs for all in the same spot.

You nailed the biggest issue with the Sprint carb, being the lack of an intake.

EDIT: for additional comparison, the primary venturi on the 265 CID Chevy WCFB is also 1 1/16 inch; while this was increase to 1 1/8 inch for the 283 CID Chevy.

Jon

The one bbl is a really good set up for a stock motor. Keep in mind that it has to cover a lot of ground. Small enough to be efficient at idle, large enough to provide sufficient power when necessary, and work effectively in between. So for what it was designed for, its a real workhorse, some designes better then others of course. But is the one bbl the be all and end all for a 235 chevy? Is it the ultimate carb? I dont know that you could ever actually answer that question.

I have run so many intakes and carb combinations over the years that I am not sure I remember them all myself. But I can provide some thoughts. In 77 I took my drivers test in a bone stock 1957 chevy three speed (I still have the car). The car belonged to my father, it was his used car. I snuck off to maple grove dragstrip on Friday night and ran the car. Yea, 26 second quarter mile. A year later I obtained a decades old Weiand 2X1 intake with two YF carter carbs. Dirty, grungy, beat up. I rebuilt the carbs, cleaned and polished the intake, fixed the linkage and installed it, along with a set of Clifford long tube headers and went back to show everyone how fast I could go.

Yea, 22 seconds, lol. But the addition of the extra carb and tube headers did assist in the performance of the motor, or maybe was just a more efficient set up. At any rate, it ran faster. I still have that intake and carb set up. Soooo, then came a 3X1 offy with three rodchesters. Oh my god, was that set up a pig pig pig. That and it did not run all that well unless the motor was really opened up. I tried Holley glass bowl carbs, 1902, 1904, 1920, ran a little better but I did not know much about carbs then and you still needed pretty close to wot before the motor cleaned up. I still have the off with teh three holley glass bowls.

Then came a 57 pick up, later a 56, both with 235, and the Weiand ended up on both. Got my hands on the Clifford 1x4 and ran a 390 Holley on that. I was lucky, I had kept up a pretty extensive amout of written communications with jack Clifford when He was alive, and spoke to him on the phone quite often. He got a kick out of a young guy (then, lol) being inerested in these motors. So I took his advice and it was always pretty spot on. He told me that I was never going to make any kind of HP out of my 235 or a 261, but I would have fun playing with the motor. He was right.

I rebuilt the motor, installed a chet Herbert $39.99 reground cam ( I still have that motor in the back of my garage). The 390 needed to be dialed in. Power valve had to be changed to meet the vacuum requirements of the motor, main jets adjusted, a few other tweaks and then, it ran good on the street in particular. And when I took it to the track, I was in the 19s. Efficiency I suppose, the cam and the increased indicution. Changed the gears in the rear and I was in the 16s. But I loved the look of multiple carbs so I went back to the Weiand, then on to a tattersfield (I wish I still had that one), one of Tommy Thickson's dog bone intakes (I really really wish I still had that one), Fenton, some others but they all ran about the same, and ran a little rich at idle. Slower then the 4 bbl 390.

One year, Pat Smith (all around good guy, former Inliners International President, Dyson Racing Team head IMSA crew chief, automotive educator, and unbelievable mechanic) and I were at a nostalgia race at the now closed Englishtown, New Jersey E-Town dragstrip at one of their famous old time drag days. He had I want to say a 38 chevy with a 302 GMC and a pair of Holley 2300 2 bbls. Street car. That car ran terrific. I think he was runing in the 13s or so. Man did I want to try that. By the way, Pat wrote what I believe is the finest two articles on dialing in a multi carb rodchester 1 bbl set up. Its complicated and time consuming but its the only real way to get them to run right. I think it is still on the inliners site if anyone is interested. I did it once on a friends 2x1 set up and it works but you need the patience of a saint. In the end though, you are still stuck with the warping castings, sticking power piston. Not really for me, lol.

But then I ran into Tom Langdon at the Carlile fall swap meet. He and I were gabbing and he was of the opinion that the one bbls were starting to become difficult to find in decent shape, reiterated that the 235 would never be all that powerful, and thought I should give a pair of Pinto Holley/Weber 5200 carbs a try. I did. I picked up another Weiand intake and installed a parir of 74 Pinto carbs (74 models because they have a threaded inlet) and truth be told, those litlle progressive two bbls were terrific. One of my favorite set ups. Ran great out of the box, small enough to work efficiently, small primary, larger secondary, mechanical linkage for the secondary). Car and the one truck I still had ran great on those carbs. Much much better then any single one bbl set up and truth be told, I think they are the better if not the best choice for a two carb street set up for a 235 (I ran it on a Weiand manifold with spacers and it ran just great). I stil have that manifold and carb set up.

A couple of years ago I changed over to the Clifford 2x2 intake and ran a pair of Weber 38 mm DGEV carbs. I did not necessarily like them. Ran fine on the street but not so great at WOT on the track. I also was not grasping Weber tuning all that quickly and never really got the hang of it and never got those carbs really dialed in.

Last year, swaped a pair of 2300 Holley 350 carbs onto the Clifford intake (on the 57 car, which is the only one of my old vehicles that is not currently apart, lol) and took it to the trifive nationals in Bowling Green, KY. Had a ball. The holly 2300s were way easier to get dialed in. Had to change the power valves to acomodate the engine vacuum, left the jetting alone, adjusted the fuel levels in the bowls, and away I went. Car ran great, really great.

That being said, at one time Holley made a really really neat 2 bbl, a 2305. It was a 2300 but Progressive just like the Holley/Webers. Primary opened first, then the secondary came in mechanically. I wanted a pair of those like no tomorrow but by the time I got back into the car/truck thing after raising the kids, weddings, college, they were long out of production and now profoundly rare.

If I was to opine on what carb I think would be the best alternative to a single 1 bbl, I would say the 2305 for both single carb operation and dual carb operation primarily because I do think the 235 could use a little more carb at certain points in the acceleration curve. But you cant get one, too rare. So what is the answer, I dont know, but my gut tells me a nice progresssive two bbl would be about right. The holley Webers are in my opinion a little twwo small for a single carb operation. The Weber 38 DGEVs are not progressive, and The 2300s are are not progressive. I am not sold on a 1 bbl being all that efficeint at lower rpm and I know they are not the best at WOT. I actually think a smaller carb would be more efficient at idle but then you run headlong into the needs after idle, hense we are back to the the 1 bbl having to cover a lot of ground, sort of a jack of all trades but master of none. So where does that leave us, well I am not sure, lol. The 1 bbl is a good compromise and absolutly nothing wrong with running one. Can you keep up with one of my motors running a dual carb set up verses a single 1 bbl, I dont think so. So its all about use, need, perspective.

Man, did I write all that, lol.

Mike (Dragsix), That is a good read, lots of good information. Personally, I decided to go with a Sprint Q-Jet on my 292. With the lumped head and gasket-matched and mildly ported exhaust ports, it should be more efficient. Not trying to hijack this thread, but I wanted to chime in with a thank you and that I agree the 1bbl is good but not great. Those 1bbl's are workhorses, though.

DragSix,

Excellent read. I had no idea that ANYONE here had done that much tinkering with various 235 carb/intake setups.

So you think a single Holley 2305 is better than a single 390 cfm 4 barrel?

Best I can tell from this Holley chart:

The 390 cfm 4 barrel (both 4150 and 4160 configurations) has:

1 - 7/16 primary throttle bore
1 - 1/16 primary venturii

If someone was able to find a Carter WCFB for a 265 V8 that hasn't been worn out, rebuilt, and worn out again, it would be interesting to see some dyno run figures on a 235. Of course, a proper 4 BBL intake would also need to be sourced from somewhere.
Jerry

An acquaintence of mine has what I believe is the most powerful 261 in the country. He has done some pretty crazy things with his motor, things I would never attempt myself. Runs the Cliffor 4 bbl and a 650 double pumper (at least the last time I saw the car). Runs low 13s and he may have cracked the 12s. In my view, if you are trying to drag out every single bit of power out of a 235 or 261, a four bbl carb is what is going to do it. Not 5 strombergs, or three rodchesters, not even two holley 2 bbls or two holley four bbls.

Those pontiac carbs were pretty trick and someone speant some time at GM figuring out the calibration to make them work right.

For a street set up, if you are inclined to multiple carbs, for whatever reason, I think a progressive carb is where its at. A holley 2305 would be my choice but they are unavavialbe and unobtanium anywhere. They were rare when they were still sold by Holley. Tom Lowe over at inliners and the owner of 12bolt.com is pretty clever and a very good machinest. He actually sorted out a way to take a stock 2300 and make it into a progressive 2300. Unfortunately I understand from Tom it was a lot of work and not inexpensive to reproduce. Otherwise, I still like the dual 5200 Ford Pinto carbs. Not quite as big as the Weber 38 mm DGEV units, and the Pinto units are progressive. My car ran terrific on those carbs.

Now all of the above being said, a couple of years ago I was salavating over an unrestored 55 station wagon. 235, powerglide so hydraulic lifters. It belinged to the man's grandmother. That motor ran so whisper quiet that I was taken back a bit. I had forgotten just how quiet they were. Stock single carb. I am going to restore one of my core motors and it will have a single carb on it. Jon and I have had a couple of conversations and I am fan of the Carter products. Never knew until he posted his list of replacement carbs that Carter sold an direct replacement for a 57 235 motor. That is what I will use for a stock rebuild. If I was going to install a pair of 1 bbls on a motor, I would go with the W1. Jon actually explained to me why the YF is a good but not the best choice in that regard (W1 has a mechanical power system as opposed to the YFs partial vacuum power system). Duals on a 2x1 conversion would be the 5200 Holley weber. Duals on a really warmed up motor, a pair of 2300 holley 350 cfm carbs. Are there others, you bet, 390, 450 holley, others. Its all about tinkering and playing and having a little fun investigating. In the end, does it really matter whether your 235 makes 120, 140 or 160 horse power if you are enjoying the experience modifying the motor. I dont think so. Does it matter that you like a single 1 bbl because its reliable and works without much fuss or muss on a nice stock motor, certainly not. Life is way too short to be worrying abuot that kind of stuff.

That 261 is naturally aspirated and running low 13s? Must be a pretty light car?

Its not light, and when you see it run, you ask your self how can that be. But it has crazy stuff done to it and truth is, I dont know all of it or even enough to scratch the surface except crazy crank work, crazy rod work, all sorts of crazy stuff.

Mike - if you still have that 3x1 intake, would really like to see what you could get with it, solid linkage, and 3 Carter W-0 carbs.

I have not personally had an opportunity to see these run, but have suggested them to a couple of customers that report back they work well.

Jon.

As long as we’re throwing stuff at the wall to see what sticks….

There was a QJet calibrated for a 4.3L Mercruiser. I know nothing, less than nothing about Marine carbs. Perhaps their setup is a complete non-starter for a motor vehicle. Educate me.

I was just curious because 4.3L is about dead nuts for a 261.

In addition to the displacement difference (230 / 292 = +27%) and RPM range (5,000 vs 7,000), the Sprint is a 12 port engine with very different activity in the intake ports. Don't count on it being a close match out of the box. I suspect the high speed air must be tweaked.

The 390 has 1-7/16" throttle discs and 1-1/16" venturis

Sorry, slipped up on AFB, must remember not to trust memory more than 50 years.

I've said it before, I'll say it again. If you want the most out of a truck which has a 216, 235, or a 261, leave the engine stock except for maybe put a Carter YF on it, and put a better drivetrain behind it.
That would be a T-5 transmission and a rearend geared best for the T-5 you end up with.
If GM would have come up with the T-5 in the '40s, there would be fewer auto manufacturers right now.
It is that good behind a stock Stovebolt engine. Just ask anyone who has done that swap.
Every time you shift gears and dump the clutch, you are in the optimal power range of these engines. You have more gears and they are closer together. No more lugging, then gradual increase in RPM until you make it scream so as to prevent it from lugging from the next gear change.
I am not trying to take the fun away from engine tinkerers, but those gains are hard to find.

Panic you summed it all up in one sentence:
"Adding CFM to a truck will only help at engine speeds you don't want to use."
If one has a stock 235 engine in a stock AD truck, that is driven at speeds and manner that it was originally designed, the Carter YF (235 replacement model) is best.

Now, to satisfy the curious (like me) and the thrill seekers (who wish to go faster than stock):
Again assuming a bone stock 235 engine.
The 390 has a slightly smaller primary venturi than the smallest Carter AFB (9400S).
The bores are the same size. Other than the venturi, what advantage does the 390 have?
Are the secondaries even used?

Jon, I do still have that intake. The last time I ran it, which was quite a few years ago now, I had three glass bowl holleys on it. They are still on the intake. I forget now, but I am pretty sure that intake has the wider later bolt pattern for the carbs. I will have to look but I a, pretty sure I had to make adapters to get the glass bowls to fit. Might be the same size as W-1. Have to keep my eye out for some W-1 carbs. Then I guess I will have to build another motor, lol.

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.

I just returned from a 4,000 mile road trip between Tucson AZ and Seattle WA round trip. The truck is my '51 3800 equipped as in my signature and loaded with a C11 Avion camper. Gross wt. is ~8800 lbs.

The 2 carbs are what I believe to be Zenith 228s with adjustable main jets but one had Bendix cast on the float bowl. I bought the pair of them decades ago for $25. They are for the 216 size manifold so I had to slot the base to fit the 235 bolt spread. Anyhow I had LOTS of time to watch the vacuum gauge and tach. It has the 848 head w/bronze guides. The engine pulls quite well above 2500 RPM and keeps pulling until it runs out of carburetion somewhere north of 3400 where I never turn it when I'm far away from home.

Just to get a fix on CFM requirements: At full throttle, where it spends a great deal of time, it will pull less than 1 inch of vacuum at 2900 RPM which is 62MPH. So It appears to me that those two little bitty Zeniths will feed my 235 all the air it needs at any useful RPM. And it behaves well even under 1,000 RPM. But it you try to lug it pulling off a stop like you would a big diesel it will bog. Keep it about 800RPM and its fine.

The cam is a Crower RV grind that Bruce Crower suggested about 15 years ago. I think it's a little hot for heavy truck use. High lift @0.440 but still pretty long duration at 220 deg at 0.050 lift. Split duration but I advanced it 4 degrees. I'd like to have it pull best at about 2600 rather than 3000. If I run it continuously above 2800 the oil starts to heat up.

Grandpas 48 Made my own 4 barrel intake in about 1967,used a 2121s carter AFB ran fine. My biggest gripe with edlebrock carbs is low economy,in your case is plenty big. A friend had a rochester 4 jet on a 261 homemade manifold ran fine .

Thank you sir.
@fixite7

I would delight in seeing a picture of the Carter 2121s AFB.

Jon.

4121S = 2121S when used as a 2-barrel?
I don't know. Haven't seen one.

Update.
I started the engine up and it sounds really good. I need to do a valve adjustment and still need to check the oil pressure. But it sounded pretty good.

Long time but the outcome is great. Engine runs great. Scrams at around 65/70 mph in 4th gear. Will be swapping rear gesrs to a more highway speed and street car friendly. See video of neighborhood drive.

ratiDrive clip

Nice video and bet you were grinning from ear to ear - hahaha!!!

How about some pics of the engine details?