MDchanic

Does anyone have any "special" information about this abomination?

I know all the usual stuff, and the stuff I haven't checked already I'll get around to if I ever get motivated, so no need to reinvent the wheel here.
Also, this is not a big deal in the long run because I'm going to put together a 425 I've got for this car, and this motor will be thrown on the "pile."

'73 Delta, originally a 350 car, TH375, 2.73:1, probably about 4,300 pounds.

PO replaced carb with fancy professionally rebuilt one for this exact engine, I believe him when he says it cost $400, it looks purty.

All that emissions crap is disconnected (for better or worse).

No vacuum leaks that I could find.

Timing off of manifold vacuum.

HEI seems to be working fine - centrifugal and vacuum (correct canister) work fine. New AC Delco wires. Timing set to 20° at idle, where it seems to run best. I just timed it by ear because I figured the odds of getting truly optimal timing advice from the manual (all emissions-smothered) or from anyone else (who the f*@& would build one of these?) were about zero.

Needs 3 fingers of fuel down the gullet if left for a few days, otherwise, starts instantly all the time.

Thing idles like crap, but give it a bit of gas and it runs smooth as a top.
No power, but at a rated 110 HP, there shouldn't be.

Uses about 10mpg, maybe less, in local, low stress, country road driving.

I'm considering taking the carb. apart to check the jets, float levels, etc., but I just haven't had the desire yet.

I wouldn't mind a smoother idle and a better transition, and if I'm stuck with a gutless wonder, I'd like to see at least a little fuel mileage love in return.

Anyone ever deal with these miserable lumps?

- Eric

MDchanic

Weekend bump - I don't expect that anyone's got any secrets to bestow about these, but there's no harm in askin'... Is there?

- Eric

2blu442

I've got a 2 barrel carb of the same vintage. I don't know anything about it, but it's yours for shipping costs. If I can find where I put the trunk lock clip I'll throw that in the box too

Let me know if you'd like to see pictures of the carb. John

MDchanic

Hmmmm... I'll think about that, John.

You mean a circa-1980 DualJet (the front half of a QuadraJet), and not the older (and better) 2-Jet, right? The 260s have a unique intake manifold that only takes the DualJet.
Frankly, I'd probably get better performance if I made an adapter and used an old MonoJet.

Pictures don't really matter, but I guess I might be more inclined to take this one apart if I had a second one to mess with, in case I found anything WAY out of whack. Odds are the "expert" who rebuilt it just set the float level high or something similar.

E-mail me how much that'd come to, if you would, and let me know if you can remember what kind of motor it came off of (I'm not sure whether there's any real difference between the 260 carbs and the 307 carbs).

Thanks,

- Eric

CQR

If the needle piston is gunked up and stuck in the up position (like low manifold vacuum) it will give you a rough tip-in and poor mileage. you can actually see that without pulling the air-horn off. You can insert a small pocket screwdriver into the bowl vent tube that sticks straight up right in front of the venturis and push down in the tab that holds the needles. it should feel spring loaded. if so, then you can place the screwdriver on top of it and start it. if it drop when running it is operating.

Hope this helps.

2blu442

I don't remember now... but the carb may have come off this engine:

https://classicoldsmobile.com/forums...on-engine.html

MDchanic

Yeek.

Worth a try.

Just let me know ...

- Eric

ChefDeadpool

Neat! A 260. I've always said that if I got a daily driver Cutlass that's 73-77 vintage, I'd want one with a 260, just because it's such a wierd, overbuilt (or under engineered, your choice) engine. Plus, good mileage, if it's running right.

MDchanic

IF.

- Eric

2blu442

Hi Eric
I dug out this carb yesterday. I was going to pull the choke and anything else that looked like it would fit the quadrajet and junk the rest. But... if this looks like yours and you think it might help its yours for shipping costs. John

P1010077.jpg

P1010078.jpg

MDchanic

Wellll... They all LOOK the same .

Sure, I'll take it - you can't have too many spare parts lying around!
Besides, if I bolt it on and it works better, then I'm in business, and if not, then I've got spare parts in case I screw up the other one (or find that someone else did) when I go through it.
Also, I think my motor is about an '80, so if it's from a '76, maybe some of the jetting will be more advantageous (maybe).

Just let me know the amount and we'll take care of it. I think you've got my e-mail, otherwise you can PM me.

Thanks!

- Eric

2blu442

PM sent!

John

MDchanic

So, It was October when last we heard from our hero...

When it started to warm up here a week or so ago, I went in and dug out that carb that John was so kind to send me.
A quick shot with GumOut and it looked darn presentable.

Checking the numbers, I found it was factory installed on a '78 Pontiac 301.

I took it apart, checked it out, and found it a little "rough" on the bottom of the float bowl (as expected), so I gave it a good soak in the "good stuff," hosed it off, blew it out, and dried it over the coal stove.
It was no longer "presentable." Now it looked brand new.

I reassembled, and set everything that I could according to the Delco DualJet Manual, available on line (earlier carbs have all their pull-offs and breaks set by distances, which you measure with drill bits - these darn newer carbs are set with a special protractor device equipped with a level, which I don't have).

I unbolted the old carb and discovered a few things that were "suboptimal."
The PCV hose was more like glass than rubber.
The brake booster was connected through a Dr. Seuss-looking run of rubber and twisted steel, with a big black filtery thing in the middle.
The throttle cable was missing its bushing, and had about ½" of play on the stud.
The choke stove tubes were both epoxied to the plate on the manifold, and the threads on the choke unit were stripped off, so that was glued, too.

After I pulled the carb off and rectified the big things, I found that the Pont. carb was not going to do the trick - all of the connections were different. Throttle, PCV, booster, vacuum lines, everything. Looks like the Pont. has the PCV and the booster connected right to the manifold, because there weren't any ports for those at all.

So, I took both carbs apart, swapped out the throttle plates, which had the important ports on them, readjusted, and reinstalled.

Poured some gas down the throat, gave her a crank, and she started right up.
Then stalled out.
Then started.
Then stalled.
I found she'd only run with my foot on the gas - let up, she dies.
It was dark outside, so I called it a day.

Got back to it a couple of days later, in full daylight.
Opened the hood to take a look - PCV hose was off.
Hard to get it to idle with a ⅜" vacuum leak.
Pushed the PCV hose on, cranked her over, and she started right up and ran.
Seemed a little rough though, even when warm, so...

Over the previous few days, I had taken apart the original carb.
The prior owner had told me he had had to buy it for $400 (about half of what he sold me the car for), as he had been able to find no other replacement options. It certainly looked like a new carb - even had a little paper bar code sticker on the back that said "Delco Rebuilt."
First thing I noticed was that the fuel filter had no anti-drainback valve (which is specified for these). That would explain the "no-start if sitting more than two days" phenomenon.
When I opened it up, it was clean as a whistle inside, clearly "new," there wasn't even anything to clean (I blew it out with GumOut and air anyway).
With nothing obvious to fix, I checked the measurements against the Delco manual.
It had a nice brass float, which was set ¼ inch low.
Hmmmm. That might affect something.
The basic choke adjustment was also way off.

Since everything else looked great, I reassembled it and put it aside.

Now, back to the car.
As I said, it ran with the Pont. carb, but not really any better than with the original.
"Well," thought I, "Since the original was so far out of adjustment, why not try it again, adjusted right?"
So, back to the car, removed the carb, disassembled both carbs, reassembled after swapping parts, installed original carb, installed new PCV hose, checked PCV valve, removed Dr. Seuss plumbing and installed new booster hose straight to a new fitting on the intake, plugged old booster connection, etc., etc.
Checked mixture screws on original throttle plate - they were both out EIGHT full turns . Hmmmm.
Turned them in to 2.

Poured about 4oz of gas down the stack and VROOM! she started right up.
Installed vacuum gauge and tach, fiddled with mixture and speed screws (couldn't get it to run crappy by backing screws off, had to settle for about ¼ turn out past too-lean "idle slow-down" point on each.
... And darn if she didn't run great.
Choke works right, no bogging or hesitation, smooth (if anemic) performance through the throttle range - just like a regular car!
After driving about 50 miles, seems to get better mileage, too.

So, she runs great now, and I can thank John for sending me that carburetor, which got me motivated to take the original carb apart and fix what was wrong with it.

And, if anyone has an use for a '78 Pont. 301 DualJet (with a missing choke rod link ),
I'd be happy to pass it on.

Thanks, John!

- Eric

lshlsh2

Cool, glad your all fixed up. Just in time for some crusing.

Larry

Tony72Cutlass'S'

Great Story,

I had the same issue with BRAND NEW edelbrock 1405 manual choke carb last year.

Took it apart, the floats were bottomed out (3/8'' lower than should be)(From the darn factory, not to mention), also the idle mixture screws were WAY off.

The tech dude at Edelbrock ensured me that "this never happens". I told him to tell his factory workers to stick a drill bit under the floats like the manual says.

I'm surprised at how that ponticrack carb ACTUALLY looks like the front end of a Q-Jet..

Bluevista

Gad to hear that the plan came together.
I remember those split down the middle half V-8 engines, that half barrel would look good on one.
That black filtery thing may have been an original brake booster vacuum filter from the future.

MDchanic

Prob'ly was.

I've had a policy about cars since I was a kid: If I can't tell what it is, off it comes!
I don't like no extra crap under my hood .

- Eric

2blu442

Well, if it helped thats all that matters

MDchanic

Hey, it helped! If it wasn't for you sending me that carburetor, I would have just put up with the car running lousy until I got around to changing the engine.

Sometimes it takes a push to get moving and fix things.

Thanks!

- Eric