i have a 78 cutlass supreme with a 260 and factory five speed. the carburetor is a dual jet 210. the carb has been rebuilt twice by two different people and no luck it still is crap. if anyone has any info on this carb or has on they dont need anymore it would be much appreciated.

 

http://www.ebay.com/itm/Acdelco-12-9...896818&vxp=mtr

Apparently a factory rebuild, and one heck of a good price!

 

What is your symptoms?
I've had the same set up in my dads 77 since new.

 

wmachine thanks for looking into it but my 78 260 will only take a dual jet 210. that dual jet is a little different then the one on mine. no one make a after market intake manifold or adapter plate so im stuck with the dual jet 210. other wise id do a holly or el.

 

What are the carbs symptoms.

 

hey dmullin whats going on with it is hard to explain top end is gone. wont idle unless the butterfly is almost closed ( tried many things to fix that) when the rpms go down from a throttle it will die (some say back pressure some say timing some say just fuel problems.)

the car is my daily driver and it gets me from a to b. at one point i was getting 20 mpg now im geting 12. some people get there 260's up to 24 mpg. and gas mileage is the only reason i keep the 260 plus the rare/cool factor of the 260 and factory five speed combo.

 

hey drolds. i think the carb is just warped i can hear air leaking from it and as of recent fuel.the car wont stay running with the buttterfly wide open i have to keep it almost closed. its been rebuilt twice not by me. because i dont have the best understanding of how just yet. but im learning. ive owned this car since my twentieth birthday and im 21 now. this car has been a learning processes. who ever has owned the car in the last 35 year has taken good care of the body and the interior. but the motor was not.

 

WTH would anyone modify a 7028251 into a Dualjet unless the carb had mangled secondaries or something

 

fuel economy, that was the whole point of the 260 and everything on it

 

A restored 7028251 is worth at least $350. That carb in the ebay listing is $140. It takes less effort to rebuild the original than modify it into a dualjet

 

the carb on ebay want the right one for my motor. but i do agree the one you speak of in much better and makes more sense but the issue is the 260 has an intake manifold that only fits a dualjet 210. and there are no after market intakes for this motor. i would much rather put a normal 4 barrel or 2 barrel on it.

 

The discontinued Edelbrock SP2P intake will fit, small triangular ports. I sold mine to a member for his 260. Others have used the 85 and later A5 intake with some grinding to match the ports.

 

http://bit.ly/1cdQUJj
How about this one

http://bit.ly/1cdRjLF
Or this one

 

If he has the same dual jet as the 77 'f' 260 then that wont be it.
The type he has may look like a q jet with the secondaries blocked by casting. It is an oddball, they also set the float specs too low and made them more anemic than necessary. No idle and poor mileage could be a basic carb problem, like a missing casting plug or vacuum leak etc.

 

http://bit.ly/P5WjYN
Like this one?

 

just like that one.
Oddball thing isn't it?

 

Looks like a waste of two good barrels to me

 

You say it wont run unless you close the butterfly almost completely? Do you mean the choke plate? If so it sounds like you have a huge vacuum leak somewhere. Check for that maybe a easy fix.

 

After rereading the symptoms I would wonder about cat backpressure...carbs get blamed too often
Drill a small hole in front of cat, then read from a fuel pressure gauge.
Should be under 1.5 psi under throttle application.

 

Yes thats typical of that dual jet turd. You can find them new nos. I may even have one. Whats the carb #. Does it have the heat plate gasket under it like the vari-jet turds? Your likely better off trying to find an alternative like a Ebrock. Ebrocks are very user friendly. Cool set up with the stick shift.

 

Did someone tighten down the carb unevenly, crack the throttle body or damage it otherwise? Causing large vacuum leak, as Greg Rogers stated.

 

PLEASE READ! hey guys thanks for all the reply's on the subject and all of the diagnosis's seem to fit what wrong with my cutlass. I attached a few pics of the motor and carb to this post so if anyone has any info from the pics about what is wrong (which i think is alot of thing.) that would be awesome.

so here is what i have gathered. the car is straight piped like the last owner just cut the pipe right where it reaches the end of the driver door. so no muffler or cats(dont know if it came with a cat converter.) which makes me believe that part of it is a BACK PRESSURE issue.

now if you look at the pictures there are barley any vacuum lines and alot of ports are caped off. the hot air choke is not connected, just bolted from the hose. all fuel emissions parts are missing. so now the question is how do i hook everything back up and what do i need? does anyone have a proper running 260 who can give me detailed pics and a description of how to run all the vacuum lines? possibly a video?

aiight guys now ill reply to each individual post thank you all and this is a kick *** community!

 

interesting i have heard of people taking olds 350 intakes manifolds and welding and dremling them so the ports match up because they will bolt on just the ports dont match there too big for the bore. but i didnt know there were others that bolt on too!

 

those are basically the one i have. its basically the front half of a quadrajet Rochester. just a dual jet Rochester.

 

very weird!

 

greg i think that is a BIG part of the problem! a few posts up from this i have pics of the carb on the block how it is and running take a look at the vacuum lines(there almost all gone) and i had to wire the flap on the top of the carb (what i call the butterfly) to a certain point so it will idle.

 

the exhaust looks like the stock one but what one of the last owners did was cut it right where it reaches the end of the driver door. so its just "straight piped" no muffler or cat.

 

I have a dualjet off a 231 v6

 

hey dr. olds, ill take a look in a little for the carb number. and i wish i could use an brock or a holly but the intake manifold will only take a dualjet 210 and no one makes an adapter plate or an after market intake for the 260. ive heard of some guys doing some welding and grinding on olds 350 intakes so the port holes match up the the block but other then that the will bolt on but that is beyond my ability.

 

interesting. got a picture? and is it in working order? didnt know they had dual jets on that block. is it a dualjet 210?

 

oh and thanks i think its pretty cool too!

 

yes it used to have a heat riser gasket on it but i left it at orileys and they threw it away ha..... and im really not sure if the throttle body is damaged it seems fine. i just concluded that since its missing so much vacuum lines and alot of what they go to are caped off on the intake and the carb that is a big issue haha..... oh boy....

 

my bad its a 2jet is that the same

 

yeah its a 2 barrel carb. if you look on one of the sides it should sat dualjet 210 link in this pic

 

oh no it's nothing like that it has the circular top like a 4 barrel and isnt so oblong

 

oh damn. well thanks anyways

 

sorry bout that I wish you luck in your quest for a dualjet have you perhaps tried eBay?

 

Before you go to drastic measures like swaps etc, I think you should eliminate the simple stuff first.
If the egr valve (the mushroom looking thing on the intake) is stuck open internally, it can cause hard start, no idle and other driveability problems.
You would need to remove it to inspect it and make sure the valve is closing properly.
Even if the vacuum line to it is disconnected, it can still cause these symptoms.


Making a block off gasket out of steel can be done to eliminate that as a cause as this would stop the exhaust gas from dilluting the intake charge.
Now, it would help all the readers to know why the carb was rebuilt in the first place? Unless of course I missed that part..