I want to put a Q-jet on my 318, some questions.

[8v-of-fury]

So, I have an 88 5th. Years back the ECU or the carb died and it wouldn't run right. To replace those items was looking at near $800. So I went the cheaper way and scored a TQ, performer 4bbl intake and a regular ignition distributor. Fast forward 7 years and 15k kms. It has always ran pretty good considering.. But I am plagued with the leaking secondary wells, and large primary's of the 850 TQ. I have tried many times to reseal the wells to no avail, so I am thinking it is time to get rid of this carb. What I have is a marine Q-jet off of a 4.3 boat engine (I am a marine tech, so GM parts are plentiful as that is what they mostly use) in running condition, so it would be a bolt on and go operation in that department. It should also be setup perfectly for my stock teener with the stock gears in the rear end.

I know I should have just found a non ECU 2 barrel back in the day, but whats done is done lol.

I guess what I am asking is, what am I looking at in terms of tranny kickdown? Should I get a lokar setup and call it done?

Ps. Other than having to bottle feed it to start it every time it sits more than 8 hours... it runs great and I put several hundred kms on it almost every weekend.

 

[Duke5A]

That's sharp. Can't believe it's a rust belt car.

I use the Lokar kit on my car. Wish the rest of the car would be as dependable as that kit.

 

[Mikes5thAve]

The difference in kick down is the rod on top that goes ton the carb.

Marine carbs are different then automotive. It's not bolt on and go. You'd be better off getting the proper Thermoquad or an edelbrock or Holley.

 

[Duke5A]

If it were me, Edelbrock 1406.

 

[Camtron]

I have a 1406 somewhere in the garage; Rebuilt it and stuck it in a box somewhere.
I currently run a 625cfm Demon carb (basically a TQ) ran great out of the box and a little better after a couple weekends getting it dialed in. I also went with the Lokar throttle and kickdown cable when I did my carb and intake swap. Super easy and user friendly.

 

[M_Body_Coupe]

Take a look at this Edelbrock part => Throttle Lever #1481 For Chrysler 1966 And Later, Gold Iridited Finish

If I'm understanding you correctly you are trying to hook up that GM carb to a Mopar...that adapter should work.

Like others have mentioned, I would go down the Lokar cable setup. So much more flexibility and control.

 

[8v-of-fury]

That's sharp. Can't believe it's a rust belt car.

Thankyou, I took that picture in my grandmother's driveway this past weekend. It spent the first 30 years of its life since brand new in that exact driveway . Scarborough, Ontario.

The difference in kick down is the rod on top that goes ton the carb.

Marine carbs are different then automotive. It's not bolt on and go. You'd be better off getting the proper Thermoquad or an edelbrock or Holley.

What I ended up having to do when I swapped to 4bbl was move the bracket on the intake back a set of intake bolts. And then I lengthened the upper rod to match. It still seemed to work properly, but you never can give enough throttle to make it kick down because then your in to to much throttle on those big primaries.

I've been through many dozens of these "marine" quadrajets in my years. Nothing special inside. Still just a carburetor.

Yes, ideally.. it would have the proper sized 2bbl. Lol. And anyone of those carbs is money spent over a running bolt on, sadly. Money rules the situation here.

 

[AJ/FormS]

Are you absolutely sure the mainwells are leaking?
There is a gasket all around those wells so even if it leaks, the gasket is the back-up seal.The reason I ask is everyone of my carburated cars and small engines "leaks" it's gas away in a a few days. But mine are absolutely NOT leaking; the fuel simply evaporates when exposed to atmosphere. To prove it, just put 50CC of gas in a mayonnaise lid and set it on the air-cleaner lid, of your recently run car.. You can stand there and watch it disappear.
It does Not matter what carb you put on that engine; if it is vented to atmosphere it will boil off the gas.
First the lighter components go at ~95*F
then the next lighter,
and 14 components later, all that is left is the impossible to ignite heavy stuff. Go ahead, set the lid on the floor the next day. If there is anything left, try to light it. It will take an open flame to start it, and if you don't keep the flame on it, it is bound to smoke,sputter, and die, leaving an oily residue behind; try it.
It is common for most of us to be splashing gas down the carb after just a couple of days. In my splash bottle, I put some stabilizer and I mix it 4% with 2-cycle oil to help seal the rings. On my Holleys, I inject 50cc of it straight into the front bowl, thru the vent stacks.

but you never can give enough throttle to make it kick down because then your in to to much throttle on those big primaries.

That is an error.
By moving the cable anchor way too far forward, the 2bbl throttle cable is no longer able to open the throttle all the way. And so the KD lever on the trans, does not travel all the way to the back any more, and so, it is not commanding a downshift.
Furthermore, the ratio on the throttle-lever of the 4bbl is different from the 2bbl; you will have to adjust one end or the other. After that you will have to synchronize the throttle action to the KD lever on the trans so that both of them are able to travel all the way to the rear at the same time.
on those big primaries....
Furthermore; the two barrel cable is not long enough, that is to say, the distance from the ferrule to the attaching point on the carb is too short. If you bend the pedal arm, you can make it fit, but it will not fully open the secondaries if at all.

on those big primaries.

Are you serious? The primary throttle blades on the BIG 850, at 1.5inch, are about the same size as were on the 2bbl you took off. The primaries on the small-TQ, which are probably one of the smallest ever put on a factory V8 Mopar, IIRC, are 1.375. That is just .025 inch smaller, than it's bigger brother.
So ; NEVER say big primaries, without a comparison, when referring to ThermoQuads,lol.

I'm gonna go out on a limb and say that your biggest problem is either the linkage, the 2bbl cable, and or the floormats.
Yes floormats. Over the years, a lotta my carb adjustments involved taking the floormats out so the gas pedal would actually reach the end of it's travel.
Good luck

 

[AJ/FormS]

I've been through many dozens of these "marine" quadrajets in my years. Nothing special inside. Still just a carburetor.

A gorilla is a primate.
A human is a primate.
There is a little tiny monkey in Madagascar, that is still just a primate.

The carb on my lawnmower is still just a carburator.
A marine carb is a pretty rudimentary item.
It bolts on, and it hooks up. sorta. Top
Now you get to take the marine tune out of it, and
convert it to an automotive application. But not a regular automotive application. You are thinking of installing that marine-tuned carb onto a car that never had a QJ on it; not ever. So where do you start? There is no book for this, so you are on your own.

 

[Mikes5thAve]

In the 80s using the proper bracket or at least set up properly the 2bbl cable is long enough to be used with 4bbl. I've used them with both a quadrajet and Thermoquad and both had cable to spare in the adjustment and full movement.

 

[BudW]

Chrysler used the Q-Jet from '85 to '89 (until they went fuel injected). The bad news is ALL Chrysler QJ's are computer controlled.
Also all Chrysler QJ's use the attached electric choke - which GM also uses.
I am not an authority on the QJ's but rebuilt enough of 'em to not like 'em as much as a TQ - but that is not the OP's question.

To use your QJ, I would find a Chrysler QJ and remove the baseplate from it and attach it to a "non-computer controlled" GM QJ and I think you might be set (maybe).
I do know there are three (maybe more) different TQ baseplates and they will not interchange - so that may/might also apply to the GM QJ (. . . or maybe not, IDK) - but if you were thinking about installing a QJ, I would highly consider checking that out.

With that said, I happen to have a Chrysler QJ in my garage that I will never use. It is missing a part going to the accelerator pump (which is the same as any GM QJ's). I got it with a vehicle package purchase and did use it once, to (bench) test start a 440 engine and it worked good for that. If maybe interested in it, send me a PM (it will be cheap).

Now going to another carburetor (any other carburetor) you will get as many different opinions as you get people answering - and all of they might be good. All I will say is if you stay close to what the factory made, you will experience the fewest problems long term.
One problem you will have is finding a small block 4-bbl kickdown linkage (and the A727 version is different from A904/A998/A999 version) - so going to Lokar cable setup might be a very good suggestion.
Another thing to keep in mind is the 4-bbl throttle cable is longer than 2-bbl version is. You "might" be able to use your 2-bbl throttle cable, at its maximum adjustment setting, but if engine tilts over, like as in a power stall, you might experience the throttle being stuck "open" - which might end with up you experiencing "a bad, to a very bad day" (which we DO NOT want to happen to you)!
BudW

 

[8v-of-fury]

Are you absolutely sure the mainwells are leaking?

Yup, pretty darn certain lol, have I seen them drip? no lol. But the fuel is gone and the oil is very gassy. I do not get days out of it sitting, it will be hard to start within 12 hours. It will stumble away on what is there for a few seconds until the fuel pump pumps some back up in there. For reference it only gets 89 octane marine fuel as well (that magical non ethanol voodoo) so its not just shitty ethanol fuel evaporating away quickly either. For further reference I maintain roughly 225 (of a total of 430) boats that are rocking their 2.5/3.0/4.3/5.0/5.7/7.4 with a Q-jet, 2-jet or Holley 2 or 4 barrel on top. I am by no means even remotely a rookie when it comes to running carb'd vehicles haha. My boat (73 I6 GM) can sit for 20 days.. two pumps and its running like it ran earlier that day.

That is an error.
By moving the cable anchor way too far forward, the 2bbl throttle cable is no longer able to open the throttle all the way. And so the KD lever on the trans, does not travel all the way to the back any more, and so, it is not commanding a downshift.
Furthermore, the ratio on the throttle-lever of the 4bbl is different from the 2bbl; you will have to adjust one end or the other. After that you will have to synchronize the throttle action to the KD lever on the trans so that both of them are able to travel all the way to the rear at the same time.
on those big primaries....
Furthermore; the two barrel cable is not long enough, that is to say, the distance from the ferrule to the attaching point on the carb is too short. If you bend the pedal arm, you can make it fit, but it will not fully open the secondaries if at all.

Not sure what you mean, I moved the entire bracket back a set of intake bolts towards the firewall. The KD still sits against the throttle arm at idle, and gets pushed back by the throttle on the carb. It may have lost some geometry because it moved back.. but I dont think it affected too much. Also dunno what you mean on the throttle cable.. If you hold 1st or 2nd out you can get well in to the secondaries (stupid on this car though with stock exhaust and gearing.. ) buuuuuuuWAAAAAAAAHHHHHHH. You must remember this is an 850TQ that came off a 440 truck, it is still setup to run a 440 in a truck. Mashing the gas simply drowns the engine, so yes, you get too much throttle before a down shift is commanded.

Are you serious? The primary throttle blades on the BIG 850, at 1.5inch, are about the same size as were on the 2bbl you took off. The primaries on the small-TQ, which are probably one of the smallest ever put on a factory V8 Mopar, IIRC, are 1.375. That is just .025 inch smaller, than it's bigger brother.
So ; NEVER say big primaries, without a comparison, when referring to ThermoQuads,lol.

I dunno man the throttle blades on the 6280 that came off this thing look like they're about 1" around.

I'm gonna go out on a limb and say that your biggest problem is either the linkage, the 2bbl cable, and or the floormats.
Yes floormats. Over the years, a lotta my carb adjustments involved taking the floormats out so the gas pedal would actually reach the end of it's travel.
Good luck

Never had an issue with full throttle, I don't ever give that much pedal because it is too much carb for the engine. It just drowns it out if you're not up in the rpms, which is also pointless when the stock 318 exhaust runs out of breathe so early.

A gorilla is a primate.
A human is a primate.
There is a little tiny monkey in Madagascar, that is still just a primate.

The carb on my lawnmower is still just a carburator.
A marine carb is a pretty rudimentary item.
It bolts on, and it hooks up. sorta. Top
Now you get to take the marine tune out of it, and
convert it to an automotive application. But not a regular automotive application. You are thinking of installing that marine-tuned carb onto a car that never had a QJ on it; not ever. So where do you start? There is no book for this, so you are on your own.

I'll tell ya right now, you're silly if you think there is anything special about a Q-jet from a boat. How is it rudimentary? cause it has no provisions for automotive stuff like EGR and EVAP? A carb is a carb. They're all pretty rudimentary in the sense.. air is drawn through and it grabs some fuel droplets on the way by. Marine tune, what is that? Some setting to let the carb know it is installed in a boat bilge? lolol

Chrysler used the Q-Jet from '85 to '89 (until they went fuel injected). The bad news is ALL Chrysler QJ's are computer controlled.
Also all Chrysler QJ's use the attached electric choke - which GM also uses.
I am not an authority on the QJ's but rebuilt enough of 'em to not like 'em as much as a TQ - but that is not the OP's question.

To use your QJ, I would find a Chrysler QJ and remove the baseplate from it and attach it to a "non-computer controlled" GM QJ and I think you might be set (maybe).
I do know there are three (maybe more) different TQ baseplates and they will not interchange - so that may/might also apply to the GM QJ (. . . or maybe not, IDK) - but if you were thinking about installing a QJ, I would highly consider checking that out.

With that said, I happen to have a Chrysler QJ in my garage that I will never use. It is missing a part going to the accelerator pump (which is the same as any GM QJ's). I got it with a vehicle package purchase and did use it once, to (bench) test start a 440 engine and it worked good for that. If maybe interested in it, send me a PM (it will be cheap).

Now going to another carburetor (any other carburetor) you will get as many different opinions as you get people answering - and all of they might be good. All I will say is if you stay close to what the factory made, you will experience the fewest problems long term.
One problem you will have is finding a small block 4-bbl kickdown linkage (and the A727 version is different from A904/A998/A999 version) - so going to Lokar cable setup might be a very good suggestion.
Another thing to keep in mind is the 4-bbl throttle cable is longer than 2-bbl version is. You "might" be able to use your 2-bbl throttle cable, at its maximum adjustment setting, but if engine tilts over, like as in a power stall, you might experience the throttle being stuck "open" - which might end with up you experiencing "a bad, to a very bad day" (which we DO NOT want to happen to you)!
BudW

I will send you a pm, thankyou sir. Guess I just gotta pop the TQ off and set it beside the Q-jet and see what the huge differences are.

 

[BudW]

Other than having to bottle feed it to start it every time it sits more than 8 hours... it runs great and I put several hundred kms on it almost every weekend.

There are a few items that can cause this (or a combination of these).

My '86 Fifth Ave runs real hot and heat soak (after driving car hard or long) will peculate (or evaporate) the gasoline right out of the carburetor. If I drive a short distance (say 8 miles (13 km) or less) then no problem restarting the next day – but if I drive a distance (say 12 miles (19 km) or more, then it takes a long time to restart because the - carburetor is empty as well as the fuel line to the fuel pump.
One way to verify this is the day after a long drive is to loosen the air cleaner and disconnect the fuel line to carburetor (note: be sure to use line wrenches for these type of repairs!).
Then find a way to crank the engine. Having a helper is a big help but there are other ways to crank the car from the engine compartment. If not sure how, let me know.
With the carburetor fuel line disconnected, and if it takes about five (5) seconds or more to see any fuel – then you at least know where the problem is.
If you see fuel drip out when you disconnect the fuel line (cold) – then you have other problems (choke or other).

The cause of lack of fuel in fuel line/carburetor is due to heat soak AND/OR due to a rubber fuel hose leak (which is typically from the “hidden hoses under the passenger side firewall area).

The (three) fuel hoses by the fuel tank do not give much problems. The three hidden hoses (mentioned above) and/or the (four) hoses by the fuel filter/fuel pump can be problematic after 15-20 years.
Note: to make it easier to access the fuel filter and it's hoses, I recommend loosening the alternator, then remove the adjustment bolt, then either remove the alternator (more work), or tilt it upwards (less work). If it is moved up and out of the way, be sure to tighten the pivot bolt so it will stay out of the way.

A bad fuel pump can always be a problem – but I believe most Chrysler fuel pumps are blamed for a lot of problems that it didn't have anything to do with (in other words, were good but people blamed then to be bad anyway). A 15-20 year old fuel hose can be a source of a ton of problems – as well as rusty metal fuel lines.

The carburetor should have a thick gasket between it and the intake (about ¼ inch (0.6 cm) thick) and not the thin gasket(s) that comes with most “rebuilt” carburetors. That thick gasket helps heat transfer. The main reason the TQ (Thermoquad) carburetor was used is because the black plastic middle also helped with heat soak. If after a long or hard drive and you put your hand on top of the carburetor – it should not be “too hot to touch”. If it is, you might have to look at ways to prevent that heat soak using heat shields and so forth.

If that doesn't work, you might have to look into replacing your mechanical fuel pump for an low pressure electric fuel pump. Turn on the ignition for a fuel moments and the electric pump will fill the lines & carburetor – give the gas petal a quick pump and it should start right up.

NOTE: all non fuel injected FMJ's, the first thing you do before cranking, is to always give the gas petal a quick (single) pump to give it a quick shot of gas and to reset the choke mechanism. On almost all cars, even if the fuel evaporated out of the fuel bowl, there is almost always one to two shots of gas in the accelerator pump system.

Another system used was by Chrysler in later year M's was to completely close off the air cleaner/filter when car is off. There is a second trap door on air cleaner that kept any evaporated fuel to remain inside the air cleaner when when it cools, the condensed fuel tends to end back up inside the fuel bowl or in the air filter. That system is commonly disabled allowing those fuel vapors to escape.
When that system is working, it does seam to help - but not eliminate the problem.

If it has been a while, I would recommend replacing the fuel hoses. Also, how long ago did you replace the fuel filter? Note: I don't need to know
BudW

 

[Mikes5thAve]

Marine tune, what is that? Some setting to let the carb know it is installed in a boat bilge? lolol

It's a real thing. A carb is a carb but they're all set up differently for the application they're used on. Different jets, differences in the accelerator pump, differences in the the little linkages. Whatever they had to do to make it work for the application it's being used for. Its the same thing as trying to use a carburetor off of some commercial application like a pump or generator. Sure it'll bolt on but it wasn't setup to drive a car.

 

[Duke5A]

Yup, pretty darn certain lol, have I seen them drip? no lol. But the fuel is gone and the oil is very gassy.

And you've driven it hundreds of clicks like this? I would be checking the compression and may even pull the pan to check a few main and rod bearings. You're washing the rings out and thinning the oil.

 

[M_Body_Coupe]

Heat soke and hard re-starts. I had this plague me for a couple of seasons (9800 TQ, aftermarket with electric choke). The fix was to properly setup the bowl vent, i.e. make sure that it is open and allowing the carb to vent off fumes so that they are not being forced out through the main jets and/or idle circuit thus flooding the motor.

As to the crap gas situation...agree, gone are the days of stable fuel, it is a lot more volatile today (by design though), however I will say that I can readily start my coupe for up to two week after it has been parked in the garage (so certainly lower heat impact during the summer by it sitting in the garage). Certainly not a problem over a 24 hrs. period though...

 

[AJ/FormS]

That big 850 TQ runs just fine on my stock-cam, low-compression, mid-70s, 318. Both with a 4-speed and with a 904 and with ANY gearing from 2.76 to 4.30s.
I fixed the leaking mainwells, no problem. Ran it for 5 years in my Barracuda (winters only). Then 5 more in my son's D100, with an A904.
Look, your 318 will only pull so many cfm, irregardless of the size of the carb, so long as it is at least big enough.
The stock-cammed 318 makes peak power at about 4000 or a lil sooner. At 100% efficiency the 318 might pull 369 cfm...... but your stock-cammed 318 will NEVER run at 100%.
Suppose it is able to achieve 70%, and that's a stretch, then
70% x369=258 cfm
It don't matter if you put 1200 cfms worth of carbs on that thing, it will never pull much over 258. It can't, the cam and heads are just too small .
Now the difference in the 750 and the 850 TQs is ALL in the Primaries; the back holes are the same. So as far as the 318 is concerned, it don't much care which primaries it gets to suck thru. So there is no such a thing as drowning her; you just got to tune it a bit. As you would have to do with almost any carb, cuz the 318 only rarely ever came with a 4bbl. Chances of finding a properly calibrated factory 4 bbl are pretty slim. Even if you did find one, chances are it still won't be right, on account of your combo is not the likely to be the same as the combo that the carb came off.


BTW
Commanding the shift is tuneable with governor tuning, line-pressure adjustment, and throttle pressure adjustment.
If you have the knowledge, you can make it shift almost anywhere you want, with almost any amount of foot-feeder. Don't blame it on the 850 ; the carb itself, has very little to do with the downshift. I'd say zero to do with it, but the carb does carry the mounting point for the Throttle pressure adjuster, aka the KD mech.
Your stuff is messed up, and that's all there is to it. You just need to sort it out. IMO, the carb is the least of your problems.