This carb was pulled from a 87/88 monte SS . Will it work with my LG4? As you can see in the pics it has a extra vaccumm line at the back and does not have that plug on top (see where I am pointing) Can I drop this carb in and leave the plug undone?

On the right is a stock LG4 carb from a t/a left is the monte carb which also has one extra mechanical piece at the back.

 

It's a little different, but if you clean it up and hook things up properly, it'll work. It doesn't have the 2-stage accelerator pump, but that shouldn't be a big problem. I don't know why they used that extra vacuum break on the back, but they did.

 

Hello,
The carb on the left won't work...The electrical plug on the top of the other is for the Mixture Control Solinoid...The carb for the Monte SS will also have another electrical plug for the Throttle Position sensor on the front next to the accelerator pump. That carb does not look like it came off an 87/88 SS! I think someone might have got to it first!
ohh...I own an 87 SS with whats referred to as the Full Function CCC system with electronic q-jet.

 

It is possible. The car I got it out from was magnled in abad accident. It was a rebuilt 305 center bolt heads. Looked stock. I bolted the carb on my car and it runs ok but has a rough startup. Any ideas?

 

Can you give more details about the carb and what your car had stock? I'll try to help!

 

I have a bastard canadian model. Acutally I feel like a big time moron because as it turns out my car being canadian isint CC. That pic above with (not the monte carb) was my original. It has one plug on the top as you can see as well as electric choke. But no tps ,etc. My dist has a small vaccum canister as well. Canadian LG4 cars seem to have this odd non-cc setup. Also the only computer I have under the dash is a little yellow box. No big silver ecm at all. Car is a 86 t/a LG4

BTW this monte ss was also canadian possibly could explain this odd carb?

 

Wow.. I must have one of the last q-jetted models....built in july 1987 in the US. It has what appears to be the last stab at carburation before the fuel injection for these cars. Very interesting q-jet set-up. I once worked on my buddies 87 iroc with the 305 and 5 speed...completely different q-jet and distributor and it was Canadian built.

 

Yea, your "cc carb" is just a extra pumpshot addon. Usually used on trucks, for a large pumpshot in cold weather. You're ok to use the other one.

 

Thanks for the heads up. Since your the q-jet guru here both carbs are not cc correct? I have this carb on the motor it runs a litte crappy on startup. I have the timing set to 6* it idles nice and low but is a tad stumbly. But the car drives nice. Also clearly I can't plug in that top connector because this carb does not have it.

 

Just so everyone is clear, that looks like the MCS plug, but as Sonix explained, it is for the accelerator pump. Most Canadian-delivered LG4s in 3rd gens were not computer controlled, but they had this nifty feature that reduced the pump shot when the engine was warm. And, it isn't necessary for the car to run properly.

I can't tell you about Montes and their carbs, as I haven't dealt that much with them, and certainly none from Canada.
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Correct, neither carb is CC.
As stated, no need to plug it in. 6 degrees doesn't sound like enough, 8-12 is more typical. Advance it some more, that should eliminate the stumble, and may help the cold start-up.

 

Ok I will give it a shot . The hood says 4* so I bumped it up a bit ( was off anyway). 8-12 will cause a decline in fuel mileage? I read various writeups here that say like 4-6 for a LG4 but since amercians use cc carbs I guess there is a difference?

 

OK...good point....not familiar with that type of q-jet..but it does ring a bell.

 

On the one I took off the car ( t/a carb with plug on top) the number on it is 17087124

 

Yea, 4* is with a CC setup. 4*, plus whatever the ECM will add. You have no ECM to add timing, only mechanical advance, so you need more timing at idle.

Since I have no idea what motor is under that carb, i'd be inclined to agree with five7, 8-12* at idle. That will let you close the throttle blades a tad. Overall you'll have more timing, so more more generally, and less fuel consumption, up to a point. Having too little timing is bad all around really.

FWIW my car had a CC setup factory, but my car was (is) all kinds of weird. Just about all other 3rd gens i've seen are non-cc factory.
I wouldn't think they would have the electronic acc pump though, I thought that was a truck only thing. But if your car has a plug for it, I guess so. Just double checking, your distributor has a metal vacuum can on it right?

 

Yep my dist has that little vac can on it. The carb in the pic with the extra canister on it was from a monte carlo. My original carb is in the pic next to it ( 17087124). I now have the monte carb on the car because the original needs a rebuild. Its a stock LG4 that looks nice

 

Well, chances are they have different primary rods/jets, as well as secondary stuff on it. It probably runs a fair bit differently.
I'd probably be inclined to stick with the monte one, without the dual stage acc pump.
That is a very clean engine bay there, LG4 eh? I guess i'll trust ya.
I'd rebuild and tune either carb, and probably recurve the distributor for a better throttle response there. I forget what the extra vacuum break is for (the rear one), but i'd probably leave it curbside.

 

Yeah im going to rebuild the original. For now I will advance the timing to 8* or so whatever the motor likes best. I would also like to ditch that vapor canister for a cleaner look . I assume 8* or a bit more is ok for a internally stock LG4? ( i know five7kid recommended it ) but im not sure if he knew my motor is stock. Monte ss.com says factory timing is 6* but thats the L69.

 

Be sure to set the timing with the vacuum advance disconnected.

I was under the impression all L69's were CC, but I don't know that with regard to Montes.