Help me find a Carburetor

[8v-of-fury]

I have an 88 5th with the 318. Originally it had the lean burn 2 barrel and 2 barrel 150lb iron intake.

That carb died years ago, and instead of find a 2 barrel solution at the time.. I put an aluminum edelbrock on with an 850 Thermoquad. It got the car running for very little spent, and it has been running that way for about 6 years now..

However, the TQ leaks down after 8hrs through the secondary wells. I have tried to fix them several times, but have never gotten them to seal. I want to find a 2 barrel to work on this, either adapted to the aluminum intake or put the iron intake back on. The larger primaries of the TQ definitely over fuel the engine at lower RPM's and i'd like to get away from that. I will keep the big daddy around for a wilder build someday.. maybe. lol

I see that I could use the same BBD as it had, but pre lean burn. Will a Holley 2100 work? They have an electric choke, so that could be nice..

 

[8v-of-fury]

I would also add that I need one that has the AC idle bump solenoid. I have working AC, and right now when at a stop I must give a little throttle to keep the idle up enough so that it isn't knocking away at like 400rpm.

 

[Duke5A]

Grab a Holley 500cfm vacuum secondary, single pumper carb, or even an Edelbrock 1406. Something that has plenty of aftermarket support and is still in production. Both of the above have idle solenoid kits available. I'm partial to Holley myself for the easy jet changes and the idle solenoid kit is significantly cheaper than the Edelbrock piece.

 

[Duke5A]

Ohh yeah, Uncle Tony just had a video concerning not being able to get the meetering blocks on a Thermoquad to seal because of warping. Might be something worth looking at, but then again, that car is way over sized for your motor.

 

[8v-of-fury]

While it is too big physically, there is no demand for the secondaries.. so they never come in to play. Unless I hold 1st or 2nd out past like 3000. Which never happens under normal operation. So really, it is just a bigger 2 barrel on there for all intents and purposes.

I don't really need a 4bbl on this old girl. She runs out of steam well before secondary territory, probably because of the exhaust i am thinking.. if I ever change that out and get some gears in the rear end. I'd definitely get a 4bbl on there.

I guess then, the best bet would be one of the 2bbl holleys as they are essentially just half of a single pumper 4bbl anyway.

 

[Duke5A]

If you plan on those upgrades later, stay with the 4bbl and save yourself time and money ahead. If not, that manifold you have is totally mismatched for the combo. Is that really an Edelbrock Performer RPM and not just an Edelbrock Performer. The RPM is rated for 1500-6500 RPM whereas the regular Performer is rated at idle to 5500 RPM. An RPM version of that manifold lops off 1500 RPM from that motors power band and it only goes to 4500.

 

[8v-of-fury]

They're plans, but nothing in the near future. I'd rather boost and EFI.. haha

But for now, I must find a good 2 barrel. I snagged a 2bbl holley from work. But it's a much bigger base than the 2bbl iron manifold I have from the engine originally. So likely wont work.

 

[Mikes5thAve]

For 2bbl I've never had problems with BBDs.
You shouldn't need that kick up solenoid for air conditioning, I've never had aproblem.

 

[8v-of-fury]

Without the solenoid, it brings the RPM down enough to bring the oil pressure light on.. If I up the idle enough to counter that, without the air con running you need to HOLD the brakes hard to keep it from pushing through it. So I dunno, lol maybe it is different because I have a thermo-quad on it?

Anyway, I have a few variations of carbs I snagged up from work;

A small primary quadrajet 4 bbl, which would be perfect if I decide to stay 4 bbl. Although it is divorce choke too, and I am not sure it will work with my current choke arm.

Large primary 2 bbl Holley variant, unsure of what number. Electric choke

Large Primary 2 bbl 2 Jet. Electric choke.

With either of the large 2 barrels, I will need to adapt on to my 4bbl intake. Logically, the quadrajet is the best choice. If I can get the choke and throttle cable to work out.

 

[Logan]

I have an 88 5th with the 318. Originally it had the lean burn 2 barrel and 2 barrel 150lb iron intake.

That carb died years ago, and instead of find a 2 barrel solution at the time.. I put an aluminum edelbrock on with an 850 Thermoquad. It got the car running for very little spent, and it has been running that way for about 6 years now..

However, the TQ leaks down after 8hrs through the secondary wells. I have tried to fix them several times, but have never gotten them to seal. I want to find a 2 barrel to work on this, either adapted to the aluminum intake or put the iron intake back on. The larger primaries of the TQ definitely over fuel the engine at lower RPM's and i'd like to get away from that. I will keep the big daddy around for a wilder build someday.. maybe. lol

I see that I could use the same BBD as it had, but pre lean burn. Will a Holley 2100 work? They have an electric choke, so that could be nice..

I’ve put a Holly 2300 on my 84 5th Ave. and my 87. It worked well on both cars and was always easy to tune. I always removed my AC units so I’m not sure about the solenoid but I would imagine Holly offers a kit.

 

[Mikes5thAve]

If it's idling high enough to keep running it should be making enough oil pressure to keep the light off. You should find with a properly working carburetor it won't have that problem. if it does it's probably from the engine getting old and tired. There will be a drop in RPM with AC on but it shouldn't be causing those problems.
Actually seeing that you're running the big thermoquad that might be what's causing the big difference in idle problem with ac on/off.

 

[Mikes5thAve]

The quadrajet is probably the best bet as long as it's the right size for a 318. Adapting a 2bbl to work on a 4bbl intake works but works a lot better if it has the proper size 4bbl on there to begin with.

 

[8v-of-fury]

Yup, the Rochester is a small primary 4 barrel. However after comparing and getting them side to side.. It looks like finding a 800 cfm (smaller primary) Thermoquad would be my absolute best option and hopefully I get one with secondary wells that will seal up.

The carb I have now is perfect aside from the primaries being a tad rich, it bogs out when its not at absolute op temp, and the bowls draining over night..

It runs so well, and it always sits like 8 months in between uses.. How could you ever ask for more?