BlueCalais79

I was hoping to get some input/opinions on intalling a Rochester Quadrojet 4 barrel carb set up on my 1972 Cutlass 350 which currently has a factory 2 barrel set up. I'm looking to get just a little more kick a quadrojet would offer. Nothing fancy, just a factory correct manifold/carb set up to replace my existing dualjet. Not interested in anything like an Edelbrock Performer or anything like that. Strictly stock.

I'm also looking to reap the benefits of possibly getting a little better gas mileage on the highway with those smaller primaries as long as I don't tap down on it......too much.

This was originally a single exhaust car that is now has full duals, so I thought putting on a quadrojet set-up if I can find one at a decent price would enhance the driving of this car, or would it just be a waste of time and $$$ and just leave it as it is.

If there's anyone out there who thinks this is a good or bad idea, I'm all ears, feel free to speak up. I will say I use this car 2000 to 3000 miles a year and it does have air conditioning (that works). I do not use this car in any way to race, it is the type of car I want to use on a 500 mile trip. Highway cruiser, so to speak, In fact I wish I had 2:56 gears rather than the 2:73 that's in it. But, I do miss that Quad punch I had in prior Cutlasses with that set up, I'll say that and it would be decent to have that power availability on occasion, as in getting onto the highway.

vette442

If you go from the stock 2bbl. setup to the stock 4bbl. setup, you'll pick up 15 net hp. (165 to 180). You already added the duals which were good for ~20. That would put you at ~200 net hp. That's all per 1972 factory specs for those various setups.

And yes, the little extra quadrajet kick is nice to have when you want to open it up once in a while. I've had 68-72 350s and 455s with both setups.

You should be able to get the intake and carb for under $200, probably even from someone on this forum.

Terry

NHolds

I have a stock 72 4bbl intake if you're interested. Don't know where you are cause shipping would be $$$. It's heavy.

Allan R

Gene I have done what you're planning. It's a nice add on. The correct carb you'll need is a 7042250 Q-Jet. I got mine completely rebuilt several years back for around $250.00. As new and delivered to boot from the Carburetor Doctor in Stoney Plain. The mileage did improve even with 2.73:1 but I'm sure it will deteriorate a lot with the 3.42:1 limited slip I changed over to.

68_convert

I have thought about this... Then I pump the gas once. It starts and idles, will cruise all day and gets 17 miles to a gallon. I then fold my money and put it back in my wallet. Come on lottery!!!!

Octania

Maybe a common EGR era factory aluminum A4 intake? They are not pricey. Easy to ship. Watch for excessive pitting in the water passage gasket areas. Block off the EGR as you wish.

I have the perfect carb for you but it needs the inlet threads heli-coiled. Rebuilt and refreshed coloring plating otherwise, very pretty.

Fun71

I agree that an aluminum intake would be a good choice. They are MUCH lighter than the iron ones and can be painted to match the engine so it doesn't look out of place to retain your "stock" appearance under the hood.

BlueCalais79

Plus it would be easier on my back putting it in. Now that's a plus. Thanks for that.

These were all great suggestions, thanks everyone. It's going to come down to this project or having front disc brakes installed, can't afford both projects this year & I'm leaning toward getting the brake work done. I've got an old school source that has everything needed for the conversion, ready to go. This car has power 4 drum brakes and the braking is horrible, downright scary. I won't let anyone else who doesn't know these cars drive it for that reason. That's basically anyone under 40.

MDchanic

Then you need to take the brakes apart, see what's wrong with them, replace anything worn or broken, and adjust them.
They should stop as well as disks, as long as you're not doing something extreme, like towing downhill.

That's a lot cheaper than a disk brake conversion, and then you can have both good brakes and a 4bbl carburetor.

- Eric

Allan R

^^ what Eric said. Our first 72 had power drums on all 4 corners and they were just fine. In fact we used that car to pull a tent trailer and it stopped just fine even from highway speeds with it fully loaded. You also might want to check your master cylinder and booster.

BlueCalais79

Well that sounds like a good alternative, thanks, that would make for a good project come spring IF the snow ever melts around here. The suggestion above on using an aluminum manifold is one I'd like to look into. So the newer ones from up to even the 80's (307?) would fit a 1972 350? Blocking out the EGR is a snap.

It's too bad, years back I bought & sold an Olds W-31 intake, that would have been handy. But, back then I felt it belonged on a W-31 car since they are so rare. If I find one now I'd say heck, I'll just intall it.

drop top olds

Don't forget to pick up a throttle cable, fuel line and a new air cleaner housing and lid. They are specific to a 4 barrel also.

I did this swap and was very pleased with the Quadra-jet.

White_Knuckles

I'm actually surprised to see the Q-Jet being preferred to other options. My experience with them has been shaky where trying to revive them and get near factory performance proved futile. They seem fussy but to be fair, they were worn cores with loose shafts etc. I've never dropped in a fresh one to see how they can be dialed in.

I'm in for the alloy manifold nixing EGR but would recommend an Edelbrock Performer 600. These are very adaptable to linkages/hoses and are a great out of the box carb. Bolt and go rarely requiring re-jetting or tweaks. The name is marketing stuff the design is based on the Carter AFB which is far away from being a racing carb. So, if it's having to maintain a factory spec originality thing I sort of get it. If it's trying to do a painless upgrade at least consider the Edelbrock setup. I'm rolling with a '70 Olds 350 that has an Edel RPM manifold with their 600 carb, duel piped with cross-over, a lumpy cam, #6 heads and an HEI sparker. This thing hauls and was easy to dial in! Spice to taste adding a pair of flowmaster 40's and as the Gladiator movie opens - "Release He**".

If this is a daily driver you may be best suited going factory but if noticeable butt-dyno gain is your goal then go crazy. Keep the options open.

BlueCalais79

Those sound excellent for performance upgrades, but you're also right in that I'm after keeping this a factory spec highway cruiser, I'll go up to 600 miles to a show or a vacation with this car. My goal would be to make this look like it was always there.


Also, there were some good suggestions above regarding (keeping) my 4 corner drums, if I were to need new pads, is there any recommended brand to buy? One thing I go by is, if you can't see it, improve it (case in point my 2 upgraded Electrotech speakers in this car) so I'm all ears if anyone has a superior brand of brake shoe they would recommend. It would be great if I could keep the drums, only time will tell.

Koda

My other old car is a 72 Chevy running stock 350/350 with a quadrajet and 2.73 gears. It has fun passing power when kicked down. Definitely more than adequate, but maybe not "Holy Moses" power. Enough to make you grin like an idiot though. The quadrajet is probably the best all around carb out there. Many people prefer something easier to tune and more performance oriented, but, once you get the carb set up right, it stays put for years.

As for the brakes, properly maintained drums will work well. I would be concerned about if they get wet, or for fade, but, assuming you're in cruising weather and not been on them recently, you will stop well for a few good hits.

White_Knuckles

There may be a secret with these ol' Rochester's? I see new or killer refurbished Q's now available from summit racing. Basically carb lore, myth and legend is a mystery science best to set aside. My influence and experience is based on not being able to leave things alone. I would be a very bad keeper/builder of a factory perfect car.

Brakes, not such a problem. Quality shoes and drums with fresh supporting componants is the deal. Make certain the E-brake cables are not worn and clean up the system with new fluid and cylinders. The drums systems are fine and when setup properly are safe. Branded parts are preferred but any quality shop that warranty's their parts can recommend their source. I would be fine with NAPA's "gold" line.

I have a disc conversion "kit" for A-bodies and honestly can't say it's anything amazing. It's cool that it installs easily but I don't exactly know it's there. That would be not driving in rain or down scary mountain passes. I do remember with other drum cars having to pull over and cool down the devils. That was trailer pulling fun back in days of yore.

Allan R

If you're trying to keep it looking stock (and the manifold is definitely a visible part) you'll want a stock iron intake which weighs in at about 45 lbs

Drums = shoes Gene, not pads. Try Raybestos -they're good quality and long life.

No, it's not a matter of time will tell. A vernier caliper will tell you quite easily. The min diameter is cast right into the drum - so measure your interior and determine if it can be machined or even needs it. Cost to turn a drum is way cheaper than buying new, and if the drum has plenty of meat left, it's more practical too.

BlueCalais79

Yep, shoes, not pads, guess I'm stuck on a disc brake mindframe. I'll move on from that one.

Fun71

My experience is that 4 wheel drums are scary:
Attempting to stop from 90 MPH resulted in slowing to ~50 and then no more brakes. Driving through a flooded intersection in a torrential rainstorm resulted in zero braking capability afterwards.

Not confidence inspiring at all.

Koda

I believe one of the legendary Dave's would stop his 68 Ramrod from a drag race via a big hit on the brakes, then coast and downshift, then another hit 20 seconds later or something.

MDchanic

Drums are fine. I drove with them for many years without a problem.

You happen to have experienced the two things that are the known weak points of drums: Fade after prolonged use (seldom a problem in normal driving, but comes up when racing or towing), and crappiness when submerged.

When you drive through a puddle with drums, you HAVE to tap the brakes once or twice to dry them. This is a non-negotiable essential. They used to teach it in Driver's Ed, and it becomes an instinct. If you don't then you get a surprise.
It's not a problem, so long as you operate the vehicle according to the instructions.

- Eric

BlueCalais79

I'm liking all of this due to the fact I never race this car or God forbid tow with it, and I do remember being taught in D/E about tapping the brake after going through excessive water, man that brought back some memories. I know Allan mentioned Raybestos but wasn't there a recent brand touting high performance shoes that were just as good as discs? 69442 alerted me to this and I'd surely like to get the best possible shoe for the car.

Allan R

Ditto

...and you wouldn't find fade on discs given the same situation??? I think so. Far as wet? If you drive through water deep enough to get the entire rotor and pad wet you'll also have some stopping issues.

Gene, maybe give Brian a call or email and ask him what shoes he was talking about. Far as I know, Raybestos is one of the better shoes on the market. There could, of course, be better ones. Just depends on how much you want to pay for a part that's not seen but does just as good a job??

BlueCalais79

Will do.....he was the one who mentioned it and I think it may come to him eventually. Quite frankly I'm glad I'll be checking this out in July when the last of the snow around here finally melts. I am certain I will find issues & a fresh set of shoes & perhaps cut drums if needed will get this car right. I will confess I have not shecked these items since I bought this car. I took for granted they were rebuilt as this was a "restored show car" when I bought it in 2011.....I've since turned it into a driver so it's overdue for an inspection/look.

Fun71

But no where near as drastic. I have hauled my front disc car down from highway speeds on numerous occasions and didn't lose braking capability like I did with the drums.

Again, the same as I posted above, not nearly to the same degree. I have driven through bumper deep flood waters with front discs and didn't notice any braking loss; did the same with drums and had almost no braking capability.

Allan R

Ken, I'm not saying that discs are horrible. I'm just saying that there's a degree of both fade and water issues that will affect discs also. I agree they're not as bad as drums but I've also seen glazed disc pads and burned rotors that create worse stopping than a properly functioning drum brake. Proper use and proper maintenance are everything.

Just an FYI, here's a quick true story about disc brakes issues we had on light rail trains up here. Primary braking is done by the engines (a regenerative dynamic brake if you will) and final parking stop was done by disc (speeds of less than 5 mph since dynamic braking was ineffective at that point) to give the train a controlled and positive stop. In very cold weather the trains would stop just fine on surface sections, but then they entered the tunnel and temps changed drastically from -30°C to + 18°C. When the train tried to stop in the first station the disc brakes would apply (and they are either on or off. On is constant pressure). The bad part is that upon entering the tunnels the disc rotors built up a layer of frost. When the discs springs were applied the train continued to roll until the frost and moisture were removed. Often this resulted in signal violations and station over runs so it became standard operating procedure to stop the train well prior to a station in those circumstances and then proceed in. Sometimes, depending on application disc braking is not the most effective or guaranteed stop. But anyway - that's just digressing. A tidbit for you from my past.

wyteon

Do you still have the stock oldsmobile 350 ci 72 4bbl intake available? I am interested. If so, let me know your price. Shipping to 85614

joe_padavano

Or, just paint the aluminum one gold.

joe_padavano

I'm going to have to disagree for a few reasons. First, the fade in a drum brake is due to the fact that the shoes are on the inside of the drum. As the drum heats up, it expands in diameter, causing the friction surface to move away from the shoes. This means that you have to keep pressing harder on the pedal to maintain the same braking force, thus the "fade". Disk brake pads clamp on the outside of the rotor. As the rotor heats up and expands, it moves towards the pads, thus no fade.

As for water, same issue. After driving through a puddle, water collects inside the drum and centrifugal force holds it there, causing poor braking the first time you try to use them (I'll never forget the first time this happened to me as a new driver in my 68 VC). On the other hand, any water on disk brakes is shed due to centrifugal force. Yeah, if you stand on the brakes while the rotors are actually under water, you'll have a problem, but if you drive through a puddle, the water will come off very quickly.

Sorry, but the examples you cite (glazed rotors and frost on a light rail vehicle) are not the best examples. Any braking system will suffer from poor maintenance, as you correctly point out. That doesn't make me want to change my disks back to drums. And automotive disk brakes, at least of the vintage of the cars most of us care about, always have the pad slightly in contact with the rotor. This heats the rotor and scrapes off any debris, so even if you were to operate your brakes the same as those on the train, you still wouldn't have any frost issues.

Allan R

True, train brakes are a different application (no pun intended) than cars/trucks and are really only used for the final part of stopping whereas car/truck brakes are pretty much constant. That example was just a tidbit of interesting history, nothing more. Just as FYI, I find 4 wheel discs even more touchy in extreme cold.

Far as braking with wet drums or discs I didn't say discs were terrible. But I have to disagree with you that there's no brake fade on glazed discs. Of course there is and when it happens it is almost equally bad as brake fade on drum brakes. I am not talking about ceramic disc pads that withstand very high heat and cool quickly and safely. Bottom line is proper maintenance, good braking skills and knowing to avoid situations were brakes can be compromised. Getting a vehicle started isn't a big deal, getting it safely stopped again is.

joe_padavano

I will point out that with some friction materials, there is a phenomena where the pads get so hot that they start to outgas. This puts a thin film of gas between the friction material and the rotor, to the detriment of braking force. I don't know that I would call it "fade", but I'm sure it would feel the same to an anxious driver standing on the pedal, so I'll concede your point.

Destructor

I’ve contemplated going to a Rochester myself. Within a few weeks of buying my car, about 15 yrs ago, I purchased an Edle manifold and the AFB carb to replace the stock two barrel. It already had duel exhaust. I like the AFB but I’ve always liked my Rochester’s that were on two Caddies I owned. They are not difficult to rebuild and they always held their adjustments. I never had to adjust them after the initial tune. My biggest reason for wanting to go back to the Rochester is because they would have been original to the car. BTW immediately off the line the two barrel was actually a bit quicker than my AFB, as speed increases the 4 barrel really takes off. You’ll be happy with an Edle carb, they do work well.

Seff

Getting a Qjet can be very good for mileage. I ran a stock 71 350 with HEI, headers and a 2.56 rear and got 21 MPG. It was a '77 Olds carb that I'd rebuilt with a kit.

The 72 carbs are a flimsier casting and thus more likely to be warped and otherwise damaged, but they work just as well when they aren't damaged. The Adjustable Part Throttle function exists on them as well, you just have to drill and modify a lot more to access it. The ATP is what really allows you to fine-tune the part-throttle fuel metering and thus mileage on the highway.

As mentioned above, Qjets can be hard to tune, especially if they're worn, as they develop vacuum leaks that throw off the tune quite a bit.

chrisneu68olds

I always thought that my all drum brakes were a little off, pedal travel is a little more than I prefer, but they always worked when really needed and under normal operations, they work fine. Just don't try to compare them to modern 4-wheel disc ABS.

BlueCalais79

Some great back and forth on both counts. I'm now leaning toward keeping the drums on all 4 corners and obtaining a 4 bbl Quad set up. These will be 2 good projects for this year.

Allan R

When you pull your drums use a vernier caliper to measure the inside wear. If they are really low mileage I'd suggest turning them, installing new shoes and possibly rebuilding the wheel cylinders. While you're at it, replace all the springs and clean up any rusty items before reassembly. Don't forget that the front and rear drums are different sizes.

Did you decide on intake?

BlueCalais79

Allan, a fellow C/O member is selling me a correct year 4 bbl intake at a good price, so the hunt is on for a GOOD rebuilt quad and the parts that go along with this changeover. I believe I have a correct throttle plate somewhere, but it's time to start collecting everything else , looks like this is going to go forward. I was thinking about selling the car but that's on hold for at least another year.


Per the brakes, I'm farming that project out to a shop I used to work for back in the day, he's still around and I used to work there. So, he said he will "hire me and fire me" in one day long enough to assist him with the job so I can meander about his shop. Not a bad gig, I worked there when I was 19.