voidusa

hey folks, I need your advice.

I have a very well preserved 69 coupe (L46 350/350) that was originally in Florida (introduced here). The first owner there decided to do some modification to the carburetor... so now I have a chokeless doublepumper, which has 2 mechanical primaries. I live in washington and I need a choke. Vacuum advance is also disconnected... not that it matters too much, but I don't like modifications that don't improve the car.

This is no hotrod and I don't need to get any special performance out of this car, I plan to use it to cruise around and to maintain it over time. I'd like to keep this to the day I die.
If it wasn't for the fact that everyone says the original quadrajet is garbage, I'd go for it. But, given that Quadrajet is garbage I was planning to go for a Holley and I was wondering if it was worth going for a new doublepumper with electrical choke or if it was better to go for a vacuum secondary, which is easier to maintain and I won't notice (I guess) the power decrease (it is also about half the price).

What would you recommend? Any other option that you would recommend?

Newbomb2469

First; Did the previous owner change the intake manifold? My guess is he did from the Holley carburetor you describe which is most likely a square bore whereas a Quadrajet is spread bore. If trying to keep costs down…meaning not changing the intake manifold, would think a new Holley would be the most cost effective option, probably one in the 650 CFM range. I’ll leave it to other’s recommendations for good Holley for your engine.
If you want to bring it back to original, a Quadrajet…tuned by Lars…mated to a spreadbore manifold would be a good combination.

stingr69

Get a good, correct Qjet and have it overhauled by Lars. Be sure to let him bless it before you purchase any carb. Not exactly cheap for the core, but you will only cry once. Next best would be a "close to correct" serviceable Qjet set up by Lars.

Holleys are easy to get, easy to service but a proper Qjet is great, easy to live with, "closed hood" type carb.

lars

Someone has blown a lot of smoke up you... It'll run circles around that badly tuned Holley.... The '69 350/350 Q-Jet is one of the best carbs ever installed on a musclecar.

All carbs have mechanical primaries. Sounds like you need to educate yourself a little bit about carbs. You also need to determine if the person who installed the Holley also installed a square-bore intake, or if you have a Q-Jet spreadbore intake with an adapter. You need to install the correct intake for the carb you choose to run - square bore and spreadbore carbs and manifolds are not interchangeable. This will affect costs, so this may drive and limit your decisions.

Well, it's not going to be very "well preserved" if you hack it up with a Holley install... But to each his own - if you're wanting to build a custom car out of your 350/350, customize away...

Eric P

The correct restored Quadrajet by Lars would be unbeatable if you still have the stock manifold

Holley style I prefer vacuum secondaries on street and this would be a real good one
Cast Aluminum Carburetor - Quick Fuel HR-680-VS Hot Rod Series Carvuretor 680 CFM - JEGS - JEGS

Street double pumper I have a couple customers with these that seem to work well
Quick Fuel BR-67254: Brawler Diecast Carburetor 600 CFM - JEGS

Edelbrock AVS2 650 is not a terrible choice either as far as aftermarket
Edelbrock 1906 AVS2 650 CFM Carburetor | Order the Edelbrock AVS2 1906 Carburetor with Annular Flow Primary Boosters - JEGS

voidusa

this is interesting. I totally believe you. Looks like I found bad information online. I'm not familiar with American engines , I am still learning a lot. And my learning source is forums/sites.

I definitely need to educate myself (main reason I am here). What I learned by posting pictures of my carb in this forums is that it is a "Frankestein" where a 2nd primary has been used to make a "secondary". I will check the intake to confirm whether I have spreadbore or square bore.

well... some mess with carburation has been made, but everything else is really well maintained.
I am planning to keep this as stock as possible but I don't want a garage queen, I want to drive it so I am willing to consider compromises where it makes sense (i.e. I think electric choke is almost a must if I want to buy a new carb).


thanks all for the replies. This is a journey, I'm learning

4-vettes

Step one. Remove the Carburetor from the intake manifold. 4 nuts and or bolts. A cable, maybe 2. And some vacuum lines. And it's off. Take a pic of the pad it mounts to and post up on here.
Then we can make suggestions. Lars is THE Guy when it comes to the correct Quadrajet carb for your car. But if the intake has been changed. Then there are other ways to solve your problem.

F4Gary

I put a Holley Street Avenger on my 72 LT-1 but it came with a Holley. I hear the Truck Avenger carbs are good too. If you actually have a Quadrajet manifold the stay with a Quadrajet.

Andysherman

Chiming in with my experience on my 69 (all-original on my purchase last September)…
it is absolutely worth it to use a well-prepared Q-Jet, as others have stated, especially if prepared by Lars, or Cliff Ruggles’ shop. I personally rebuilt the carb, using Cliff’s & Lars’ suggestions… it was night and day difference in response & driveability. If it has a square bore manifold then it MAY be best to use a Holley, if so keep the single pumper unless you’re making over 400 HP. KISS principal.

MelWff

Look at the pictures in this other post, number 4. He has a primary metering block installed on the secondary side and the carburetor has a disconnected mechanical choke. Appears to be aftermarket intake.
https://www.corvetteforum.com/forums...post1607675087

voidusa

hello folks, work life has been horrible and I could only get back to my C3 today, after 20 days!
I removed the carburetor to find out the heads intake manifold and... behold, it is not the original one. It's an edelbrock (aluminum I guess) head intake manifold.

pics attached.
this is the intake manifold


this is the adapter that was used:



now, resuming my initial question, given the head I already have, what would be a decent carburetor choice? I'm not against the quadrajet, would it require any adapter to fit?

MelWff

You have a dual pattern intake. It will take a square bore or spread bore carburetor. The spacer is not required or recommended.. Can see no evidence in your picture of an aluminum head only aluminum intake manifold. If you no longer have the original Quadrajet, look at a Holley 750 CFM vacuum secondary with electric choke.

Andysherman

That’s a spreadbore (ie. fits QJet) manifold, intended for Q-Jet… the adapter is to allow a Holley (square bore) to be fitted. Suggest sticking with a properly set up Q-Jet, can send to Lars, Cliff Ruggles, or Quadrajetpower.com for fast parts order/delivery. Lars & Cliff are the super-experts. I’ve done a few for local guys in my area & I follow their teachings to a tee. I have an awesome-running Q-Jet on my 69 & like it MUCH better than all the Holleys that I’ve previously had…

MelWff

No, it is a dual pattern, it has 8 holes for mounting either type.

stingr69

Some of the Edelbrock Performers had bad vacuum leaks and the spacer/gasket will seal it. Been a long time but it was an issue years ago. This might be one of those early manifolds.

Rescue Rogers

Yes it's made for both but yes it needs the adapter, without it the holley would have a gap where the secondaries are bexausebit is too narrow which would cause a vacuum leak. I had one and the directions said it was required

69L88

There is a 7029207 in the Parts forum now. Contact the seller and have them shoot some good pics and send to Lars for his assessment.

randallsteel

The original concern was that it doesn’t start well? And you attributed it to a bad carb that doesn’t have a choke?
I personally would inspect and tune all the aspects of the engine before throwing the parts cannon at it.

for instance, you could put a brand new carb on it, but if your timing advance is set to idk, 2 degrees advance, it’ll still run/idle/start like crap.

Same if you have a massive vac leak. A perfectly built Lars Qjet would still run like crap if you have an intake vac leak.

I have a chokeless full mechanical Holley double pumper and my c3 starts without issue winter or summer, and idles by itself within seconds of starting. I run 25 degrees advance at idle, if I dropped that to idk 5 degrees, it would turn into a turd.

voidusa

I agree with you. I live in a cold climate and not having a choke means starting the car is a challenge.
Also, I've adjusted the carb following the guides, it's much better now, but still way too much fuel. I suspect this is ripe for a rebuild.

I agree but both these things seems to not be a problem on mine. Advance is good and I don't have leaks in intake.

may I ask where you live? I would not expect this to be a problem if you live in Florida or Texas... here in Washington state it's quite a different story.

randallsteel

i have no idea what temps are like in Washington state, but my c3 has primarily been in NC, GA, and now SC. which I agree GA/SC are extremely hot and don’t have winters. Mid to western NC however, does actually have a winter season and I would say it still ran fine.

but the main point of the post was just caution/advice to make sure something else isnt the problem and it’s being masked as a faulty carb.