I have an 85 Camaro Z28 w/350. Currently has the stock rochester carb. A friend of mine is willing to practically give me a Holley 750 double pumper with mechanical secondaries. I have a TH350 trans, and was wondering whether or not the hassle of tuning would be worth any potential benefits of the carb. Please bare in mind I have a strong dislike of vacuum systems, and plan on upgrading my intake (considering Weiand) as well as the heads. Possibly a cam change. The intake at the very least would be done at the same time as the carb change. Thank you for your help/opinions.

 

Anyone?

 

Stock converter? What rear-end? Against a well tuned q-jet on a near stock motor, I think'd the benefits would be minimal, and you may end up with a slight negative impact on gas mileage. If the q-jet is already performing in a less than desirable manner, and the carb is cheap enough, it may be easy to just replace it. Judging from the TH350 trans this is not the original computer controlled setup, and you already have a vacuum advance distributor, is the correct? If not, and this is a CC-Qjet/CC-distributor setup, you'll need new ignition as well.

Looking towards the future, if you're going to continue to build for performance with cam, heads, converter, gears, etc - then the benefits of the mechanical secondary carb would be better realized. If everything is working well, on a stock convertered automatic, I probably wouldn't bother.

 

is your 350 very built? if not get the 750 and trade it off for a 600cfm vac secondaries 4160 series holley.

my neighbor went though this last race season. Hes got a built 355 and was running a 750 and i somehow got him to try a vac secondary 650 and omg he picked up well over .6 at the track!

im just saying a 600cfm should be perfect

 

The stock q-jet is not running anywhere near what I would like and the holley would be cheaper than a rebuild. The ignition is the stock computer controlled setup, but I don't know about the trans, I do know it isn't origional. The 350 isn't built, but it either will be or it will be replaced with a 400hp crate this summer (have not decided which yet). The trans has a shift kit, and will probably have a torque converter w/2300-2800 stall this spring. I would like to take advantage of the deal provided there will be some benefit now as well as later. As far as I know it has the stock rear end.

 

Based on your plans, and a poor functioning carb now, might as well take a good deal. You'll need a new distributor, because the computer controlled ignition will not function right without the computer controlled carb.

 

Please elaborate what you mean by not function right with the current distributor. And what kind of distributor should I look for? Can I find if in a scrap yard or is it something relatively inexpensive new?

 

The computer controls the ignition advance in a computerized system. With the input provided by the computer controlled carb not available to the computer, the computer will not properly control ignition timing. So, if you remove the computer controlled carb, you need to put in a non-computer controlled distributor, one that has vacuum and mechanical advance built into it. Common junk yard item.

But, truth is you'll be giving up more and spending more putting that Holley on than fixing whatever is wrong with your factory carb and system. The factory set-up really is the best street performance carb and ignition system available. If you think you'll gain power by putting on a Holley, you would be mistaken.

Just fix your carb. Save yourself grieve and expense.

 

as much as i liked my quadrajunk i wont miss it. My 85 trans with numerous rebuilt quadrajets was okay but was a dog. I swapped to a 4160 series holley and will never look back lol. my throttle response is 100% better.....yes my MPG went down a tad but its also due to me not having to baby it around with it running like a 283

quadrajets deserve to stay in the 80's and let the better carb's lead the way for race cars

hell my new 92 t/a is tpi thank god...carbs are my thing but carb's havent been put on cars from factroy since 1987! So its time to follow suite and figure this efi crap out

 

Not my goal at all. My stock q-jet isn't running worth a damn. It will be cheaper for me to buy the holley than it will be to rebuild/replace my q-jet. I just want something I can bolt on that I can adjust and then drive my car. I'm sick of all the little computer and vacuum stuff. The fact that whoever swapped the motor in my car was a hack didn't help either. I want to jettison my emmisions, the majority of my vacuum, and most of my electonics. The idea is bare bones to limit complications down the road.

 

you might want to look into a cheap edelbrock carb maybe. They are a carb to throw on adjust and forget about them. I have one on my tow rig and love how i can go out and fire it up and now mess with tuning and such.

gas mpg is okay also

600cfm is a 1405 i think and a 1406 is electric choke IIRC

 

I've looked into edelbrock and a couple others but I was pretty much resigned to rebuilding my carb and electronics (lack of funds) when this deal came along.

 

I had a similar situation with my computer controlled carb LG4, the wiring was a hack job, engine bay full of vacuum lines and emmisions junk, when I started having some intermintent problems with the ignition the I chased into the wiring, I got rid of it all. I went to a vacuum/mechanical advance ignition, and an Edelbrock 1406 vacuum demand carb. It was the best decision I made for the car. I sacrificed very little in real world MPG and driveablility, while I gained lots of simplicity of operation, simplified tuning, cleaner appearence, and gained some very real-world throttle response and power acrossed the board.

I'm told a good working computer controlled setup can give equivelent performance and better economy, in the real world I've encounted very few computer controlled setups at 20+yrs of age still working well as intended, and I have seen numerous examples of them doing all sorts of undesirable types of behavior. If you want a near stock d/d with a strong suit of drivability and economy, I would consider freshening up a computer controlled carb setup. Any performance oriented application where a few mpg at cruise arn't a big deal, I'll gladly trade it for the mechanical stuff. You've already downgraded (from a fuel economy standpoint) to a three speed trans, fuel economy is clearly not your aim, I say go whats gonna work the best for your setup.

 

As the saying goes, "You can lead a horse to water, but you can't make them drink."

Edelbrock or any vacuum secondary type carb will be no better than your q-jet. If your wiring is hacked up, get another harness - there have been enough people who have removed them that getting one in good condition isn't that big of a deal (I have an '82 harness that's in fine condition).

In my opinion, you're going down the wrong path. But it's your car, and your money. Have at it.

 

My knowledge is limited when it comes to cars but I speak from experience when I say that five7kid is pretty much right on. I have an 84 TA that I got in stock condition and it ran like crap at first but I had my neighbor rebuild my quadrajet and it was giving me about 19 mpg city with my aging LG4/700r4 which is fairly good considering how I tend to drive. I have since switched to an edelbrock performer RPM intake manifold and consequently a holley carb and vacuum/mechanical advance distributor and have been having problems for months now. When the stock setup works right, it works well. Also, all those people preaching about how you should rip the emissions equipment off should be ignored. Sure, yanking all of that stuff will free the engine bay of some clutter but you'll pay for it. My friend is one of those "emissions equipment is the devil" types and he pulled out all of that stuff for me. With the emissions stuff gone and still running the quadrajet and CC-distributor I went from roughly 19 mpg city to 14 mpg and noticed no increase in power. Since this was done when gas prices were above $3/gallon, that was a costly decision. One of my other friends went to Wyotech out in PA and his teachers told him the same thing, don't touch the emissions equipment, it's worth keeping (not to mention being illegal to remove).

Take advantage of that deal but don't trash your old stuff, you might find yourself wishing you didn't change over.

 

Stock stuff works great when working right, I don't think anybody would argue that. I wouldn't argue for removing it, or any emissions equipment, on a daily driven car. The car in question in this thread is clearly moving away from that direction and towards that weekend warrior/toy car. Its a 3spd, the owner is talking about motor swaps and higher stall converters. Never once has he mentioned fuel economy. He has mentioned working towards performance and simplicity. Getting away from a computer controlled setup and the plethora of emmissions control devices will certianly help with the simplicity - if thats what the owner wants - which he does.

A proper working mechanical setup can run great, have good manners, and still give reasonable fuel economy when compared with the computer controlled setup. I gave up about 1.5mph highway when I switched from computer/emission to all mechanical. Most of that can be attributed to no longer running a torque converter lockup. I understand exactly where you guys are coming from with regards to retaining the computer controlled carb and ignition, and the emissions devices. From a near stock, daily driving point of view, it has merit. I don't think thats the point of view presented by the original poster.

I'm sure your genius friend that helped you gut your emmisions stuff has overlooked a few key components of the computer controlled system and did more harm than good. If you're now all mechanical and still having problems, maybe you can start a new thread and we can help trouble shoot some of that.

 

At near stock, a 750 is going to be too big. You can tune it to work but you'll actually get better performance out of a smaller carb. As has been stated already, if you dump the computer controlled set up, you need to replace the dist. with a reg. HEI. I understand not wanting to, as I'm in the limited budget boat myself, but your timing will not be right and you'll hate it if you don't. If it were me, I'd go with either a plain ol' Edelbrock 600 or Holley Street Avenger 570 or 670. So to answer your original question, no the hassle of tuning it would not out weigh any benifits.

Dan

 

Well, I appreciate all the opinions and information, but I picked up the holley. $40 for a 750cfm double pumper beats $40 and downtime for a rebuild kit. And definitely beats tracking down a decent reman. Atc3434 hit the nail on the head, I am trying to build this car more for performance. If gas mileage becomes an issue I will worry about it then. Danandamy, I understand that a 750 is a bit much, but I do not want to spend the money on a 600 or 650 for this car. By mid summer (with any amount of luck) this motor will be capable of near ideal volumetric efficency (ideal for my motor and the way I drive being around 800),a 750 will be a good choice. For the time being I can deal with tuning hassles. It beats my car flooding the motor whenever I gas it, or stalling out at random while driving and/or sitting. If desired I can update after I have swapped out and tuned the carb.

 

Sounds like a pretty decent buy. Its defintely a bit much for you setup now, but like you said, thats all gonna change. You can sell the the stock Rochester for a few bucks as well, I think I sold my CC-Qjet for about $40, in good working condition.

 

Perhaps I scanned through this thread too quickly, but I don't see what intake manifold you have. The Holley won't bolt to a stock factory q-jet manifold.

Don't forget you also need a different distributor.

 

I have stock manifod of some kind (GM markings) but the Holley bolted right up, just needed an EGR block off plate because the carb body wouldn't clear it. Have not gotten to tuning yet, it keeps snowing over here and I don't have a garage. Should be able to tell more in a few days.

 

It might be a GM manifold, but it isn't stock.

Either that, or the Holley isn't the typical squarebore. What's the "LIST" number on the carb?

 

uhhhh you ever see a old sbc? like pre smog lol they had sqaurebore holleys on camaros and such.

i have one somewhere.......doesnt look like it will flow great but im think bout buildin a "oldschool 327 one day"

my 327 is getting tpi for now LOL

 

Did I ever see an old SBC, you ask?

How old would be old enough for you?

 

I don't have a clue what the list number is, most of the markings on this carb are worn beyond recognition but it is a spreadbore. Which kinda surprised me as well. All I needed was carb studs. Have not got around to tuning it though, head gasket blew on a parts run with the stock carb before I bolted the new one on.

 

The "LIST" number is stamped on the front of the choke tower.

So, it is a spreadbore. Probably a 4165 series then.