j.prince428

hello. i have an 83 z28. up until now it has the terrible smog controlled carb on it. i am pulling off the intake carb and distributor and replacing with a holley 570 street avenger, edelbrock performer, and msd street fire distributor. any tips or things to be aware of while doing this swap from anyone who has done this in the past and also can i trash the ecm once the swap is done? also what about the charcoal canister on the drivers side. i plan on still running it to the the tank but do i need to run it to the carb?

Sparkytfl

If you have an auto, you'll have to deal with getting your torque converter to lock up another way.

If you're going to pull the char can, do the complete job and either get a vented gas cap and plug the return line, or connect a fuel filter up to the return line and then a hose to the ground in case it ever overflows. Some people say the can helps your gas mileage. I cant tell, but I do notice that it makes the garage smell like gas.

There may be tons of smog crap on the car, but the quadrajet is not a problem. It's just harder to rebuild and tune.

j.prince428

So can I just plug the carb port on the canister and than just leave the tank line hooked up along with the pcv line that runs to it?

Apeiron

Why do you want to downgrade?

j.prince428

How is it a downgrade?

Air_Adam

Because the quadrajet is an excellent carb! Performs very well once tuned properly, gets excellent fuel mileage, very reliable and generally very headache free. Its one of the best carbs out there.

Apeiron

The Performer intake is pretty much the same as stock, the distributor doesn't offer any gain over stock, and the carb is smaller, less responsive, and doesn't tune itself.

j.prince428

As far as I'm concerned, even if I get no power gain at all everything be much simpler. Setting timing will be easier, installing spark plugs will be easier, working on anything on the top end will be easier. Dealing with all those vacuum hoses was a nightmare. Well worth it to me.

Sparkytfl

The quadrajet works just fine without all the emissions junk hooked up. Mines just running the pcv. I dont understand how it relates to spark plugs at all. For timing, just disconnect the computer to distributor cable, set it to 6 before, plug it back in.

Yes a mechanical/vacuum setup with a holley lets you fine tune a bit more thoroughly. Maybe get a better advance curve than the computer gives. But then you have to deal with weights, springs, adjusting vacuum canisters and limits. Dealing with torque converter lockup. Also swapping out jets and power valves and secondary springs until its all perfect. Theres a lot you can do to get that setup how you want it, but you cant say it's going to be easier.

I do still admit that rebuilding the 4160 was much easier than the quadrajet.

J91

It sounds like people may be afraid of Holleys? Maybe I am wrong? But it's not that hard to tune a Holley and a dist., once you get it right, it's right. To me the advantage of being able to fine tune your car to personal preferance vs. being locked in by an obsolete OBD1 setup is a no brainer. JMO...

Air_Adam

Its not that anyone is afraid of Holleys, they are pretty good carbs too. My 454ci has an 870 Holley on top of it right now! But there is a right 'application' for different carbs. With a fairly stock or tame engine, like your 305, you could use a Holley and it would work just fine, but the quadrajet would work BETTER - the tuning is much more 'set and forget', better fuel economy and driveability, and being the giant carb that it is, you will run out of airflow with the Holley LONG before you ever will with the Qjet. The Qjet is rated at 795cfm, but because of the way its designed, its impossible for it to be 'too big' for anything. They were used, with much success on engines as small as 267ci all the way up to 454ci, with no major changes at all, aside from calibration. IMO its the best 4bbl carb ever made.

J91

I'll buy that, I just don't like the q-jets that came on the early third gens. Edelbrock makes a good carb based on the q-jet, that would be perfect for his 305...

Air_Adam

If you're talking about the Edelbrock AVS carbs, then those are NOT qjet based. They are based on the old Carter AFB, which came out in the 1950s and is a FAR inferior carb to the Qjet in every way. Qjets are the best street carbs out there, Holleys second, and Edelbrocks a distant 3rd - but thats just my 2 cents.

IMO, they best thing to do would be to find a Qjet from a 350 in the early-mid 70s and have it rebuilt to its stock specs. It would be slightly richer on the secondary side than the 305-tuned Qjets, which is exacty what they needed. Those were not computer controlled carbs, and are very easy to find so you can be picky about finding a GOOD core to rebuild.

Ariel_X

Im not an expert on carbs at all but all the money u can spend on a Holley that would problably give you a downgrade u could spend on tuning ur qjet to spec and use the money on something else like headers or cam or the likes also IDK how spark plugs relate to your troubles changing the carb won't move your spark plugs to a better location also if its tha air cleaner that's in the way juts change it to an aftermarket one, i read a lot of tech on carbs and most experts agree on the q-jet being the best carb out there and it is bigger than your 570 holley just remove the emission junk and save some $$

Air_Adam

IMO, the Qjet is the best carb out there, especially for a primarily street engine... the reason alot of people abandon them for a Holley is that, because of the complexity of their design, the Qjet can be somewhat intimidating to work with if you're still new to carbs. Once you understand how they work, its really not that bad though. Since this is for a fairly tame street engine, especially if it will be your driver, I would stick with a Qjet. If you want to ditch the computer controls, which I wouldn't if they still function properly, then use an all-mechanical Qjet - but you'll have to revert back to a vacuum advance distributor at the same time (which you would if you changed to a Holley anyway).

j.prince428

I realize that a carb swap does not change the position of the spark plugs. If I thought that than I would have no business being anywhere near an engine bay. What I was referring to was the emissions tubes that inject air into the exhaust manifold, and all the other useless junk on top of that block. Now with that mess out of the way doing simple things like changing spark plugs, or pulling valve covers is no longer a dreadful situation. And yes I realize that the qjet is the better carb, but the holley is much simpler and that is what I am most concerned with right now. The car is a daily driver, and I do not have another car to drive while I mess with this one. I do appreciate all the feedback and help with my questions.

Sparkytfl

The quadrajet works just fine without the AIR, cat, EGR, charcoal canister, EFE.

five7kid

iTrader: (14)

I've said this so many times people think I'm a Holley hater.

I'm not a Holley hater. They are a fine race carb. However, the 570 is just wrong thinking all the way around. This would be a downgrade no matter how you slice it.

The "smog control" carb happens to be a great street performance carb. Setting the timing is very simple. The computer control distributor may benefit from an aftermarket 7-pin module and coil, but beyond that, the distributor is superior to mechanical units. The performance issues of the combo have absolutely nothing to do with the carb. The Performer intake is slightly better than the stock unit, but not if you don't do anything about what is really holding the engine back - the air cleaner, exhaust and cam. If you do get a "worthy" cam and exhaust, then the Performer RPM Spreadbore intake would be the more logical choice.

You can listen to what you're being told by those who have been there, or you can continue with your preconceived notions and waste your money. Doesn't make a lot of difference to me, it's your money.

Apeiron

Sounds like an argument for not messing with the current setup.

DoubleV

That's what I was going to say.

The qjet with or without the CCC system is the best street carb period. The CCC version on a stock to mild engine is even better IMO. Why nobody wants to beleive that is beyond me. It's always about ripping off the 'computer crap', swapping the 'Quadrajunk' for a cool Edelbrock/Holly, and ditching the 'smogger' intake for an a 'high performance' new Edelbrock Performer. Oh well, it just makes it more funny when your properly built/tuned car dusts their's with all their poorly thought out shinny go fast parts!

Blown84Bird

SHINY GO FAST PARTS!!!! keep the qjet. On a stock motor best thing for it. And as far as removing the wiring for the computer everything on the passenger side can go. I've done it Just look Where they go before cutting good luck