My computer controlled Q-jet has a couple "dead" spots. Not to mention gummed up beyond hope. I wanna do the 600cfm Holley and HEI conversion. So besides intake carb and distributor, what do I need? Any power gains from this? Any snags that you ran into? Is the standard HEI any better than my separate HEI? Thanks AND DONT TELL ME TO GET A 350 CAUSE I HAVE ONE in the other car

 

You will see absolutely NO gain from going with a Holley. Sorry.

The amazing thing is that the QJet is the finest carb you can use on that 350. Go over to www.thirdgen.org and look up the QJet mod articles on the Tech Article board. Also post your questions on their Carb forum. Ask for Damon, five7kid or F-Bird'88--they know how to make a Qjet sing! Tons of GREAT tips that will make you glad you stayed QJet.

 

Yeah, the Qjunk may be the finest carb to use on a 350, just as long as the 350 is in a truck. Get a square bore Holley or an AFB, and you'll never want to mess with a Rochester again. Spread bore carbs belong in motorhomes, not Camaros.

 

That is a lame argument. Care to lend some science to your claims?

 

Well, to begin with, he has a 305 not a 350, and the smallest Qjet is 750 cfm. Forget that he'll never need more than 600 cfm, even if he spins his motor to 6800 rpm, the pressure drop across those huge secondaries with that motor isn't helping performance, but hurting it. The venturi velocity will drop too much, and that's assuming the air valve would ever open more than half way. Qjets are harder to tune, I know because I've been playing with carbs for over twenty years. Qjet rods aren't exactly hanging on the racks at the local speed shops, and their are several different non-interchangable types. To make the economy designed Qjet a performance carb, you'll need to modify the fuel circuits by drilling them out. The Holley is basically a bolt on and go deal, already designed for performance. Lets not forget the "dry bowl" syndrome. You know, when the car sits for the weekend, and will only start after cranking for a while to refill the float bowl. Don't get me wrong, Qjets can and do work in performance applications, but the extra effort needed to just match the out o the box Holley, not to mention the added expense isn't worth it, especially for a novice. I'd recommend the Holley every time for easy tuning, good economy, (yes they can and do get good mileage), and outstanding performance.

 

The QJet is a vacuum secondary operated carb and thus provides the engine with no more fuel than it can use. Size in cfm is irrelevant.

He has a computer operated QJet and they are simple to tune. As are the ordinary ones. Rods and hangers are available at almost any speed shop that handles Edelbrock equipment, and are readily available on the web. We at www.thirdgen.org have numerous articles posted showing how to achieve both ecomony and performance.

Drilling out circuits is not necessary unless one is seeking a race only carb. No Holley in creation can match a QJet for economy, period. And I think you know that.

Dry bowl syndrome, as you describe it, is easily remedied by capping six easily located plugs with epoxy.

And the cost of a rebuilt QJet, set up for good street performance, is not nearly as high as a Holley. Unless one wants to pay Jet Performance an outrageous price for their modifications, which is entirely unnecessary.

 

When is the last time you seen a open plentum duel plain intake manifold for a spred bore for around a $100?
How about spredbore nitrous wet plates?
Go square bore.

 

What on earth is that supposed to mean?

I believe we are talking about a carb for daily driver.

Duh!

 

Yes, I am referring to a daily driver (wifey's car ) Anyhow, thirdgenners said that I would also have to deal with the lock up TC! When I think about it, all that stuff may not be worth my effort if no gain is acheived. So I emailed The Carb Shop. To get a rebuild on mine, it would be $250-$300!!!!! I asked for a slightly tuned and tricked rebuild. Dang, that is crazy, plus I don't think my stock set-up would benfit from that much. Is the HEI I have now, performace wise any worse than the standard HEI?

Thanks

BamaZ28

 

With the computer controlling your timing, its able to compensate for bad fuel, etc. The coil can be upgraded with an MSD, put a premium cap, rotor, plug wire and plugs in it and, in my opinion, they're hard to beat. As far as the Qjet, they aren't really hard to rebuild if you have any mechanical qualities at all. A performance rebuild would benefit the secondary side anyway, as the primaries are computer controlled. You can always get a different metering rod / hanger combp at your chevy dealership or even through Summitt. I believe thirdgenresource.com or montecarloss.com has a tech site that may help you. I've had both the Holley and Qjet and, I know we're far and few between, but I like it!!!!

 

Actually, the Qjet has an air valve metered by atmosphereic pressure, not manifold vacuum. That's why the Qjet suffers from bog, it has to recover velocity to increase fuel flow through the secondaries. Why have those huge secondaries drop the mixture velocity for no reason? The Holley has secondaries that are controlled by manifold vacuum, and while similar, it is much more efficient, and a lot easier to tune.

HAHAHAHA again. I guess you never tried a Holley 4360 have you? It bolts right on to a Qjet intake, has way better throttle response, and gets much better mileage than any Qjet ever made. I don't recommend it for anything other than a daily driver though, just like the Qjet. Let's not forget that Holley also makes the 4165/4175 spread bore carbs that give identical mileage results, with the benefit of more dyno proven power figures, not just some opinion.

At the expense of a rebuild kit and tearing the carb apart to fix something that shouldn't have been a problem to begin with.

Well, for a rebuilt Qjet from the local parts store, I was quoted a price of $380, and that's rebuilt, and for a stock application. Summit sells the Edelbrock Qjets, and the last time I looked, they were a lot more $$$. A Holley 1850, brand new runs around $200. A kit to rebuild one is 15 bucks, how much for a Qjet kit?

I will say one thing about Qjets, they are dirt cheap at the swap-meets, but that's because no one wants them.

If you put the time and effort into as many carbs as I have, including the Qjets, Thermoquads, AFBs, Holleys, 2Gcs Autolites and multiple carb setups, I think you'd be singing a different tune. We can always agree to disagree though.

 

No, most of us realise that the so-called bog of the QJet is because the secondary rods are not rich enough to deliver the fuel being demanded. This is easily remedied by installing different rods, usually a set of DRs working the fix.

As you mentioned, there is an abundance of QJets to be had for a song at swap meets and junkyards. A rebuild kit is not expensive and lots of people, like me, have the carb working wonderfully.

We could argue all day over this but you have your opinion and I have mine. C'est la vie.

 

Upon researching the Holley 4360 referred to, I couldn't find any info on it? Please help

holley.com
summut and jgs

have not the actual carb

suggestions

 

I found that ALL 4360's are only 450cfm? Isn't that a bit small? Still didn't find any prices.....

 

i agree that a properly tuned and rebuilt q jet is as good as any other carb out there. most of them that i have seen have been a mechanical secondary type, and even a couple of the comp. controlled ones i have seen are. as for the rebuild kit, i bought one for a q jet off of a 1976 gmc pickup for $10 at autozone as opposed to the $25 for the holley or edelbrock kit.