Need to put a Holley on a qjet intake...

[crazeetxn]

So my son bought a used 305 to put in his '69. It came with a QJet so he put it back on there. It's running a little rough, butterfly doesn't open all the way and could probably use a rebuilding. I happen to have my '86 sittin there waiting to get the heads rebuilt and I have a Holley 600 on it.

Tried to swap them out...yeah, not so much. Who knew that it wouldn't just bolt right on to a stock qjet intake

Do they make adapater kits for such a thing? I've looked around and most I could find was something like I have on mine, but the studs don't have a place to screw into to hold the carb down. I have an Edlebrock intake though.

Any ideas?

[Mikec10]

Im pretty sure they make adpaters, check with http://www.summitracing.com/

Another thing, a 600 cfm carb is borderline too big on a stock 350.. putting it on a 305 is totally over carbing it lol.

Also is this what you were talking about?

http://www.holley.com/17-6.asp

here's a cheaper solution
http://www.carburetion.com/products/...px?part=TD2066

[crazeetxn]

You mean there's such a thing as over carbing

That is something I was looking for, I guess I'm just not sure how it's going to work because when I put the allen head bolts in the manifold, the carb studs just fall out the hole.

There has to be some way...don't there?

[79Betty]

The bottom gasket "holds" the nuts but when i did mine on my 79 same carb n adapter it had a gap at te front of the area where it bolts too about a half inch back 2 inc wide. MAJOR INTAKE LEAJ
Posted via Mobile Device

[68longhorn]

a 600 is over carbing? isn't a Q-jet 795 or something like that?

[Tucson38]

My '85 350 came factory equipped with a 790 cfm Q-jet.

[INSIDIOUS '86]

600cfm is fine. Airflow doesn't matter as long as the motor can get what it needs and it gets signal to the booster.

So why not find a square flange intake on Craigslist? It's a worthwhile upgrade. And everything will fit. Just food for thought.

But yes there are adapters to put a square bore on a spreadbore flange. Mr gasket and edelbrock make them
Posted via Mobile Device

[wraprail]

Originally Posted by 79Betty

The bottom gasket "holds" the nuts but when i did mine on my 79 same carb n adapter it had a gap at te front of the area where it bolts too about a half inch back 2 inc wide. MAJOR INTAKE LEAJ
Posted via Mobile Device

The "cheaper" adapters, where the carb studs have shouldered nuts under the adapter, are a pain and do have problems with vacuum leaks.
I'm using the Edelbrock adapter and it has carb studs threaded into solid aluminum, is wider to prevent vacuum leaks and is made from a solid piece of machined aluminum. The cheaper ones are cast from beer cans in china.
I have had no problems with the Edelbrock. Sorry I don't know the part #
Posted via Mobile Device

[crazeetxn]

He picked one up at AZ. It's the spectre brand. Probably not top of the line but he's running the streets again so he's a happy 18 yr old

I put a vac gauge on there and didn't detect any leaks. It bolted right up and had threads for the studs. Little loc tite and its good to go. I appreciate y'all's inputs.

And just for the record, he said that's the first time the tires have spun a little on excelleration. Lol
Posted via Mobile Device

[INSIDIOUS '86]

Originally Posted by crazeetxn

He picked one up at AZ. It's the spectre brand. Probably not top of the line but he's running the streets again so he's a happy 18 yr old

I put a vac gauge on there and didn't detect any leaks. It bolted right up and had threads for the studs. Little loc tite and its good to go. I appreciate y'all's inputs.

And just for the record, he said that's the first time the tires have spun a little on excelleration. Lol
Posted via Mobile Device

Lol prob a good idea to keep it slow for now with some stock stuff then huh? 18yr old tire burner already
Posted via Mobile Device

[Mikec10]

Originally Posted by INSIDIOUS '86

600cfm is fine. Airflow doesn't matter as long as the motor can get what it needs and it gets signal to the booster.

So why not find a square flange intake on Craigslist? It's a worthwhile upgrade. And everything will fit. Just food for thought.

But yes there are adapters to put a square bore on a spreadbore flange. Mr gasket and edelbrock make them
Posted via Mobile Device

Correct me if i'm wrong but wont a carb that's rated at lets say 800 cfm dump more fuel to compensate for more air?

[donut]

Originally Posted by Mikec10

Correct me if i'm wrong but wont a carb that's rated at lets say 800 cfm dump more fuel to compensate for more air?

The way I understand it, yes and no.
The vacuum secondary's on the Q-jet will only open depending on the air requirements of the engine. In my mind, I see the q-jet (and possibly any VS carb) as up to 750cfm (or whatever it's rated for). Basic Q-jet can be found on V-6's up to big blocks without major changes.

Holley's I know very little about, I do know double pumpers are a completely different animal.

Hopefully someone with superior knowledge can chime in and explain it better.

[snm95ls]

I'd fix the Q-Jet personally.

<zips up flamesuit>

I could honestly never get a typical out of the box 0-1850 600 CFM vacuum secondary Holley to run right and not be pig rich all the time on a mild small block.

[rehoward]

Personally, in my limited experience I found Q-jets to be mystery carbs to repair if they don't work right. I think your biggest bang for the buck is an aftermarket manifold designed for a small Holley or possibly better yet a Carter 4bbl rather than screwing with a Q-jet manifold etc. I am sure you will be happier with the results. But yes, I have seen Q-jet adapters sold.

Randy

[INSIDIOUS '86]

Originally Posted by Mikec10

Correct me if i'm wrong but wont a carb that's rated at lets say 800 cfm dump more fuel to compensate for more air?

No, this is a common misconception. Say your engine can only draw 650 Cfm. And you put a Holley 800 with annular boosters so it gets a good signal and works as good as a proper sized carb. All a carb does is meter x amount of fuel for x amount of air. Under power that's about 13:1 13parts air one part fuel. And at cruise about 15:1. So with that in mind more air does mean more fuel but only if your engine can use it. So if its only pulling 650cfm of air through an 800cfm carb and you put on a 650cfm carb it will give you the same amount of fuel granted you tune them similar.

Now the question why you would put a big carb on a small motor? No reason othe than to not limit top end power but an oversize carb will kill low end due to less velocity through the Venturi, this velocity means the cylinders fill more and gives you better low end. Technically you can put a dominator on a stock 305 and not use any more fuel than a 500cfm carb. As long as your booster can get signal to the booster so it can meter the fuel curve.
There's a lot to read on for carbs and I could prob write you guys two pages of stuff on carbs easy but this gives you the basic idea. As long as you properly size the carb to your purpose you won't be disappointed with how it works
Posted via Mobile Device