Thread: Holly & Edelbrock 650's - How to set up?

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So, I now have two Chevy 350's (one with a Holly 650 and the other with an Edelbrock 650) and I need to learn how to adjust these carbs.

I am currently trying to get the Holly powered engine on the road. I can get it running, but there is a lot of popping (backfiring) as it idles and more when the engine is revved.

I am starting from scratch here. The fuel pressure is about 3lbs (I may need to adjust the regulator for more?) and the warm idle is around 1100 rpm.

Since this is in the back of a Fiero, my dual-exhaust is pretty short. I am only running high-flow cats, so perhaps the cats are igniting the extra fuel - causing the pops?

I also don't have the electric choke wired up. I imagine that will help me start it a little quicker, but even when it is warm, the engine wants to die if I punch the gas. Easing into the gas makes the engine rev just fine. After running the engine, by garage smells like gas - big time.

Anyway, I don't know where to begin since I have never played with carbs before. Any good sources for info?

I can help with the Performer but you'll have to look elsewhere for the Holley stuff......
http://www.edelbrock.com/automotive/eps_intro.html

It sounds like the power valve is blown in the Holley. Get a book like this one, it'll tell you everything you need to know.

Well, I am still at a loss. No numbers to be found.

Here is the closest carb I can find to mine (a 390 CFM model)


and here is mine


The only difference I see are the choke power tabs (mine are angled away from each other instead of parallel) and the circled area on mine.

Could these be the same? If so, why would anyone put a 390 CFM on a 330hp 350? I bought it with this carb installed.

Why don't you just put the Edelbrock on the engine that now has the Holley and see if the situation changes? That is the easiest way to see whats up.

Don

The numbers on the holley should be on the choke horn. Look at the pic of the book above. The chok horn is the "near rectangle" inside the main body "circle." Looking at the side of the actual carb, the choke horn is the tallest part of the carb.

It says

"List 6619-1
3324"

I'm using Google now...

Got it - 0-6619-1 = 4160 600cfm

Thanks for the help!!

Now - is that a good carb for a 330hp crate engine?

Yup say max usable revs are 5500

therefor 350 x 5500 = 1925000

1925000 / 3456 = 557 CFM at 100%

so allowing for pumping and plumbing ineffececiencys here

557 x .080 = 44.46 cfm

557 - 44 46 = 512.54 CFM at 80% engine efficiency

Do this last bit again thanks Tech 557 x .8 = 445.6 cfm

So this is a quick ballpark calculation, and 600 cfm Holley is right on the money.

Originally Posted by southerner

Yup say max usable revs are 5500
therefor 350 x 5500 = 1925000
1925000 / 3456 = 557 CFM at 100%
so allowing for pumping and plumbing ineffececiencys here
557 x .080 = 44.46 cfm
557 - 44 46 = 512.54 CFM at 80% engine efficiency
So this is a quick ballpark calculation, and 600 cfm Holley is right on the money.

So, 512.54CFM=600CFM? Are you messing with me here? I'm missing something. Sorry-

Southerner, let me help you a little with your math....
You deducted 8%, not 20%. Deducting 8% would mean the motor was 92% efficient. I think you were shooting for 80% efficiency, in which case you would multiply the 100% effieiency figure by point 8 (.8).

557 times .8 equals 445 cfm

Oops 1 decimal point to many !!!

No saxman not messing with you, this is what a flow calculation will show that your engine will flow in cubic feet of air per minute. And a vacume secondary Holley will automatically flow to the engines air requirements.

PS we are/some are all guilty of hitting a decimal space to many

Thanks, southerner - and everyone else. I will hook up the choke to get things running smoother as soon as I get the intake back on.

I posted two other threads with questions about the intake. I really learned a lot tonight just by pulling the distro and intake. Since I have never broken into an SBC, I never knew just how simple they are to work on.

I do have a ton of questions, though, so thanks for all the help!