Thread: holly carb

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hey guys i have a carbourator question. i have a chevy 350, with a edelbrock performer rpm intake, a holly street avenger carb 570 cfm, headman hedders. i had just put the intake on and noticed a loss of acceleration and overall performance. i had a edelbrock eps intake on before. the new one is about an inch taller. it seems to be dumping a lot of gas and not burning it all. Could i need to change jets? i live up north and the elevation in around 640 meters above sea. do holly carbs crap out easy??

hows the timing looking? also hook up a vacuum gauge and see what kind of vacuum you're pulling from the manifold.... and yes holley carbs crap out easy just like all carbs, if they sit too long or or get backfired thru, you'll probably be replacing parts.... with newer holley carbs they have a powervalve that doesn't go out from a single backfire now, but you can still toast your air filter, and then get bits of burnt air filter in your carb

Holley's don't work well with spread bore manifolds.

Sometimes I just can't sit here and be quiet. I know everybody has opinions about everything. I can make a Holley work on your toilet if you prefer that. Every carb is saveble. sometimes more surgery is required, but I have spent way too many years producing workable pieces out of garbage to get the customer happy. I have my preferences too but all carbs have some quality. And you don't want to hear my choice of the right piece to run. If we discount everythng, we become parts changers, not mechanics. To me, being a mechanic and builder has substance beyond compare.

Originally Posted by nitrowarrior

Sometimes I just can't sit here and be quiet. I know everybody has opinions about everything. I can make a Holley work on your toilet if you prefer that. Every carb is saveble. sometimes more surgery is required, but I have spent way too many years producing workable pieces out of garbage to get the customer happy. I have my preferences too but all carbs have some quality. And you don't want to hear my choice of the right piece to run. If we discount everythng, we become parts changers, not mechanics. To me, being a mechanic and builder has substance beyond compare.

Well said!!!! Take what ya got and build what you want! That's where Hot Rodding started, and that's the direction I'd like to see it go.

Anyway, how do your plugs look? Clean, rich, or lean? Many times a problem is a combination of things. What is your timing set at? What is the condition of the ignition components? Could be your carb is fine, or perhaps need to move a step or two on jets and you just don't have enough spark to make it work correctly!

Let's clear some things up here. Did you have the Holley on the other manifold and it ran OK, or is the carb fresh too? How long did the carb sit before you installed it?

checked plugs they were black sooty, timing is set at 8 deg. distributor, dist cap,rotor,coil,wires are all new. I had the same carb on the other intake no problems, when i put the new one on i noticed a loss in everything, I figured i just had to fine tune things,but no help. Then on my drive home it just started to bogg out. when it is at idle it sound good, when you give it gas theres a lot of grayish black smoke out the tail pipes.when i put it in gear it bogs out and barely goes. It wont even spin the tires on gravel

The EPS that you had on the engine is a square bore and the Performer is a spread bore and IMHO that is your problem. For some reason, I'm no engineer, the primary signal gets messed up when a Holley is mounted directly to a spread bore manifold.

what is the difference from square to spread bore?

On a spread bore the secondary opening is considerably larger than the primary opening.

like how a rochester qjet carb is setup

so i should go backto my EPS intake???

You can still use the Preformer manifold with the addition of a carb spacer. Go to www.summitracing.com and do a search for carb spacer. I wouldn't go much thicker than .500 or 1/2 inch. I prefer 4 hole as I think it matches Holley flow characteristics better.

what would be better for my application. the EPS is form idle to 5500 and the performer RPM is 1500-6500. i have stock heads a 570 cfm carb,a mild cam(dont know the specs) hedders. is the rpm intake compatible with my setup or is the EPS a better one to go with. It seemed to run better with the other intake but wanted more power thats why i put the RPM intake on.

More power in most cases equals more money. I personally think that you would be better off changing the manifolds out. I would then sell the Performer and use that money for a K&N air filter and some quality plug wires.