[JamesRS]

Hey all, I have a question for everyone about my carb. First let me tell you my combination. SBC 350, 10:1 hypereutectic, 224/234 @50 (290/300 adv.) duration with .465/488 I/E lift. Vortec heads with z28 springs and 1.5:1 roller rockers. Intake is a Performer RPM and the carb is a Holley 600 cfm Double pump. The carb is starting to act up a little now with mid rpm hesitation (actually it's always had this problem), and slight off the line stumble. Basically it's time for either a rebuild, or replacement. My question is this. Should I rebuild the carb, and try to resize the power valve to correct my mid power band problem, or should I upgrade to a little larger carb? Several people have told me to go to a 650, or 750 with vacuum secondaries, but I don't want to lose that crisp throttle response I get with the mechanical secondaries. Whaddya think guys, should I rebuild and retune, or replace? (...also, does anybody have anything good, bad or other about the Edelbrock carbs?)

[fireschenie]

Stick with the Holleys they are the best out there. I would go with a new 750. I run it on my 65 Chevelle and it is awesome. I have a little bit bigger cam but it should still work fine.
Good Luck
Fireschenie

[DoubleVision]

I`d just get a 650 Demon and let it ride, unbreakable baseplates, billet metering blocks and far superior quality is my reasons for the Demon, I run a road Demon Jr, and I wouldn`t trade it for nothing, fires up when I hit the key and has excellant throttle response. only if you get a Demon, take my advice, Read the instructions, it may look like a holley, but it don`t adjust like one, Demons are very precise.
Good Luck.

[1BAD80]

Save your money and retune the carb.
The amount of fuel that can be delivered by one accelerator pump stroke is determined by the pump's capacity and the profile of the pump cam.
The period of time that it will take for this pre-determined amount of fuel to be delivered is affected by the pump nozzle size. A larger pump nozzle will allow this fuel to be delivered much sooner than a smaller pump nozzle. If you need more pump shot sooner, then a larger pump nozzle size is required. During acceleration tests, if you notice that the car first hesitates and then picks up, it's a sure bet that the pump nozzle size should be increased. A backfire (lean condition) on acceleration also calls for a step up in pump nozzle size. Conversely, if off-idle acceleration does not feel crisp or clean, then the pump nozzle size may already be too large. In this case a smaller size is required.
The same applies to the accelerator pump cams. Once a pump nozzle size selection has been made the accelerator pump system can be further
tailored with the pump cam. Usually the red cam works the best. For a DP its good to put a 50cc pump on the secondaries for any lean spot or to help the carb to catch up.

[gilflite350]

hey guys, just bought myself a ski boat. It has a mildly worked 350 chev fitted with a near new 6050 holley carb.
My problem is after running the boat for a while and i suddenly stop it; after a minute or so later I go to start it again and it wont fire.
I can give it no gas or some gas (have tried both a few times) and it wont start, i have to wait nearly 10 mintues and then try again and it will finally start.
Anyone have any ideas what is wrong and how to fix it?
My guess was the heat was evaperatingthe fuel in the bowl but im really not sure, im new to holley carbs.

[bprumos]

gilflite, most likley vapor lock. specially cause boat engines gets very hot and dont have a whole lot of airflow available to them in the engine bays. try putting a phenolic carb spacer on it. that should reduce the heat transfer to the carb from the intake manifold. that might help fix it

[kc8oye]

take that single feed holley 600 off and throw it in the trash, it's a piece of junk.

pick up a 650 dual feed, vacuum secondary.. my engine is very similar to yours (214/224 @ .050 and 9.75:1)
I went from a Qjet to a holley 600
and it would starve for fuel higher up in the rev's from that single feed carb.
I rebuilt and retuned that pos until I was ready to put it in my punkin chunker.. lol (I used to suck the float bowl dry on the qjet, it'd fall on it's face at the top of 2nd gear, I'd get out of the the throttle for a second, get back in it and it would come back)

bought a brand new 650 and after some initial tuning.. my engine ran SOOOOOO much better.
still using the same fuel pump, but using a dual port pressure regulator too...

also, holley's are a little funny about fuel pressure.. the doc's day 7psi max, but I found trying to run more then 6 tends to invite flooding issues.

[kd5icr]

Originally Posted by bprumos

gilflite, most likley vapor lock. specially cause boat engines gets very hot and dont have a whole lot of airflow available to them in the engine bays. try putting a phenolic carb spacer on it. that should reduce the heat transfer to the carb from the intake manifold. that might help fix it

That is what I told him yesterday.