Seems like my fuel system is fighting me every chance it gets. I have a Holley 600 on my cruiser, not a race car or even a want to be. Don't know if I should just go back to a two barrel or what... Purchased the carb at a swap meet from one of the local hotrod shops. They told me put it on a build and the customer opted for a Edelbrock instead. Carb was still in the box and looked brand new. Car was having running problems last year when we finally got it on the road. Replaced fuel pump and re routed hose away from the hot engine and that fix those problems. This year I am trying to fix the gas guzzler problem. Carb is dumping way to much fuel into the engine. My combination is this: Ford 302 (1968 block, 77 heads) Edelbrock Performer 289 Holley 600 (1850-5 over 1390) electric choke 18 pounds vacuum at idle timing is at 12 DTC jets are 66 Where do I start without replacing the carb or do I need to drop down to a smaller carb?
The carb is the perfect size...have you checked for a blown power valve?It will still run,but like a pig,and it will drink fuel like nobody's business.
Probaably TRASH in the needle and seat. Holley 600 will pour more gas if not filtered properly. What type of fuel pump ??? Wiyh a performance fuel pump you may need a fuel regulator............ Jeff
sadly this is the deffinition of hell i have an edelbrock 500 cfm on my 69 302 straight out of the box no problems and no worries if you go this route make sure your fuel pressure is under 6 lbs
I do not want to step out of line here being a newcomer but in my opinion holley carbs are great on the drag strip but piss poor on the street. I would ditch the holley and put on a 600cfm edlebrock and look forward to many trouble free miles
Replaced the power valve last fall. Fuel pump is mechanical on the block cheepo. Left out a big piece of info... Sent the carb off to rebuild guy here in town (Bubba) who does a lot of the race car carbs and he took it apart, cleaned it and gave it back without replacing anything. Said it was clean. After having more problems with it he said to bring it back, and he did the same thing. All at no charge. Greg has since past and is unable to help me. (We will miss you Greg)
I hate the fact that the fuel pump is on the left and the fuel inlet is on the right. Why cant Edelbrock get it fixed.
holleys have alot of small passages that can get plugged up easily but if your dumping too much fuel more then likly your float is stuck
Checked them(floats) again today before I pulled the front and removed the jets to see what they are. New glass bowl filter just before the carb also. And it's still clean.
Start by adjusting the floats, or maybe by pulling the bowls and seeing how much crap is holding your needles open.
Yes, I did it again tonight before taking it back apart. Are the jets to big? Do not have the power valve in the house but it was a standard/stock one that I replaced.
I'm no Holley expert and there's some good troubleshooting advice above, but here's a few things to check. *If the power valve's not blown, what rating is it? It may be opening sooner than it needs to. *Check floats for leakage. Check float level. Maybe adjust slightly lower. *Maybe look into smaller accelerator pump nozzles, smaller capacity accelerator pump. Adjust pump linkage if needed. *Make sure secondary throttle plates are fully closed at idle. If they're not closed completely they may pull uneeded fuel thru the secondary nozzles. *Is the choke working properly and opening fully after a few minutes after a cold start?
The jets do not come into play on a Holley at idle. I always restrict the idle circuit on a Holley with wire,they are built to be fat at a idle. You can always put a power valve plug in and jet up accordingly but I doubt the power valve is your main issue.
Fine tuning the Holley is work. The OP is needing tuning advice not a sales pitch/switch to another carburetor, right? A vacuum gauge and setting your idle circuit will be part of the tuning process. Each screw should be turned out equal amounts at the highest stable reading on the gauge.
Try cleaning or replacing your needle and seat assemblies. If your floats are set correctly. At idle on flat ground, if you take the site plug out if should just weep slightly. When you take the needle and seats out, keep track of the turns it takes to remove it. Tighten it in that same amount after replacing or cleaning them with carb cleaner. Double check the float levels afterwards. Clean the carb main body too with the engine running. Check for vacuum leaks while you're at it.
Biggest things I see is if everything is ok in there, most likely jets are too big, then maybe the power valve is the wrong one for the job. I jet down about 4 sizes at a time until they are too lean then go back the other way. Use genuine Holley parts, not cheap rebuild kit parts. There is extensive info on the web but here is a copy from a PDF from Holley. http://holley.com/TechService/Instructions.asp JETTING (MAIN JETS): [FONT=Arial,Arial][FONT=Arial,Arial]Due to varied applications that a universal performance carburetor will work with, a few tips on jetting are provided to help you understand their purpose. 1. Out of the box jetting is extremely close for most applications. 2. Carburetors are calibrated at 70 at sea level. Decrease the jet size primary and secondary, one number for every 2000 ft. increase in altitude. 3. Holley® jets are broached, flowed, and stamped according to flow rate. [/FONT][/FONT]NEVER [FONT=Arial,Arial][FONT=Arial,Arial]drill jets, as this seriously alters flow characteristics. Stamped numbers are reference numbers and [/FONT][/FONT]DO NOT [FONT=Arial,Arial][FONT=Arial,Arial]indicate drill size. 4. In most cases it will be [/FONT][/FONT]unnecessary [FONT=Arial,Arial][FONT=Arial,Arial]to increase jet size more than four numbers greater than out of the box jetting. Exceptions could arise when the carburetor is mounted on a very large volume, plenum-ram manifold. 5. Spark plugs provide the best indication of proper jetting. Consult an ignition manual for proper reading of spark plugs. [/FONT][/FONT]POWER VALVES: [FONT=Arial,Arial][FONT=Arial,Arial]The number stamped on a power valve, such as 65, indicates the manifold vacuum below which the power valve is operational. In this case, all manifold vacuums below 6.5" Hg, the power valve is operating. Generally a 65 power valve is sufficient for most high performance applications that have a manifold vacuum of 12" Hg or higher. However, some problems can result with radically cammed machines equipped with automatic transmissions. These vehicles often "idle" at 2000 rpm, approx. 6.0" Hg. At this point the main nozzles are starting to feed and richen the mixture (supplied by the power valve) and the engine will probably "load up". To correct this problem, install a 45 or 35 power valve. If the engine has a manifold vacuum of 12" Hg or less, a good way to determine power valve size is take the manifold vacuum at idle and divide that number by two. The answer is the power valve size. This will provide idling and proper fuel flow under wide open throttle conditions when manifold vacuums seldom rise above 1" Hg. [/FONT][/FONT]
For what it's worth, I've never had issues with Holleys. Rebuilt many Holley and Ford Holley carbs. Simplest issues I have corrected is the wrong gasket used in a rebuild and blocking off a passage, wrong jet size (usually too big) and improper float settings.
Link with all the general guides for correct power valve, jets, etc. http://www.holley.com/data/TechService/Technical/Carb%20Numerical%20Listing.pdf
Smartest piece of advice so far. Trying to dial in a carb , esp a Holley without a vac gauge ? You're wasting your time. As said, get the highest vac reading you can with the engine warmed up and the car IN GEAR. Assuming of course everything else is OK and you have no vac leaks. Its its trickling heaps of fuel into the boosters at idle - then its likely your float levels are incorrect. Holley are piss easy to work on, but like anything else, you have to know what your doing. It ain't the carbs fault 99% of the time, its the bloke wrenching on it. Your 302 is mild, esp with 18" of idle vaccum. Some thing else is wrong. Rat
I had a similar problem with my 600 (had a few more miles on it than your by the sound of it tho) I replaced power valve, checked float levels, etc etc.. While the carb was off the motor, I stripped off the bowl and metering block on the primary side. Holding the body in a vice, and ran a wide flat file over the body to metering block, surface. I found they distort around the screw holes, allowing fuel to leak internally (bypassing the passages).. Make sure you give it a good clean off to get rid of the filings before reassembling.. hope this helps..
Ditto on checking for a blown power valve. That's a very common problem on Holleys. All it takes is one backfire through the carb to rupture the diaphragm in the power valve. Also make sure thjat you have the correct number power valve for your application. The power valve needs to stay closed at idle and open up when the vacuum drops when you start to accelerate from an idle. Find out what your manifold vacuum is at idle and choose a power valve with a number one. one and a half. or two steps lower than what your idle vacuum.is. Mart3406 ==================
OK, went back to the first post. What makes you think it is dumping too much fuel? The picture is just a pic of condensation out of the tailpipe, along with a rich mixture, due to a cold start, most likely. Have you set the idle mixture screws? Jets only come into the picture when you open the throttle a bit. What type of choke? manual, electric? Is the fast idle cam stuck on high? DO you have electric hooked up to the elec. choke? If not, it will run too rich for a long time after start-up. Also, didn't Holley start putting anti-blowout power valves in the new carbs, quite a few years ago? Unless the carb is pretty old, it should be OK there...if not, get the kit and dput it in.
Don't plug the power valve. All that will do is lean the hell out of the mixture at speed unless you increase the jet size a lot. 66 jets are fine. If the mileage has gone to hell after installing the carb, the advice about a bad power valve (even if it is new), or a warped metering block is where I would start. With the amount of vacuum you are pulling, make double sure the power valve is the correct size (numbered roughly half the vaccum at idle in gear). The float is the most common problem, but you seem to have that covered already.
Good call, I had a Holley that for some reason leaked internally and I think this was why. I wish I went back and looked harder, but i got it for free and didint care. I run a 750vac secondary in my daily driver, and I love it. I wouldnt trade it for any other carb, not even a EFI setup. My car starts with one pump the second you touch the key, everyday, even in 10 below in a snow storm. I spent alot of time when I first built my car, changing jets, getting to know how it reacts to the idle adjustment, and setting it up to run as lean at idle as possible without any negative effects. I rev around 2500-3000 at 60-70 mph on the highway and still get over 20mpg. My cars been together for 4 years, and after the first couple months I havent touched the carb. I cant tell you how to make yours run like that, if you brought your car over for the day, I could make it run like that, but I suck at explaining lol. I'm just saying dont give up, set up correct you can have a wonderful car, not like what everyone says about Holleys. I love when guys tell me they hate Holleys becuase you cant drive them on the street, and they need constant attention. Most people think my cars EFI.
I am trying to hook up with one of the local guys to see if they can come out and look at this issue. I am an R and R guy not a trouble shooter on engines. I have built my car from the ground up so I am not an idiot either when it comes to working on the car. Carbs are NOT my forte... Condensation does not burn your eye and evacuate the garage in 60 seconds. Plug is after 10 min. of running. And thanks for all the suggestions.
FWIW fuel pump pressure can affect the float level. I have an old yard-sale 600 cfm Holley 4160 on my GM 4.3, seems to work fine. As I recall I'm running a 5 psi fuel pump.
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