Hi everybody I have some problems with my holley. its a marine holley 4150 850cfm with vac. secondarys and no choke at the moment. It was freshley rebuilt a week ago from a friend at work who has done this many times. We started off with 78 jets in the primary and 86 in the secondary and it would not start at all. Changed the primarys out for 60's just to see what happens, and it did start and revs but falls flat on its face when the throttle is released. Same thing happened when we switch the jets to 72s. We adjusted the idle mix screws from all the way in to all the way out and still nothing. Has anybody had this problem or can point in the right direction to start. I need to drop this car off in storage hopefully this weekend. The motor is a 72 455 with long tube headers, mild cam and mild port and polished 72 stage 1 iron heads. The car did run on my old quadrajet but was very old and leaked. and timing is set at 32 degress total advance.
The engine should idle on the idle system of the carburetor, so swapping jets around is not the answer. I know you said it has 32* total, but what does it idle at. It may help to temporarily advance the ignition timing. That may help it idle, but if it won't idle once it has warmed up a bit, it points to the idle system of the carburetor. There may be a passage blocked off, or plugged. Anyone can make a mistake when rebuilding a carburetor. It may have to come apart again.
thanks to the quick reply ill have to take it apart and blow it out better. Im at 8 advance with a timing gun and everything else is set to factory spots. Could there be a vacuum leak that would effect the idling?
Yes. Depending on the cam, you should be seeing 12-15" of vacuum when fully warmed up. You say mild cam, but vacuum depends on the cam. Vacuum gauges are inexpensive. Get one if you don't have one. With it connected, you can spray carb cleaner around the base of the carb and watch the gauge. You can also adjust idle mixture with it.
yeah I do have one of those and have used it with my old carbs to set everything. I guess tomorrows job is pull it apart and blow it all out again. the idling passages in the metering block or in the carb body?
cleaned everything out made sure all passages were good and clean now it wont even start at all. Bought new gaskets for the carb plate. Anything else I can try?
Ascertain why it won't start. It either has no gas, too much gas (flooding), or no spark. Find out which and correct the problem. Check your spark plugs, they may be fuel fouled.
Make sure the floats are set correctly. It is easy to set them too high. The fuel level should be just at the bottom of the sight plug or a little less. Be very careful here because of fire hazard. (One reason I don't like Holleys on a street car). Also, once you get the engine started and take a vac. reading make sure you have the proper power valve(s) in it. You need to start out with a power valve that opens 2"-3" of mercury lower than the idle vac. reading. Larry's vac. leak test around the carb. is also important. Bump the timing up a little more. Ignore for the most part the factory spec. With a cam those #'s go out the window. Is the curb idle screw in contact with the linkage? you might have to set that also. Mike D.
its definatly getting fuel you can smell it from 10 feet away from the car. Ill double check my float level and make sure its not to high. Is there any other spot that could be making it flood. The power valves that are in it were in a 350 blown chevy so I cant imagine them being to big.
I would pull a few plugs, and make sure they aren't fouled. Flooding should be pretty obvious if you look down the carburetor. Power valves are rated by vacuum level they operate at. Calibration of a carburetor for a blown application is different than a N/A engine.
no luck with the power valves. I think I have made the conclusion that its not the carb. The car was running really good with the quadrajet on it so I thought I would toss it back on for the time being. It didnt start or run. So now I am replacing all the old parts that should be replaced anyways on my igniton setup and starting from scratch at TDC. Ill let you guys know how it works out for me. Appreciate the help
