I noticed the 55 has a slightly rougher idle and smells a little rich so I am thinking its probably time for another power valve,can not remember any backfires and I have almost 3 years on this one and that is about how long I got from the others so is this the norm. I presume the crappy gas is the problem if there was no backfires and I used Holley power valves so does anyone know if there are better ones made or to be safe just replace it every other year.
Try and buy some av gas at the airport and run it and see if helps,Best thing in the world for the holly's
damn it....live for those days we/I worked at the airport....draning and pumpin' some of that 100plus avgas into my runner's....
Pull the needle/seat and look (magnifying glass) at the O-rings condition. Should be full not even with the body. Mine was going away and acted like what you are describing. Stop any ethanol use.
Still has the original needle valves so I will check them,carb has about 25,000 miles so probably about time for a kit.
Take the time to install the kit to prevent a backfire blowng the power valve, I don't remember what its called, been a while since I've done one. http://www.holley.com/125-500.asp. found it.
no backfire ball , the first time it sneezes, with one man been a few years since I rebuilt them on my freinds car and runs every summer when the weather is nice and uses EPA E-10 ... most of them die from backfiring or overtorquing them down ( distorts and rips the diagphram ) . I would check the needle,seats and float level .
Chopolds, you are correct. JunkyardJeff, you could check with companies providing e85 holley conversions to see if they will sell just power valves if you think the E10 is eating them.
I had a similar problem. Mine too was deteriation of the "O" rings on the needle and seat. The lower "O" ring was almost gone and allowed fuel to seep past avoiding the needle and seat. I replaced with a new needle and seat assembly, re-set the float level and all is good. Didn't even have to pull the carb off the car. It may be possible to just replace the "O" rings, but I could not find the right size, plus the carb was about 20 years old, so I figured it was time for needle and seats anyhow. Pull the sight plugs (one at a time) and carefully check the float level. If fuel spills out and you formerly had the float set right, my bet is on the needle and seat.
I bought tuning books and researched Holly problems getting my last SBC 400 running and I don't think the power valve is involved with idling problems. It's function is to aerate the fuel from main jets in the transition off idle. It does sound like a float level problem or sticking floats.
We had lots of power valve problems on dirt circle track racers. The engine is revved way up then backed off going into the corner making maximum vacuum and it seemed to suck the diaphragm right out of the power valve. Most would fail after a couple of races. Vacuum holds the power valve closed so when the diaphragm fails, the power valve is open all of the time and it will dump gas at idle. The carb shop that sponsored us found some heavier duty power valves.
Some good ideas above. I would replace it with a 4.5 personally. Even though your vacuum may dictate a 6.5 I have had better luck dropping down. Depends on how radical your cam is. peace
As soon as I get the radiator repaired I will get back on the carb issue,last weekend it started leaking so I put some stop leak in it to get me home and was hoping it would last me the rest of the season but fond a very large puddle in the garage today so out it came. Recent recore and third time leaking from the same spot which is a seam where the tank is soldered,do I take it back to the guy who fixed it twice or find a new shop.
I always plug the PV.... But hey, 3 years and now a rebuild? I would take that. Especially with todays gas..... Freshin it up and roll another 3... 1/2 the fun with old cars is workin on it right?
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