Hi guys,...... I was checking out a ticking noise in my 72, at first it sounded like #2 exhaust was off. I hot adjusted it but still no better. I pulled the rocker off, ( comp magnum roller tip) it looked fine, checked the ball it was good, checked the pushrod it wasn't bent. Tried to push down on the assembled rocker but couldn't so the lifter seems good. Exhaust header- new gasket and tight, no escaping air. Good oil pressure, runs strong, no sign the pressed in stud is pulling out. So today I went back and rechecked the noise at the fuel pump bolts and pump and I can hear it clearly there. So the noise is either starting at the pump or being transferred down. This is a stock replacement pump I put on about 8 - 9 years ago when I did the car over. So who knows, probably is an imported pump and my next thing is to remove it and since I'm going to do that I might as well replace it. So the question is who makes a good pump these days? I always used AC Delco but I can't say I trust much of them anymore then anyone else's. I don't care about the AC cast into it, I just want a good part. Thanks
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Re: Ticking noise - New Fuel Pump
Gary,
Went thru that years ago, the ticking. I found a broken spring on the pump arm. A weak spring might do the same.
The 72 pump is probably different as the arm return mechanism is inside. But good catch on the noise, I went much farther before I found the broken spring.
Dom -
Re: Ticking noise - New Fuel Pump
Gary,
You might keep a eye on ebay as some of the good AC pumps show up from time to time. Is the 72 fuel pump the same as the AC40503 that is the replacement pump for the later c2's.Comment
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Re: Ticking noise - New Fuel Pump
Gary - The replacement fuel pump I had in my 66 L79 had only 6K miles on it and then the ticking started. Never had this issue before but heard it's not uncommon. Here are a couple pics showing the busted spring. Luckily, I had another pump around and pirated the good spring from it.
Mike T. - Prescott AZ.Comment
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Re: Ticking noise - New Fuel Pump
Thanks guys,... I was out in the car all day today put on another 200 miles taking advantage of the Fall weather. I probably won't get much time to work on it before the Cold weather starts.Comment
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Re: Ticking noise - New Fuel Pump
Tim,.. I don't believe this is the same pump. I still can find this new from AC with and without the logo. Not sure how good it is compared to the original. The common one I see is #41240 which covers the base engines. In my case I just need to know about the outlet configuration because I made my own fuel line up with an inline filter. I would like the same so it is a straight forward replacement without getting into fabricating a new steel line.Comment
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Re: Ticking noise - New Fuel Pump
To follow up on this noise. I ordered the new AC pump and rod and today I figured I would swap it out. I checked my records and saw I used a NAPA M6104 9 years ago. I figured I would go to the shop about 9 and be on the road by noon. Well you know how plans go when working on a corvette! So I get the right side on a jack stand and pull the pump off. Then I compare it to the new AC pump and see the bowl is about 1/2" shorter on the AC pump. I run a custom steel line to an inline alumnum filter then braided line to the Holley 670 avenger. All my tube bending tools were sitting in my home tool boxes 15 miles away and I sure didn't want to start bending up steel line on a Sunday so I called the local NAPA's. The only store that had a vette pump was 40 miles away. All the local NAPA stores told me the M 6104 has now been replaced by the M6955. This one has the same psi but about double the flow rating. I drove up and made sure the size was the same, came back and installed it. The rod was fine, I mic'd it up and it was the same diameter as the new GM one, maybe a little longer-not much to speak of, so I polished it in the lathe and reused it. The steel fuel line fit fine. I fired it up after letting the RTV on the gaskets setup a couple of hours. The ticking noise is not as loud but I can still pick it up and it still sounds like the #2 exhaust is the loudest point but I can't compress the lifter and the car runs pretty good. Any more ideas? I probably won't get much more time to work on it before I put it away.Comment
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Re: Ticking noise - New Fuel Pump
Gary - was the return spring broken on the old fuel pump? If you pulled the old pump and the spring was still in one piece and no other defects or problems seen, it appears you can eliminate the pump as the source of that ticking.Mike T. - Prescott AZ.Comment
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Re: Ticking noise - New Fuel Pump
Hi Mike, .... the spring was in place and not broken. I did notice the inline psi gauge is now a steady 7-8 psi where before it was 0-3 and I thought the gauge was bad, and it could be. I just drove it from the shop to home so I didn't really put it to the test. It's better but I still can hear it. Wed is supposed to be about 65* and sunny here so I may just take the day off and take the car out all day.Comment
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Re: Ticking noise - New Fuel Pump
Gary,
Some small exhaust leaks sound like a lifter noise. With my ears I need help so I wrap a rag around each outlet and see if it makes a difference. I remember picking that out (exhaust leak) right away but lost a bet about a year ago when there was a crack in the exhaust manifold. There are not gaskets on some and then again there are gaskets, a good place to leak a ticking exhaust leak. Just a thought.
DomComment
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Re: Ticking noise - New Fuel Pump
Hey Dom,,, I thought about that too and this car is running headers. I replaced the gasket and checked it again. I never noticed it until I swapped the heads and wonder if the shop created a possibly issue with these one head. I may move back to the WP heads once I machine the guides for positive seals. For now I plan on driving it, tick be dammed!!Comment
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Re: Ticking noise - New Fuel Pump
Gary,
I would do the same and see if it wants to show it's face. On another note. Years ago there was a problem with ticking and we decided to do a valve job, cam & litters. When I took the valves out there was a valve seat that had the 3 angle grind on the seats and the valve was actually seating on one surface then snapping to the 45 making a click. The guides and seats were tired on that head but you could see the problem clearly when I ground the valves and seats.
One other tick that another mechanic showed me was a broken valve spring that looked like the others. He told me to run my fingers around the spring. When I did I felt a ridge on one of the coils. The spring would snap in & out of the break when the engine was running. It would slide out when compressed and back in place when up. I have found a number of broken valve springs but mostly because of a issue as to how the engine ran.
I know you checked that but I had to run my finger around the spring to feel about a .010 ridge where the spring popped almost completely back in. Engine ran good as the spring still had enough pressure to close the valve.
DomComment
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Re: Ticking noise - New Fuel Pump
Dom.... That is what I plan on doing. I looked over that #2 ex spring but didn't see a thing and it was a new spring set. In the mean time I have couple of 12 bolt conversion to machine so that will take my time up then it will be cold out.Comment
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Re: Ticking noise - New Fuel Pump
Hi Gary, One thing I would suggest is to get a hold of a good mechanic's stethoscope. It is a valuable tool that can help you pin point an elusive engine noise. It's helped me many times. If the problem is in the valve train, you will hear it loud and clear. B/T/W the rear you built for me (64 with the oversized Toms pin) is still running sweet! Good luck , DanComment
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Re: Ticking noise - New Fuel Pump
Hi Dan,... good to hear from you again. I do have a scope and heard the tick both at the #2 exhaust and the fuel pump. It looks like a nice day tomorrow, probably the last before the salt hits the roads so I plan on going out for the day in the car. Glad the diff is running strong that was back in '09 and a good example that diff endplay is not always worn yokes.Comment
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