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Mysteriously, after changing intake manifold from two AFBs to one AFB, a ticking sound started. It is not at all RPMs. It doesn't seem to be valves and it's not water pump, alternator, or A/C compressor, I isolated those by removing the belts. Put in a new set of hydraulic lifters. Any ideas, anyone? Driving me nuts!!!
Have you pulled the valve covers and listened to each rocker with a piece of hose while its running to be sure?
Do you have a stethoscope with a solid rod probe, that can help find noises. Distributer noise?
Check your flange gaskets.
Welcome to the site and great question. Since you say it isn't at all rpm's do you have a vacuum gauge to tell us at what rpm and how many inches of vacuum you hear this sound? I'm wondering if something like the distributor cap isn't back on "just right" and the rotor is touching..??..?? Or as JB mentions a gasket is an issue.?.? Since the manifold is different, did you verify the angles ? does the manifold actually sit "flat" to it's mating surfaces?? It's happened many times before, especially on a used manifold mounted to a different engine. Hope it helps, you have some things to look at now, Let us know what you find.
I had a noise I could not detect where , I heard everything form lifters to broken ring to piston slap . I asked a friend of mine , an old mechanic with really good ears . He listened and said it was not coming from the engine , it was farther back . He said it sounded like a crack in the flex plate , It was , I saw the crack , put in new flexplate , no more ticking . Bob
I had a flex plate crack that sounded like a rod knock.
I had a knock only when driving my v8 s-10 that made me crazy, I was about to pull the engine when I discovered a wrench I had left between the top of the frame and floor, it would rattle against the floor sounding like an engine noise.
My v8 miata had a random knock that confounded me for a while turned out to be the purge valve was resting on the fender well and transmitting a knock every time it would purge, sounded like a random rod knock.
Yes, with a stethoscope. Even with the valve covers off, and cannot isolate the sound.
I do have one, and it's not the distributor. Thanks.
Do not have a vacuum gauge. (Yet!) Distributor cap is installed properly. New Edelbrock 2701 manifold that fits correctly. Not an exhaust leak. This noise appeared after changing out manifold and fuel pump. Replaced the fuel pump rod. Some kind of a gremlin....
I would love to find it was something crazy like that! This '38 Chev street rod has no purge valve, dang it.
Have you checked your oil for metallic sparkles? Thinking flat tappet cam with a flattening lobe, coincidental with your intake swap.
No sparkles. All the old lifters came out pristine, not cupped. Thanks.
A stethoscope is nice, but a piece of wooden broomstick works just as well. I've used one for years to find noisy lifters and other strange noises. Check around he fuel pump.
Good on the no sparkles! How about another approach - What all did you take off/apart when you changed the intake manifold. Just thinking about unique things to your build that might have been in the way and removed for access/convenience and might contribute to a "tick" later.
You say it's not at all RPM's, but is it a consistent, steady tick at specific RPM points or random? Always the same RPM point? Just one RPM point or more?
The mechanical fuel pump seems like a suspect.
Exhaust leaks sometimes making funny ticking noises that sound like valve adjustment problems.
FINALLY tracked the tick down: a defective fuel pump from Edelbrock. The position of the pump's operating arm was different on the "old" pump as compared with the next one I ordered. There was nearly a quarter-inch difference in the positions, which meant that the operating rod in the engine had quite a lot of clearance before it actuated the pump. Summit Racing authorized the return of the defective pump. Thanks to all for your suggestions. Add one to your list of weird engine occurrences!
Thanks for for the update! I guess the prize goes to V8 nutz for the correct answer! :)
I hate it when these kind of threads never tell you how they fixed it, so it's nice to see a happy ending to the story.
So true, thanks HR3 for the update!Quote:
Originally Posted by v8nutz