Ticking at higher rpms in drive?

[MonteCarloGuy]

My friends and I recently did some minor work on his 350 it is slightly worked. It has an eldelbrock carb, which will become significant in a few seconds. We recently upgraded to a performance distributor, higher gauge performance wires, and redid the exhaust manifold and valve cover gaskets. Then we unknowingly put in 87 octane gas. Upon driving it a ticking noise can be heard. It appears to be coming from the carburator. We spoke to some muscle guys around town and was told it could be the gas so we siphoned it and put in 93 octane then added octane boost. Ran it for about an hour then drove it still the ticking sound. Then someone told us it could be a loose or over tight valve so we went in and redid all the valves. Still the ticking remained. Then we retimed the engine realized the vacuum advance was unconnected so we hooked it up, and retimed it. We then checked the fuel pressure made sure it was good at around 8psi and drove again, but still it ticks. Currently the car is straining to start and we are out of idea's on what is wrong, hopefully someone has had this problem or can lead us in a direction to fix it. I know the engine is out of a corvette and the block out of a school bus "yea i have no idea aboout that" Thanks guys

[J-Ri]

If you had the pushrods out, make sure they are in the correct order. Use a screwdriver as a stethoscope and see if the sound is coming from the carburetor or something lower. I don't think a carburetor has anything in it that could make a ticking sound unless it's computer controlled. Check for exhaust leaks or spark plug wires arcing to ground.

[MagicRat]

Originally Posted by MonteCarloGuy

, and redid the exhaust manifold

Exhaust leaks can make an annoying tick noise that sounds a lot like a valve/lifter problem.
Try a re and re of the offending manifold, with new gaskets Run a flat file over the manifold where it meets the block to be sure the mating surface is smooth, flat and shiny.

[MonteCarloGuy]

We though of another piece of info that might be the problem. Now the car was kind of laggy with the accel, which is why we decided to get a better hotter spark. Now one spark plug was in a position by the header where it was unreachable without unbolting the exhaust. Well the previous owners the genius's they were welded the header to the exhaust, and over the years had never changed that spark plug. Now we did change it and the carbon build up was rediculous. Once the new plugs were in the car, it moved but the new ticking started. Could it be a bad cylinder that was not firing due to an inactive spark plug and now that it is getting a spark, broke due to lack of use over the years. I am going to go back and redo the exhast manifold gaskets and make sure they are tight and check for sparks in the dark will let you guys know?

[MagicRat]

Did you loosen/remove the header but re-used the gasket?? This will cause an instant leak, every time.

A dead cylinder is noticeable in that the engine vibrates a bit, is noticably down on power and makes an unusual stuttering sound. IMO if that cylinder was not firing at all, but now is good, then you would likely notice and would not have to ask. Chances are, the cylinder itself is not the problem.

Headers are notorious for leaking at the gaskets, especially the small block Chevy. The tubes for the center two ports on each side are the worst for this.
After you re-do the header gaskets, keep re-tightening the bolts after each drive, (after the engine cools down) for about the first ten drives. You would be amazed at how much extra tightening is required before they take a 'set'. If you do not retighten, they will start leaking again.