1987pachanga22

Ok here is the deal I have recently put a used 454 330hp into my 22 Mirage.
Last night I started it for the first time and tried to get it timed but started hearing a noise that concerned me and I stopped. About an hour later after changing my drawers and stopped crying I tried it again and everything was going great without noise for about 5 min of run time and then the noise came back louder and no it’s not just a small noise so I stopped again and pulled the valve covers off to see whatever I could find out. One of the intake rockers was vary loose so I ran through the entire procedure with the rockers and put it all back together thinking I was done, fired it up and now it was louder.

How do I diagnose this? Is there some one close to Omaha that could help me figure it out?

4bus

iTrader: (4)

How does it run? How was the oil pressure? Do you know the history of the engine, how long has it sat out of a boat?

Could be a number of things, but the loose racker makes me think it has a stuck valve and you bent the push rod. Having a stuck vavle can cause a back fire through the intake that sounds a lot like a knock. Have you verified that all valves are opening and closing?

I would start with a compression and leakdown check, if you have valve train problems in will show there.

1987pachanga22

Oil pressure was good, water temp was good and I was turning about 800-1500 rpm I never got the chance to actually time it because I was still warming her up when it got ugly.

I don’t have a good history about the engine other than the reason it was sold was because it came from a twin engine boat and the guy hydro locked the other engine.
Rather than rebuild one he bought two new engines and sold both of these to me one runs and the other needing gone through.

1987pachanga22

Going home tonight to do the compression check and to pull the valve covers back off and to check for any obvious signs of problem.

How do I check for a collapsed lifter?

tommymonza

Turn it over by hand and watch the movement of the valvetrain.

Or you could start out by loosening all the rockers and pulling the push rods 1by 1 to see if any are bent.
Just my suggestion there are many more on this site who are much more knowledgeable than me.

Griff

What area of town do you live in???

Is the noise consistent??? More like a loud tick??? or sort of inconsistent with a deeper knock sound???

1987pachanga22

Thank you Griff but I found cylinder 8 has no compression even after I loosend the lifters so i am going to pull the head and see what is going on. Is there anything else that i should check before i go that far? What can cause a loss of cylinder compression keep in mind that I am pretty sure that I lost a lifter on that same cylinder.

4bus

iTrader: (4)

I'm guessing that you have a valve issue on the cylinder, which may be a cam issue now as well.

Sounds like you got somewhat of a deal the engines, and the prob the other one had may be starting on this one is well. They are inexpensive to rebuild, I would pull it and go through one of them the right way.

Good chance you took a lobe off the cam and that metal is floating around in there too

1987pachanga22

The noise was not constant it went away and then came back. Is there a way to measure the lift and see if the cam is bad?

JMS322

If the rockers are loosened and the valves don't open.....you will have no compression. You can't check compression with misadjusted valves.