Terrible tick on rebuilt engine (intermittant)
 

If I were a betting man I'd say piston slap coming from #3 or #5... but I'm hoping it's something on top.

Both engines were rebuilt by the same shop. They have about 2-4 no-load hours on them (trying to tune carbs on land). Only one with the knock.

It doesn't start knocking right away... worst part is that it comes and goes. Sometimes it purrs perfectly. When it starts knocking the exhaust changes pitch a bit. It's loud at idle... enough to make a grown man cry. At about 2500-3000 RPM it's more a faint tick, it also changes the exhaust tone pitch and also comes and goes.

Is there anything I can try before tearing it back down?

Thanks!

Re: Terrible tick on rebuilt engine (intermittant)
 

Sounds like a lifter.

Re: Terrible tick on rebuilt engine (intermittant)
 

I agree with cuda. It's gotta be in the top end, bottom end problems dont come and go. hows your oil press.

Re: Terrible tick on rebuilt engine (intermittant)
 

Oil pressure reads 60+

The knock at idle sounds pretty deep... do you think it could be a collapsed lifter or something? When it's collapsed it knocks the crap out of the lifter/rod/rocker/valve?

A new set of lifters is quick and cheap so I'll give it a shot. Do you think I'll be able to see any signs from the old lifters?

Thanks for the input!!

Re: Terrible tick on rebuilt engine (intermittant)
 

The main reason I suspect a lifter is that it is intermittant. Sometimes, a lifter will get a piece of crap that blocks the oil hole.

Re: Terrible tick on rebuilt engine (intermittant)
 

JH,
When you remove the intake manifold, pull the sparks have someone crank the engine and watch the lifter and valve action you should be able to see a failed lifter pretty easily.

Re: Terrible tick on rebuilt engine (intermittant)
 

I assume you broke the cam in and soaked the lifters in oil to prime them. You need to do this quick before you take out a lobe on the cam, I bet it is a lifter also, oil may be coming and going and causing the inheritance. I would check the rockers also. The fact it sounds deep would lead to a lifter, they are down there a ways and would radiate down also.

Re: Terrible tick on rebuilt engine (intermittant)
 

Thanks for the input guys!!!

Got it apart... Well at least the side where I thought the sound is coming from. I can't get the other valve cover off because of the exhaust manifold is in the way (can't get it off cause the other engine is in the way).

Looks like some strange wear on the cam (not that I'm an expert). It's not even. I was also surprised to see the lifters not being centered on the cam lobes... last engine I had they were dead center, but it was a roller cam so I figured it was normal to have flat lifters off center this way. Is it normal?

The lifters are shiny and actually look pretty good. I was cranking and watching closely... all lifters were rotating and lifting normally. Rockers looked good, rods look new.

Do I cross my fingers, put new lifters on 1,3,5,7 (suspect side), and fire it back up? or do I put the forklift back on it for the second time in a month? decisions decisions...

Re: Terrible tick on rebuilt engine (intermittant)
 

Jackhammer-- Based on what you said, I'd try changing the lifters. Piston slap typically is worst at startup when very cold and quiets down or goes away when the engine is hot. If the problem comes/goes and the tone of the exhaust changes, then I'd suspect something in the valve train. Lots of things can cause knocking (Excessive bearing clearance, loose wrist pins, exhaust leak at head,etc.) but they usually don't change the tone of the motor. My experience with wiped out cam lobes is that they go almost immediately and give you either a miss (intake) or backfire (exhaust). As I recall, the lifter bores with a flat tappet cam are off center so the lifter rotates. As for the strange wear on the cam, if the lobe isn't wiped, I can recall years ago where the cam lobe was shiny for part of the surface and darker on the rest. If the lobes were wiped, you'd see it the way the rocker arms went up/down. I'd try the lifter route, you've got nothing to lose.--Lou

Re: Terrible tick on rebuilt engine (intermittant)
 

You may want to check for an exhaust leak. I had the similar symptoms and it turned out to be an exhaust leak.

Re: Terrible tick on rebuilt engine (intermittant)
 

If it is not an exhaust leak I would first pop the valve cover and inspect the rockers. It is possible one could be slipping off and hammering the spring retainer. I have seen it happen and if this is the case you need to catch it before it frees the keepers. Oh and it is VERY most likely you have a bent pushrod as a result of any of the forementioned cases.

Roby

Re: Terrible tick on rebuilt engine (intermittant)
 

This is very true and not many people know this. If the lifter didn't spin in the bore (the flat tappet type) the cam lobe would be wiped out in a day. Lmarth, you must be a gracefully aging engine builder like me. :D:D

Roby

Re: Terrible tick on rebuilt engine (intermittant)
 

Roby--I refuse to respond to that comment on the grounds that it may incriminate me! Lou

Re: Terrible tick on rebuilt engine (intermittant)
 

Jackhammer-- You can't take anything for granted when you get into a situation like this. There's another thread in this section where there wasn't a lot of oil coming from the pushrods/rocker arms. You need to make sure those lifters are pumping up and not sticking or collapsing. Just trying to help.

Re: Terrible tick on rebuilt engine (intermittant)
 

I had a very bad knock in two cylinders at idle and pulled my hair out looking for the problem, thought it was a lifter, then bearing, was ready to pull engine,, turned out the carb was bad and needed a re-build, was running very lean until the primaires opened and the knock was gone.. just another avenue to explore.

Re: Terrible tick on rebuilt engine (intermittant)
 

Thanks for all the input!!!

Chris - I am at the time also battling a carb backfire (lean) condition. I had some rochesters on it that would idle fine, but that's about it. I just bought the Holley's (4010's) and was going through the fine tuning on those when the knock showed up. I put some 7.5 power valves and #86 main jets thinking it should be a bit rich... I even put idle adjustment 3 turns out when all I really need is about 1.5-2 for a smooth idle. I thought I had the backfire fixed... drove my neighbors crazy blipping the throttle. There was some hesitation but no backfire. Just before I turned it off I gave it that one last blip after it was sitting idle for minute and POW, another freakin carb backfire!

It's about this time I'm thinking.... hmmm, maybe I should fix the 'lifter' problem and see if that could be the cause of my backfire problem. (I also have the same carb settings on engine #2 and it seems to run okay... I haven't ran it through the ringer like I have engine #1 though).

Okay... Thanks for the input, I'm about to put the top back together... I was really struggling with yanking it back out and going thru it all over again (I once had a $12 part cost me $4000... one of life's lessons learned!).

Jack

Re: Terrible tick on rebuilt engine (intermittant)
 

I think I found it... It's a demon banging in my oil pan!!! I've heard of this happening before! All my engine needs is an exorcism!!!!!!

I was turning it over watching my new lifters and it started, dong, dong, dong... it hit about 20 times and then stopped. Craziness! Guess it's time to fire up the fork lift! yipee! I can't wait to see what this is!

I had something similar happen with a stroker motor... One rod bolt was just barely hitting the pan. The only difference was it hit every time around.

Re: Terrible tick on rebuilt engine (intermittant)
 

Found the little bastard!! Course it took out the cam too...

Would you guys think I was nuts if I put a bit more cam in this engine now? leaving the other engine for winter... I'm not going racing (ever) I just want to cruise around a bit before summer is over!!!!!