Help starting my new rebuilt engine

[Razorbackbronco]

Another dip on this bronco roller coaster. I started it this afternoon and set the timing to 10 degrees and then I started to hear a knock. At first I was thinking it was a loose valve but its not a tapping sound but a deep knock.

Now before I start to panic could I have spun a crank bearing? It literally has been running for less than 2 minutes since the rebuild. I always thought that a crank bearing knock was from
Heat and wear tearing up the bearing and then giving the rod room to move up and down and knock.

I'm gonna run out and start it and try to get a video with some sound

 

[Razorbackbronco]

What about a bent push rod. I had them cinched down super tight at first so could that have bent one?

 

[Viperwolf1]

Could be. Or might be exhaust leak or lots of other things.

 

[Razorbackbronco]

Well I'm gonna pull out the push rods and hope to find a bent one first!

 

[KBUCK1]

I guess pushrod manufacturers make pushrods in .050" increments for no reason, hell any old pushrod will do with that magic adjusting nut on the rocker stud.. LOL

Imagine if you can, this pushrod an inch longer for illustrations sake.. Think it might push that valve open when the rocker is 'adjusted' down tight?

Congrats to the OP for getting it going.


Let me start off by saying that I know nothing about engine building. But, I feel Ive got a good amount of common since. If a cam shaft has .500 inches of lift then it has .500 inches of lift. The push rod length can not change that. If that was the case then if you decided that You wanted a cam with more lift you could just install longer push rods. I have to agree with the other guys on this one. I am a self proclaimed moron when it to engine building. So, no need to call me one

 

[Fairlane514]

Bent pushrod would be a noise in the upper part of the engine. A rod knock would sound deep and low.

 

[Razorbackbronco]

Pulled the rods this morning and they are all straight. I'm gonna pull the oil pan tonight and look at the rod bearings.

 

[ugly74]

What a pain in the a$$! Id be cursing a blue streak and then let it sit for a month if I were in your shoes.

Did you try pulling the timing back, to see if the sound changed? Does the sound vary with RPMs?

 

[Razorbackbronco]

Ok since I'm among friends I can admit a mistake I made. A big mistake!
So I drain the oil and its super clean and then pull the pan and find out the #2 rod is the one knocking.
The reason it's knocking is not because of a spun bearing but because the top half of the bearing is not there. Apparently the idiot (me) who assembled it forgot the top half of the bearing. Good news is that there was no damage to the crank journal or bottom bearing. I found the missing top bearing on my work table and put it back in, and should be good to go. Gotta get a new pan gasket and then fan get it broken in.

I'm just thankful to have caught my mistake before it became major

 

[Ourobos]

Let us know how it goes.

 

[DirtDonk]

Ok since I'm among friends I can admit a mistake I made. A big mistake!...

But can we still laugh out loud and point accusing fingers in your general direction?
As we're handing you a beer and the torque wrench that is.

Phew! Glad you got it fingered out. Sorry to hear it was such a potentially dire issue though. Would have been nice if that pesky bearing half hadn't hidden itself behind other stuff.
That was pretty diligent of you to dig in and find it though. Lots of work and no (or very little anyway ;D ) whining about the extra work you had to go to.

Like Ourobos said, let us know. Can't wait to hear the results.

Paul

 

[ugly74]

Better late than never! That seems like one of those lessons you only have to learn once, and ya never forget it.

 

[Fairlane514]

Extremely lucky there was no damage to the crank!