ROD KNOCK

Guys, at idle (around 1000rpm) the car sound fine. When I rev it I hear this loud knocking sound. It almost sound like its under the valve cover. I though maybe the HLA's were bad, but I replaced them with all new ones, and I am still getting the same noise. Its a freshly rebuilt short blcok and head. The head has new big valves and stock springs. If the valves were floating would it sound like that? I really sound like its coming from under the valve cover. Any ideas

Pull the ign. wires one by one...

Louder = Main bearing
Quieter = Wrist Pin
Same = Valve train

This is, of course, a generalization, but can be helpful as a quick diagnostic. You may also want to invest in a mechanics stethascope. Not very expensive, and can come in VERY handy.

Would not be valve float until fairly high rpm. Assuming new valve springs, shouldn't be valve float at all. Valve float normally makes the engine run bad for a few to several seconds after the rpms come down.

Besides what tr-guy mentioned. look for exhaust leak at around the manifold/header

It gets loud around 2800 to 3000 rpm. I will check it out tomorrow and get back to you guys. Keep your fingers crossed.

sounds like a rod bearing. if it is, you'll have some oil pressure loss. check the oil pressure while the engine is warm.

also, if the knock is not as bad when the engine is cold, it's probably a bearing...

2800 to 3000 does sound like a rod knock. If you take it up to that rpm, and feather the gas, does it get worse?

The reason a rod knock will, is because you are unloading the bearing, by very breifly causing the crank and rod/piston to travel at the same speed. This is the same reason that pulling the ign. wire causes it to get louder. When you pull the wire, you are causing the bearing to go unloaded twice per revolution, once tdc, and once bdc.

UPDATE: I got a stethescope and the knocking is coming from under the valve cover. My oil pressure reads good (half way), so hopefully that eliminates the block. When I pull the wires, there is no change and knock does not get louder or quieter.

It has a junkyard ranger cam, brand new HLA's, junkyard roller followers. What do you guys think? Weak springs? Clearance issues?

The 2.3 can make very loud knock from the valve train. It sounds just like a rod knock. The 85 TC I sold to 2.3skidoo had two HLAs on cylinder # 1 that did that. Sometimes, it would be quiet, the next minute, knock, knock, knock. A rod knock does not come and go. Hopefully, this is what is going on with your engine. It is easy to fix.

Did you check the cam-follower for proper clearance? Shim the HLA if necessary?

SAGA continues!! I figure out that the noise is coming from the head. Well, while I'm revving it, my son notices that with every rev there is water shooting out the exhaust. I'm thinking the head is cracked. Maybe ported to a water jacket? I am going to pull plugs and post pics. Hope fully its just the head. I would rather pull a head than a whole motor.