I installed a 408 in my truck yesterday, and it started knocking about 5 minutes after I started. I pulled the ignition fuse and turned it over until I had oil all through the motor. When I started for the first time, I had 42 psi of oil pressure almost immediately. It idled great, and there wasnt any rattling at start up. I brought the rpms up to about 1700 (idle was 700), and the motor starting stumbbling then died. I started it again, and it knocked immediately. Has anyone else spun a bearing on a new motor? What could have been the culprit? All I know is that I'm tired, sun burned and don't want to pull this damn thing.

 

how did you install your lifters?

 

I had the motor built by Kotzur Racing. The motor didnt make any noises at startup, it had 42 psi of oil pressure, starting shanking and then died. When I started it again it was knocking, but I still have great oil pressure.

 

it could be all kinds of things

Rockers not torqued right
lifters not being soaked
crank no being polished, or turned too far - not the right sized bearings


Have you tried to locate where it's coming from?

 

If it's still got good oil pressure, then it's prolly not a bearing.

Pull the valve covers off and see what gives.

 

I dont think they would have turned his crank any on a 408, odds are they had to use a new crank being that theres no factory 4" stroke cranks.

-Lurius

 

I dont think it is a bearing either. I am wondering if I had a piece of debris from the last motor lodge it self in the intake that is now lodged in to the head and getting hit by the piston. I am going to pull the heads off to see if there is any damage in the top of the motor. I was also thinking that a rod bolt wasn't torqued properly and maybe hitting the block.

 

Why not contact the builders? It is likely something they did that is causing knock. Ask them to look it over as warranty work or something.

-Lurius

 

exactly what Lurius said if you tear into it they probably wont warranty it or fix it any more. They can take care of it.
Dave

 

After spending all of that money, I'd go after the builder first. I'd go as far as the lifters, and that's it