38386ta

I just rebuilt my 383 and threw it in the car. Started it up, had 90psi of oil pressure but after about 10 seconds it started knocking loudly, sounded pretty deep. I shut it off. Checked the pistons and no witness marks from my bigger cam. Pulled the rockers off found witness marks right under the trunion. I hope this is the issue, but I thought I may aswell ask and see if anyone knows. If not, im going to grind down the rockers and run it again.

Specs are, 11-1 compression 383. Aluminum 200 Dart heads. Comp cam custom grind cam. 555 lift and 262 duration. If any more info is needed just lmk.
Thanks, Sean

SbFormula

Is 90psi normal? Seems high, but what do I know?

38386ta

Yeah its pretty high. But the engine is fresh and I have 10w40 in it. So I think it should go down after it warms up

38386ta

Update, I grinded the rocker arms down and reinstalled them. Seemed to help the noise, but I couldnt get the engine to run long enough to be 100% sure. Tomorrow Im going to throw on a new carb, which should make it run, and see if the noise is gone.

Komet

Does it make noise when you turn it over by hand?

AlkyIROC

Sounds like a slapped together engine without checking a lot of clearances. 0.555 lift is a lot of lift for a standard rocker. Not sure how well roller rockers would work but with the old stamped steel rockers, you would have needed to install long slot rockers. I'd bet your rocker arm geometry is all out of whack also.

As for knocking, rockers usually tick. Rod bearings create loud knocking. Sacrifice an oil filter. Pull off the oil filter and cut it open to see if there is any metal in the oil.

38386ta

Lol you're not completely wrong about the slapped together engine. I did plastigauge the mains and rods, they were in spec. I forgot to mention its on an old set of crane 1.5 roller rockers, .555 lift is a lot, but it was the only cam I had on the shelf, couldn't afford another camshaft. College kid things. I'm pretty sure the rocker geometry is off, but I measured the pushrods and they fell right in the middle of the valve stem. I'm pretty sure it was the rockers making the noise, the grinding made the noise almost disappear. I'm also going to open the oil filter and see what it says. It could have been something else other than a bad bearing. Tomorrow will definitely tell the whole story. Thanks for your time and wisdom.

38386ta

Nope, turns over quite easily with the plugs out. Im almost ruling a bad bearing out. Pretty sure it was the valvetrain making noise

38386ta

Update again, I started it and sure enough its clanking around, but Im almost 100% sure its the cam. Time for a new cam

AlkyIROC

Everyone needs to start somewhere to gain experience.

38386ta

Yessir. Eventually I will have a running motor lol

GTA matt

iTrader: (1)

What oil pan do you have? Depending on rods and rod bolts, they can touch the stock oil pan where in turns in slightly near the oil filter. Makes a nice little knocking sound.

38386ta

Stock truck pan. But Ive ran this setup before and it never had clearance problems, but Ill be sure to check when I rip open the oil pan.