86WS6_T/A

Well, after thousands of dollars and 5 weeks, I thought I had my car done...

I originally started building the motor just as a "when I have time" swap but my stock 305 started knocking from a faulty oil pump as I later found out so I parked the car and finished building the motor.

Yesterday, I fired the motor up and brought it up to about 2000 RPM, set all my valves and set base timing. I continued to run it at 2000-2500 for about 10 mins to break in the cam. Oil pressure was good (stock gauge was maxed out over 60 psi) so I shut it down. Checked the oil and it was fine, down about 1/2 a quart. topped it off, got my valve covers bolted in and cranked it back up.

Got in the car, put it in gear and my rpms dropped, but when the rpms dropped, so did my oil pressure down to like 5 psi so I shut it down. Cranked it back up and I can hear a noise now. Shut it back off and took the valve cover off to see if something was hitting..... nope. Went to crank it back up and its starts clattering.




Any possible ideas to why this motor did this??? Everything internally is brand new. Only used part is the block itself.

Sorry for the long winded post; I'm just upset and confused and need to tell someone before I throw gas on the car and blow it up.

Air_Adam

I thought it was supposed to be run at 2000-2500 for 30 to 40 minutes to properly break in the cam?

Maybe your running lean or your spark is too far advanced at idle? Or maybe too low octane gas?

I don't really trust the stock guage for any reading more accurate than a 'ballpark reading' but if it was way over 60 like you say, then that may have been a little too high... with a SBC, alot of times, if its over 55 or 60psi, then it can whip air into the system.

I think the best way to find out whats going on is to take a compression test and/or drop the pan.

GASGZLR

Maybe your oil pump failed or something else in the oiling system that caused no pressure and your rockers or rods to start clattering.

sqzbox

Pull pan and re-check main and rods. Sounds like you lost clearence somewhere. That would account for the sudden loss of oil pressure. Clatering is probably from low oil pressure to the hyd. lifters.

ede

did you measure or other wise check any of the clearances before you reassembled it? did you remove any oil plugs and not get them back in or not use sealer on them?

1986redbird

that was my first thought, he lost an oil gallery plug. with that high of pressure and pressed in plugs it may have blown one of them out.

86WS6_T/A

Well, I found the problem. Number 2 rod had a bolt that started to back out and started to eat the bearing. Crank looked perfect so I checked the rod bolt stretch and it was fine, slapped in a new bearing, bolted it all back up and it runs great now.

Don't know why the bolt backed out cause they were all torqued to 50 ft/lbs.

Oh well, now I need to get my chipped burned and I'll be in business.

Also need to update my sig.

sqzbox

GLAD to hear that! Bet you are too! Funny story? I put a new set of bearings in my 283 ci. once, and had my dad underneath the car keeping the rod bolts from hitting the crank. after we got it all back together and started it, BIG knock!! So I got underneath and started to remove the pan again and I found a bearing half laying on the ground. I said DAD!!!! he said sorry, I wondered what that ding sound was when you were tapping the piston down! Evidently, he didn't see it come out. I wanted to choke him but, he's my dad right? We still laugh about it today!

iggy1991

I'm having the same problem with my new engine. I wish I would have read this before I put my oil pan back on. I'm gonna check the rod bearings sometime soon to see if I am having the same problem.