I don't know if I should post here, with stupid things done to car, or engine swap.

Last week I was drag racing ny '87 IROC (350, 700R4, 3:27 rear, Borla cat back) and blew something at 5200 rpm, yeah the engine was hot. Sounded like a rod, but the engine kept running, stalled some, no leaks, no power, no loose parts. Now it has a loud knock like hitting two hammer heads together. The noise went away in reverse and during idle when the fan came on. Started it today and a lot of smoke (white/blue) came out tailpipe and quickly went away. Never smoked before, car either. Harmonic balancer is good, flexplate looks good. Used stethescope, but could not track noise down. Very loud under car and sound like coming from valvetrain on passenger side. Plan to teardown to manifold removal this weekend. If still don't see problem, it must be a rod. Does this sound right?

If this is a lifter problem (collapsed or broken) can I simply put in new or must I have a new cam? Anyone have ideas on what broke?

Also, removed fuel pump fuse and car would not stop. How long does it take to remove fuel pressure this way? Where else can the fuel pump be disconnected?

If I need a new long block, I plan to go with goautocenter.com's 350 with 300 hp unit for TPI to simplify the swap and try to keep it one-to-one. Plan to keep tranny and rear, but add headers. From experience users, how is the performance of this engine with the cam for 300 hp?

 

There are a lot of possibilities. I'd start with a compresion or cylinder leakage test to help determine the general condition and possibly identify the area to concentrate your search.

You may have damaged a valve train component, like bent a push rod, rocker, or popped a rocker stud loose. You may have floated and bent a valve. You may also have done some piston/cylinder damage, like a wrist pin, cracked a rod, spun a bearing, or even broken a ring.

 

Don't forget about breaking a spring. Blue smoke is oil. Smoke on start up that clears up says valve damage to me. Probably wacked an exhasut valve and scored the guide. Clearing up under load could be from the lifter pumping up under higher oil psi. That would point to a bent valve or stud coming unpressed. Like Vader said, valve problems accompany piston problems and vice versa.

 

i'd suspect something in the valve train, but do a leak down test, see if you can spin the engine by hand

 

5200 RPM is nothing for the stock bottom end if it's in good shape and properly lubricated. I hit that, and more, just about every expressway on-ramp; and did when I had a stock bottom end too.

Is your oil pressure different than it was before, especially hot? If not, you don't have a bottom end problem. If it is, it's motor pull time.

Like ede & ato said, start with the valve train. Most likely you trashed a rocker and/or push rod, especially if it idles rough. Stock valve trains are garbage when new for high RPM operation, and just kep getting worse with age, so I'd also suspect that some part in it is where your malfunction is.

 

Dude....I feel for you. Something similar happened to me, only without the smoke. As I started pulling things apart, I kept hoping for something simple. Nope.....killed and spun a con-rod bearing, which resulted in the crankshaft being gouged about .045", the piston smacking repeatedly into my AFR head, and me being really pissed off when my $1300 internally balanced 383 rotating assembly needed replaced due to one $5.00 bearing after only 494 miles!!!!!!!!
Hope yours is something simple like a vlave spring. Good Luck!!!