Gordiggz

Well, just as I laid out the perfect plan to swap in a 350 tpi and gathered many parts, then the perfect deal on an LT1 fell right in my lap. 250 bucks for a running '94 Caprice Wagon. 75k on the odometer. Runs like crap, rear main seal leaks, dual fans don't switch on. All fluids are within reasonable tolerances. No SES light.

Well, I dragged it home the other day and started toying with it. Obviously the goal here is to increase performance in the 'bird, so I need to get this beast running right before I make the big swap.

When you turn it on, in park of course, it starts right up, then idles just fine. But when you shift it into gear (R or D,2,1) it the whole car jerks and bucks, even the mirror vibrates. There is a bit of a knock sound associated with it as well. At first I thought this might be a rod or the crank, but I was also paranoid/skeptical with the car being so cheap. It's still a possibility but I want to rule it out very badly. There is also a sulfur/unburned fuel scent to the exhaust.

Since I heard the knocking noise, I went ahead and pulled the valve covers and relashed the valves. I did it with the motor running and went 1/4 turn after the loose rockers started ticking. This seemed to clear up a little bit of the noise I was hearing, but there is still plenty of this knocking/jerking. It does seem to directly related to RPM, will do it slightly in neutral when revving it a bit.

I started reading the plugs as well, all of the driver's side plugs were looking pretty decent, looked like originals (still AC Delco's), no abnormal wear for the most part. One plug looked like it got hotter the the rest, could've been the flourescent shop light too though making it look whiter than it was. Pass. sides are going to wait until I get a new set, just because they're so bad to get to I can't see going in there twice.

I looked over some of the vacuum lines, they seemed ok. Is there a way to test these by the way? I figure a visual blemish would indicate performance issues.

Any insights as to what I should do next would be appreciated. All I can think of is a misfire of sorts causing the unburnt fuel, but there's no SES light and I would think that would trip it.

Gordiggz

Update: Looked for damaged vacuum lines for a little while today when I go a minute and no problems so far. Looks like the probability of that being an issue is a little lower, but still out there. Would appreciate any insight at all anyone could have, even if it seems simple.

Air_Adam

Does the sound go away when it warms up at all? Some LT1s had piston slap problems when started cold, and it really sounds terrible. Not so audible at idle, but when you rev it up a little bit (like driving speed) you can hear it. My LT1 does that, especially when its really cold, but it hasn't caused any problems for me yet, and the sound does go away when it warms up some.

I would also check the flexplate - it sounds very likely that its cracked, which can cause a noise that sounds alot like a rod knock.