So last weekend I dropped the hammer to get around traffic and I over-revved my engine. Now when I drive it, it seems fine at idle, but when I try to accelerate it hesitates and backfires a bit. I just replaced my opti, plugs and wires a year ago and have not gotten water in there, so I really doubt it's ignition.

I pulled the valve covers, but honestly don't know what to look for. Shoebox mentioned a possible push-rod in an earlier post. Just wondering if anyone else has had this happen?

 

You could unbolt all the rockers and take the pushrods out and roll them on a level surface and watch if they are bent. But be sure to follow the guid on shoebox's site about timing the rockers when you re-install them. I've over-reved and hit rev limiter on my car many times and it seemed to come out fine...knock on wood...car please don't brake again.

 

EDIT:

I know this is a blurry picture (I need new camera), but is it normal for the rocker to be this off center of the valve spring?

 

no, thats not normal. Could be due to a bent pushrod, then again they are self aligning so you may have just caught it at a bad time. Hopefully someone else will chime in.

 

Remove one RR and push-rod that is out of alignment, then carefully inspect everything. Roll the push-rod on a flat surface to see if it is bent. Check the washers on the S/A, RRs to make sure they aren't damaged and are slipping off the valve stem.

Check the roller tip and roller fulcrum to make sure they aren’t binding (turning freely). Check the RR aluminum body to make sure it doesn’t have any fractures. Inspect your valve spring to make sure it isn’t broken.

I be you’ll find something bad when you look everything over.

WD

 

I agree!!

I wonder if there was piston to valve contact knocking the rocker out of alignment.

Mike

 

That looks scary.
Are those self aligning rockers? It appears so, I don't see any push rod guide-plates.

 

The guide-plates are there, the picture is just too blurry, i'll see if I can get a better one


Here's some better pics




Even the one next to it seems a little off

 

There are only two guide plates that work forthe LT1 due to subtle differences in the rocker positions fom old SBC.

The GM bowtie plates (14011051) which are the most popular.
The Isky adjustbles which are a PITA to install but alo work well.

What plates are you using and do they show signs or wear in the slots?

 

I'm not sure which guide plates are on there in all honesty, I didn't put them on there, the previous owner did, but they don't look adjustable.

I pulled the one rocker that was crooked and it has a little chip out of it



It seems to spin fine though.

The pushrod didn't look crooked either. I rolled it on the garage floor and it seemed straight. I can't quite figure out why the rocker won't go on even with the spring, the spring doesn't look to have any cracks either.


EDIT: Here's a pic of the guide-plate

 

The wear on the aluminum rocker tip indicates a "bad" misalignment (valve stem hitting the rocker body). You must not have the correct guide-plate for the LT heads. Or, possibly the O-Lash was too loose.

WD

 

Do LT1 heads and LT4 heads use the same guide-plates?

 

Yes, LT1s and LT4s use the same guide plates. However, you must have guide plates installed on your LT1 heads from some other version SBC (not 2nd Gen guides). When you get an engine that someone built-up, you never know if they used all the correct parts.

Self-Aligning (S/A) RRs are an option for you, but not as cheap as the correct guide plates.

WD

 

I get that these probably aren't the correct guide plates, they do not have the 05 stamped on them. I'm gonna see if they're upside down, but I need to run to the store to get a long 11/16" socket. I need to double check though, the GM part #
# 14011051
off GM Parts Direct is the correct guideplate for the LT1??

I guess I don't understand though, I've had this car for 2 years now, never touched the valvetrain and it's worked fine before now.


Also, is it ok for me to reuse the rockers even though they're chipped a little? They roll fine and everything else seems in order.

 

There have been a lot of posts regarding the GMPP Guideplates wearing out real fast due to not being hardened.
I myself experienced some wear in a set after about 4000 mile use.
I found that the trickflow guideplates for the LT1 heads have the same spacing and are hardened.

RG