When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
88 Z51: I bought it a couple years ago with zero history, it sat for 12 years and once I got it running, I found it had a bad engine vibration around 3k rpms. I had a feeling it was a rotating assembly balance issue, I was in denial or just was hoping it was something easy like a harmonic balancer or motor mounts. I finally tore it down and found that the engine was rebuilt poorly, someone put a new RA in it and didn’t have it balanced. I pulled the engine and rebuilt it with a new RA and had it properly balanced, I also had the heads rebuilt and had the intake, runners and plenum hot tanked and soda blasted. It’s been a 3 month weekend rebuild journey, but it’s finally done. Got everything back in today and it fired right up on the first turn. Runs fantastic, zero vibration, very smooth, trying not to get it over 3k rpms for at least a 100 miles, but it’s tough, this engine wants to go.
In this pic:
The two dowel pins that locate the head and head gasket aren't installed. Did you put them in before the head(s) went on? If they were omitted, you're probably ok, but the pins are important to locate the head and gasket accurately around the perimeter of the bores.
It looks like you may have gained a small amount of compression with 2 fewer valve reliefs.
Thanks. It’s been a journey for sure !
The pistons are Keith Black Hypereutectic flat top. They work great with a stock L98 cam and stock TPI set up. They do bump up the compression a bit, so maybe a little more torque ? All I know is my L98 sounds really nice and runs like butter. If you use any hyper piston, make sure you go by their recommendation for top ring gap, that’s very important.
This comment is not addressed to this thread in particular as I have noticed it in numerous threads before but have not highlighted it till now. Just an installation tip.
In your picture #1, it shows the block being lifted by a chain. It would be a good practice to have a cross bolt installed between the two chains under the hook. This prevents the hook from shifting positions.
Years ago, I was at a friends transmission shop and they were installing an engine with a cherry picker. The engine at one point bounced a bit and without warning, the weight shifted, the hook slid to the front and the back of the engine dropped like a stone, damaging the oil pan, snapping off the distributor and bending some brake lines on the car all to ****. Even better than the "through-bolt", I purchased a "happy hooker", a very useful tool.
The pistons are Keith Black Hypereutectic flat top. They work great with a stock L98 cam and stock TPI set up. They do bump up the compression a bit, so maybe a little more torque ? All I know is my L98 sounds really nice and runs like butter. If you use any hyper piston, make sure you go by their recommendation for top ring gap, that’s very important.
Thank you.
Hypereutectic is nice, but I prefer a low expansion forging for this kind of build.
I know they cost more, but as I tend to do my own tuning, it gives me an extra chance or two if I screw up the ignition timing.
L98 Vibration Is Fixed !
