Piston Installation Issues?

[OK-944]

Installed one piston today…using a Lisle band-type spring compressor - and after a few tries, seeming to have a hard time getting the band snugged up enough to allow the rings past the top edge of the cylinder, I finally got it to work, but not without having to really tighten down hard on the clamping band, and not without tapping pretty hard with a wooden handle to get the piston to move downwards.

Thing is, it seemed like the compressor’s clamping force was uneven, even after I’d tried re-adjusting it a number of times, and that much of my effort at getting the piston to move downward was simply to overcome the excessive counterforce caused by this unevenness. The piston now seems to move ok in the cylinder, with no evidence of scratching or marring…but I am worried that I may have overly scuffed the piston skirt.

Before I go ahead and remove the fully torqued rod cap nuts to push the piston back out so I can check it, I just need to ask if my experience with the Lisle band type compressor sounds typical, and if I should just assume that all is well. Out of the box, this clamp did seem a bit lopsided - but my assumption was that this is a result of design and materials, and that exerting enough pressure on the adjustment screw would round the clamp out over the piston head.

At this point I’m kicking myself for not spending a few more bucks on a ring compressor with a more “rounded” shape, or perhaps even dedicated tapered compressor, such as those available through Summit Racing. But these band clamp style compressors have been around forever…so they must work. Anything I might try differently here?

[dme]

I remember having that kind of problem when rebuilding some old turbo Dodges. However this time last year I took my time and the pistons slid very smoothly into the cylinders. First, make sure you have the piston square in the clamp and line up the piston with the bore. Next, with the clamp setting on the block, press down on the clamp with a 2x4 across the top to get it even with the block. When all is set, push down with a piece of wood on the piston and it should slide right in (Don't forget to oil liberally). If you have to use a mallet to whack it in then it's not straight. The pistons went into my 951 smoother than any I've ever done. I'm ashamed of how I did it in the old days. The Lisle clamp worked just fine.

[OK-944]

I've gone ahead and ordered a tapered compressor from Summit Racing...but its great to hear that the Lisle worked well for you.