Pistons & Sleeves

Question:

“I’m rebuilding the engine. Should I get 3 ring or 4 ring pistons?”

Answer:

Go with the 3 ring pistons. The 4 ring pistons which are touted to seal better actually have more drag (friction) which causes more heat and faster wear that would offset any gains from the extra ring.

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Question:

“Which type sleeves do I have?”

Answer:

If your engine is serial number 8N433578 or later, you have the .090″ wall thickness cast iron sleeves. All earlier engines could have either sleeve since many were rebored at overhaul time. The only way to know for sure is to disassemble the engine and take a look. I’ve heard that some suppliers of sleeve kits only sell the heavy wall sleeve and tell you that the older block must be rebored for the newer sleeve. This is not true. The .040″ wall thickness sleeves are available and will still work fine in the older engines.

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Question:

“How do I replace the sleeves?”

Answer:

There are numerous methods for removing and replacing the sleeves. Obviously, the easiest and safest way is to use a commercial sleeve puller set.

Reverse the puller setup to install the new sleeves. Most machine shops that do engine rebuilds will have one, and it’s usually a pretty reasonable price for them to do the sleeve R&R for you.

You may be able to rent one, or you could make your own that will do the job. The .040″ thin wall steel sleeves (commonly referred to as tin can sleeves) can be removed by using a tool to crush the sleeve inward away from the cylinder wall. This is a risky proposition however, as many cylinder walls have been damaged and even broken by people trying to wedge a screwdriver or other tool between the sleeve and cylinder.

Another method that seems to work well on both types of sleeve is to run a bead of weld from top to bottom of the sleeve (not too hot!). As the weld cools it contracts the sleeve and you can usually slide them out by hand.

Clean the bores of carbon and scratches but do not remove any stock or you could find your new sleeves are loose. Freezing the new sleeves (VERY cold) will contract the diameter and allow the sleeve to drop right in the bore.

However, I’ve never had a lot of luck with freezing at home since the sleeves warm up by the time I get them from the freezer to the engine block. Usually, the sleeve will press in the bore by pushing it down by hand.

Place a short length of 2×4 across the top of the sleeve and lean on it. Make sure the sleeves are starting into the bore straight! You can tap on the 2×4 lightly with a soft mallot but never hammer on the sleeve itself. If your sleeves are tight in the bores and won’t push in, make a puller to pull them in. Get a piece of heavy flat stock that will span the top of the sleeve and another that will span the bottom of the engine block. Drill a 5/8″ hole in the center of both pieces of stock. Use a length of 5/8″ threaded rod and 2 nuts between the 2 pieces of stock to pull the sleeves in. The top of the sleeves should be flush with the top deck of the block when installed.

The sleeves were intended to be a light press fit into the bores. If you find that one of your new sleeves is loose in the bore, try another sleeve. Don’t assemble the engine with loose sleeves, call a machine shop and see what other options they can offer.