Questions about rebuilding my stroker motor..

Melissa

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Joined
May 9, 2023
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Wesley Chapel, FL
Guys go easy on me. I am a woman who usually works on my own Jeeps, but this is way over my experience level. I have an 89 YJ with a 91 motor that has been converted back to carb and is a stroker motor. 3 years ago it had been stumbling and stalling for a while and then wouldn't start. It sat for all that time with no air filter, and a louvered hood. Ouch. The carb was full of gunk and got tossed. The intake had a lot of aluminum oxidation so I pulled it off and soaked it for a week. Inside the ports there is surface rust on the valves. I pulled the oil pan and there isn't rust anywhere else unless it's on the upper part of the cylinders. The motor won't rotate by the crankshaft bolt. Any more force will snap the bolt. But,, it rotates when I push the Jeep. It seems to hang up in one spot on every rotation. Going to pull the head so I can see inside the cylinders, so I may as well replace everything. Looking for rebuild kits and all I can find is conversion kits. I also need to find out what my bore is. Can I just take the head somewhere so they can tell me? Any advice would be really appreciated.
 
Your stroker should be a 4.0 with the crank from a 4.2. Largest bore with longest stroke. How much it may have been over bored can be determined with a dial caliper but the head will have to be taken off.
 
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Your stroker should be a 4.0 with the crank from a 4.2. Largest bore with longest stroke. How much it may have been over bored can be determined with a dial caliper but the head will have to be taken off.
Thanks. I plan to pull it off tomorrow. Can I just buy a rebuild kit for a 91 and buy the pistons, etc seperatly?
 
Thanks. I plan to pull it off tomorrow. Can I just buy a rebuild kit for a 91 and buy the pistons, etc seperatly?
Yes you should be able to do it that way. You may not need new pistons though. And if the rebuild kit comes with rings make sure it’s the correct over bore .