1983 Jeep Cherokee street fighter project

[ghinmi]

Commence the teardown. I'm going to lay this out so that hopefully people can see what worked and what didn't on a high hp mostly stock engine. I went through it with a fine tooth comb and improved what I could on a budget. The motor got hurt on July 18, it was back together August 1.

Well that's nice. Porcelain is harder than aluminum for sure.



Obviously got the head too. Might be a little hard to see but it failed the head gasket and you can see where it torched the head into a water passage in the upper part of the photo.



Probably not related but intake gasket was funky on that hole as well.



The valves were interesting. Evidence everywhere of major valve float. If you look, you can see the valve tips are mushroomed over and I had to file them to remove them from the heads. It also had smashed the valve job basically flat. Live and learn, the stock valve springs were not up to the task of 6400 rpm, haha.



Bearings all still looked decent. Reused them.



Stock cast crank still mint.



Now this is wild to me. That's an entire engine's worth of rings. 1mm 1mm 2mm. Hard to believe.



Bare block honed and ready for the jet washer and hand wash.



Instead of welding up the one head, I just used a spare I had laying around. Fresh surface on both.



Valve job done and in the jet wash. The existing valve job was so ugly from all that valve float.

[ghinmi]

These babies should take care of that valve control issue.



Got lucky. The porcelain didn't smash down the ring grooves. Dug the porcelain out, knocked off the high spots, good as new.



Short block back together. I swapped the #1 piston to a more conservative cylinder just in case.



Degreeing the cam.



Ready to drop back in.

[ghinmi]

Back together. Always wanted to drive it around with the front end off so why not?







Unfortunately the driving was short lived. It nearly immediately started dumping coolant out the radiator cap under boost. Thinking it was possibly an air pocket in the engine, I kept trying to bleed it and also found a leak in the radiator that I temporarily patched while waiting for a new one. Turns out the whole radiator got ballooned out when it torched that head.



On Wednesday the 12th while sitting at work I decided I was going to drive it down to Indy on the 15th to help my friend with his car at the 1/2 mile airstrip event. I would have to quit grasping at straws and tear the engine down, find the problem, fix it, and put it back together in 2 days so I could leave on the 14th. I lucked out and it was a simple blown head gasket. Confirmed to be a defective gasket, $15 unit straight from Mexico. #6 cylinder this time. I was able to get it all apart, fixed, and prepped for reassembly Wednesday night. Cometics and head studs showed up Thursday, got it all back together Thursday night. Drove it to work Friday. Did a quick retorque on the heads after work and drove straight to Indy with my fingers crossed.



Got down to Indy late Friday night. Went to spectate. And wouldn't you know it, I've got some great friends. There was a racer ticket waiting for me. Now here's the dilemma. I'm 3 hours from home. I have been WOT with this engine exactly zero times since it's hurt itself twice. And now I'm about to go wide open 1/2 mile at a time. So I pulled a bunch of power and ran it. Made 4 passes the first day. Best mph 155. No carnage. Pretty thrilled.









On the second day it went 156 on the first pass and I got talked into turning it up just a teeny tiny bit and it went 160 on the second pass. Awesome. Back to the reliable workhorse it has been for the past few years.

[ghinmi]

Got a chance to do one autocross with the Porsche club. It's the only one of the whole season in our area, everything else is cancelled. It was a very tight course which was not good for the Jeep but it still did ok. They never posted the results online and I haven't been able to find any action shots.





And did some camping.

[ghinmi]

Now. Back to the fun times. Party tires back on, we're going to the track!





I had noticed that the injector duty cycle had gone WAY up at the same boost levels. So I had a good idea the freshened up motor made a fair bit more power but I had no idea it was that much. The previous best 10.36 @ 136 was at 24 psi. I ran it at 22 psi all night this time. First pass straight off the street, soft launch, short shifting was a 10.13 @ 139! Wow! Huge gains! I turned the launch up 400 rpm and shifted higher. And was rewarded with............



Heck yes!!!!! Finally in the 9s! And at 140 mph!

Went back around again and another one! 9.97 @ 140 mph!









Best part is that I got to drive it home and didn't work on it the whole time!

[ghinmi]

And what do you do the morning after you run your first 9 second passes? You hook a buddy's turbocharged hyrdo to the back of it and go for a boat ride.









And another boat on Holley EFI that I got to tinker on.

[SSLance]

Heck of a summer so far! Thanks for posting the updates here.

I've caught bits and pieces elsewhere but still read all the way thru again here.

[WSSix]

You weren't kidding, lol. 9s are awesome! Congrats on doing such good work.