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Project Unicorn - a light duty trail rig

I need to stay in L.A. long enough to do that.

I will grant that it helps to be home.

My XJ is my daily driver, if I am home. Just yesterday I noticed I was down to about a quarter tank so I stopped and fueled it up. Pulled out my fuel log and saw that the last time I fueled it up was in mid-January.

Dang.

I am ready to be done with this particular season of life.
 
Not a whole ton to update here.

When I did the genrite tank, my fill hose and vent were in really lousy condition. I changed those out Friday. Only took one picture of everything on the ground, the old hoses were filthy enough that I never wanted to touch my phone.

Gates 24710 1.5" fill hose and a 5/8" fuel hose for the vent.

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Saturday I pulled the dash and changed out the heater core. Kind of a PITA job but not as bad as I was expecting.


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Turned out I didn't quite have enough hands to get everything back in place with the dash in the way, Itscheesy came by to help me slam it all back together and then took it for a test drive.

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I think he enjoyed it.

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Today I filled the tank all the way for the first time since installing it. It takes ~9 gallons after the fuel gauge pegs on full. Did 180 miles up to Tholke's and back, 80 mph the whole way there and 65 all the way back, averaging 18.9 mpg. Not terrible, but I think a new torque converter may improve it some.
 
Well, I'm still getting some pinging. Talked it over with Russ and we've decided to lower the compression ratio a bit.

Before pulling the engine for new pistons, we're going to try making adjustments to this one. Currently we're at 11.4:1 with .026" quench on a .043 head gasket. Going to pull it and try a .060 head gasket for 10.93:1 and .044 quench.

Also going to try out some new lifters while its apart.

Started out by calling up SC_Redneck and having him catch a flight out to visit.

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We yanked the head off this engine like we're pull starting a lawnmower.

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Noticed a couple of things here. Kind of an excess of carbon buildup for an engine with ~1K miles on it. And way too much JCR Handicorn.

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This does not excite me. More on it later.

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.... Project Unicorn you say?

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The exhaust valves are pretty clean but the intake are just caked.

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Went ahead and pulled the Comp lifters out (right) and replaced them with Johnson lifters (left). I've had some lifter noise since day 1, and it is becoming more common with the Comp lifters. Russ is looking at these as a replacement.

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New Cometic .060 gasket.

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Must be built for a TJ. Slight interference with the AC bracket, we just trimmed the gasket.

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That's a lot of gasket. Would be an issue if if the pistons werent .016 out of the hole, but it may be a problem solver here. Time will tell.

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The supervisor approves?

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Head back on, rockers checked for proper preload (which amazingly was just fine).

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5 spark plugs looked healthy, but Cylinder 6 has clearly been detonating.

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Valve cover back on, and waiting for the new manifold gasket to arrive today.

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We're pretty certain at this point the crappy baffles in the Crown valve cover are letting the engine suck oil, which is burning poorly and contributing to pinging. I'll be adding a catch can to the PCV and probably go back to a stock valve cover.
 
I'm curious to see the outcome from the compression drop, my experience has been worse pinging because of quench increase....but my experience was not on a jeep....so??


Also, maybe this has been covered....but have you flowed your injectors? I have a fancy machine for it if you want me to check them out?
 
Have not seen SC Redkneck in a while....
 
I'm curious to see the outcome from the compression drop, my experience has been worse pinging because of quench increase....but my experience was not on a jeep....so??

As a general rule, you are absolutely right. Russ believes that because this one was so tight to begin with, that we may get away with it. Our final quench will still be exactly half of what stock is.

Also, maybe this has been covered....but have you flowed your injectors? I have a fancy machine for it if you want me to check them out?

I have not. They are brand new 30 pound injectors from Five-O motorsports, so I didn't really feel the need, but I may take you up on that.
 
Ton of buildup on those pistons. Any idea what's causing it?

Sent from my SM-G975U using Tapatalk
 
Ton of buildup on those pistons. Any idea what's causing it?

Are the 30-lb injectors too rich. Sure looks the way.
So much for custom tuning.
I'm running 27-lb injectors in my Russ stroker, with a lower compression ratio.
 
Are the 30-lb injectors too rich. Sure looks the way.
So much for custom tuning.
I'm running 27-lb injectors in my Russ stroker, with a lower compression ratio.

Don't knock the custom tuning. The name of the game that day was "try and tune out the pinging" and I documented it as such.

It was still pinging under some scenarios, which is why we're now trying a thicker head gasket.

A lot of theories on the buildup. Obvs it is rich under load (we knew that), and there are some interesting theories that overtight quench may be extinguishing burn in the quench zone (not sure I buy that one, russ sure doesn't).

I cleaned up as much of the buildup as I could, gonna put some miles on it and do a seafoam, and if I don't see immediate pinging, schedule another tuning session to see if we can dial it back without more pinging.

If it still pings after that, probably have to have a new set of pistons knocked up dropping the compression a bit more. Our original goal was 11:1, the 11.4 was an accident (I re-used the race car crank and didn't consider it was offset ground). It will be interesting to see what happens, about to go out for the first test drive now.
 
Pinging is gone. Have what sounds like an exhaust leak that I haven't looked into yet.
 
It has been six months since your last report, how is the stroker running and what else have you done to the Unicorn?
 
Stroker has some valvetrain noise that Russ and I have been chasing. I've been documenting along that path but not updating as we havent resolved it*. It runs with good economy and a lot of power, but it sounds like a cummins 12v.

Would be long done by this point but my tow rig was pushed into DD duty while I was working on it, but keeps ending up in the shop - so i've been driving the jeep and don't want to take it apart. Truck seems to have weird electrical gremlins is in getting a complete engine harness now and hopefully I can get back to this car.



*Suspicion is either my custom cam was ground wrong or the lifter bores in the random core block that we used are worn and the lifters arent maintaining pressure. Have changed lifters, rockers, push rods, head, valve cover. Next top end comes off and we check the lifter bore with a new dial bore indicator purchased just to start checking this, and a new cam goes in (or the block comes out).

Its literally just waiting on me to have time and i haven't had any.
 
The sound of a 12V Cummins is a wonderful thing.

Except when it shouldn't be there.

I have the same glorious rattle in my 8.1L Suburban. I am just biding my time, waiting for the day I have good reason to pull that thing and rebuild it with decent tolerances instead of all the slop Gubmint Motors put in there.
 
Yeah, at idle its like "ok yeah thats neat".

Its not really neat at 2500 RPM though..
 
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