It’s been about 2.5 years since I first tested compression on my Justy project car’s three cylinders. That was when I found out it was running on only two of them. Adjusting the valves made it a little better, but it still needed not only a valve job, but a full rebuild. Now that the (finally) rebuilt engine has more than 3,000 miles on it, I thought I’d check compression again.
If you recall, I had my machine shop port the head, and mill the head and block for an increased compression ratio. I also had a Honda motorcycle header modified to fit. I haven’t yet taken this car to the dyno, but it should make significantly more than 46 hp to the wheels. I’m hoping for 55, but that’s probably fantasy land. I’d say it feels quick, but the engine’s better at making noise than horsepower.
One thing I noticed while setting up for this compression test is that the motorcycle exhaust flanges don’t mate perfectly to the head. There’s a bit of an exhaust leak, which I will someday try to remedy with some red silicone gasket sealant.
The black soot in the area also suggests to me that this car runs a fair bit rich. Too rich? I don’t know, but the side-dump exhaust loves to pop and bark on overrun. Maybe that’s just the way they are. That certainly would help explain its poor fuel mileage : EPA ratings and my observed mileage are both in the mid-20s. Not exactly Geo Metro numbers.
So. How did the compression score?
Numbers like this fill me up with satisfaction. They also serve as a reminder that I should probably continue running higher octane fuel in it. It’s well above the upper end spec in the Subaru service manual.
I ran this last test with the engine warmed up, and jotted it on my garage whiteboard next to my previous numbers and the car’s to-do list. The first row of “after” was before I ever started the engine, so it makes sense that the rings seal better now that they’re seated in the cylinder bores. This chart is also my regular reminder of how far this car has come, and that all this work was worth it.
Other things it currently does, that make me less happy:
- Leaks oil. Maybe oil pan, maybe rear main seal. I have a new oil pan gasket on hand, so I’m hoping that’ll do it.
- Is loud. I love the side-dump exhaust (ahead of the passenger-side rear tire), but I really should get a proper muffler on this thing. It’s just too much for any drive longer than about 20 minutes.
- Not cool the cabin. I haven’t refilled the A/C system since I cracked it open for the engine rebuild. It was converted to R-134A by a previous owner, so all I need to do is rent a vacuum pump and set of gauges from the local auto parts shop so I can load it up with a fresh can of cool-juice. It barely worked beforehand, but I’m hoping a properly tightened accessory belt and a purge-and-fill will help.
- Seems to consume or leak coolant, albeit a very small amount. This will make it hard to find the source of the leak. Should be fine as long as I keep it topped up.
It has multiple other needs, of course, but those are my biggest concerns right now. Major work on the Justy has taken a bit of a back seat since my sister-in-law has started borrowing it as a commuter. This ’86 Toyota MR2 that I bought from a co-worker has taken my attention and temporarily taken over weekend recreation duty. Once the MR2 is fully straightened out (it needed a brake master cylinder and new oil cooler hoses, among other smaller things), I can sell it for a tidy profit.
Maybe then I can refocus on the Justy. Or maybe I’ll have a Mazda RX-8 to build for LeMons. Yes, for real. Yes, legit price. But we’ll see if it materializes.
Oh, you’re perhaps wondering about the free Fiero that I had previously mentioned turning into a LeMons car (in the background in the photo above). That went back to its previous home. It had too many needs and ultimately it wasn’t a car that piqued my interests. Fiero engines are heavy, underpowered and unreliable. That particular engine had spark plugs completely rusted to the cylinder heads, and dammit, I’m done doing engine disassembly.
I also keep telling myself I should reduce my number of project cars, so once I got the MR2, the Fiero had to go. I should focus on the Justy and make time to ride my mountain bike. And yet, somehow, I still ended up shopping for broken RX-8s.
Thankfully, I have an extremely patient wife.
[Photos copyright 2017 Alan Cesar | Hooniverse]