This is our 5th CRX (really nice $400 California car!) but my first time tearing into a 1493cc engine. 235k miles, rebuilt at 110k. Previous owner dumped it since it smoked & used oil. I didn't investigate, just ground valves, stuck on new valve guide seals & slapped it back together with new head gasket. Now, it has 180-190 psi compression, but for some reason, it is sucking oil into cylinders 1 & 2, and smokes profusely out the tailpipe. Bores were nice & smooth when checked with the head off; after seeing it smoke, I pulled the pan- piston skirts & bores look good from below. Checked air intake, most vacuum hoses, PCV, disconnected brake booster, anything remotely connected with drawing air into the engine. I'm missing something.

FYI, I grabbed this CRX to run it on 2 cylinders, as a 750cc twin. I plan to weld & regrind the middle cylinder cam lobes to breathe every stroke, and supercharge the outside cylinders. Should get upwards of 14 psi boost. Looking to increase mileage to 75 mpg with this, and a few other engine modifications and eventually modify car to around 100 mpg or so.

But first, it has to run on 4 cylinders without smoking like a steam locomotive!

 

Of course, check the PCV system. You could do the card over the oil cap test to check for blowby gas. Smoke that gets worse when you floor it is going to be due to worn rings, even though the compression test seems OK. (Note that worn rings let a bunch of oil into the cylinder, which "seals" them and raises compression readings). For a project such as this you could probably just slap in new rings and maybe new pistons and not bore the cylinders.

 

Thanks for that suggestion. Already checked. Virtually no blowby.

This isn't just a little smoke in the exhaust, this is pouring out, filling a 5000 sq ft building with a dense cloud in minutes where you can't see. I realize, vacuum at idle will draw oil into the works, but this seems to be above and beyond that. The 2 plugs are wet and fouling out in a matter of seconds.

I did take notice that the cylinder walls are still immaculate and a new set of rings wouldn't be that big of an ordeal, but with the compression readings as high as they are, and the fact that it is 2 adjoining cylinders, I can't see it being rings. Instead of new pistons, I'd probably just knurl the old ones a touch.

We used to have a '64 Ford with a 289 & automatic. The vacuum line to the transmission was allowing ATF into the intake past a worn out diaphragm.

With all the emission stuff, I could see mixing up vacuum lines or having some rinkydink device leaking oil, but I'm not that well versed in these "late model engines." For our '87 CRX, I made my own manifold and stuck on 750 Honda motorcycle carbs.

 

One little note about piston rings... for the 2 cylinder conversion, I've considered remachining the 2 center cylinder piston ring grooves and installing teflon piston seals, and while I'm at it, maybe do that to the second ring on the other two pistons, too.