So, I have a new head coming tomorrow. The cylinder walls are pretty well glazed, some very minor vertical scratches, carbon ring at the top. I am NOT going to drop the pan and remove the piston assemblies at this time (not until I pull the whole thing out for the max effort IT rules build in January). The question is thus: I do feel like I should run the ball hone down the bores, at least as far as it can go with the pistons still installed, to de-glaze and put a fresh crosshatch on the upper 80% of the bore length. My logic tells me it can't hurt and might reduce some of the stupid amount blow-by it has. I would press an oil-soaked rag down on top of the pistons to keep the slurry from getting down into the gap and wipe the bores clean before I removed the rags. I still need to keep this car in commission until I pull the engine in January for the re-build because I use it most evenings for pizza delivery, AND I want to make the October track session Hallett.
So, can anyone think of any GOOD reasons to not deglaze the upper 80% of the cylinder walls while I have the head off?
06HHR
HalfDork
9/21/16 1:10 p.m.
Amateur Engine Assembler here (definitely not skilled enough to be a builder) ordinarily I'd say go for it. But in this case, since you are about to dive deep into it for a rebuild in January I'd leave well enough alone. Unless you are completely certain in your ability to keep any of the slurry from de-glazing out of the bottom end of the engine I vote against it. No need to subject what may be questionable bearings anyway to any additional stress, and increases the chance that it will stay together until January. I did a cylinder hone, re-ring and rod bearing replacement on the SR20 in my Infiniti and it was great until it spun the #1 rod bearing after roughly 1000 miles. Not saying that doing the hone caused my problem, but in your case I don't think it's worth the risk.
In reply to 06HHR:
OK, some good reasoning there to consider. Anyone have any thoughts on the effectiveness of just de-glazing/re-cross hatching the upper 80% of the bores?
The rings, at least as designed, are supposed to ride on a film of oil and not the wall. Honing it even a little will open up the cylinders a very tiny bit. I would think that would cause more blowby and a decrease in power.
Maybe imperceptibly but I would be surprised if it helped. I would just de-carbon it all and run it. Especially if you're going to rebuild in a few months.
After the new head is installed give it an Italian tune up.
iceracer wrote:
After the new head is installed give it an Italian tune up.
Oh hellz yeah! Especially since I have learned a few additional porting tricks for this particular engine. You wouldn't believe what the Brits and Germans can make these engines do.
Don't hone with the pistons still in the bore. You will hit the pistons at least once with the hone and the aforementioned metal slurry is absolutely deadly to the motor. If it gets in the sump (and it will), the oil pump will metastasize it all over the motor.
Just put it back together, you're playing with fire (gettign abrasives in the engine) for minimal (if any) gain.
