forcefedeg01

Working on a 1991 civic hatch with a d15b1. i am using hastings std piston rings *75mm* and getting a .024 ring gap on top 1st ring and .022 on second ring. checked half way down the bore and an inch off the top, same results. checked bore diameter on all 4cyl and its perfect, pistons are perfect too no ringland issues or anything. I called Hastings and they said that is what they make them to be at, so i bolted it all up and get around 85-93psi per cylinder. i can hear air coming thru the cylinders when i spin it by hand coming from the bottom of the pistons.

What do you guys think? should i go with 75.5mm rings and gap them to honda specs or what. Ive never had a problem like this before and im thinking the ring gap is the problem causing it to be 100psi under what it should (180psi or so per helms)

D16SiHatch

these are the ring end gap numbers for the d15b1

top ring: .0012 in-.0024 in.
bottom ring: .0012 in.-.0022 in.

so either you missed a zero, or your engine is already bored .020 over.. assuming you meant .0024 and .0022 respectively, then you are at the max allowed gap based on the ranges above. so that being said, the engine should still run fine with those numbers. did you hone the cylinder walls? how did you get the compression numbers exactly? was the engine warm, and how many times did you crank it over? did you attempt a wet test after to see if numbers jumped up? not being in time would also cause low numbers.

compression specs are as follows:

minimum: 135psi
nominal: 185psi
max variation: 28psi

forcefedeg01

its stock bore, cylinders are fine and not honed. I used a cyl pressure tool from snap on, the engine hasn't fired up since its low in pressure, so yea its cold.

what is the wet test? ive heard about it but never looked into it. it seems that when i turn the engine over wit a ratchet on crank bolt and have my ear close to the crank (oil pan is off) i can hear cylinder pressure bleeding down thru the piston walls. like if the rings arent sealing the pressure from having too big of a gap.

the feeler gauge i used to get them numbers are not missing a *0*. its straight up a .024 not .0024, .0024 dont come close to touching the ring ends. i just ordered 75.5mm rings to achieve my ring end gap and follow thru with that

D16SiHatch

trying to test the compression on an engine that hasn't even run yet is not going to yield accurate results. also, you need to be able to sustain numerous revolutions with the starter motor, so doing it by hand is not really going to work either.

i don't know why you wouldn't hone the cylinders though, it is extremely important for new rings to seal.

it's very odd that those are the numbers you're coming up with. because effectively it means it's not stock bore, it's already 20 over. with the new rings you will now have approximately a .0040 gap on the top ring, and a .0020 on the lower. so you'd still be out of the acceptable range by .0016 on the top ring. the only way this thing is every going to seal properly is if you get the engine bored to 76mm.

forcefedeg01

i know how to do a compression test, i use the starter to crank it not by hand. i spin the motor by hand and can hear the cyl pressure from under the pistons hissing thru the rings from what i can pretty much tell. idk if its cuz of the ring gap or not, thats where im stuck. im going to check the bore size and piston size to make sure its stock bore. pistons dont say anything bout being std or watnot, so ill check up on that to verify everything and go from there. ill keep you posted, its the first sohc engine ive done but an engine is an engine. bad part is the thing seems like someone had played with it and riped it apart b4 from what i can tell.

thanks alot tho

D16SiHatch

sounds like a plan

forcefedeg01

ok, after measuring all the pistons and all the bores, the pistons are stock bore, measuring 74.952mm in diameter bore is 75.319. im think im done playin with it and takin it to the machine shop to get +.5mm bore. im thinkin of going with d16z6 .5mm over pistons in it to get it over and done with.

jlicrx

my manual shows 0.006"-0.012" for both on one page and 0.006"-0.014" for both on another page

D16SiHatch

interesting, i was just going off what alldata said. i suppose it's possible that what they have may be wrong. not sure

forcefedeg01

yea, im using alldatadiy myself for all work i do. jlicrx, is that a honda book? or other?, if i can get a hold of a Honda engine book that be way better

jlicrx

those pages are from the 1991 USDM CRX Service Manual

forcefedeg01

well thanks to you guys the motor now runs great. i ended up buying .50mm over pistons and getting it bored/honed/decked. started on the first crank. again thanks, its my first sohc rebuild and possibly my last lol. b-series all the way