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Discussion Starter #1
Hey Honda experts,

I am having an issue with the D16a6 Engine after a fresh rebuild. Here's what was done:

Engine:
Bored block to 75.5mm
Rehoned cylinders
Oversized OEM style pistons
Hastings Rings
machined top for flatness (not sure how much the machinist took off)

Head:
New seals
New guides
Valve and head grind to ensure good seals
Head machined for flatness

After rebuild, i took it for a few spirited drives to ensure that the rings seat properly. I've run through 700 ish miles already on this rebuild and here are the things i've noticed. It is still burning oil. I have burned through a quart in the last 700 yet there are no oil burning smells or signs out of the exhaust. No visible leaks of exhaust or coolant.

I pulled the plugs last week and they show signs of normal wear. Electrodes and center insulations are clean vs the outside is the dry sooty color. However, the pistons are covered with oil and have the dark brown carbon deposit already. The pcv system is fine and I don't see any plumes of smoke after engine braking with hard acceleration so I don't believe my valve seals are leaking. I was under the impression that the piston rings are bad / not sealing so I ran a compression check. Numbers were low, 115, 115, 110, 110, well below the book specs but the engine fires up, idles and has absolutely no hiccups. Even at high >5000 RPM there is no visible smoke and it pulls strong. Yet it burns oil and has very very low compression. My timing is fine but since the head and block decking, i have turned my distributor all the way advanced to compensate for the decrease in pulley to pulley height. Would the compression change be a result of mismatched timing marks?

I wanted to get some input from the more experienced D series builders here on what I can check before i pull the trigger and pull the engine out and inspect the rings / bores. I am planning a leak down test soon but afraid of it coming back as normal or that I wont be able to see where the leak is coming from.

All suggestions appreciated and will be looked into.
 

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Discussion Starter #3
I did not, i was planning on seeing how the leak down test turned out but I might do a wet test later tonight. Then try leak down when I get a chance to stop by the local harbor freight and grab a compressor from a somebody.
 

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have you adjusted your a valve lash since you built it and ran it?
What was your ring gap?PTW?
You said you bored it to 75.5 then honed the cylinders.I don't understand why you would hone after a bore?Did you take the pistons to the machinist when he bored it so he could bore it to the piston.They mark them after they bore them the number cyl it is if it is done right.
 

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Discussion Starter #5
Yes, the machinist bored and honed to pistons. He said that each cylinder had .001 clearance between the piston diameter and the honed diameter and that everything should be good for installation.

Also i'm not sure what the ring gap is to be honest at the moment as i did not measure it when installing. I trusted the machinist that it should be ready to go with the over-sized parts he ordered for me. This is my first build and I don't have much experience with this yet. It's a learning process :/

I have not adjusted the valves also since i had the machinshop adjust them with the head rebuild. Although I read I should do it after 500 miles on the rebuilt engine to make sure everything is within spec and nothing has moved. It is my weekend task if all the leak down numbers come out good or the wet compression test comes out good.

Much appreciated for the reply!
 

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Discussion Starter #7
Stock cam and stock internals. Only thing that was changed was the boring due to worn cylinder walls. When i got the engine it ate a quart of oil a week and after getting measured, the walls were .003" over the limit, therefore constituting a oversize bore. The pistons are oem style .5 mm oversized.
 

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My timing is fine but since the head and block decking, i have turned my distributor all the way advanced to compensate for the decrease in pulley to pulley height. Would the compression change be a result of mismatched timing marks?
you first of all need to reset your ignition timing and leave it alone.. the adjustment of the dizzy does not actually correlate with physical cam timing
 

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Discussion Starter #9
Timing was set to the service manual spec. alignment mark on the pulley for the SI model was aligned to the valve cover notch, and the crank pulley set to TDC. Then the timing belt was installed properly after too. I am not sure how much the machinist took off but since both head and block were decked, the ignition timing was advanced quite a bit. The distributor was correct to result in ignition timing at 16 degrees.

As far as resetting the cam timing, is there another way I am suppose to reset and adjust it? So far I have read that for resurfaced head and block combo, I need to get a new pulley that allows for timing compensation?
 

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Timing was set to the service manual spec. alignment mark on the pulley for the SI model was aligned to the valve cover notch, and the crank pulley set to TDC. Then the timing belt was installed properly after too. I am not sure how much the machinist took off but since both head and block were decked, the ignition timing was advanced quite a bit. The distributor was correct to result in ignition timing at 16 degrees.

As far as resetting the cam timing, is there another way I am suppose to reset and adjust it? So far I have read that for resurfaced head and block combo, I need to get a new pulley that allows for timing compensation?
This is incorrect. Your crank pulley will not be true after years of abuse. the "proper" way to set mechanical timing is to drop the lower cover and line up the mark on your OIL PUMP COG with the arrow on the oil pump case. and then set your cam to TDC, then add the belt, then tension it up, then ROTATE IT TWO OR THREE TIME COMPLETELY AROUND to make sure your marks are still on point. Do this and set valve lash and report back.
 

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Discussion Starter #13
Hmm, I will double check the timing and check/adjust the valve lash then report back. Much appreciated for the help!

Also rings were clocked per the FSM. Ring 1 and 2 had a 90 degree offset and the oil control rings were also offset respectively. Although I read that the first and second ring could have been clocked 180 degrees offset as well. :T
 

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i just did a rebuild. i noticed the mark on the oil pump but not on the cog. i used the timing on the pulley and it came out ok.


i dont trust a pieces of plastic for timing marks but its all i had to go by.
 

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If your engine is burning oil it has nothing to do with timing. Its your piston rings. When the spark plug ignites the air fuel mixture in the combustion chamber its getting blow by, which means the rings are not sealing good and air from the combustion chamber is going into the oil pan thats why you are buring so much oil. Did you oil the ring before sitting it inside the cylinders? Do you align the rings to the correct positions? This is my opinion on your issue. Hope it helps..
 

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I wouldn't have worried about a rebore with .003" ptwc on a stock build refresh. I know it's above a stock spec but you built it up quality. It sounds like the rings didn't seat right.

When you did the compression test, did you hold the throttle wide open while cranking the starter? You said you put the Rings 90 degrees to each other did you have any of the ring end gaps on the thrust surface of the piston? 90* to each other is kind of close for ring positioning.
 
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