Dempseybe

Ok guys, I have a S13 SR20DET That had been rebuilt. Has about.. 10 miles on it maybe

After initial crank test drove it around the block and noticed it was smoking.
Immediately went home, took off the exhaust manifold and noticed the exhaust ports for 2&3 had black ash in it, and oily residue

Piston rings are new, and were gapped correctly to my knowledge. Compression is 145 - 160 on all 4 (all within tolerance)

Mods to the SR20
HKS cam gears
T28 S15 ball bearing garret turbo
Brian crower stage 2 head kit
Valves, springs, retainers
264 cams
Z32 MAF

Was untuned when it was started.

If it were the rings not seated properly I should see a noticeable decrease in compression on 2&3 correct?

Could a valve not be seated properly? Allowing oil into the combustion chamber?
Possibly the cam gears adjusted wrong?

Dempseybe

I'm not looking for a 100 percent "that's the problem" answer. More of like a opinion in the step to take next to be cost effective on how to narrow this issue down. The short block had been redone also by a local machine shop. Not by my uncle joe in his step moms garage

Kingtal0n

Did you adjust the camshaft gears after using a degree wheel on the camshaft lobe to determine optimal centering (for decked head/blocks)? If the head/block was not decked then why does it even have cam gears? Did you ask the builder how much he has taken from the head/deck?

The above has nothing to do with your problem, its just for reference (you can think about it).

On to the problem. I would have never run home and removed my exhaust manifold. Pictures of this situation?

It is normal within 10 miles to find a drop of oil or some smokey behavior on a new engine. If it has good compression across the board then the oil in the cylinder should clear up. How do the plugs look?

You need to do an oil change soon, what did the builder recommend and what are the main clearances. A .0012" main bearing uses a different oil than .0022" so you need to figure that out before even starting it.

Finally, after you get the right oil, and figure out how the cams need to be adjusted (by degree'ing them in), you can run the engine 10+ miles, and hopefully the oil clears out of the chambers. If you get to 20~ miles and find oil on the plugs still, then you need to investigate further. Perhaps someone put the wrong valve seals on it, or installed them wrong (it happens). Perhaps there is a problem with a piston ring (poor machine work). Perhaps the PCV valve is passing oil to the combustion chamber. (inspect intake side PCV for oil residues). Do not boost an engine that shows oil on it's spark plugs.

Dempseybe

Ok I pulled the motor expecting to send the short block back the machine shop. Thanks for the advice, I'll end up checking the valve seals, that could have easily been overlooked when putting it all back together. I'll post back once I do that and drop it back in and run it for about 50 miles

Dempseybe

What you have was EXTREMELY good advice and I appreciate the time you put into that post. Thank you.

Croustibat

Some smoke is normal, that is assembly lube burning out.

Having 15psi compression difference on a freshly built block is not.

Finally, Z32 maf, untuned ? I don't understand how it can even move, except if the tuner put a base map in it.

TheRealSy90

That engine needs to be put under load to seal the Piston rings. As well as under extended vacuum/decel.

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Dempseybe

Yes base map tune. The machine shop that redid the rings also honed and cleaned the short block. No bore, no decking. Nothing out of the norm. So I imagine their work was done 100 percent. oily residue was found in the exhaust ports of [email protected] but 1&4 are clean, so I figured all residue would be out. It also idled for about 30 mins before I drove it. Maybe I should drive it for a break in period.

Secondly if a valve is not seating correctly, if maybe there is a small gap between the valve face and the seal that could be allowing the 15psi difference in the cylinders?

Dempseybe

Just for safety measures, probably going to pull the head, lap the valves to ensure a complete seat. Put it all together and a good break in period. I want to put ARP head studs in anyways.

Kingtal0n

If you are using a stud instead of a bolt, the engine needs to be bored with a deck plate to ensure round cylinders.

Many people skip that step, but it is the right way to do the job.

Dempseybe

Part of the rebuild was metal head gasket and ARO head studs. Was decked

Dempseybe

Edit on the last post. Talked to the builder and he said head studs were installed

Kingtal0n

He put head studs in without using a deck plate? And now your bottom end is passing oil on two cylinders? Probably a coincidence,

but what does the leakdown say? You need a leakdown test to verify.

Dempseybe

I'll perform a leak down. But I just asked the builder if they used a SR deck plate when the short block was honed and torqued down, no reply yet but I'm almost positive they did. The machine shop knows better than to hone aluminum without using a deckplate

Dempseybe

If it wasn't done and now 2&3 are oval shaped and not sealing correctly.. I'm sorry for mixed information the builder isn't the most reliable source. It's pretty much me trying to find out exactly what was done to this engine

TheRealSy90

Lapping the valves is going to throw off the valve to rocker lash as well fyi.


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Dempseybe

So how are you supposed to lap the valves on a sr20 then?

TheRealSy90

Have a valve lash job done at the same time to make sure it's all in spec.


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Kingtal0n

Yeah these engines arnt easy to build. I have a list somewhere...

Dempseybe

I need to find a place somewhat local who knows SR20s well to machine it

Kingtal0n

let me know if you find one. I've been looking for 10 years and havn't found a single place. I used to think mazworx had their shit together but recently I am starting to even doubt them.

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Dempseybe

Ok, so if I take this to a regular machine shop, I'm going to need to know exactly what to do to this head so I know they will also. If I reuse my old valves, springs, retainers(which are brand new, maybe 10 miles on them) get all new seals. Have the shop do lapping, valve to rocker lash job, resurface the head. What else?

Dempseybe

UPDATE: ok so i took off the valve cover to check for wear on the camshafts from the rockers. No scratches on the cams, but what I did find looks to be some lapping compound in a puddle of oil sitting on the heads... Fuck

Kingtal0n

pictures really help, i notice you dont post any. Makes me think you are making this stuff up. If you run the engine, everything under the valvecover gets absolutely pressure washed with oil within seconds. So I dont see how some liquid could sit around.

Dempseybe

I tried uploading pics, said too large. Let me try to setup a tinypic account

Dempseybe

The motor hasn't been cranked in months, so it's all just standing oil under the valve cover

Dempseybe

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cotbu

Lol, that's a rookie build move right there! Your oil pickup is gonna have rtv up all in the screen, so you know some gets through.

I would do a tare down and rebuild if that engine was given to me for free.

Anyway, depending on how long this was built it could be assembly lube, and the oil puddles are normal unless you never tried to start it.

If it feels gritty, you probably got beat, especially after 10 miles that oil should have been change twice by now.

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Dempseybe

If that isn't lapping compound, what would be the grit?


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cotbu

Meterial from your cams, cam journals or head. Hence the you probably got beat portion of the post. It could be anything left over from a sloppy build really, which is why we change the oil a few times during break in.

If you can feel it, its already to late!

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