madkaw

Well there was no smoking gun that I found . I pulled #6 piston to find oil around the top ring , but the second ring was pretty clean . Tends to make me believe the oil was coming from the top . I only replaced the 6 intake seal earlier , but since have changed all the seals back to the Ford seals . Inspected the piston and threw it back in . Haven’t fired it off yet - will keep my fingers crossed .

That’s pretty crazy it’s so versatile

PCV is basically located on the bottom center of the n42. https://images.app.goo.gl/s7MedL1SofYUqDMXA It actually looks biased towards front . I run through oil catch can to the PCV . I also think the #4 would get most of the junk being close to the PCV .

Okay - turns out I have an oil issue . Oil is getting into to cylinders 4-6 , progressively worse from 4 on . The oil is diluting the charge and causing a misfire - especially in 6. 4&5 seems to be able to burn it off . I removed the intake to check for vacuum leaks to find an oily film in the runners 4-6 . Runners of intake and head both had oil film. First suspect was/is the valve stem seals. I tried a different kind on this build vs my L24. Visually they looked fine . They took a lot of persuasion to install and thought maybe I used too much . Last seals were a Ford seals , which were difficult because they are finicky as hell to install. Actually replaced #6 seal while head was in motor - ran motor and still have same results . Not being able to pin this down I decided to pull the head and look at the guides and anything else . Getting good at this now I guess - 1 hour later the head was on the beach . But no smoking gun found . I ordered more seals anyway. Decision time now . Do I go deeper and pull pistons or throw all new valve seals on and reinstall head and keep fingers crossed ? I was getting ready to leave town and really wanted an answer so I dropped the pan and pulled 6. Still no smoking gun - as far as my experience(novice) eyes can tell. Got on the phone to my machinist - but didn’t hear back yet. My inspection was very quick , so when I’m back in town I will scrutinize closer . Just trying to determine source of oil . I was expecting to see a collapsed expansion ring or another failed ring . There was marks on the bores on the thrust side that were fairly significant visually , but nothing you could feel. I have an extra assembled f54 flat top short block sitting there untouched by amateur hands with 110k miles with perfect wear in the bores . Also pulled a couple of bearings and everything looked spot on. Depending on what I find or not find it might be the next plan. With the head off it makes assembly decision equal. Though this is frustrating , the hobby of engine building will have these outcomes I guess . Not being a stock engine makes this more of a challenge . Missing the L24 right about now because I enjoy driving my car - a lot ! I was hoping for more engine swap and tune - not engine swap and troubleshoot . Hopefully I learn from my mistakes

It’s oil

Well after trying about everything I could think of I pulled the head . I definitely have an oil control problem . Since this is a fresh assembly I must of got something wrong or something failed. I tried different valve guide seals on this build, but examining one of them I couldn’t say if it failed . Removing the head revealed a oil film on 4,5,6 with 5&6 being the worst. Maybe oil control rings broke, failed ? Im going back to the Ford valve seals, but really should pull a piston - ugh. Just weird it happened on the last three . Or is possible it’s just #6 and engine vacuum is dispersing it between the closer runners ? Learning a lot in this build - the hard way

I started a thread #6 fouling. I swapped to a zx dizzy and nothing changed

I will also say I’m a bit reluctant to swap the O2 sensor over for fear of ruining it with oil . Not sure what else it will tell me that nits obvious from the plugs at this point

Running rich from a dilution of mix from the seal leak possible?

FPR is after the the tail . I could split the batch. I have the hot running to the fuse box , just got lazy because MS said it was okay to run all 6 with one hot. Need to get sequential going , but this should work unless the demand can’t be met with a bigger engine . I do have some kind of oil issue from a seal or something . Maybe get away with swapping intake valve guide seal on #6 will help

So I pulled the intake and found and oily residue lining the intake runner of 4-6 . Looks like # 6 could have a bad oil seal . Maybe bad enough to foul the mixture . The plug always looked more like carbon fouling and brushed off pretty well with a wire brush so I didn’t suspect oil . Not sure if a bad oil seal would cause my bouncy vacuum readings unless I’m seeing this as a misfire . Hopefully the guide itself is not bad . I tried a different type oil seal instead of the Ford seal and I guess I didn’t get one right . I’m assuming the color in the plugs on 4&5 is from a small amount is containment from #6 oil getting sucked over from the plenum . The pic is brand new plugs ran in a warm up cycle- I know , not the best, but car is on lift . 1-3 looks clean and is running 13-14 AFR. 4-6 get progressively worse. Valve pic is #6 .

Pretty sure I can the cam timing right , but maybe time to check. Not sure how I could get 225psi on retarded timing

Sprayed it down and couldn’t find anything

I see as high as 10 at 1000rpm

Running a stock n42

Well it’s batch fire and I swapped the leads between 5&6 with no change .

So the intake was biased forward or backwards ? So are you saying this didn’t cause a vacuum leak but caused inconsistency in the runners ?

Running batch fire so all cylinders should be the same . plug shows carbon fouled - dry stuff that brushes off pretty easy .

L28 54/MN47 Short block is fresh for the most part. New bearings , rings rebuilt head 530 lift cam megasquirt 3 - NA It’s a long story but this is what I’ve done Compression test 220 + or - 5 all cylinders . Coolant pressure test - passed leakdown - less than 5% swapped coils , plugs, wires , injectors, injectors connectors . Checked valve lash - several times checked for vacuum leaks vacuum is about 9 at idle vacuum needle bounces badly - especially at idle . It’s hard to make out a reading. The MAP gauge on MS is not that erratic , but it isn’t smooth either . Is it possible to have a bad HG and still get 225 on a compression tester? Is it possible to have a broken ring and pass a leakdown ? Is it possible for either of these tests be mute under running conditions ? I am at a loss and ready to rip it’s head off but will take any last ditch efforts and thoughts .

Okay - I am in the same boat here and I’m glad you posted . A while back I had a misfire issue that was very hard to diagnose . It was the spark plug wires were leaking and cross firing . These were genuine GM wires that weren’t very old . It took forever to figure out . Put a new set Magnacore on there and fixed it Now I have put a bigger motor in and have a high compression build I am having issues again. #6 is fouling for no apparent reason . I swapped everything possible , coils, wires, plugs, injectors - nothing helps . 225 cylinder pressure , good leak down test, good coolant pressure test . Getting ready to install a zx dizzy and wires to check to see how things go . I think these smart coils trigger to easy . #6 coil sits right above my starter . Maybe proximity is going to be the issue . If not I have a hardware problem - like piston ring ?

Is this group buy still active ? I’m ready to pull the trigger .

P79 sold

I have a clean p79 from a fresh part out . Deck surface is flat , and valve train looks good. All the spark plugs had nice burn to them . Should be able to bolt in and go -250$ E-88 is late model with OEM valves . Looks completely stock with a good cam and rockers . Deck surface is .002 out of flat - probably be fine. 99% compete , but missing some mouse traps . Just a great core with most pieces including spray bar - 150$ shipping extra

L2.4 is gone and the L 2.8 is in. Time to challenge my tuning abilities .

Well I let this thread slip along with the build. Anyhow, it’s running with a Don Potter cam 11.25:1 CR A little vid of me driving around breaking it in.