madkaw

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.

Still have ECU, injectors , AFM,

Getting ready to install next week

Hard to imagine that’s Pertronix out performed LS2 coils

The gas smell drove me to EFI also. It worked well for me to shut the fuel off a couple of blocks from the house and empty the float bowls that way, but EFI is a better solution. Love those Jenveys

Looking great

It looks like you have all the ingredients to whip up some good power . I’d see what a 3” down pipe could do for you . It might change more parameters than you think. Do you run a knock sensor or did they have one at the dyno?

No experience with turbo builds , but from lots of reading here it seems that the very first things the guys do is the down pipe increase. You have invested a lot of money in forged pistons and other goodies , but you are choking all your investments with a tiny exhaust. Timing might also be a victim of your small exhaust. Don’t want to build heat by bottle necking flow. What was your timing at?What was your AFR’s?

P90 had steel seats already. Only heads that had brass were very early heads

Distributor is sold . Taking offers on remaining pieces.

Just installed mine . Numbers are good - especially P2V clearance for a 535 lift cam