iroc.86

i just recently purchased a nitrous kit.

i installed kit per directions

started with 75hp jets
sprayed it monitored afr all chcked good

100hp jets installed 4*retard and all checked good

150 jets installed 6*retard the afr went extmely rich and started poping thru exhaust

now engine claters under medium load never did this before.
it still has all its power though.

do you think i hurt something or maybe the plugs just fouled out or something

xpndbl3

iTrader: (5)

how rich did the AFR go? is it a rod knock noise? what is a "clater" ?

how do the plugs look? did you go 1 or 2 step colder on the plugs when spraying the 150 shot?

Sonix

iTrader: (1)

Pop the valve covers and check that stuff first, that's easiest.

Maybe help us help you - tell us what the heck this is even installed on eh? Year, engine size, induction style, carb model, etc etc?!?

iroc.86

its a 350
lunati 60101 cam
810 casting on the heads
hsr intake
accel 24lbhr injectors
commander 950 ecu

it clatters like if you have bad gas but only under medium load light throtle
it doesnt do it at idle or anything

the o2 read like .98v

the plugs were bosch 7575 and there are toast now hoping thats all it is seems like its got a dead hole nowthe plugs were brownish red with heavy deposits

Sonix

iTrader: (1)

Hmm, probably just plugged up a few plugs and it misfired = rich.
Change the plugs and go from there. Hopefully it was just the plugs (crosses fingers)

iroc.86

i def hope so thanks for being optimistic man

xpndbl3

iTrader: (5)

i hope you're not tuning off a narrowband 02 on nitrous instead of a wideband 02. wow.

iroc.86

yeah its a narowband

Batass

iroc.86

well i am not trying to tune the kit yet jets installed are the factory calibrated jets. nothing wrong with a nb o2 theres plenty of people using nitrous that dont have anyway to monitor there afr so i dont know why yall are making a big deal about it

Batass

I would say that it is dangerous at the 150 shot level. Especially with cast pistons. Just trying to warn you man.

iroc.86

i do have a wideband butt its its in the mail going back to holley ause it took a crap. i want to stick with delco plugs so does a R42T sound right?
if the plugs arent the problem its gona get beat on to make room for my 383 that was gonna go in my corv8

leeperryracing

clatter with medium engine load after nitrous use is usually a sign of broken rocker(s) and/or wiped out flat tappet cam lobe(s).

iroc.86

broken rockers how would it break them. they are stock stamped rockers

leeperryracing

stock stamped steel is exactly why they would break...lot of flex and not made to any kind of strict tolerances, its GM in the '80s what do you expect?

iroc.86

i wont be able to use 1.6 rollers on the stock heads will i
with out work to the valve guides rigt

the 1.6s will put me at .483in .499ex

Batass

Might want to post that somewhere where somebody that knows what a 810 casting is will see it.

Orr89RocZ

iTrader: (20)

well wouldnt you beable to hear that at idle and light part throttle? i would think a broken rocker arm is somethign that would stand out...lol

Sonix

iTrader: (1)

WHOA! Ok, .499" lift on 810 (like 193) heads?!? Guide work done?
A "clatter" sounds lighter than a bottom end noise, that's why I suggested checking the valvetrain. It's SUPER EASY to remove valve covers, you can see if any rockers broke, if any studs started to pull out, and you can run the engine (briefly) and see if any lifters aren't moving as much (wiped cam).

So.... you try it yet? Nothing to lose...

F-BIRD'88

Check the muffler for a broken baffle and or the cat for a broken core.
Check the exhaust system for a leak (collector gasket).
Check the torque converter/flywheel bolts and the ring gear welds.
Look for cracks between the flywheel/flexplate crank bolts

Batass

Im with you there fbird. If it only happens at an engine load, I would also think its exhaust or drivetrain.

iroc.86

havnt checked rockers yet, def not exhaust. dont see how it could be drivetrain it sounds exactly like clatter from bad gas. its only undr medium load its nice and smooth under wot

iroc.86

should i use r42tl's or 43's with my 150 shot

xpndbl3

iTrader: (5)

2 steps colder from stock

iroc.86

lets say that it is a rod noise that would be from a spun bearing right? and if that were the case the there would be metal in the oil correct?

Sonix

iTrader: (1)

Yes. You could drain the oil and cut open the filter and check for metal. However it might be from bearings or it might be from camshaft or from... etc etc.

Have you checked the easy stuff first though? hell, have you checked ANYTHING that we've recommended in the last few days??

iroc.86

ive been out of town and just barely getting to mess with it

no metal in oil or filter will post anything i find
appriciate the help guys

iroc.86

well i changed the plugs r42ts
still has a lope as if theres a dead hole

pulled vc's no broken rockers and all appear to have the same amount or movement wile engine runs.

so im thinking its a rod but wouldnt it make noise all the time if that were the case

Sonix

iTrader: (1)

What did the old plugs look like?

Clamp your timing light on each plug wire in turn to see if it'll flash the timing light. Or pull each plug wire in turn and put a plug in it and hold it against the block to watch it spark.

Got an IR gun? Shoot each header tube after it's been idling for a few minutes. Look for the cold one.

Pull all the plugs, crank engine over with a finger over each plug hole in turn. Find the one that isn't blowing your finger away - ie. not making compression.

Batass

If your thinking about a hole in the piston, it should be burning a lot of oil, shouldnt it? He said it still has all its power. Probably hammered a bearing. If your oil pressure is the same, then its probably a rod bearing.

But if theres no metal in the oil.....maybe you broke a piston skirt?

iroc.86

yeah i think its a rod bearing stacked oil press is same about 30 at idle 62-65 above idle.

so im going to build a 383 with some afr 180 eliminators

Sonix

iTrader: (1)

It wouldn't be a dead hole if he spun a bearing. It would clatter all the time, and it would be "knocking" more so than "clattering". I know that's more semantics than anything though.
The dead hole part makes me think about ruling out bearings etc. Unless a conn rod BROKE. But I kinda doubt it was major harm for some reason.

iroc.86

what kinda noise would a broke ring make?

Sonix

iTrader: (1)

You might be onto something there. A clatter.

Drive the car around the block a few times. Go home and pull all plugs and check them. If something is wrong with one hole it'll be SUPER obvious by the plugs. And should have been on the old plugs too!

iroc.86

it does seem to smoke a little bit more than usual when reved up
when i put the motor together i set the ring gap at i belive 15-17 thous acording to the mfg directions

Batass

Your probably right there, a busted ring would fit all those symptoms.

iroc.86

this is so wierd if i activate the nitrous system with the bottle off just fuel the noise will go away!!! butt the afr gauge never reads any richer

chevymec

iTrader: (5)

Have you checked the compression yet??

Also does it sound like spark knock?? What is the timing set at??

Wishmaster's87IROC

iTrader: (4)

the video I posted in this thread is what I broken piston skirt sounded like on mine. didnt do it at idle only at part throttle and WOT.

https://www.thirdgen.org/forums/tech...tml?highlight=

ross

If I understand you it only claters some of the time? Have you checked the flywheel and torq, converter bolts? I have seen the flywheels break around the mounting flange and make a noise that sounds like a rod knock and the noise will come and go.

Wishmaster's87IROC

iTrader: (4)

ive had that happen too. So theres a vid of that sound floating around here as well. Ive also got a vid of my rod knock and that will sound all the time not just at certain rpm's.

iroc.86

yeah it starts in 3rd above 2500 or anytime at about half throtle under a little load its not as loud at wot butt is faster

i have spark on all 8 cyl and valvetrain is functioning prop. engine still has dead hole it sound pretty close to your vid clip. so im pretty sure its a piston or such considring my small n/a ring gap

valencia1z

check ure converter bolts maybe loose cracked flywheel and if its injected tpi or so does it do it when its first fired up real cold or after it warms up a lil maybe a bad knock sensor mine sounded like the valves whould float or the motor was going to come apart detonating like a rod knock but it was just a dumb knock sensor