Having teething issues with new LT1 build, need some advice.

[Thirdgen89GTA]

Have u pulled the spark plugs? Are they all similar or is there one w a different coloring or no coloring? Amazing that a motor would idle w 1" Hg vacuum. Doesn't sound right.

Well, it took roughly 2-3% throttle with the MAF plugged in to idle @ about 900rpm steadily. But occasionally it would surge to 2000-3000rpm all on its own. I haven't pulled the logs from the laptop to look at them yet. With the MAF disconnected the engine will NOT go below 2300rpm no matter how long its given to calm down. With the MAF connected and no throttle given it will NOT run. Starts, revs to like 2500, the dies in the space of a second.

With the brake booster vacuum port blocked off it made zero difference on the vacuum gauge. So I don't think the booster is the problem.

But I did pull the plugs to look at them (pain that it is on thirdgens with LTs).

The front 4 cylinders, 1,3, and 2,4 were black/powdery/dry, I expected that since its been running rich as hell at times and has never even gotten up to temp.

The rear 4 cylinders 5,7, and 6,8 had a whitish powder on them on top of the black/dry fouling. Lean.

I can't find an external leak anywhere on the outside of the intake. All ports sealed. I would think if the leak is that bad on the outside it should be either audible, and show up if I was spraying carb cleaner where the head meets the intake, TB area, and vacuum ports.

I think its pulling it from the inside the galley somewhere where I can't see when everything is bolted together.

Either way, next step is to pull the intake, and then the head/s.

I'm leaning more on the heads, as they are the ones that had the most port work, unless the intake flange is warped I can't see a leak developing there. It wasn't ported anywhere near that much.

 

[Turbocharged400sbc]

does the crancase pull down to manifold vac?

first things first. block off pcv (a bad pcv valve can cause high airflow even at high manifold vac...the spring tension is tuned to keep the valve in the correct low/high/low flow positions at low/med/high vac.
its possible its the issue, remove and block the ports.
make sure the oil fill cap is sealed, and put your thumb over the crankcase fresh air supply (should be going to a metered air source behind the maf but in front of the TB) and the dipstick and see if it tried to give you a hickie.

if it does...and manifold vac climbs (your restricting the leak)...then yeah, internal vac leak.

 

[Thirdgen89GTA]

Thanks to all who helped. It's running right now. Video to be posted. High idle in speed density is gone as well.

Perfect 900rpm idle with 14". Which is probably about all I'll get with this cam.

 

[Turbocharged400sbc]

oh fer fucks sake...whad ya find?!?!?!?!

 

[Xfirez51]

oh fer fucks sake...whad ya find?!?!?!?!

Yeah. What's the story?

 

[Turbocharged400sbc]

spill the beans you vapid cunt

 

[Turbocharged400sbc]

probably got his mullet caught in the fan

 

[Turbocharged400sbc]

you had 2 plug wires swapped didnt you

 

[Turbocharged400sbc]

you found one cylinders rockers still sitting on the bench under a towel?

 

[Turbocharged400sbc]

found yer old ladies missin panties plugging a port?

 

[Bru]

 

[Turbocharged400sbc]

thats what you get when you hid all the batteries in the house

 

[Turbocharged400sbc]

bitches be trifflin' over tha steel mistress

 

[Turbocharged400sbc]

hampster was on maternity leave?

 

[Turbocharged400sbc]

you found a cracked butt plug didnt ya?

 

[Turbocharged400sbc]

vandals cut the ignition cables?

 

[Thirdgen89GTA]

Lol @ turbo. Lmao right here.

Yes. It was something stupid.

Don't have great signal and eating awesome chicken Diablo right now.

 

[Turbocharged400sbc]

how stupid?
"oops i forgot to connect that" or "accidentally closed the hood on my pecker" stupid?

 

[Thirdgen89GTA]

Corner of #8 on the intake gasket somehow split and was sucking air in from the galley.

No idea how I did it.

Also, the port just under the TB, I had a pipe plug in there, when I went to remove it to install it into the stock intake, the plug came out in two pieces and the center section was a hole. This plug leads directly to the IAC passages under the intake. Thankfully the plug, unlike the intake, is a ferrous metal and a magnet removed all bits and pieces left behind.

I sprayed with carb cleaner there before, but idle hadn't changed.

So, some air from one spot, some air from another spot…etc.

Cest la vi.

Sounds good now. However when it goes closed loop it starts to see some knock retard, about 1-2°, but its open header, so I am not sure if its in the tune. Looking at the logs tonight, need to see what happens to the timing when it goes closed loop, as there was none when it was warming up.

 

[Turbocharged400sbc]

good bit of suction at the fill cap/crankcase eh?

glad ya got er licked

a redneck tuneup down the street should fix er right up, post vid, kthnx

 

[Thirdgen89GTA]

good bit of suction at the fill cap/crankcase eh?

glad ya got er licked

a redneck tuneup down the street should fix er right up, post vid, kthnx

Currently has no brakes, needs a serious bleed and I was out of daylight. But I was itchin to put it on the ground and drive it.

Got to arrange a tow to my preferred exhaust shop so I can get the Y-pipe made and then look at the spark retard I was seeing when it went closed loop before I really drive it anywhere.

 

[Turbocharged400sbc]

pussy

 

[Thirdgen89GTA]

pussy

Every time I get the car going after a length of downtime I'm always nervous about actually driving it.

First time I had it at the track after the LT1 swap I was sweating bullets, and it was freezing.

Need to rent a truck and trailer to tow it to the exhaust shop now. Or risk driving it open header. But with the O2s so exposed I don't think that will be wise.

And the cops would probably be unhappy as well.

I think the first thing I'll drive it to is a DIY carwash.

 

[Turbocharged400sbc]

i dont even think my jalopy's even remember driving

 

[Thirdgen89GTA]

It LIVES! And it even did 40mph!

But man its too loud to drive.

I'm going to have to tow it, definitely tow it.

After 5 minutes in the car, my ears had a quiet ringing. The dB meter on my phone says it was over 110db the time I stabbed it in 1st a little to see if the engine would bog or go.

It went. Snappy.

Steering is amazing with the rebuilt front end + Lee 670 steering gear. The internal stop when turning to the right isn't short enough. I can feel it move to the edge and strain a bit. So I may have to send it back and have the steering stops adjusted.

I wasn't able to find any 100 octane up here, so I'm taking the gas can with me tonight and getting some 100 octane close to home, then I'll bring it back tomorrow.

I really think its false knock because it doesn't even do it with timing is advanced. It shows up when timing is at like 24-28° with no load, and even then its about .3-.7 retard.

Got some thumbs up while I was driving it around too, people wanted me to hammer it.