1_MEANZ28

iTrader: (4)

recently got a 383 lt1 camaro forged bottom end small cam (untouched heads and intake mani bolt onts) as some of u may have read,ivd been have the idle problem since i got it.on a cold start it fires up real goo and rpms stay at 600-700 at idle.at a stop thee same..after time of using it it starts idling at 1100 1000 at a stop..but thing i put it in park and it comes up to 1500 rmps and stays there till i shut her dwn..i replaced 1 o2 sensor due to the fact the idk how but i was draging it on my way to work.spoke to the previos owner said they were installd no to long ago so im assuming the other one is still good...thanks alot for ur help

93z383

iTrader: (-1)

could be anything...

vacuum leak
bad tps (or needing adjustment)
bad IAC
throttle body needs adjustment (do you have holes drilled? Do you have the IAC hole drilled through)

When going 383 the idle is a big thing to get down that plagues a lot of people. You need to slot your TPS and read the volts and make the proper adjustment as well as drilling through the IAC hole starting with stock diameter and moving larger if you need it. Better idle quality than drilling the blades or tipping them.

1_MEANZ28

iTrader: (4)

thanks alot for your help..ill look into these things..im fairly new to lt1's and well the 383

93z383

iTrader: (-1)

No problem man PM me if you need any detailed help. I've become somewhat of an expert since building my 383 and doing my whole car by myself with no prior experience lol... lot of blood, sweat, tears, and cursing but it's all worth it in the end.

do you have an aftermarket tb, and if so, is the IAC hole drilled through? The first thing to check for is that... to get a nice smooth idle you'll need the IAC drilled through to the stock dimension. If that's sufficient great, if not, take it one size up at a time and check it out. You'll also need to make sure your TPS is reading the proper voltage, and if needed drill/grind slots into it where the bolts go to allow for further <----> adjustment if needed. You go by the voltage reading. Vacuum leaks are a common culprit, and a dead IAC won't be able to compensate and adjust the idle and can also be an issue.

I chased down this **** on my 383 build for a long time and eventually found a combination of the IAC passage issue, a bad IAC, and a TPS out of spec.

1_MEANZ28

iTrader: (4)

wow,,yeai have the holly 58mm..i wouldint know where or how to check if the IAC AND TPS is drilled as u say ..how could i check if their still good?

ahritchie

iTrader: (1)

Not to derail your thread, but just curious why you (and many others) choose an aftermarket TB over a ported 52mm stock TB The reason I ask is they cost 2-3 times as much as a stock ported one and cause far more issues than a ported factory piece. From what I've gathered; 58mm is more than needed for 99% of LT1 builds....just saying....all these aftermarket TB's seem like a scam to make money for the aftermarket companies for very little HP gain and cause problems like you mention. Discuss!

1_MEANZ28

iTrader: (4)

unless its machine port it aint worth it ..hand port heads intake tb.might be good but in order fo good results cnc machichd is the way to go

1_MEANZ28

iTrader: (4)

but then again idk how they port stock tb.i may be wrong on the rwhp gains

ahritchie

iTrader: (1)

...nobody's using a dremel tool or hand porting TB's.....a machine shop bores it out to 52mm and installs new throttle shaft and 52mm blades for a little over $100..here's one on ebay: http://www.ebay.com/itm/52MM-THROTTL...4362d9&vxp=mtr

Once you put a airfoil in it there should be no difference in flow vs. an aftermarket 52mm TB...for less than half the price and no idle issues.

1_MEANZ28

iTrader: (4)

this ....

93z383

iTrader: (-1)

A 52mm tb is great for a stock/bolt on LT1, or anything small-mild build wise. But for the 383 guys like me and him, a 58mm tb is well worth it. I would never pay what they cost brand new, I agree with you there. I got my Holley 58 brand new for 200 bucks... Bought it not only for the upgrade but to match the rest of my engine. When you've got a few grand in powdercoat / polishing a few hundred on a throttle body already polished that's great quality and will net some good HP gains is well worth it.

Since you've got a Holley like me start off with the IAC passage. Take the TB off the car and look inside straight on, the same way it would be mounted on the car. At the bottom of the )( there will be a hole that directs air into the IAC that mounts on the bottom.

Take a drill bit and check the hole on the stock TB, and use the same size to drill through the Holley. Compare the two TB's, stock and holley, and you will see exactly what needs to be done. Drill straight through and be precise.

This is a necessary thing with a 383 build especially and should solve your issue. If not, it's gonna be the other things I mentioned. Like I said if you need more help PM me and I can walk you through it!

1_MEANZ28

iTrader: (4)

thanks alot for the help ..will do

1_MEANZ28

iTrader: (4)

bump previous owner told me that tb might be sticking,,what does that mean ?? new tb?

ahritchie

iTrader: (1)

lol...means it was manufactured/assembled poorly by some chinese kid

I want to see some evidence of gains going to 58mm TB; who's got a dyno (or timeslip) comparison of a 52mm vs 58mm TB on a built stroker? Inquiring minds want to know how much this 52mm TB is supposedly holding back my mild 383