I have a 92 Camaro RS 305 5spd

just got the car last week, have been driving it too work everyday no problems
well it’s getting that time of year and when looking at the car to buy it.
I seen the heater core was bypassed
I already knew what that meant !
replaced heater core yesterday and flushed the cooling system with air and water hose refilled everything with coolant, go to fire up the car and it’s surging at idle and attempting to die. Holding the rpm’s up in drive way it still surges a little.
running fine going down the road but stalls at stops not sure if I got something wet ?
i only unplugged one vacuum line and plugged it back in. I’m pretty sure the system is bled good I have amazing heat not sure what has caused this issue
any thoughts ?

 

I am very interested in this also. I had my engine (305) tided up by doing front and rear mains in addition to stim seals and basically doing a few alterations. The engine and 4L60E transmisson were taken out. When engine and trans were returned to the car it has developed exactly what was happening to the above question. I have checked vacuum leaks, IAC, etc. going next week to put on DYNO for further checks. I will add more to this thread when I have a result from the DYNO. Any help would also be appreciated.

 

Check timing, also check to make sure your balancer hasn't slipped. When I had a 305 in mine years and years ago my balancer slipped a bit giving me issues

 

I was using some Channel locks to replace the down hose on the heater core and it was a tight spot ! I’ll check the distributor make sure It’s tight and I didn’t bump it out of time

 

Nothing about this sounds like a sudden timing change problem, and I can't even IMAGINE how changing a heater core would cause a balancer to "slip" (which wouldn't even cause a change in timing, because the balancer itself inserts over a keyed shaft locking it in place).

I would look around under the hood everywhere in the vicinity of anything you touched while changing heater core and look for things loose/disconnected.

 

Lol how are you even real bro?? Hahaha the balance is rubber bonded and over time WILL slip. If I still ran crappy gen 1 SBC motors I'd give you a complete breakdown on how it can happen. Not saying that's gonna be his issue but it's something to look for. Man oh man

 

Have checked the timing and is ok!!

 

Hey,

First off, the heater core has NOTHING to do with your idle problem.

One these cars, the timing chain can become so worn that idle is a problem. But the timing chain is a deeper problem. Make sure easier things are OK first. Check your vacuum at idle. If good enough then likely timing chain slack is allowing the cam to move around too much at low idle causing a bad idle.

 

I would take offense, but by the sounds of it you are new to internal combustion engines so instead I'll explain in a way that hopefully helps you understand (if you care to learn).

On these engines the harmonic balancer does not directly affect engine timing. The marks on the outer ring of balancer do correspond to a timing tab which can be used to measure and then "set" the timing. The balancer has a bonded rubber ring that CAN slip over time (my thirdgen Camaro I drove today actually has that happened). The balancer itself does not set or directly affect engine timing and is mounted to the crankshaft over a keyed slot, effectively locking it in place. If the rubber ring deteriorates and allows the outer metal to slip it still has no affect on timing, UNTIL the mechanic goes to check the timing and points his timing gun at the timing tab and related mark on the outside ring of the balancer. In that case the slipped rubber has not actually changed the engine timing, but the mechanic gets a wrong reading because he may not realize his timing marks are no longer accurate and the mechanic compounds the error by THEN ADJUSTING the timing when in fact no adjustment was needed.

The OP in this thread has given no indication that such a process has been attempted, so there is no concern for change in timing in relation to the balancer causing his issues today.

I recently discovered the balancer rubber ring on my 1987 Camaro had slipped. Rather than adjust the timing by timing gun I just adjusted it to run where the engine is happiest. It happens to be 0* at the moment, but I suppose that is a moving target as the rubber will probably slip more as time goes on. Not worried about it, and in fact the rubber could slip the outer ring a full 180* and it still wouldnt affect my timing.

And there you have a brief lesson on harmonic balancers and timing. Hope you find it useful. Lots of good info on these forums, but only if you can find it "bearable" to learn.

 

I drove the car for about 30 minutes and got her up to temp. Parked the car and took off the radiator cap for a day or so to allow if possible the system to “burp”. I got off work the next day rechecked the areas I was doing work in, checked all the vacuum lines. I found nothing.
i realized the radiator level dropped a good 3 inches or so, I filled it up put the cap back on and fired the car up to listen for vacuum leaks and the car was back to running perfectly fine on its own
so I have a couple options
1. I got something wet and just needed time to dry
2. there was a large enough air pocket in the system causing it to flutter like that !? But doesn’t really make sense 100% being a mechanic
3. I have an intermittent issue !

I didn’t unplug anything so there’s no way of loose connections when looking it over and didn’t adjust any vacuum lines because I only took one off and I knew it was on

If problem comes back I will repost !
this doesn’t really help because I don’t know what exact cause it was ! Thanks for the support and quick response !

 

Okay boomer.