jgcable

My 77 4spd. Motor runs so good its insane. Idle is rock steady. Throttle is as crisp as a brand new FI motor. No hesitation of any kind. No smog equipment. EGR is blocked. My stock L48 has Hooker side headers and side pipes and an Edelbrock air cleaner. I notice a VERY slight pop in the passenger side exhaust only. It almost sounds like an exhaust leak but I can't find one. Its not every firing of that bank of cylinders. It could be intermittent but its constant enough to notice. What else should I be looking for? Timing is perfect, new plugs, new wires. Whatever it is it doesn't affect the way the motor runs at all.

gdh

It does sound like air is finding its way into your exhaust. I had the same problem when I installed my Hedman headers years ago. I didn't inspect the welds at the collector on the passenger side well enough as it had a pin hole sized leak. I imagine that you checked that they sealed up well to the engine with a bit of liquid.

Cool95vette

I was getting popping in my sidepipe exhaust. The header bolts had backed out. Tightened them up and it was gone.

Gale Banks 80'

Take the Coil Wire off so that it can't start. Then Crank the Engine with the Starter and listen to it. If its got a Miss when Cranking then You have a Cylinder with very little Compression. This probably isn't your problem, but its so fast and easy it rules out internal Engine problems.

MelWff

describe how you adjusted the idle mixture screws?

jgcable

I didn't touch anything on my carb. When I started the car it started immediately. All I did was set the timing. It idles rock steady and perfect. It has no hesitation of any kind. It warms up and kicks down beautiful. Idle is right around 850 and steady eddy. Car runs like a champ. I don't want to touch anything at the moment!!

MelWff

Is there something you left out from the recent past about this car. Did you install this motor recently? Somebody had to have adjusted the idle mixture screws at some point?

jgcable

I am the 4th or 5th owner over the last 10 years or so. The last 3 owners had never driven the car. Its had 80K miles on it since 2010.
2 owners ago the car had the 4spd tranny completely rebuilt. I have all the receipts. The motor had a new intake manifold gasket, wires, plugs, an alternator, battery and an oil change. The last owner did that work. When I bought the car a year ago it ran perfect. The car was basically completely stock with 95% of its parts original and untouched. Since the motor ran so good stock I didn't mess with it. Regarding the motor.. I did the following...
Edlebrock Valve covers and gaskets
Edlebrock open air cleaner
Removed EGR and blocked it off
Removed all the AC components
Hooker side headers and side pipes
New 8mm MSD wires and heat socks to protect them from the headers
New plugs
Oil and Filter
Timing set
Upper and lower heater hoses removed and ports plugged up.
The IAC and those other sensors on the manifold were removed and the ports plugged up.
I figured I may have had to adjust the air/fuel mixture but the car started up instantly and after it warmed up I set the timing and its been running great ever since.

jgcable

A little more backstory. I don't know how many people owned this car. I know that it spent time in Florida. It might have started off in Florida. Its very possible that the original owner was in Connecticut. He owned the car from 1977 until 2010. He sold it to a guy who sold it to another guy and so on and so on and so on. Technically... according to the DMV... I am the second owner because it has only been registered one time other than me.

MelWff

You are the gentleman who almost went through hell with the Connecticut DMV!
Anyway, if the only thing wrong is the occasional pop at idle and you dont want to try and adjust the idle mixture leave well enough alone.