Feeling Defeated. Exhaust Back fire.

[Fox Slaughter]

I am feeling defeated.
I've worked on Chevy stuff all my life and now this has me boggled.

I had a top end oil leak somewhere so I pulled the intake manifold and valve covers off and changed the gaskets.
The passenger valve cover is now leaking but I will take care of that not important right now, gasket must of not set right.

Anyways.

So I marked the cap and dizzy but didnt mark the intake so I am only guess what it was at before.
I have my timing light hooked up but the pointer only goes to 10*.
So after 10* I have to guess. I tried putting timing tape on it but that didn't work, waste of 9 bucks.
So I put the vacuum gauge on.
I can get it to pull a max of 16in vacuum.
But it still back fires.

Its only back firing either at start up or when you hit the throttle and let off.

Sprayed carb cleaner around the carb and intake, no leak discovered.

Tried advancing/retarding the timing and still getting back fire.
The only plug I removed was #1 to verify TDC and put it back in.

My next step is going to be replace plugs, wires, cap, rotor.
Didn't do this before I pulled the intake off.

 

[moparleo]

Before you start to replace everything, lets find out the problem first. Throwing parts at a problem is the wrong way to diagnose a problem. Always start from the beginning and the problem is usually something simple. Which engine are we working on ?

 

[Fox Slaughter]

Before you start to replace everything, lets find out the problem first. Throwing parts at a problem is the wrong way to diagnose a problem. Always start from the beginning and the problem is usually something simple. Which engine are we working on ?

340.

Sorry forgot to mention that.

 

[challenger6pak]

Your engine is firing on an open exhaust valve. That could be timing or a mechanical issue. Have you ever driven this car or just heard it run? I ask because some people will set timing to cover a jumped timing chain and then sell the car idling. If this were the case with your car it would show up when the timing is put in the proper position.

 

[moparleo]

First thing. Check the firing order 1-8-4-3-6-5-7-2 clockwise. Also check inside of distributor cap and rotor for any damage.

 

[Fox Slaughter]

I've driven the car a couple hundred miles before I did this.

I verified firing order was correct today.
I'll have to take the cap back off and check tomorrow

 

[challenger6pak]

Since this is a new thing and you have driven the car, I agree with Leo. Start here. If you have another cap and rotor , swap them out, one at a time, and see if anything changes.

First thing. Check the firing order 1-8-4-3-6-5-7-2 clockwise. Also check inside of distributor cap and rotor for any damage.

 

[Fox Slaughter]

I walked outside this morning and now its leaking coolant from the lower radiator hose where it connects to the water pump. I already replaced the hose and cleaned the fitting on the waterpump but some how its leaking again.

 

[Fox Slaughter]

Tightened the hose clamp with a socket. Got a couple turns out of it so must of not been tight with a screwdriver so we will check again.

Also when I replaced the valve cover gaskets they are leaking. Just read that after market intakes require you to grind the lip off the valve cover for it to seat to the head. When I was removing the intake I discovered I need to remove the valve covers to get the intake off. Does anyone know what exactly must be grinded off?

 

[moparleo]

Where did you read that ? Sometimes there will be an issue with using aluminum valve covers and aftermarket aluminum intakes. This is not a rule of thumb. Sometimes there is a fitment problem and sometimes not. I would grind on the intake manifold before I would modify the valve covers. Remember that you can't put back what you take off. Do you have any pictures for us to work with. We are like blind men trying to help you without pictures.

 

[challenger6pak]

I wouldn't grind either of them. You need all the sealing surface you can get from either of them. If you need more height run a thick gasket. Felpro has decent gaskets. If you grind the lip off of the valve cover, the gasket will squish out when the cover is tightened. Then you will have a REAL oil leak.

 

[edison1970]

Points or electronic ignition?