Was putting the engine back together (heads and intake manifold only) and when i went to fire the car up it would sound like its timing was off and the carb would back fire BAD. Only difference that i have done is that i am using a 1" carb spacer so i can get rid of those stupid spacer rings for the HEI setup.

Danny Sarvis (w30post i think his name is on here) says it sounds like a vacuum issue and might be because of that spacer (using the thick gaskets on both sides of the spacer with it). Just looking to see what everyones inputs are that may have dealt with this issue or might have an idea on what it can be.

Thanks
Sicky

 

Tom, double check your firing order.
Sounds like a crossed wire.

 

Check your firing order. Make sure the cap not cracked and is sitting flush. If that's correct look at the movement of your rockers and make sure they are all moving about the same amount.

 

Firing order is fine, I have a loom and didnt change anything in the Dist. Only changed out one wire on the dist cause the MSD wire slipped off and that is on number 3.

From what i saw on the rockers they seemed to be fine, might have to check that number 6 though to make sure seeming that was why i disassembled the top end. It looked like the valves were fine but if there was something wrong with that could that be a cause of this happening

 

So none of the valves were
stuck then? And the pushrods
were fine as well?

 

Backfiring through the carb, if it's not a wiring or timing issue, is generally valve related.

 

"Backfiring through the carb, if it's not a wiring or timing issue, is generally valve related."

I have to disagree here. It can also be too much initial ignition lead where the flame travels back up past the intake valve and into the intake causing a backfire through the carb.

 

If I have the rockers off anything
I will always give the valves a shot
on top with a rubber mallet just to be
sure none are stuck before reassembly.

 

Not from what i could tell the valves and pushrods were perfect. Nothing inside the pushrods either, still had airways and such

 

What do you mean by too much ignition lead?

 

Erics PM reminded me of something i should add to this story. I somehow got metal chunks in my cylinder 6 that caused the spark plug to be bent, not sure where the metal came from. Our only guess is that it fell into the carb when i was swapping out the air cleaner on the drivers side and when i gassed it and the secondaries opened it fell in and got ate up. Nothing was in the oil and appeared to only be in the #6 cylinder and in the intake right at cylinder 6 port. But valves still mated with the head properly and the cylinder wall and piston head were great.

 

Putting too much initial timing into the engine. If your engine calls for for 8* initial timing (on the balancer) and you put 15*, 20* whatever into it you can easily get a backfire not to mention hard starting.

 

Ouch! Metal in any cylinder is BAD.
You may try cranking it with the wire off
#6. It will miss, but not backfire if that
is the bad cylinder.

 

The initial timing was good when we built the motor.

Tru Blu i will have to try that when i get home to work on it.

 

How did you set initial timing when you built the engine? Also, how do you know the valves are seating fine in the #6 cylinder? Did you do a compression test on it right after the metal fell into it?

 

That was all Danny on that part and i can not remember. But the engine ran great (OldCutlass can verify) before this issue and i daily drove it for over a year.

I just did a visual inspection of the valve and it was flush with the head like the others were.

 

Would I be correct in assuming then that these problems started after the metal went down the carb?

 

That is correct sir.

 

Kinda narrows it down then doesn't it? I think you found your problem. Take the head off.

 

but with the metal in the cylinder even the carb did not backfire like it is doing now.

 

This whole thread makes me think of this flow chart:

 

So your saying i should have just left the metal in the cylinder and just changed out the spark plug?

Dont know why you are calling me a dumb **** for trying to fix my car sir

 

He wasn't calling you a dumb sh**, he was bringing some humor into it. I did mention timing but should have went into more detail, sorry. Yes, way advanced initial timing can cause backfiring through the carb. If the valve came into contact with what ever that was in the cylinder, it may have bent. A bent valve can be hanging or galling in the valve guide or not sealing 100% on the seat allowing the flame to travel back up the intake.

 

I will have to look into that. Hate it that this internet doesnt have a sarcasm button . Just kinda stressed out about this and with the job right now >.<

 

Yeah, just to agree with the others, just as "2+2=4," "Metal in Intake + Poor Running = Head Comes Off."

- Eric

 

going to pull the #6 and try different gaskets on the carb first as it will be easier. Just really sucks as i dont have the time to put into it as i am moving Very soon....

 

Good luck Tom.
Keep us posted.

 

Lets bring up that flow chart again cause MAJOR Dumb **** took place lol. Timing was the issue, I unplugged the number 3 on the dist and plugged that wire into the broken wire (#5), which means; 5 was firing when 3 shoulda been and 3 wasnt firing at all....

Car is now running again

 

Ah, so it was the firing order. Glad it wasn't anything major.

 

Well, without the "Poor Running" part of the equation, the "Head Comes Off" part no longer follows.

Glad you figured it out!

- Eric

 

Glad to hear you figured it out.
Now back to happy motoring.

 

Glad it's fixed