# Car won’t start and carburetor backfiring



## Hauspitality (Dec 22, 2021)

Ok, I’ve seen similar posts on this topic on both this message board and others but my issue is slightly unique. I’m assuming it’s a timing issue but I can’t seem to figure out how to fix it.

The details:

I have a 1968 GTO numbers matching on the block. I bought it a month ago. It’s important to note that it was sitting in a guys garage for 3 years without being driven much. The first few weeks I had it, it was running great but after noticing the radiator fluid was a bit murky I decided to have the radiator flushed and an another oil change. After the oil changed I started noticing tons of white smoke coming from the exhaust and the radiator depleted heavily. My assumption was a head gasket leak and I was right. I replaced the head gaskets myself. Now I’ve put everything back together and I’m not able to get the car to start. At first it was backfiring back from both the intake and the exhaust and I realized I was 180 out of time.

Whats under the hood:
Edelbrock Heads
MSD 6AL Ignition 
High Torque Starter (newly rebuilt)
Holley Carb
MSD spark plug wires 
MSD distributor 


What I’ve done so far:
I’ve checked the firing order multiple times and ensured I didn’t have my wires crossed. 

sed a compression gauge as well as a long screw driver to check for TDC. (Did so after finding out I was 180 off)

Made sure I was getting good fuel and good fuel pressure.

Swapped out the spark plugs.

Cleaned the carburetor

Now I’m stumped! Could it have been something I did when I put the heads back on? Would that prevent it from even firing up? Anyone that could help would be great!


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## PontiacJim (Dec 29, 2012)

Hauspitality said:


> Ok, I’ve seen similar posts on this topic on both this message board and others but my issue is slightly unique. I’m assuming it’s a timing issue but I can’t seem to figure out how to fix it.
> 
> The details:
> 
> ...



Assume you know that the Pontiac firing order is counter-clockwise. You may be lining up the rotor where it appears to be at the No 1 cap position. If so, then the rotor is most likely too far advanced. The timing has to actually be set Before Top Dead Center, meaning the spark plug fires just before the piston reaches TDC. If you had the piston at TDC and lined the rotor right dead-on the No.1 spark plug wire in the cap, you would be off. Expereinced this myself. So first thing would be to move the distributor around while someone is starting the engine. You can simply make the distributor hold down bolt snug enough so you can move the distributor with a little bit of effort, but not to loose. I would retard it first - looking at it, turn to the left. See how the engine reacts while cranking it to start. You can tell by sound. Make sure you are not pumping the gas while doing this as you don't want to flood or overload the cylinders with gas and wet down the plugs as they may not fire when wet with gas.

My next guess is that since you added the E-heads the valves may not be adjusted correctly. if any of the valves are being held open, you will get popping/backfiring/no start issues. Did you check your rocker arm geometry? The E-heads use longer valves and you may need different length pushrods other than stock. Assume you have poly locks holding the rocker arms. Again, if too tight, valves are being held open, so best to adjust the valves with then engine running.

You did use the correct and recommended head bolts for the E-heads and not the factory 400 head bolts? The E-heads require a few longer than stock head bolts and if not used, might be why the head gasket blew out and you could pull the head bolts out of the block because they are too short and don't go deep enough to grip the threads properly and will pull out - then yo will have a real problem on your hands.

Give that a look and see what you find.


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## Lemans guy (Oct 14, 2014)

Yes agree, you have to get that distributor turned into a range where it will fire, if you are off just a little it can move the timing enough, where it will not start.

sometimes it will hit the very first time, others takes a little turning. Double check your coil and distributor wires and grounds especially the one behind the head or connected to the coil bracket. Wires can get left off or on wrong when jobs like heads and intakes come off and on…


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## CoveKid19 (Nov 18, 2021)

Don't forget that you can also check ignition timing while the engine is cranking.


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