Starting issues - weird situation

[DreadPirateRob]

Hi guys, hoping to hear from all the experts here.

I finished building a 440 for my 73 Charger, removing the 400 that previously died.

I have a 67 GTX Block, with 915 Heads, a Comp 268H cam, steel crank, vintage Hooker headers, Holly 750cfm Carb...

I drove the new engine 3 or 4 times after I built it, but the carb was running funny. I rebuilt the carb, and on my very lean, initial start up of the engine the muffler exploded. It turns out the muffler shop I took the car to had a piece of slag remaining inside the exhaust pipe, and it blocked the muffler baffle and when the engine started up, backfire ignited the gasses and it blew. I found the half dollar piece of welding slag 5 feet away embedded in one of the plastic engine covers on my motorcycle, lol.

While waiting for a new muffler, I replaced the rear differential gears with larger gears and a sure grip. When the new muffler came I only replaced the blown one, since it was similar enough to the old muffler to not make much of a difference.

The issue I'm having now is the engine won't turn over. I tried 2 different coils, another carburetor i had, 3 different distributors, ( 2 points and 1 hei style), and 3 ignition boxes( chrome and orange).

I had a viper alarm installed, which I disconnected. I wondered if that could be killing the ignition boxes and that was what was causing my errors. Doesn't seem to have been the case.

I have spark, I have gas, I have timing dialed in at TDC.

The only possible things I'm seeing are that the distributor doesn't seem to be fitting flush with the engine block, it seems to be raised maybe a 16th of an inch off the block. I checked the intermediate gear and it seemed to be fully seated, with one caveat, it looks like there was a very tiny chip taken out of the brass gear. I'll be trying out a new intermediate gear this afternoon, but I'm not feeling that's the issue since the car ran before. I dont recall if the distributor seated fully initially or if that's a new issue. The intermediate gear seems to be aligning with the cam gear, so I don't know if it's raised due to the oil pump height or what.

Could my engine need higher octane gas, and that's why it's not starting? I'm in California, so I've only got access to 91 unless I go to a gas station near a race track or add octane booster myself.

My mechanic friend is suggesting a leakdown test, but I think the car would still turn over if there was a exhaust/intake leak, right?

I'm stumped. Any help or suggestions are welcomed.

 

[RemCharger]

Quick observation.. a brass (bronze) gear with a 268 hydraulic cam?? Not saying it's the problem, but it's not right.

 

[DreadPirateRob]

Quick observation.. a brass (bronze) gear with a 268 hydraulic cam?? Not saying it's the problem, but it's not right.

You know, I did say brass gear but thinking back now I'm not sure that it is. I think I was reading about other issues so much this morning I may have added that arbitrarily. I have a steel crankshaft, so I would have gone steel for the intermediate as well.

 

[BLK 68 R/T]

So it doesn’t even turn over ? Or won’t start, but turns over?

 

[beanhead]

The issue I'm having now is the engine won't turn over

This means it isn't cranking, which can be things like a dead battery, poor cable connection, dead starter or problem with the starting relay/circuit. Is that it? Or does it crank and just not fire.

I have spark, I have gas, I have timing dialed in at TDC.

Okay that's a good thing!

Could my engine need higher octane gas, and that's why it's not starting? I'm in California, so I've only got access to 91 unless I go to a gas station near a race track or add octane booster myself.

Our (crappy) gas isn't your problem....my 10 to 1 505" starts and runs wonderfully on pump 91 year-round

My mechanic friend is suggesting a leakdown test, but I think the car would still turn over if there was a exhaust/intake leak, right?

Yes, a leakdown test is not what you need at this point...that checks for air/vacuum leaks that cause running problems, but not a no-start condition.

The only possible things I'm seeing are that the distributor doesn't seem to be fitting flush with the engine block, it seems to be raised maybe a 16th of an inch off the block.

That's not good! Not causing your issue...however I wouldn't attempt to run it like that! You'll have oil all over and possibly break some parts too.

... the muffler exploded. I found the half dollar piece of welding slag 5 feet away embedded in one of the plastic engine covers on my motorcycle, lol....

THAT is awesome!!

Okay seriously, let us know exactly what it's doing/not doing. Cranks but no fire, or doesn't even crank?
Could be as simple as a dead battery from sitting during the rebuild.
Clean ride by the way!

 

[pnora]

I drove the new engine 3 or 4 times after I built it, but the carb was running funny. I rebuilt the carb, and on my very lean, initial start up of the engine the muffler exploded. It turns out the muffler shop I took the car to had a piece of slag remaining inside the exhaust pipe, and it blocked the muffler baffle and when the engine started up, backfire ignited the gasses and it blew. I found the half dollar piece of welding slag 5 feet away embedded in one of the plastic engine covers on my motorcycle, lol.

Now thats a tall tale.

 

[DreadPirateRob]

Now thats a tall tale.

Here's the muffler, and you can see the motorcycle behind it, lol. I don't have a picture of the slag, it was nickle size and had a smooth curve in it, the same angle as the inside of my pipes.

 

[DreadPirateRob]

So it doesn’t even turn over ? Or won’t start, but turns over?

The ignition turns on, and it cranks, but the engine won't start. I've had my battery on my trickle charger and it's still at 12v, so I don't think it's a dead battery.

This means it isn't cranking, which can be things like a dead battery, poor cable connection, dead starter or problem with the starting relay/circuit. Is that it? Or does it crank and just not fire.



Okay that's a good thing!


Our (crappy) gas isn't your problem....my 10 to 1 505" starts and runs wonderfully on pump 91 year-round



Yes, a leakdown test is not what you need at this point...that checks for air/vacuum leaks that cause running problems, but not a no-start condition.



That's not good! Not causing your issue...however I wouldn't attempt to run it like that! You'll have oil all over and possibly break some parts too.



THAT is awesome!!

Okay seriously, let us know exactly what it's doing/not doing. Cranks but no fire, or doesn't even crank?
Could be as simple as a dead battery from sitting during the rebuild.
Clean ride by the way!

Thanks bud. Yes, it's cracking but not firing. My battery is fully charged and I have spark, so I'm thinking it's timing related, probably to do with the intermediate gear.

The distributor is down far enough that the gasket is below the surface of the block, so no oil is spraying out, lol.

 

[pnora]

Here's the muffler, and you can see the motorcycle behind it, lol. I don't have a picture of the slag, it was nickle size and had a smooth curve in it, the same angle as the inside of my pipes.

View attachment 1449101

You can bet that explosion in the exhaust is from the issue you have going on now. No way in hell would a piece of old cold slag cause that. You has a lot of un-burned fuel in the exhaust and the ignition lit it off. To your problem. Start with getting number 1 on TDC compression stroke and see where the rotor is pointing.

 

[Will-Fonkjam]

 

[BLK 68 R/T]

You can bet that explosion in the exhaust is from the issue you have going on now. No way in hell would a piece of old cold slag cause that. You has a lot of un-burned fuel in the exhaust and the ignition lit it off. To your problem. Start with getting number 1 on TDC compression stroke and see where the rotor is pointing.

Probably worth giving the oil dipstick a sniff as well to see if it smells like gas.

 

[Geoff 2]

Dist will not fully seat. My understanding is the 318-360 dist [ shaft length ] is a tad longer than the 440. Wrong dist would explain the gap plus no start because the dist turns on the opposite direction & the phasing is out.
So make sure you have a RB dist.

 

[DreadPirateRob]

Probably worth giving the oil dipstick a sniff as well to see if it smells like gas.

What a great call. I gave it a sniff and it does smell like gas, so it's likely the piston rings not sealing. I'll do a compression test and see if it verifies everything, and then I'll get new rings for it.

 

[BLK 68 R/T]

New rings…not exactly what I’d call an easy fix…if in fact they are actually damaged that is.

 

[Fran Blacker]

Is the spark white or blueish. Wonder if it's possible that the explosion made timing chain jump a tooth? Doubt it but others might know.
Geoff2's idea wrong dist worth a look. A closeup picture with the cap off would tell.

 

[Don Frelier]

Is the spark white or blueish. Wonder if it's possible that the explosion made timing chain jump a tooth? Doubt it but others might know.
Geoff2's idea wrong dist worth a look. A closeup picture with the cap off would tell.

Just a picture of the vacuum advance would do.

I wouldn't expect anything to change internally from a blown up muffler. But I suppose it's possible.

I'd suggest checking compression.
Double check that the spark on #1 is on the compression stroke and firing order as well.

 

[66 Sat]

What a great call. I gave it a sniff and it does smell like gas, so it's likely the piston rings not sealing. I'll do a compression test and see if it verifies everything, and then I'll get new rings for it.

Hang on hang on. Dipstick smells of gas so straight to new rings??
You've been cranking on this thing trying to start it, and you have a rebuilt carb that was "running funny".
That's probably why your disptick smells of gas.
Find the issue, get it started briefly to confirm it runs, then put some fresh oil and a new filter and you're away.

 

[DreadPirateRob]

Dist will not fully seat. My understanding is the 318-360 dist [ shaft length ] is a tad longer than the 440. Wrong dist would explain the gap plus no start because the dist turns on the opposite direction & the phasing is out.
So make sure you have a RB dist.

Yeah, I thought of that as well, of the 3 distributors I ordered all the shafts measure out at 4 inches, and my old 400 is 3.5 - the Hei style has a 4 inch shaft, but the area where the ring gasket sits seems to be longer. It appears to be as seated as the proform distributors I bought, it's just got a taller shaft base.

 

[DreadPirateRob]

Hang on hang on. Dipstick smells of gas so straight to new rings??
You've been cranking on this thing trying to start it, and you have a rebuilt carb that was "running funny".
That's probably why your disptick smells of gas.
Find the issue, get it started briefly to confirm it runs, then put some fresh oil and a new filter and you're away.

You're not wrong, but I'm saying I'll test the compression first, if it fails I'll check the rings. It's a new engine, so if the rings didn't seat I'd assume they may be damaged from the failures to start. I drove it about 30 miles after breaking it in for an hour in my driveway, but if it didn't seat correctly I may have to rehone the cylinder walls anyway.

I'm not trying to jump to conclusions, I wrote that out as I did because it's a better way for me to try to run down solutions to the problem. I am 100% willing to try anything at this point, I'm far from an expert. I'm hoping it's as quick as new oil and a new filter!

 

[RemCharger]

Di you check if the plugs are soaked?