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Discussion Starter #1
Alright,

Car is having troubles starting, I think its related to timing but here is what I know, looking for some advice.

BBC 468
Holley Street HP 850
Edelbrock Air Gap
Comp Cams 295th7
10.5:1 Comp
Billet MSD Dist
6AL-2 Ignition
MSD Coil

Checked TDC and Harmonic Balancer is reading correct (also watched valves open and close to ensure cam timing looked on as well)

Distributor set to 12 points advance. (gone through a lot of steps to ensure my distributor is set correctly, basically at TDC rotor points to wire 1)

New Carburetor Holley Street HP 850 Mech Sec

New Intake Edelbrock Air Gap

New Cap and Rotor

All wiring double checked, no idea what it could be at this point

Fire is shooting out of the carb. I believe this means I am too advanced but i don't know how that is possible at this point?
 

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It has been my experience that if you are having flames and popping back thru the carburetor that the timing is probably low. If the starter starts dragging and has a hard time cranking the engine over the timing is probably high. Pull the number one plug out and have someone turn the engine over while putting your finger over the number one spark plug hole. You need to have the engine at TDC on the compression stroke. When the compression blows your finger then check to make sure your pointer and the distributor is pointed right. As stated above your distributor could be 180 out.
 

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Fire shooting out of the carb is a classic indication of LATE ignition timing. :yes:

It sounds like from your original post that you might have had the distributor removed from the engine and you now think that the rotor is pointing at #1 cylinder?

If so, it sounds like it is probably off a tooth retarded.

You want the rotor to be pointing a little before #1 cylinder with the distributor installed with the vacuum advance canister in a position that allows for plenty of adjustment.
 

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Discussion Starter #5
Fire shooting out of the carb is a classic indication of LATE ignition timing. :yes:

It sounds like from your original post that you might have had the distributor removed from the engine and you now think that the rotor is pointing at #1 cylinder?

If so, it sounds like it is probably off a tooth retarded.

You want the rotor to be pointing a little before #1 cylinder with the distributor installed with the vacuum advance canister in a position that allows for plenty of adjustment.
So one tooth or 180 does not make sense to me. It all depends on relevance to TDC. Ensuring your motor is at TDC, install the distributor however you want. Then install the cap ensure the rotor is pointing at spark plug number one with correct firing order you can place the distributor on any direction you want just as long as you have it point at number one plug wire on the cap with correct firing order. From there you can retard and advance from zero. Thoughts?

Also from my understanding fire out of the carb was too advanced timing to too early. Intake valves are still open letting the combustion come up through the intake and out the carb? Too retarded and it will backfire out the exhaust but of course through the exhaust valves?
 

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So one tooth or 180 does not make sense to me. It all depends on relevance to TDC. Ensuring your motor is at TDC, install the distributor however you want. Then install the cap ensure the rotor is pointing at spark plug number one with correct firing order you can place the distributor on any direction you want just as long as you have it point at number one plug wire on the cap with correct firing order. From there you can retard and advance from zero. Thoughts?

Also from my understanding fire out of the carb was too advanced timing to too early. Intake valves are still open letting the combustion come up through the intake and out the carb? Too retarded and it will backfire out the exhaust but of course through the exhaust valves?
I think you are correct.
 

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So one tooth or 180 does not make sense to me. It all depends on relevance to TDC. Ensuring your motor is at TDC, install the distributor however you want. Then install the cap ensure the rotor is pointing at spark plug number one with correct firing order you can place the distributor on any direction you want just as long as you have it point at number one plug wire on the cap with correct firing order. From there you can retard and advance from zero. Thoughts?
You are correct but the key is TDC on the compression stroke. The piston comes up twice for every on turn of the crankshaft. If you aren't on the compression stroke you will be 180 out no matter where your pointer is turned or how you time it.
 

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Yeah you're probably right if he has a backfire in the carb. :yes:

I was thinking of backfire in the exhaust.

Either way, it sounds like his distributor is off one or more teeth if he had it out.
 

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Pull the valve cover, turn the motor over and watch the #1 INTAKE rocker arm to open, keep rotating engine until it closes. Watch the damper to come up to TDC. Back the motor up from TDC (watching damper) to where you want your timing. (by turning motor backwards you are advancing your timing) Set in the distributer pointed to number 1 plug terminal on the cap and your timing will be real close. Set final timing with a timing light and install new rear tires after test drive! :thumbsup: (this is if you are positive your balancer is not spun on the hub)
 

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Fire up the Carb

2 things---look closely at the harmonic balancer outer hub to see if it has slipped//rotated. usually if this happens the rubber ring will be sticking out the front---it should be flush. This would cause any incorrect timing setting. 2nd--I know you have a Holley,does it have metal or plastic floats ? Rochester carbs will melt the floats when backfiring occurs. Holleys may as well,which will make them sink like a stone & flood causing more flame shows. Just read Kids post---well said .
 

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Unhook coil wire(so she doesn't start) remove #1 plug and put your thumb over the hole , get someone to bump it over a bit at a time. When you feel compression,stop . Put a pencil about an 1" in the role then rotate by hand(crank bolt) until the piston pushes the pencil to it's highest point. Your are now on TDC on compression stroke. Pop off your cap and see where rotor is pointing. Also look at your timing mark on balancer to make sure she hasn't slipped. If you have valve covers off...you can rotate engine until #6 intake and exhast rockers rock(exhaust closes/intake opens). This puts #1 cyl at TDC.
 

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Discussion Starter #12
Alright so this is what I have done and the results. I removed the timing cover, had to get in there to verify what is going on. I watched my intake valved open and close and then I aligned my crank marker pointed up. This should be TDC. Looking at the cam gear now the dot on the cam gear is at the top of the gear, opposite of what it should be? (Pointed down towards the crank I believe). This means my cam is 180 degrees off? See picture pleases, sorry they are a little blurry but you will get the idea. I was told that is is possible the cam dot should be pointed up? Never heard of that on a chevy BBC?
 

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When the dots on your timing gears are aligned, it is for assembly purposes and will be TDC for #6. True TDC for the #1 hole will put your timing dots on the timing gears at 12:00. From what you are posting in the pics, it is CORRECT! :yes:
The motor as you have it in the pics is on TDC for the #1 hole!
Pull the cap off the distributer and see where it's at. Rotor should be pointed at the #1 terminal, also double check your firing order for the plug wires.
 

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Discussion Starter #17
I am getting mixed answers here?

Could the plug wires cause a backfire out of the carb?

It ran before just showed crazy advancing at idle like 60 degrees, then i reset the distributor to point at #1 terminal at #1 cylinder TDC and it does not want to run, just shoots flames.
 

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I am getting mixed answers here?

Could the plug wires cause a backfire out of the carb?

It ran before just showed crazy advancing at idle like 60 degrees, then i reset the distributor to point at #1 terminal at #1 cylinder TDC and it does not want to run, just shoots flames.
The timing marks on the timing gears in the pic look as though it might be a tooth off. Both timing marks on your timing gears should be at 12:00 o'clock when the motor is on TDC like I said! (guarantee it) Are both marks at 12:00 o'clock when on TDC? Looks as though the cam gear might need to be back up a tooth. As far as it gaining advance when running, is the vacuum advance canister screwing with ya? Are the manual weights in the distributer screwing with ya? Is the rotor screwing with ya? :2cents:

Don't have a 4 - 7 swap camshaft do ya? Plug wires wrong?
 

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Flame Shooting up the Carb

When the dots on your timing gears are aligned, it is for assembly purposes and will be TDC for #6. True TDC for the #1 hole will put your timing dots on the timing gears at 12:00. From what you are posting in the pics, it is CORRECT! :yes:
The motor as you have it in the pics is on TDC for the #1 hole!
Pull the cap off the distributer and see where it's at. Rotor should be pointed at the #1 terminal, also double check your firing order for the plug wires.
What he said---12 o'clock & 12 o'clock is #1 TDC Firing .
 

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Turn your crank so that the dot on the crank gear is at 12 o'clock, It doesn't look like it's straight up. I think when you turn the crank so that the dot is straight up at 12 your cam dot will line up. Either way cam dot and crank dot should be at 12 o'clock for TDC
 
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