[GanoMan]

Hello, new to this. And I have a 71 Nova 350 auto. The carb is a 750 Holley. I can get the car to start but it doesn't seem smooth and when I put it into drive and give it gas it dies.

• Can anyone give me some tips on what to check first and what tools to buy to check into this issue? Thanks in advance.

 

[GanoMan]

View attachment 400434 View attachment 400434

 

[CEW]

Due to the vast amount of possibilities that can cause what you describe, I think your best option is to find a knowledgable local gearhead shop to help time/tune your engine.

its very difficult to help someone set timing or diagnose fuel/ignition issues online. That kind of stuff is better done in person.

Maybe a forum member lives close and can drop by to take a look?

 

[OEM Chevrolet Nova]

View attachment 400434 View attachment 400434

I couldn't agree more with CEW. Too many variables; a possible vacuum leak, float level too low or needle and seat sticking etc. I would find a shop that's been around a long time and politely seek advice. If you have time, please let us know how you make out. Thanks..

 

[RifRaf]

As others have already stated... too many variables could be causing your engine issues.

BUT, if you want to start troubleshooting and resolving engine issues, I suggest you get some basic hand tools, a timing light, vacuum gauge, multi-meter, and a compression tester to start with. You then need to educate yourself about how to tune/troubleshoot a Chevy V8 engine (with an HEI) and also learn how to tune/adjust a Holley carb. There are many online articles and videos that could help (... but be warned that there is also some really bad info on the web). There are also a lot of good books on these subjects. Search out any local car groups in your area to see if any members can give you some guidance.

Question: When you say your engine dies when you put it into drive and give it gas, does the engine completely die and you have to restart it? ... or does the engine bog/hesitate and then begin to accelerate? A bog or hesitation could be as simple as a carburetor pump/squirter adjustment.

But many other items could also contribute to your engine issues... poor/improper ignition timing, bad spark plugs or wires, vacuum leaks, improper carb adjustments (float level, idle mixture, transfer slot, power valve, etc), not running 12 volts to your HEI, stuck mechanical advance weights, and clogged fuel filter are but a few that are easier to resolve. Engine issues could also be caused by a worn timing chain or low compression in one... or several cylinders (bad rings, valves, wiped cam, stuck/bad lifter, rocker arm adjustment, etc).

So if your up to the task... educate yourself, get some tools, and start with the easier stuff first. The more "diagnostic" information you are able to relay to this site, the easier it will be for other members to help.

 

[GanoMan]

I bought a compression and vacuum tester. I have a Haynes manual, I will do what I can and report back.

I will also check the fuel pump to make sure it is actually pumping gas.

For more about the problem. I am having trouble starting it. It starts but feels like only half the cylinders are firing and then they start firing. This is all including some big back firing. And I put it in gear and give it gas and dies immediately and I have to restart it.

I appreciate the help fellas.

 

[GanoMan]

Did anything in these pictures look not right? I noticed some things not hooked up.

 

[RifRaf]

Electric chock is not is not wired. Is the top choke butterfly closing all the way while the engine is running?
Also, distributor's vacuum advance is not connected / return spring on carb has no tension / transmission detent cable is not connected... but the disconnected detent cable should not effect how your engine runs.

It also looks like some fluid has "pooled" on the intake manifold under the throttle bracket. Is this fluid gas or oil?

One other thing, be sure the spark plug wires are connected to the correct cylinders.
I also noticed in your photo that some of the spark plug wires looked very close to your headers... be sure to check for lost spark/misfire due to burned wires or boots.

When it's dark outside, start your engine > lift the hood > and look for any signs of sparks jumping from the wires and/or distributor cap.

 

[utterson]

Electric chock is not is not wired. Is the top choke butterfly closing all the way while the engine is running?
Also, distributor's vacuum advance is not connected / return spring on carb has no tension / transmission detent cable is not connected... but the disconnected detent cable should not effect how your engine runs.

It also looks like some fluid has "pooled" on the intake manifold under the throttle bracket. Is this fluid gas or oil?

One other thing, be sure the spark plug wires are connected to the correct cylinders.
I also noticed in your photo that some of the spark plug wires looked very close to your headers... be sure to check for lost spark/misfire due to burned wires or boots.

When it's dark outside, start your engine > lift the hood > and look for any signs of sparks jumping from the wires and/or distributor cap.

This is very good advice, I would think all your problems are there.

 

[GanoMan]

Electric chock is not is not wired. Is the top choke butterfly closing all the way while the engine is running?
Also, distributor's vacuum advance is not connected / return spring on carb has no tension / transmission detent cable is not connected... but the disconnected detent cable should not effect how your engine runs.

It also looks like some fluid has "pooled" on the intake manifold under the throttle bracket. Is this fluid gas or oil?

One other thing, be sure the spark plug wires are connected to the correct cylinders.
I also noticed in your photo that some of the spark plug wires looked very close to your headers... be sure to check for lost spark/misfire due to burned wires or boots.

When it's dark outside, start your engine > lift the hood > and look for any signs of sparks jumping from the wires and/or distributor cap.

I Will get on those things today. Thank you so much. Thank you and the fluid was from me.

 

[GanoMan]

Having trouble finding spot to connect distributors vacuum advance. Any ideas?

 

[krash55918]

start here. Your port may have a black plug on it. Hopefully these pics will help you. How long has this carb been on the vehicle? With everything that is disconnected I am assuming someone just installed it?

where does my vacuum advance connect to my holley 750 carburetor - Bing images

www.bing.com

 

[GanoMan]

I think it was worked on the past August.

I got a hose attached.

 

[GanoMan]

Electric chock is not is not wired. Is the top choke butterfly closing all the way while the engine is running?
Also, distributor's vacuum advance is not connected / return spring on carb has no tension / transmission detent cable is not connected... but the disconnected detent cable should not effect how your engine runs.

It also looks like some fluid has "pooled" on the intake manifold under the throttle bracket. Is this fluid gas or oil?

One other thing, be sure the spark plug wires are connected to the correct cylinders.
I also noticed in your photo that some of the spark plug wires looked very close to your headers... be sure to check for lost spark/misfire due to burned wires or boots.

When it's dark outside, start your engine > lift the hood > and look for any signs of sparks jumping from the wires and/or distributor cap.

As long as my system is the hei and not the points the spark plugs are in the correct firing order.

 

[krash55918]

Good to hear. Still looks like the electric choke isn't totally hooked up. Not sure where the upper wire goes. It may be a ground. How about the rest of the stuff that Rifraf mentioned? Did you get the tranny detent cable connected? Find a different place for the throttle return spring? You said it was backfiring pretty bad. Is this the first time you're running the car since the carb was replaced? Did they do anything with the distributor cap or wires when they were working on the vehicle? I assume you didn't have issues with backfiring before the carb was replaced. I did a tune on a car once and it was backfiring like crazy when I was done. Checked the firing order and it was all good. Was driving me crazy before I figured out that I had the wires off one hole in the cap. Felt like a damn idiot.

 

[GanoMan]

Good to hear. Still looks like the electric choke isn't totally hooked up. Not sure where the upper wire goes. It may be a ground. How about the rest of the stuff that Rifraf mentioned? Did you get the tranny detent cable connected? Find a different place for the throttle return spring? You said it was backfiring pretty bad. Is this the first time you're running the car since the carb was replaced? Did they do anything with the distributor cap or wires when they were working on the vehicle? I assume you didn't have issues with backfiring before the carb was replaced. I did a tune on a car once and it was backfiring like crazy when I was done. Checked the firing order and it was all good. Was driving me crazy before I figured out that I had the wires off one hole in the cap. Felt like a damn idiot.

I just bought the car yesterday and we drove it onto the trailer and it died as soon as the back wheel hit the top of the ramp. Pushed it on.

I wish I new more about the car. But it was running when I bought it and it did drive.

So how do I know what order I have to follow? This is what I am going off of.

I am going to change the fuel pump and get a new spring.

Then I will mount the top wire to ground and see where that gets me.

I really appreciate everyone help. Thank you

 

[krash55918]

why are you replacing the fuel pump? Is the carb getting fuel? If the carb's getting fuel I wouldn't mess with the pump. The backfiring through the carb is a classic timing issue, it may also backfire loudly out of the tailpipe.. The firing order you are using is correct. I would make sure the wires are in the correct spot on the distributor cap. If they are, then I would check to make sure they are going to the right plug. I suspect you are going to find the issue there. If not, check to make sure none of the wires are burned. Rifraf's suggestion would be the easiest way to check. Pop the hood at night and start the car. Check to see if you can see anything sparking. I would also suggest that you keep a clean rag handy (old hand towel would work well) in case you attempt to start and flames come out of the carb. If that happens, don't panic, just cover the top of the carb with the rag, it will douse the flames.

 

[GanoMan]

why are you replacing the fuel pump? Is the carb getting fuel? If the carb's getting fuel I wouldn't mess with the pump. The backfiring through the carb is a classic timing issue, it may also backfire loudly out of the tailpipe.. The firing order you are using is correct. I would make sure the wires are in the correct spot on the distributor cap. If they are, then I would check to make sure they are going to the right plug. I suspect you are going to find the issue there. If not, check to make sure none of the wires are burned. Rifraf's suggestion would be the easiest way to check. Pop the hood at night and start the car. Check to see if you can see anything sparking. I would also suggest that you keep a clean rag handy (old hand towel would work well) in case you attempt to start and flames come out of the carb. If that happens, don't panic, just cover the top of the carb with the rag, it will douse the flames.

I will try that tonight. And I was going to change the fuel pump because the original owner had bought one. I figured I'd start fresh with the part as long as I had it.

 

[OEM Chevrolet Nova]

I think it was worked on the past August.

I got a hose attached. View attachment 400472

For improved idle, and better engine efficiency, switch your vacuum advance to direct vacuum. ( below the carburetor)

 

[RifRaf]

I forgot to ask you... how old is the gas in the fuel tank? Old gas (over 5-6 months old) will cause problems and definitely effect how your engine is running.

I also agree with krash55918 that a backfire thru the carb is usually a timing issue (... or some spark plug wires are not routed to the correct cylinders).

So how do I know what order I have to follow? This is what I am going off of.

To be sure what is the #1 terminal on the distributor cap is, follow the procedures below.
What you need to do is get your engine to #1 Top Dead Center (TDC). To do this, put your car in "Park" and leave the ignition switch in the "Off" position. Next, remove the #1 spark plug and (for extra safety) disconnect the 12 volt wire connected to the BAT terminal of the HEI. Next... using a remote starter switch (or a helper at the ignition switch), bump start the engine while looking for the timing mark on the balancer and hold your finger over the #1 spark plug hole on the cylinder head. When you see the timing mark on the balancer begin to come around and line of with the timing tab, you should fell air pressure on your finger being held over the #1 spark plug hole. NOTE: If you do not feel any pressure as the timing mark on the balancer begin to come around and line of with the timing tab, no need to worry (you are at #6 TDC). Keep bump starting the engine while looking for the timing mark on the balancer to come back around to the timing tab until you feel the air pressure on your finger. When you start to feel the air pressure, slowly bump crank the engine until the timing mark on the balancer is on the TDC (0 Line) on the timing tab.
Another way to confirm #1 TDC is to remove the valve cover on the driver's side of the engine and watch the rocker arms as you bump start the engine while watching the timing marks as described above. If both #1 cylinder valves are closed as the timing marks on the balancer and timing tab are lined up, you are at #1 TDC. If one of the #1 cylinder valves is open when the timing marks line up, you are at #6 TDC. Continue to bump start the engine until the timing mark comes back around and line up with both #1 valves closed.

Now that you are at #1 TDC, remove the distributor cap and notice the position of the metal tab on the rotor. Try to make a reference mark somewhere on the engine that lines up with the metal tab on the rotor. Reinstall your distributor cap and notice what terminal/wire lines up with the reference mark you just made. That is the #1 terminal on your distributor cap and the spark plug wire should go the the #1 spark plug. Once you determine what the #1 terminal is, begin the trace the rest of the wires in a clockwise rotation from the #1 terminal using the 1-8-4-3-6-5-7-2 firing order.

Once you are done remember to reinstall the #1 spark plug and reconnect the wire to the BAT terminal on the distributor cap. NOTE: Before connecting the BAT terminal wire, turn your ignition key to the "Run" position and check the voltage of this wire. It should be at least 12 volts.

Once you confirm all of the above, please post what your initial timing is at idle (vacuum advance disconnect while checking this) and we can go from there. If it is way off, try to set at 12°-14° BTDC.