I had the same problem from a collapsed fuel filter- easy to check/change. What about your timing- is it a vac advance system?

 

I have it set to 6 degrees without vaccuum advance.

I checked the filter already, I can blow through it.

 

pop and sputter

Well if you say it was not doing it before you change the spacer I would change it back and see what you get. That will knock that piece in or out of the equation. Then yes fuel filter and or enough fuel period could be the problem. How old is the pump and is it mechanical or electric? I assume we are talking Holley or some square bore carb correct? Metering plate could have a chunk of dirt or teflon tape blocking enough of the enrichment flow.


Over advance will do it ALSO full advance timing light on the balancer rev to over 3000 rpms and see what you get. if it is over 42 degrees( with vacuum adavance disconneted) your too far. see what it maxs at (vacuum advance disconneted and plug)

So there is some stuff to check. Make certain the cap on the distrib is good too NO cracks...STUFF HAPPENS! Just go through step by step thorughly and knock the simle things. Even a spark plug is not out of the question. Jim

 

Well if you say it was not doing it before you change the spacer I would change it back and see what you get. That will knock that piece in or out of the equation. Then yes fuel filter and or enough fuel period could be the problem. How old is the pump and is it mechanical or electric? I assume we are talking Holley or some square bore carb correct? Metering plate could have a chunk of dirt or teflon tape blocking enough of the enrichment flow.


Over advance will do it ALSO full advance timing light on the balancer rev to over 3000 rpms and see what you get. if it is over 42 degrees( with vacuum adavance disconneted) your too far. see what it maxs at (vacuum advance disconneted and plug)

So there is some stuff to check. Make certain the cap on the distrib is good too NO cracks...STUFF HAPPENS! Just go through step by step thorughly and knock the simle things. Even a spark plug is not out of the question. Jim

The fuel pump has been there since I've had the car, and it seems to leak a little.
It has a Demon 625 vaccuum secondary.
Do you know what the initial timing is when its about 36 all in?
The distributer cap is brand new.
I'll check the plugs tomorrow.

 

I'd say check your air filter, fuel filter, and fuel pump...it's could just be getting choked up once you put a load on it and are at WOT.

You mention adding a spacer...if you unhooked fuel lines and drained the fuel bowls on the carb then, once you put everything back on, the pump had a lot of extra demand put on it to quickly fill the line and fuel bowl.

An older pump that is beginning to wear out could easily have a desintigrating diaphragm, and once all that extra strain was put on it, it tore up a bit. I've seen in happen once or twice before--I always cycle the pump into a jar for a few seconds to make sure the fuel comes out clear before adding a new carb, or re-hooking the old one after beind drained. Maybe I'm just too cautious?

Also worth checking out your timing...has anything changed there?
What are you running for a distributor? It's been noted that STOCK gm hei's can start to break up around 4,500 and cause similar symptons.

 

I didn't drain the bowls.
Timing is 6 degrees without vaccuum advance.
Stock, points type distributer.

 

Two quick recommendations:

1) Fix your leaky fuel pump
2) Update your distributor to electronic

Try these items (or atleast the pump) and see what happens

 

Two quick recommendations:
1) Fix your leaky fuel pump
2) Update your distributor to electronic
Try these items (or atleast the pump) and see what happens

Big +1 on both suggestions.

If you have a leaky fuel pump, it could likely you're starving the motor for fuel when it needs it most. A replacement mechanical pump is pretty cheap...
Besides, leaking fuel is a HAZARD to yourself, your car, and everyone else at the track.

Upgrade to HEI and you'll be sitting pretty. A well tuned HEI distributor with a quality coil/module will vastly outperform your old points distributor...especially in the upper RPMs.
You'll probably see increased mileage, hp, throttle response, blah blah blah. I know I did.
You can get pretty good aftermarket units for around $150 (including coil).

 

I'd check/replace plugs and wires also.

 

Do you have a MSD with a rev limiter chip?

 

Your description of "Popping and Sputtering" sound like ignition problems. Do you have a coil you can swap out for a test? Coils will crack up under load when they go bad. Al

 

It sounds like your points are floating. Are they a high performance points set or a cheapie set from your local parts house? Points have different spring pressures for different applications. Get a set from an aftermarket ignition company like Crane or Accell. Your coil could also be going bad.

 

Sounds like the points as Mr Big Block has pointed out. Get a good set of Accel and see what happens.

67 Nova Boy

 

I have a stock distributer, cheap points, and an MSD Blaster 2 coil.

 

I think you should convert to an electronic distributor. It's going to be much better for you.

 

doesnt anyone rememer my big bout... i had the exaxct.. exact same problems... had like 16 pages and blah blah... i knew where my timing was FOR SURE...... but i just couldnt figure out the problem... full throttle .. like clockwork sputter at 4200rpms... everytime.. but if i eased into it.. i could go higher... well it was timing.. it was way off... may your balncer has slipped... but defenitly.. reset your timing.. put it to 14degrees btdc...

 

could you explain how you found out, and what you did to fix it?


Did you set the timing to 14 BTDC and leave it that way, or what?
What's that going to do for me?

Also, do you know what the timing should be set at when I don't have any vaccuum advance?

 

hmm.. i dont know.. but i had the exact same problems.. right after i changed heads... and i retimed it.. but it must have gotten messed up because i swore my timing was set good and it couldnt be the problem... i drove it that way for 6 months.. popping and kicking at 4200 rpms like clockwork... finally these guys on here forced me to check my timing after 16 pages of stuff..lol and it was wayyyy off.. like 55 degrees...lol im not sure what you want to set it for... if you dont have vac advanced.. maybe 22btdc..??? anyone else help out.. but im 99% sure thats your problem..

 

If you want to know where to set your timing, look in the BEST OF TECH section...

Basically you want to have a TOTAL timing of around 36 degrees, all in by 3,000rpm. The goal is to get all that timing in as quickly as possible, but without detonation.

In my case, that's 14 degrees initial w/ 22 degrees mechanical advance which starts it just above idle and is full in by about 2,600rpm.

My vacuum advance can is limited to 12 degrees and is hooked up to FULL manifold vacuum.

 

ok, I checked the harmonic balancer today, it did not slip at all.

The timing is where it should be.

I bought a fuel pump and I will see what that does for me.

Does anyone have any more thoughts on what the problem could be?

 

How did you check for slip? Did you use a piston stop and re-verify TDC? Why are you buying a Fuel pump. Did you put a fuel pressure gauge on it and see if the pressure falls off at the sputter point?

We spent 17 pages diagnosing Voodoo's problem because he didn't diagnose anything. Just a lot of guessing on his part and replacing parts without following our advice or instructions.

This looks like the same kind of thing. ANY engine problem can be figured out by conducting some simple tests. Guessing and replacing is a waste of our time and your money.

 

im telling you man.. reset your timing... i told everyone it wasnt my timing....

 

Here is a list of the things members have told me to check/replace:


Fuel filter. (already checked, its good)
carb spacer. (Turns out, this was the problem)
timing. (Still where I had it set)
points.
distributer cap. (brand new)
spark plugs. (Brand new)
fuel pump.
plug wires. (checked for spark with timing light, seem fine)
coil. (not the problem)
harmonic balancer. (checked, it didn't slip)


Tomorrow I will check the timing, coil, points, spark plugs, then fuel pump and carb spacer.

 

Here is a list of the things members have told me to check/replace:


Fuel filter. (already checked, its good)
carb spacer.
timing.
points.
distributer cap. (brand new)
spark plugs.
fuel pump.
plug wires. (checked for spark with timing light, seem fine)
coil.
harmonic balancer. (checked, it didn't slip)


Tomorrow I will check the timing, coil, points, spark plugs, then fuel pump and carb spacer.

If you are stuck using the points...don't forget to add a new condenser when changing them.

 

Back in the mid 70's I had a high revving smallblock (7K) and I used to cut a spring from another set of points and doubled them up to keep them from floating. I had that popping sound also. Of course now you can buy aftermarket points with strong springs. Also had a coil go out and same kind of symptoms but at a lower RPM under load. Crack in the distributor cap will also cause a missfire.

 

PROBLEM SOLVED


It was the carb spacer. I took it off and put my old one back on, and it fixed it.


today, I checked the timing, it was where I set it. I checked the spark plugs and replaced them (looked pretty bad). I put an old coil on, and that didn't fix anything, so I swapped out the carb spacer and that was the problem.


thanks to everyone who replied, I appreciate all the help.
and thanks to monzaz who said the carb spacer was the problem.

 

What size was the spacer?
Was it a 4 hole or open or??
Want to know why spacer was a problem?? Was going to put one on my 302 to help with lower end and throttle responce{4 hole x 1"} Will mine sputter at 8 grand?

67 Nova Boy

 

why or how would a spacer cause that problem???

 

Could have been warped, causing a vacuum leak?

 

i dont see how the spacer caused that problem...

 

it was warped, causing a vacuum leak thus resulting in a lean fuel mixture...lean fuel mixture=the hesitation experienced at 4,200rpm

 

New problem


Ok, I went from a 4 hole plastic carb spacer (which was causing the popping and sputtering) to an aluminum open spacer. It fixed the problem. I figured the plastic was warping from temperature or something. Then I changed from the aluminum open spacer to a 4 hole phenolic spacer. Now here is what's going on:

In first gear, I floored it. the rpms rose to 4500, then it started sputtering and popping, but I kept my foot in it, and when the rpms got to about 4800, it stopped popping and sputtering.

has anyone ever experienced this before? it's the same as my last problem, but only for 300 rpms, between 4500 and 4800, then it runs fine after that.


Here is an updated list of what people have told me to check, and what I done about it:

1. Timing. (it is set where it should be, I checked it several times.)
2. Coil. (I checked it, it is not the problem.)
3. Fuel Filter. (I haven't checked it recently, but wouldn't it have caused problems with the open spacer too?)
4. Carb spacer. (seems to be the problem, but I don't know why or what's causing it.)
5. Points. (seem to be in good shape.)
6. Distributer Cap. (brand new, no cracks.)
7. Spark plugs. (brand new)
8. Fuel pump. (brand new)
9. spark plug wires. (seem to be working fine.)
10. Harmonic balancer. (It didn't slip.)

 

Here is an updated list of what people have told me to check, and what I done about it:

1. Timing. (it is set where it should be, I checked it several times.) Have you tried advancing your timing? Pretty sure you could use more that 6*
2. Coil. (I checked it, it is not the problem.)
3. Fuel Filter. (I haven't checked it recently, but wouldn't it have caused problems with the open spacer too?)
4. Carb spacer. (seems to be the problem, but I don't know why or what's causing it.)
5. Points. (seem to be in good shape.) But didn't you say there were "cheapo" points? Could still be the problem...causing sputtering at higher RPMs
6. Distributer Cap. (brand new, no cracks.)
7. Spark plugs. (brand new)
8. Fuel pump. (brand new)
9. spark plug wires. (seem to be working fine.) Seem to, or ARE working fine?
10. Harmonic balancer. (It didn't slip.) How did you determine this--just by looking? I it didn't involve a piston stop, how can you know for sure? Also, if you're using a generic timing tab, it could be off a few degrees...

Of course, those are my thoughts in red...

 

Why not just change back to the aluminum spacer that fixed the problem?

 

Because the 4 hole makes the car faster even with the sputter.

Maybe The Spacer Is Causing Some Problem With The Booster Signal
@ Wot.

 

Maybe The Spacer Is Causing Some Problem With The Booster Signal
@ Wot.

 

.

tune your carb...

 

It's the same problem showing a slightly different effect. I don't believe changing the spacer did much of anything except changing the problem rpm around a bit.

Keep it simple. Vaccuum leaks, timing, ignition components, carb rebuild/tune, etc.

Kev