Hi everyone,
I've got some serious trouble to get my el camino rollin'!
I really need to get this thing on the road since I've owned it for 3 years now and still haven't driven it!

I put this 396 engine in it a while ago.
When i bought the engine it fired up nicely, but once in the car it's been like a on/off switch.
A few times it's been running allright, but most of the times it doesn't fire on all cylinders! If it manages to start up at all it idles very poor and only runs on 5-6 cylinders!
I've been dealing with this problem for a while now.
I now it gets fuel, so that is not the problem.
I've installed new sparkplugs.
Iv'e set the timing at around 36deg.

I've used this kind of tool that you clamp around the sparkplug cable to see if it fires correctly. I've found out that a few plugs doesn't fire as they should. But it comes and goes...

My best idea now is that something is wrong with the distributor or it doesn't get enough power to deliver good sparks.
But I don't now what... It's been running allright a few times!
What could possible break in a distributor?
Should I just get a new one?

Im a rookie on this so please let me know what you think!
Could I have done something wrong when I installed the engine?
Could some other electrical problem on the car cause this kind of trouble?
:confused::confused:

I need to get this 70' camino out on the Swedish roads!

Sorry guys I forgot to tell you, the engine has a HEI distributor which I believe is GM original.
I removed it when I installed the engine but it's back in same position now. I also set the timing with a light after that.
That was one of the few times the engine ran allright...

You're not telling us what type distributor

but it sounds like your instincts about weak voltage are right on, and that could be the old resistor wire for a points type car being used on an HEI newer unit snafu.

And I have a brand new cheap junk -chinee -ebay -worthless -waste of 39 good dollars -distributor that no matter what supply voltage it gets won't fire much more than 6 or 7 plugs at a time.

Did you set the initial timing or total timing at 36 degrees?

HEI, Ok

so you started the engine with this distributor, either on a stand or in another car and it was good?

now it is sporadic, in your 70?

HEI came out in 73 huh guys?

run a hotwire from the battery + to the distributor cap batt terminal, try it like that and see if it is happy

70 still had points distributors that needed 9 volts to run, with the key in the on posistion check the voltage of the battery wire going to the distributor. If it's less than 12v that's one problem for sure. HEI distributors won't run correctly with less than 12v. Also ensure you vacuum canister is disconnected and plugged when checking the timing. Somewhere between 36-42 degress total is the sweet spot for most BBC, you'll need a timing light with a dial to do it right, but setting the initial to 16 degrees is a good start, HEI distributors had all kinds of advance built in depending on the year. I hope this helps.

We had a similar problem. Turned out to be the distributor module. Usually they just quit this one didn't. If the above suggestions don't fix it have the module tested.

A few times it's been running allright, but most of the times it doesn't fire on all cylinders! If it manages to start up at all it idles very poor and only runs on 5-6 cylinders!
WHICH cylinders misfire? The same ones all the time; or is it random?

I've been dealing with this problem for a while now.
I now it gets fuel, so that is not the problem.
I've installed new sparkplugs.
Iv'e set the timing at around 36deg.
36 initial, or 36 total. With or without the vacuum advance connected?

I've used this kind of tool that you clamp around the sparkplug cable to see if it fires correctly. I've found out that a few plugs doesn't fire as they should. But it comes and goes...
Again--same cylinders all the time?

My best idea now is that something is wrong with the distributor or it doesn't get enough power to deliver good sparks.
But I don't now what... It's been running allright a few times!
What could possible break in a distributor?
First Guess: defective distributor cap, or defective wires--IF (big IF) the problem is always with the same cylinders. If this is random cylinders--things get more complicated.

Another possibility is a vacuum leak into the intake manifold that upsets the air/fuel ratio for the two misfiring cylinders. Typically, that'd be worst at idle and better as RPM went up.

Should I just get a new one?
No. Find and fix the problem, don't just replace parts.

Engine grounded good?

You're not telling us what type distributor

but it sounds like your instincts about weak voltage are right on, and that could be the old resistor wire for a points type car being used on an HEI newer unit snafu.
quote]
What should I do in this case???:confused:

[quote=Mr Chevelle;2283593]Did you set the initial timing or total timing at 36 degrees?
Total timing is set at 36deg.
HEI, Ok

so you started the engine with this distributor, either on a stand or in another car and it was good?

now it is sporadic, in your 70?

HEI came out in 73 huh guys?

run a hotwire from the battery + to the distributor cap batt terminal, try it like that and see if it is happy

Yeah I ran it in a stand!
Sporadic? sorry for being stupid but what's that?
I tried with a hotwire from battery + to distributor cap. But i didn't seem to help!

WHICH cylinders misfire? The same ones all the time; or is it random?


36 initial, or 36 total. With or without the vacuum advance connected?


Again--same cylinders all the time?


First Guess: defective distributor cap, or defective wires--IF (big IF) the problem is always with the same cylinders. If this is random cylinders--things get more complicated.

Another possibility is a vacuum leak into the intake manifold that upsets the air/fuel ratio for the two misfiring cylinders. Typically, that'd be worst at idle and better as RPM went up.


No. Find and fix the problem, don't just replace parts.

It seems to be the same cylinders all the time, sometimes it's just one that's firing incorrect and sometimes it's two or three.

It seems to be the same cylinders all the time, sometimes it's just one that's firing incorrect and sometimes it's two or three.
WHICH cylinders? Is there a vacuum fitting on the intake runner supplying those cylinders?

Are those plug wires good?

Are those terminals in the distributor cap good?

Engine grounded good?
Yup, I've got a serious cable between engine and frame!

WHICH cylinders? Is there a vacuum fitting on the intake runner supplying those cylinders?

Are those plug wires good?

Are those terminals in the distributor cap good?

Well I can't remember which numbers now... facing the front of the car, right side of engine (drivers side). 1st and 4th on that side.
There is a vaccum fitting at the back of the intake (close to the distributor).

The plug wires are brand new so they should be allright.
I have a hard time to find wires that works out good with my headers though...
The terminals look good to me..!

My biggest problem is that I am so lousy with these old cars!
I guess it's a simple thing that anyone here would fix in no time!
I would pay someone to do it, but I don't know anyone around here who's capable of fixing it. Darn...
But you allways learn something new when you get to fix things by yourself!
I Just want to get this thing going:D.

Mike,don't give up. These types of problems can be tough to find. There are plenty of people here that can help. Did the engine run good, until you removed the distributor?
Mike

So you just did an engine install, and put new plug wires on an engine that ran fine on a stand with this same HEI distributor. You have a badass ground and good 12V and a good cap/rotor. Your timing is set correct like these guys have been explaining.

Is the cap sitting down on the distributor good? It should feel right when you set it on there, and there is a little lug on the perimeter that indexes into a slot in the distributor body. My boy did that wrong one time, they run like crap.


Double check your firing order, then triple check it

18436572

goes clockwise around the cap

and make sure the plug wires click on good. Some makes of them you really have to push hard to get them to click into place.

I just swapped my ZZ4 back into the car before winter and this is my spare pump gas / winter time engine and it is a great engine and I do engines all the time. It ran like crap when I started it in the car so I double checked my wires and all seemed right, went in for the night figuring I had cracked a plug or 3 doing my headers. Next morning I rechecked my wires and lo & behold I had 5 and 7 crossed down by the plugs.

i got my pen and pad because im going through this exact same problem now!

my 396 did this as well....not sure if this was mentioned, but my was a result of a bad ignition module. actually, after i replaced the ignition module it ran great for a few months, then one day after getting on it the engine just shut down...this time it killed the ignition module completely which is more common. after replacing the cheap Accel distributor with a full msd setup I haven't had any issues.

Mike,don't give up. These types of problems can be tough to find. There are plenty of people here that can help. Did the engine run good, until you removed the distributor?
Mike

Yeah, it did. But I only started it up a few times.
It's so strange... like a on/off switch.

It's so easy to tell when the engine is gonna run on all cylinders, it fires up the same second you turn the key. Just starts so easy!:yes:
Then it can run like that for a few seconds and then drop down to 5-6 cylinders. It doesn't want to idle and you have to give it some throttle to keep it alive...

A few times its been running good for a short while so I've been able to set the timing. Sometimes untill I turn it of myself. (Not for a long time now:()
But then when I turn the key again it's back in the same old mood. Really difficult to get it runnning. The starter just turns it around and around and you can hear it fire once in a while, but it won't start.
You can force it to start if you give it a lot of throttle. I guess the cylinders that actually fires gets enough power to keep it turning around...

Thanks for all the advice so far!

So you just did an engine install, and put new plug wires on an engine that ran fine on a stand with this same HEI distributor. You have a badass ground and good 12V and a good cap/rotor. Your timing is set correct like these guys have been explaining.

Is the cap sitting down on the distributor good? It should feel right when you set it on there, and there is a little lug on the perimeter that indexes into a slot in the distributor body. My boy did that wrong one time, they run like crap.


Double check your firing order, then triple check it

18436572

goes clockwise around the cap

and make sure the plug wires click on good. Some makes of them you really have to push hard to get them to click into place.



I'm gonna re-check all of this a 10th time, I guess there is allways a chance to miss something!
But the firing order should be correct and the cap is in position.

Im gonna double check the ground!
Can a weak battery cause this kinda of trouble...?
Im not 100% sure my alternator is working.
The cap and rotor looks allright to me, but then again Im a rookie on this!

This might be a stupid question but anyway...
You dont need a separate coil like you do on a "points" engine right?

Since this is a 70' camino and it was not not made for HEI, can this cause any trouble?
(But I Should have got rid of that when I ran the hotwire one would think...)

Mike,you won't need a seperate coil with that type HEI. If you believe it is the same cylinders that misfire each time,about the only things I can see that would cause that would be a cracked cap,bad wires or plugs. Did you happen to have the distributor in, when you installed the motor?
Mike

Do you have another distributor to try out, it might be the module like mentioned before.

Mike,you won't need a seperate coil with that type HEI. If you believe it is the same cylinders that misfire each time,about the only things I can see that would cause that would be a cracked cap,bad wires or plugs. Did you happen to have the distributor in, when you installed the motor?
Mike
No, I had to remove the distributor to squeeze in the engine!

Do you have another distributor to try out, it might be the module like mentioned before.

No, I wish I had one! If I don' find the problem soon I will have to buy a new distributor I guess...

Well I can't remember which numbers now... facing the front of the car, right side of engine (drivers side). 1st and 4th on that side.
There is a vaccum fitting at the back of the intake (close to the distributor).
If you have a dual-plane intake manifold, both of those cylinders are fed from the same primary venturi on the carburetor. Also from the same idle mixture passage.

How do the MIDDLE two cylinders on the other bank run?

I would be testing the idle mixture screw adjustment on the carburetor.

Does the vacuum passage in the back of the manifold lead into the runner for the rear cylinder that's misfiring? What is connected to that vacuum fitting? If you cap the fitting, does the problem go away (or decrease)

The plug wires are brand new so they should be allright.
I have a hard time to find wires that works out good with my headers though...
The terminals look good to me..!
How about the plug wire insulation?

my 396 did this as well....not sure if this was mentioned, but my was a result of a bad ignition module.

Do you have another distributor to try out, it might be the module like mentioned before.

If you believe it is the same cylinders that misfire each time,about the only things I can see that would cause that would be a cracked cap,bad wires or plugs. Did you happen to have the distributor in, when you installed the motor?
Mike
As M.Maner said--a misfire on the same couple of cylinders cylinders over time CANNOT be the module. The module could conceivably be the cause of a random misfire affecting all the cylinders--but it CAN NOT cause a misfire restricted to the same two cylinders.

ttt,, I think everyones delt with this at one time or another.

Only things I can add are some of the things I try:

Set the engine up as best you can, plugs wired right, although if it it ran ok they should be fine.

Hook up a remote starter button or get someone to turn the key.

Check each plug wire with a clamp on timing light to see if they are all firing.

If so, it appears you have fire.

Next, take off the top of the air cleaner and spray some starting fluid down there and see if it starts. If so, they it may be a fuel issue.

The random on/off does sound like a ignition prob. You need 12v to an HEI. The country boy would run a wire from the bat + to a toggle switch, to the dist. A female spade on the end will fit the hei connector. I put a fuse in line at the batt just in case.
Plug it in and crank it. This will eliminate stuff like the actual ignition switch, the neutral start switch, etc.

If this fails, troubleshoot the HEI module or replace it. I have only checked out one, but it died at the exact same time as a cylinder head cracked, and was annoying to have to fix just to troubleshoot the head prob.

I am not an HEI expert, but you do have to pay attention to the coil connection, module connection and the button to the rotor. I have had a similar prob on a sbf, and I can change a Duraspark pickup coil, box and coil in about 10 minutes if needed. That, after the hardwire power wire testing should find the prob.

You should also check your pickup coil in the distributor. Sometimes they are good until the vacuum advance moves them and then they misfire or quit altogether.

I'd try a known good, as in new, ignition module, given everything else sounds good...

Thanks for all the good advice!
I won't be able to work on the car untill this weekend.
But I will use this thread as a checklist and hopefully come up with something!

Mike,
Please let up know what the final fix is.

Ok...
Things are nog going good.:mad:

I've done some work on car today, but still I have not found the problem!

*I've got good 12v to the distributor
*I've got good ground to engine and distributor
*I've checked all the plugs and wires.
They all seem to work when I run them one by one... Only one cable with a plug connected to the distributor, turning it around on the starter.

It did fire up quite easy and ran on idle when I put some new fresh fuel in the tank. Not all cylinders I'm afraid, but it made a big difference with fresh fuel:D.
But I've been here before.
It starts and idles, but not on all 8.
When I hit the throttle quik it pops/backfires and sometimes shoots flames out of the carb.
Seems like number 5,7 and 8 only wires now and then.

Should I just throw the dist in the bin and get a new one??

run a compression test.
ck vacuum hoses (leaks)
I'd put a new cap and rotor on it.
jim

Mike, disconnect the vacuum advance and plug the vacuum port on the carb,then crank the engine. When the engine is at idle and you check the timing,what does it read?
Mike

The pickup coil could be causing problems too.

When it comes to buying a distributor, what should I go for?
This is no high performance engine so it doesn't need to be fancy:D.
Can I buy summits cheapest stuff, Proform or their own Summit stuff?
Or do I need to get MSD??
Planning on buying ANOTHER set of wires as well, cause the ones I have seem to interere with my headers... Same question there, do I need MSD?

I think everyone is kind of saying 'man this thing ran on the stand, don't throw parts at it'.

I never saw a HEI module drop a few cylinders. frigging just quit is what I've seen with an HEI module. But that doesn't mean they ALL friggin just quit. But on the same cylinders..... nawwww,,,, the module could give a rats butt about which cylinder is next. That's a cap or wire, plug or compression or mix to that cylinder. But not a device that serves all 8 cylinders.

And I've seen lots of threads where guys get asked if they have a spare distributor or carb they can stick on to eliminate causes:)

Ain't much better than having good spare pieces laying around in wait for when you need em.

I have an $89 Summit distributor I bought one time just to have a spare. I liked it, and it isn't a spare any more. It runs my ZZ4.

I have 2 sets of MSD wires, they are OK but I don't consider them extra special. They are expensive and not really worth it imo.

I think everyone is kind of saying 'man this thing ran on the stand, don't throw parts at it'.

I never saw a HEI module drop a few cylinders. frigging just quit is what I've seen with an HEI module. But that doesn't mean they ALL friggin just quit. But on the same cylinders..... nawwww,,,, the module could give a rats butt about which cylinder is next. That's a cap or wire, plug or compression or mix to that cylinder. But not a device that serves all 8 cylinders.

And I've seen lots of threads where guys get asked if they have a spare distributor or carb they can stick on to eliminate causes:)

Ain't much better than having good spare pieces laying around in wait for when you need em.

I have an $89 Summit distributor I bought one time just to have a spare. I liked it, and it isn't a spare any more. It runs my ZZ4.

I have 2 sets of MSD wires, they are OK but I don't consider them extra special. They are expensive and not really worth it imo.

What your'e saying about the module sounds reasonable...
I did a compression test when I bought the engine, and as far I can remember it looked allright... But Im a rookie. Maybe I should do it again.
But bad compression shouldn't come and go like this problem...:confused:

Thanks for all the advice I've got so far, I really apreciate it!

Hi again!

I've might have mislead you guys a bit...
I've got the thing running last night, not good but running.
Checked all the cylinders with a firing indicator and now they do seem to fire!
I must have been doing something wrong the last time I checked it.

I then did a compression test and luckely it came out good!
They are all within a 5% range. So I guess that is not a problem:thumbsup:

Still it shoots flames out of the carb when i hit the throttle hard, and runs a bit rough!

Which are the most common causes for backfiring like this??

My money is on the dist. timing being a tooth or more off one way or the other. Go through the procedure and reinstall it and get the timing right - about 16 - 18 Degrees at idle with the vac. advance unhooked and plugged, if you haven't already done it. Sounds like that was the only real change from the stand to the car. Good luck.

Your timing is WAY advanced, DON'T keep running for long this way. One good backfire and your carb WILL catch fire, ask me how I know. I did this when I was in high school. I would take out the distributor and ensure everything is right, then time as said before with no vacuum advance and the vacuum ports plugged.

Ok I will try and re-set the timing!

I don't know what kind of cam I've got.
Let's say I have a GM stock cam, should i still go for 16-18 deg initial:confused::confused:

What is the best way to know that you're installing the distributor in right position, so it's not coming one tooth off.
Is that something that you need to do very accurate or don't you just fine tune it by turning the distrutor once its in?

Take the car to a mechanic.
Mike