383 starting issue

[hardcore]

A good friend has a 66 B Body Charger, with a 1967 383. The heads are newly reconditioned 906 series. He bought the car cheap, and not running, although everything was intact. The original heads had valves rusted into the guides, so it sat for some time. I helped him get the old heads off, new heads on, checked the cam, and replaced the timing chain. Everything has been checked and rechecked mechanically; the engine has very good compression.

When he purchased the car, it came with a tunnel ram intake with two carter 650 cfm carbs. The car has an electric fuel pump and holds 12-15 psi fuel pressure. There is also an aftermarket electronic ignition with an accel performance coil. The cam is aftermarket and slightly hotter than stock. Everything seems to be operating as it should, except the car simply WILL NOT START.

I've checked the distributor installation three or four times; everything correctly on top dead center and the firing order is correct. There is fuel in the carbs and the fuel definitely sprays from the carbs' accelerator pumps. We almost had the thing fired a couple times, but it keeps popping back through the carbs. I would usually assume timing, but its been checked and rechecked, (TDC on compression stroke, timing mark on TDC, rotor pointing to number 1 plug, etc.)

Has anyone else experienced this problem? The only thing I can see possibly causing the problem is the spark looks a little weak. I don't know if the tunnel ram intake could cause hard starting...I've pulled the plugs but they aren't wet or fouled. Any help would be appreciated. Thanks.....

 

[tarvin890]

Got spark? oh i see you do.... fresh fuel? todays gasoline turns to doodoo water if it sits a long time...if you have spark and good fuel it should start... unless......180 out or timing chain was set off...

 

[67Dart273]

I would not TRUST ANYTHING. I would check EVERYTHING

1...TDC. Check the timing marks for accuracy using a piston stop. This is no1, first, and takes no time at all. First time? I give you 1/2 hour

2...Cam timing. Easy. You can estimate intake valve closing with no special equipment, as it happens close to TDC. You do need to pull a cover, and you need to find out what the cam "is"

2A..."More involved" Put a degree wheel on the crank and REALLY check cam timing. This is easier on B / RB because it's so easy to pull the intake, but you CAN do this by just watching valve movement

3.....Compression / leak down. Google, you can MAKE a leak down tester, and Horrid Freight has them cheap. No excuses

4....Spark timing........Yeh. You said. Check it AGAIN. HOW did you set it? Let's have DETAILS on how you set it. Popping through the carb is either cam timing, open valves, or spark timing (or crossed wires) . End of story.

5....Fuel.........AFTER you have done all of the above, make sure the plugs are good, clean, and dry. Squirt a bit of KNOWN fresh fuel in the carb throats.

 

[hardcore]

Thanks for the responses.

I checked all the mechanicals myself, at least four or five times. (I actually went to a trade school for auto mechanics and have an associate degree. I worked as an automotive technician for 6 years.) I checked the top dead center issue (again) but its right on. I've had the valve cover off and a couple degrees after TDC the intake starts to open, as it should. Had the timing chain cover off and rotated the crank and the crank gear lines up with the dots on the cam gear every time.

Firing order 18436572....I know it by heart. On TDC (compression stroke) I aligned the mark on the harmonic balancer with the "0" degree mark on the timing cover. The rotor in the distributor is pointing to number one plug wire. I have enough room to twist the distributor a few degrees either way to adjust timing with a timing light once its running. Cranking it over I see the timing is in the ballpark.

I do see the spark starts strong but then gets a little weaker. It is an electronic ignition. I actually had the engine almost fire last night, spraying 2+2 down the carbs to make sure it had fuel. Then it almost burned my face off in a fireball. I am starting to think the fuel might be bad. It smells okay, but almost all gas stations here sell ethanol blend, which as tarvin 890 said turns to crap rather quickly.

Thanks again for the suggestions; I was just wondering if anyone else experienced this with a tunnel ram set up and I was missing something.

 

[TrailBeast]

If you are sure of everything else, from your description I would be checking pushrod lengths and lifter preload if it's a hydraulic cam.

 

[tarvin890]

I have had issues with coils before. start no start.... weak spark... new coil all better... try a spare yet?

 

[Bad Sport]

Firing order 18436572....

CW or CCW?

 

[jerry6]

ballast resistor , if it sounded like it was about t start

 

[Dubob]

Is the ecu grounded good? Have you tried hot wiring the ignition? Just remember if you hot wire it the key won't shut it off. At least then you can isolate if it's electrical or not. As stated try a coil. I've had Accells fail and do funny things. Reluctor gap good, polarity correct to pick up coil? Just some added thoughts of possibilities.

 

[Ben Drinkin]

Thanks for the responses.

I've had the valve cover off and a couple degrees after TDC the intake starts to open, as it should.

I might be smoking crack, but shouldn't the intake valve start to open after TDC on the exhaust stroke vs the power stroke? Sounds like 180 out to me.

 

[tarvin890]

BTW do something about that fuel pressure when you get it running.. waaaayyy too much pressure...

 

[hardcore]

If you are sure of everything else, from your description I would be checking pushrod lengths and lifter preload if it's a hydraulic cam.

Pushrod lengths are good. Thanks

 

[hardcore]

I have had issues with coils before. start no start.... weak spark... new coil all better... try a spare yet?

Replaced the coil with an spare....same issue

 

[hardcore]

CW or CCW?

Counter clockwise

 

[hardcore]

I might be smoking crack, but shouldn't the intake valve start to open after TDC on the exhaust stroke vs the power stroke? Sounds like 180 out to me.

Yes exhaust valve. Sorry, its easier looking at the engine doing it than typing at my desk. The distributor is in the right way.

 

[hardcore]

ballast resistor , if it sounded like it was about t start

So far, I've pretty much tried everything posted here, checked and rechecked. I though ballast resistor was just good, or no good. In other words, if it hard spark the resistor was good and if not, no good. It has spark, strong at the first couple cranks, then weaker.

Could the ballast resistor do that?

 

[hardcore]

BTW do something about that fuel pressure when you get it running.. waaaayyy too much pressure...

Thanks. I don't like the electric fuel pump anyway; its pretty noisy (at least until the engine fires.) There is a valve to reduce pressure though.

 

[AJ/FormS]

-Any oxygenated fuel that's been exposed to atmosphere for more than 2 weeks, will be very difficult to fire.Even after the first week, the lightest components have evaporated.
-When I get a situation like this, that is, all the ingredients are there, I do 1 of 2 things. Since I've been working on small engines for the past decades, I just put my hand over the carb airhorn while cranking.I am looking for a very strong suction signal, trying to inhale my hand. That tells me the rings and exhaust valve are sealing. If the suction signal is weak, I go around to the tailpipe, and do the same there. If the tailpipe tries to inhale my hand during cranking, then it's off with the head(unless the valves are adjustable) . Now I realize that in your situation this is not possible. So the next best thing is to put a vacuum gauge on it and see what the cranking vacuum is.Remember that it's possible for the vacuum to be low if the intake gaskets aren't sealing, and she's sucking from somewhere else. Or if the PCV circuit is faulty.
-Sometimes the rings are dry from fuel wash, and it doesn't suck properly. A little oil in the cylinders might wake it up.
-The second thing I do,after the above fails, is to throw a new set of plugs at it.Small engines seem to be particularly sensitive to needing perfect plugs.In your case a full inspection and cleaning might be ok, after all there are 8 of them.
-Let's revisit the cranking vacuum. If it is too low, it won't activate the low-speed circuits, and if the fuel is old, the engine will have to try and start on the syrup that's laying on the plenum floor, which has little to no vapor pressure left.

 

[67Dart273]

"Fireball" is ALWAYS timing, either cam timing, ignition timing "or both" or else valves hung open, caused by various things, including stuck guides, wrong cam timing, or bent, or burned.


LET'S START by making absolutely certain this damn thing is actually IN TIME.

1....TDC markings. What has been done to determine the balancer markings (timing marks) are actually correct? If not please DO this with a piston stop.

2....CAM timing. What has been done to confirm the cam is "right" and I do NOT mean "looking at the cam sprocket markings." Have you degreed the cam? If you know the cam specs you can estimate intake valve closing events by marking ATC / BTC near TDC

3....Let's say that 1 and 2 have been done. Let's set the timing. Put your finger in the no1 spark plug hole. Bump the engine until you start to feel compression. Alternatively, bring the marks up to TDC and look at the no1 valves. If they are both open, and both no6 are closed, rotate the crank one turn.

DO NOT set the timing marks "on TDC." Rather, set the marks WHERE you want timing to be set, perhaps 15 BTC with any sort of performance cam.

With the distributor in, the vacuum can in a position with freedom, the rotor should be "just coming to" the no1 plug tower as it rotates CCW. You can move the wires a hole if need be. Rotate the distirbutor RETARD, that is CCW for B/ RB. Rotate the dist ADVANCED slowly, that is CW, until the reluctor tip is in the center of the pickup coil.

YOU CAN check timing "on the starter" with a timing light. You want at least 12-15 with any sort of "cam" and perhaps MORE.

4....CHECK spark and let's resolve that issue. Don't use the coil wire, it may be bad, it may be a suppressor wire and will "throw you off."

Realize that there is TWO conditions for starting

4A....."Normal" using the key. When you twist the key, the bypass circuit in the switch (IGN2, brown) bypasses the coil resistor. CHECK that. Clip your meter to the coil + and read the meter while twisting the key to start. You should have "same as battery" and at least 10V

4B.....Jumpering the starter relay......a temptation. When you jumper the relay "under the hood" the IGN2 circuit is NOT active and the ignition is still being served through the ballast resistor, which greatly decreases spark intensity.

So.........rig yourself a spark gap, such as a screwdriver and clip lead. Check spark by holding your grounded probe "in" near the top of the coil tower. If you have two people, have someone twist the key to start. IF NOT clip an alligator clip lead from coil + to the starter relay battery stud. This "simulates" the IGN2 circuit. Now crank, jumpering the starter relay, and check spark.

You should have a nice, "snappy" blue spark at least 3/8" long, and many times more like 1/2" long.

5....If you do NOT have a reliable hot spark, start by "working" the distributor connector in/ out several times, as well as the ECU. Make CERTAIN the ECU is grounding. The coil should draw current through the ECU with key "in run." To check this, turn key to run. Measure coil + and coil - voltages. Coil + should be below battery, perhaps 6-8 volts. Coil NEG should be very low, perhaps 1/2--1 volt. If these two readings are much higher, the ECU may not be grounded.

 

[tarvin890]

excellent^