loyaltyisking

So my car diesels kinda bad.. Ive checked for intake leaks- no leaks. So leads me to think it may be the timing?? I had a buddy adjust the timing and I am thinking its all off... Any help or ideas would be GREATLY APPRECIATED....

29@0
26@1000
35@2200
38@4000
37@5700
36@6100 to 7200

Does this seem right?? As far as initial timing I am thinking way too much?

Some specs of setup.
66 chevelle
3100lbs
3.73s
T56
Cam: 231/239 gross 617/624 lobe 113
Holley hp ultra 750
Vic jr intake
Afr 210 heads

ANY HELP WOULD BE FREAKIN AWESOME

ZONES89RS

iTrader: (25)

Very possible. Mine is at 20 from 0-1000 rpm, then ramps up to 35 all in by 2000. What octane? That timing needs to come down up top.

loyaltyisking

Right now I run 91 octane.. From what i calculated i have 10.2-1 compression so I thought 91 would be fine. And when you say needs to come down up top do you mean at higher rpm timing needs to be lower?

ZONES89RS

iTrader: (25)

20* from 0-1000 rpm, then ramp to 34* all by 2000. Then lock it in all the way across. Unless you want to dip it to 32 at 5000 then back to 34 by 6000.

Pop N Wood

iTrader: (1)

I agree with zones, too much timing at low RPM. Less timing should make the car easier to start too. You may need to readjust your idle mixture when you drop the timing.

Higher octane gas will help with the dieseling problem. I think we have 93 octane here.

speedtigger

iTrader: (16)

Are you using the vacuum advance? If not, but 10 to 12 degrees in the vacuum advance and see if that stops it.

loyaltyisking

Yep the car has issues starting too.. I will change the timing to what zones suggested n see what happens. Also no vacuum setup. I will change that too. Ill get this done inna couple hours, i will post results. Thanks for the input all!

Pop N Wood

iTrader: (1)

If you add vac advance keep the total timing at idle (static plus vac) down around 20 degrees.

speedtigger

iTrader: (16)

I often run 38 to 44 degrees total timing (including vacuum advance) on engines at idle depending on how they "like" it. I also like this kind of timing at a light cruise also.

speedtigger

iTrader: (16)

I set mine to 8 to 12 degrees until 400 or 500 rpm then to 24 to 26 degrees to 1000 rpm. This allows the car to start very easily.

After that I run whatever timing is the fastest in the 1/4 mile from there to redline.

loyaltyisking

So I set up the timing and the map table to the settings and still dieseling... Maybe I need an instuctional video or something??

This is what its doing

The gauge display-
2 bar setup-
(guage right most) 19psia
(center) 19 deg
(left most) 700 rpm

Maybe it needs better gas??

loyaltyisking

The rest of the way the car rips, just at idle and starting and shutting it off its all off.

ZONES89RS

iTrader: (25)

Turn the MAP off and try it without.

loyaltyisking

Turned map off n still bad... Maybe i do have an intake leak.. I will recheck and see where im at. The timing is jumping all over the place. Rpms jump from like 30-70 rpm at times.. Is this normal?

speedtigger

iTrader: (16)

How rich is the idle?

ZONES89RS

iTrader: (25)

Something crazy goin on there.

loyaltyisking

Im assuming it DOES have a leak... I just read another article where some guy was running 40 deg at idle?? He said with 87 oct on 200 water temp. That sounds nuts, but i will try this next.

loyaltyisking

Ok so heres an update.. Its almost 1030 and imma try again 2mrw.

Last thing we did today-
We hooked up the map sensor and zeroed out the map table.
Gradually added more and more timing until we got to 52 deg at idle. Tried it several times and lo n behold the car shuts off! We still think its too much timing at idle so brought it back down to 40 at idle and 2mrw we will mess with the carb and hopefully we get this figured out.

Any input or any more ideas?? Thanks again for all the help.

Pop N Wood

iTrader: (1)

I didn't think the timing alone was going to fix it. Octane is usually what does.

Do you have a wideband? What are your AFR at idle and slightly off idle? I had and old car that had a solenoid in the carb idle circuits to turn them off and prevent dieseling. If your car is sucking too much gas through at idle combined with high compression and low octane gas, that is what causes dieseling.

Did you readjust the idle speed and mixture when you dropped the timing? Primary and secondary? What do the plugs look like?

Pop N Wood

iTrader: (1)

Yeah, the problem I had with this is the idle speed was so high I had to shut the butterflies down to the stops to get a reasonable idle speed. This covered up so much of the transition slots that the AFR's were squirrely coming off idle. This forced me to run the idle rich to make up for it. I finally set the butterflies to expose the right amount of the transfer slots and tweaked the timing to fine tune the idle speed.

Every car is different.

The ignition doesn't have much to do with dieseling when it is off. If the engine gets too hot and/or has carbon fouled combustion chambers, that is what causes it. Beyond that it is fuel delivery and octane, IMO.