366 Timing Off

[jaredg]

Hey fella's,
Got my coolant leak under control and am now trying to tackle my "engine run-on or dieseling" problem. I am 99.9% positive that it is timing related. When I go to start her after a few days or a week, it is really tough. I even experience mild back firing when trying to crank her over. Sometimes I can get her to crank over but it idles really rough for a few minutes and then craps out. Usually I can get her going though giving it enough gas and holding down the pedal for a few minutes to get the idle up, then once I drive it for 5 - 10 minutes she's perfect. Well except for when I shut her down and it does the dieseling thing.

So I guess my question is, do you guys think its timing related? If so, where do I start? I am learning how to do these things one engine component at at time so if you can school me on how to fix timing (if that is what it is wrong) that would be great.

In the meantime, I took some pictures of things that I am not quite sure of what they are. The arrows point to those things and if someone could chime in and educate me that would be great:




This is on the rear of the Alternator. It looks burnt, what is it???


Thanks for all your help as always!!!

[jaredg]

Does anyone know what the timing specs are supposed to be on a 366?

[the_experience03]

I'm not sure what the exact specs are and would have to look, but 10* BTDC with the vacuum advance disconnected should get you close I would imagine.

[jaredg]

Is there any fuses that would keep this bus from starting? Its cranking but not firing.

Things I've replaced:
Distributor Cap
Distributor Rotor
Ignition Coil
Ignition Control Module in distributor
Starter
Battery

Ive checked and there is 12v to the power lead on the distributor. I did the spark plug test and I believe I am not getting any spark.

[Griff]

Have you checked for spark on all plugs? Your "replaced" list doesn't include ignition wires or spark plugs, have you changed them? If you pulled the distributor to perform any of your tasks, make sure it was reinstalled in the correct position (timing-wise). Ensure that you reinstalled your ignition wires correctly between distributor cap posts & appropriate cylinders after changing your distributor cap (I know it sounds silly but it has to be mentioned).

Originally Posted by jaredg

Does anyone know what the timing specs are supposed to be on a 366?

Somewhere on the engine/in the engine bay, there should be a manufacturer's label with those specifics listed. Mine are on my battery mounting bracket and on the firewall beside the battery bracket on my dog-nosed gasser).

[jaredg]

Thanks for your reply!

I havent checked spark at all wires though I will try that today. As for the replaced list. I did replace all spark plugs and wires about a year ago.

[sportyrick]

You should have an anti diesel solenoid on the throttle side of your carb to stop the run on. Timing will have a little to do on the run on thing but so does mixture. Make sure you don't have 5 & 7 plug wires crossed or mixed up. Are your plug wires getting burned on the exhaust manifolds? Even with my anti diesel solenoid my 427 will run on sometimes if it's not set right. If it's bad then I just turn the engine off while in gear. It seems more prevalent in the summer time. sportyrick

[jandncope]

Timing is probably a bit off. not sure on the specs but most big GMs like 10* advance. I think your problem is fuel leaking past the power valve and or metering block in that holley. Reubuild or replace.

[Russell]

Jandncope has got a good tip on the power valve on that demonic holley. If you rebuild the holley another thing that you should do is get a anti backfire check to guard your power valve against back fires. I had what sounds like the same problem with my 366 and cured it with a new distribitor. Good Luck