# timing advance maxed out



## freddy770 (May 16, 2011)

I've got an 86.5 D21 with the efi and computer controlled ignition. I just put a new crate motor in about 1500 miles ago and all the sudden it started pinging. I checked all mechanical timing parts and all tune up parts to find nothing wrong. Stuck my timing light on it to find the timing at idle to be between 25 and 30 deg. WOW... not sure what's forcing it to advance that far. checked out the tps and it seemed to test ok, but I still think it could be the culprit. Any other thoughts???


----------



## jdg (Aug 27, 2009)

25-30 degrees at idle is normal for most engines, at idle, without disconnecting the vacuum advance, or putting the computer into some sort of 'timing set' mode.
Not sure about your particular engine combination, but you'll probably want to check the Haynes manual or Chilton's manual or similar to make sure on how to set the timing properly.
And getting a tank of crappy gas from a cheap gas station is one sure way to get it to ping for ya.


----------



## freddy770 (May 16, 2011)

Turns out it was a blown head gasket between cylinders. Makes for some funny situations when troubleshooting.


----------



## freddy770 (May 16, 2011)

Replaced head gasket with a Fel Pro gasket and dropped the head back on. fired it up and only had to adjust the timing about two degrees from where it landed the last time I had the distributor out. runs like a top now. Can't believe a blown head gasket caused so much havoc with the base timing. Oh well, the Z24 is known for it's ability to eat a head gasket or two. thanks for the input.


----------



## SPEEDO (Jun 9, 2003)

I didnt know the Z24's went thru head gskts... I've had mine for 25yrs now and the engine has never been apart  replaced the water pump once but thats about it...


----------



## CMax03 (Jan 17, 2009)

freddy770 said:


> Replaced head gasket with a Fel Pro gasket and dropped the head back on. fired it up and only had to adjust the timing about two degrees from where it landed the last time I had the distributor out. runs like a top now. Can't believe a blown head gasket caused so much havoc with the base timing. Oh well, the Z24 is known for it's ability to eat a head gasket or two. thanks for the input.


What eats up head gasket is timing that is retarded and extremely advaced timing....from what I remember timing is only suppose to be 5* BTDC not 20*+....Now I normally run 15* but I'm cammed, ignition upgraded, headers, etc, Plus I'm using RACEWARE head studs with much more clamping force of those Oem stretch head bolts....Hopefully you are using a new batch of OEM head bolts not those same ones that you pulled off during your headgasket repair!


----------



## jdg (Aug 27, 2009)

*BASE* timing on practically all engines I've ever dealt with is right around that range, 5-20 or so. And by base timing, I mean the timing used while the engine is cranking without any additional advance put in by a vacuum modulator or centrifugal advance or any added advance put in by a computer.
The timing when you're actually idling or tooling down the highway, that's a completely different story. With gasoline, timing could be as much as almost 38 degrees advanced under light or no load conditions (i.e. idle in some cases) in most V8's and V6's, inline 4's also. But, that being said, that's not including things like turbo's, superchargers, nitrous, etc. Those things throw another wrench into the mix.

Incidentally, you'll know if you've got your *base* timing way too advanced if it gets all herky-jerky when you try to start the engine cold. The 'too far advanced timing' will ignite the mix way to soon and try to push a piston down while you're starter is trying to push it up.

And ya...of course, too much retard or advance ain't good on anything anyways


----------

