Thread: Timing Madness. Cam timing = Good. Base timing = Not Good?!? (A Mystery)

Weird. Why wouldn't it go into timing mode? Also, how did you know it wasn't in timing mode? Timing was still jumping around?

Has the head or block been skimmed before?

I'm not sure what that means, but I don't really know the history of the engine. Was bought from an importer. It's a W10 Avenir. How can I check if the block has been skimmed and how would that relate to my situation?

Thanks!
-G

Decking the block or head will require you to advance the dizzy to get 15* timing.

Well, I was reading about decking the block(assuming 'skimming' is the same thing). It's a process to remove some of the material on the block to increase compression. Like I said, idk the history of the motor but it came w/a T25. If this is the case than props to the person to had it lol. Would mean maybe I have a rebuilt race motor on my hands for under $1k I really doubt that's the case though. An explanation though none the less!

-G

okay this may be stupid sounding but i was having pretty much the same problem w/ my old DE and after about 3 weeks of constant work checking thing 2-3-4-even 5 time i went to find ou i stretched the timing chain YES streched i never really heard of it ether till it happened to me and i only had about 60k on the motor another possability is a chain tensioner???

I've had a chain stretch to the point of slapping and sounding like a DIESEL motor at idle and right throug the rev range, as much as they're supposed to last the life of the motor, i'm sure there's got to be one every now and again that is subject to not being perfect and wears a bit quicker. My motor had ~80k miles when i had the issue.

hmmm, why would a stretched chain cause timing to be off? Also, is there a test I can do to test for a stretched chain? Is the only fix in that situation to replace the chain? How would I know it's the chain and not the tensioner?

We did kinda hear the chain rattling around a bit, but assumed it would go away over time and was only from the cams. I don't think I remember hearing it doing that before we started but maybe I just never noticed it. Either that or was from removing the timing chain guide.

Let me ask you this:

When you said that you had the cams at 10 and 12 o'clock, did you mean the DOWEL PINS, or the small dots that are on the outside of the cam gears closest to the chain?

The DOWEL PINS that are part of the cam are what need to be at 10 and 12 o'clock. These are obviously in different positions than the indentations on the cam gears. Those need to line up with the colored links on the chain, if you're doing it by color and not by other methods.

Secondly, remove the valvecover and rotate the motor by hand. Every other revolution, the links should match back up again, with both colored links on the dots for the int/exh cam, and TDC should be present on the crank pulley.

Also,

I've never seen a timing chain stretch to the point that the tensioner couldn't compensate for the slack. Do you have an upgraded tensioner in there? I would get the RR tensioner for security.