Unless it's a tooth off, I would doubt that it's cam timing. Hall sensor disconnected?

 

I put in 3° advance on my '86.5 auto, which I have been complaining about lethargy with the stock cats installed, and it has perked up nicely, thank you.

I actually followed (the adjustment tips), and the whole process was done in a flash.

Note the 5° adjustment setting because the engine was hot. (If it had been cold, I would have set it to 3° while adjusting.)

 

Ken,

Presumably bank 5/8 was timed at plus 3 [with hot compensation]?

Regards

Fred

 

Fred - Yes. The 5-8 side can be set to the desired setting, hot or cold.

 

FYI, in digging through some old directories, I found this one showing the change in timing checked cold, versus another time later, hot.

 

Thanks, Ken. Now I'll just have to troubleshoot connections, flappy, vacuum, etc. to see if I can narrow the problem down. I really didn't want to replace the Hall Sensor if I don't have to (PITA). But I do miss the torque. The car doesn't knock any but I do get an occasional backfire.

Harvey

 

Uhm,

I must be missing something Ken,

You show that it goes from -2 to 0 cold/hot
And explain that your engine was done hot.
So then shouldnt you have set both to +3?

 

I think what you missed was reading the blurb...

Old pic.

 

so, hot didnt change the timing of the passenger side at all?

 

In the countries indicated in orange, yes.

 

That was funny.

 

Another dyno today to test -4° retard. Cold weather so it doesn't compare properly with the earlier dynos when converted to SAE because of the large temperature differential. (First run was 327 rwhp, uncorrected at ~40F. )

DIN correction was a better comparison, being right in the middle, temp wise.

Anyhu, -4° retard didn't seem to help any, HP just flatlines and carries on until the rev limit.

Also, more than +3° advance tends to increase knocks, so you may not get any more torque, because you have to back out timing.


±2° still seems to be the 'safe' range, AFAICT. Maybe ±3°, if you are feeling randy.


OTOH, -4° retard doesn't seem to hurt, and it feels 'effortless' to keep it at high revs. Hard to describe, but it is very quiet, and exceptionally smooth, at high rpms, with more retard. Almost feels like you are a gear higher than you are. Makes first gear more useful.

 

That is interesting about the additional knocks.

I had set my cams at 3 deg advance for use with the turbo, I had to back off my timing some. I think I am going to put them to zero or -1 and see how it responds.

 

As it turned out, somehow I didn't adjust it to -4°, but -1°. (On the plus side, the dyno place gave me a freebee for being a frequent flyer.)

I decided to try max retard instead. (Maxed out in the cam gear slot.) -8° retard, set hot HOT, vs. -2°, using DIN because of the temperature difference, 63°F/17°C vs. 79°F/26°C.

Torque is traded from 2700 rpm to 5000 rpm, with >10 rwhp/tq gained at 5000 rpm. HP is again clipped by ??, but extends all the way to the rev limit.

Unfortunately, you can't just adjust the cam timing to get these results. I had to richen WOT fueling (more overall, even more 4500-up), and add more ignition advance (6° overall, 4° from 4500-up), otherwise, the result would likely be the same, or worse. More ignition advance is possible with the cam retard, as the dynamic compression is lowered.


UNCorrected, or what it feels like to drive right now, shows the difference air temp/pressure along with the cam retard makes. It also explains why I don't feel the loss in torque.

 

Took me a sec but that was truly funny.