Having read more than once that timing advance tends to yield more high rpm horsepower than low rpm hp, and having somewhat experienced that _ I guess... - with my setup, I was wondering what y'all who either tow heavy or up long hills find to work best: timing advanced or not. Beyond that, what setup you found to work best: currently mine is in the sig, i.e. 60mm wheel and 16cm2 exhaust housing.
Thanks!

 

The thing you have to watch out for with towing and lots of timing is cracking the pistons due to lugging. If you work it hard I wouldn't do much more than the traditional bump. Auto trucks can get away with more since they really never lug.

 

I towed with mine once on a trip after 1/8 inch bump. I gained a bit of mileage and I noticed no difference in low rpm power. Unloaded I gain 2 mpg's as well. (I didn't check it while towing that trip) For a truck that works hard a 1/8th bump would be helpful with rpm but not hinder you down low or damage anything.

 

If what I suspect is correct, I'm running at as much advance as mine likes. I have noted difficulty getting started with a heavy load, but once the RPMs are up there it does great. That may be due to the 3.07 gears though. If you know were your timing is (I don't ), a timing spacer is the direction I would go. It is supposed to give you the best of both ends timing wise by extending the mechanical timing range.

 

Well, yeah, lugging is the issue, especially that 4th gear...

Yep, I have the same issue with getting rolling with heavy loads. Even with 4.10 gears, the power delivery is sluggish in the low rpms and then the power comes aplenty as the rpms increase. An analogy - exaggerated - would be an old school 125cc 2-stroke motocrosser.

I've read some about that spacer. One thing I don't know is: do you have to put the pump back to stock position to install the spacer?

 

You dont have to put the timing back to stock. It's just been stated that you start there. Probably to make sure you dont start on the high side of things, ya know?

I did both the spacer and skipped a tooth (seems iike i just posted that somewhere) and it runs real strong.

It doesnt blow the tires off before the turbo spools but once the turbo lights, its game on (until the pump stops fueling). It still will burn the tires some before the turbo lights but not a lot.

 

Since we are going into a little more depth about dynamic timing I will add some more. I don't run a spacer, but I get the same affect by having the timing piston machined down allowing more movement. Its very close to the same amount of advance you would get from the spacer. I run stock initial timing. I have not towed with this setup yet. I can say that it has more low end than my old cranked up stocker did at 2.1mm timing. As far as keeping it free, do the 1/8th bump. If you want the best of both worlds a timing spacer could be the answer for you. On a side note running high initial timing (2.1mm as I had on my stocker) can make for hard starts and it rattles a lot. The new pump with the extra advance idles like stock and it gives it the extra timing in the higher rpms. It truly is the best of both worlds.