I know this subject has been beat to death, but for my truck I am wanting opinions on what to set timing.

It is a 1997 12 valve, which will have a 3k rpm gsk, a fuel plate (not sure which yet), and run 30 psi. It's a daily driver, and occasional hauler of not more than 10k lbs gross trailer weight.

I am thinking 16 degrees. My 95 with the same mods is set at 16.5, but I read somewhere that the earlier 94 - 95 trucks like more advanced timing. Can someone elaborate on this, and give your opinion on what to set my timing and why.

 

15.5 seems to be the common number for those trucks

 

I ran my 97 at 16.5 with the stock turbo and injectors for a while and liked it alot better than stock timing.

 

I'm running mine at 15 currently. Runs good, has decent bottom end.

Is your truck a 180hp or 215hp? The latter retards timing with rack travel, so you could go a bit more timing on it if you like.

 

My 97 has a 215 hp engine. So the 215 hp engines retard timing with rack travel? I read somewhere timing was fixed on P pump engines, but variable on rotary pump engines.

If that is the case, that timing is retarded with rack travel on the 215 hp trucks, then why does everyone recommend less timing (less advanced) on the 215 hp trucks?

 

Never seen anyone reccomend less. If they have, its probably because the pump will flow more fuel than the smaller pumps with just a plate, easier to make the headgasket go pop. IIRC, the 215 pump drops 4 degrees timing at max travel.

 

OK. I think I will set mine at 15.5 degrees. That should be safe for my headgasket, and still improve engine efficiency (over the range of RPM's I will drive in the most) over the stock setting. The way I understand is that the stock setting, was set in order to reduce cylinder pressure, thus reducing combustion temps, and thus reducing oxides of nitrogen, in order to meet emissions. Would someone like to comment on this?

Thank you Tate for your advice.

 

That's true, but it's done at the expense of fuel economy, throttle response, and overall power.

Mike