I've had four early CRX-si's. In every one of them, I've set the timing as far ahead as I can, and it makes the engine run with more power, and produces better gas mileage. I can't find any downside to it. I had one of them running this way for over 100,000 miles. It still ran fine. As far as I can tell (and this is largely a guess), the factory timing is a way to beat the EPA emmissions standards. Once it's been imported, and the EPA is satisfied, is there any reason not to set the timing ahead again?

When I do this, I usually pull both vacuum hoses off the distributor and plug them. I originally did this because the vacuum diaphragm had torn ($600 to replace it, yeah right). It ran so good that I decided to try it with my other CRX's. They definitely run better, and have more power and better mileage. Once a year I have to set the timing to factory spec to get the emissions tested (California, not EPA), and I drive it that way for a week or two. I'm always very relieved to get it back to the "good" timing. Can anyone tell me why I shouldn't do this?

Matt

 

You're trading the stock vacuum advance for more static advance... I'd rather keep the stock system working, then start screwing with the static timing.

When I reworked the vac system on my old '87 Si, I capped the A/C advance but kept the normal vacuum advance connected.

 

Advancing the timing from the stock settings increases power but also increases the possibility of detonation. Factory settings are "safe" to avoid warranty replacement costs. If you run premium gas you can jack up the timing a lot but then if you fill up with regular the engine will probably ping on acceleration (detonation). Advancing the timing is about the first mod you make to pretty miuch any performance automobile. Unless you advance it too far and cause detonation, there is pretty much no downside to it, except you may have to set it back to stock to pass emissions. Advancing the timing increases combustion temperatures which promotes the formation of oxides of nitrogen. (NOx) It also makes your engine run a little hotter. However if you do advance it too far you could melt a hole in the top of a piston or cause other serious internal engine damage. Detonation is no fun

 

I've never heard any detonation sound (of course it is a pretty quiet engine). I use premium gasoline anyway, my owner's manual recommends it. It's a small price to pay for a good boost in power and mileage. I've never seen the cars overheat either, except when my radiator got blocked once. I guess I should feel guilty about the nitrogen oxides, but this car uses so little fuel that I expect the emmissions are still minor.

Having run one of my cars for over 100,000 miles with that timing, I don't worry too much about damaging the engine, but I'll keep it in mind. Thanks for the advice.

 

Seriously? I'd like to see a picture of that page. The compression ratio of the 85-87 Si's was too low to make good use of premium gas... it is a good idea to use it with advanced timing though.

Reconnect the stock vacuum advance and see if it still runs fine. Remember, the stock vacuum advance is there to advance the timing under engine load for more power. It helps more then a simple advance of the static timing (which stays the same regardless of load.)

 

:chuckles:
I run no cat and my car is constantly blowing out a good sized cloud of visible exhaust. I don't feel bad.

 

I run no cats on a hydrocarbon-spewing rotary and don't blow clouds of visible smoke. You might have a problem there. :eek3: