high compression with stock cam?....

[z-ya]

I use one of those timing lights that has the knob on the back. Have someone hold the throttle at around 3500RPM (or where the timing is max advance). Then adjust the knob on the timing light until the timing mark on the damper alighns with zero on the timing tab. Let off the throttle, and then look at where the knob points. That is you max advance. It's really the only way to know for sure.

 

Pete

[z-ya]

I use one of those timing lights that has the knob on the back. Have someone hold the throttle at around 3500RPM (or where the timing is max advance). While pointing the light at the timing tab, adjust the knob on the timing light until the timing mark on the damper aligns with zero on the timing tab. Let off the throttle, and then look at where the knob points on the timing scale. That is you max advance. It's really the only way to know for sure.

 

Pete

[FEnatic]

thanks for all of the GREAT responses. This is my first L rebuild and I am going to tune it in slowly for sure. I knew using the stock cam was going to hold me back, but till I replace it this will get my tuning skills moved up a few notches.

[Mack]

yes, ping is bad. I have a P47 (maxima) on a flat top block ...........about 11.5:1 compression, higher than most racers on this board..... with a stock 260Z cam (256 duration) and I get pretty bad ping above 3500rpm, but I have determined this to be an FI problem. Around 3500rpm is when the stock airflow meter maxes out and the computer goes to a preprogrammed a/f ~ rpm curve. it is no longer measuring airflow, the fuel is injected based soley on RPM.

 

the car only pings at lower RPM when I am running in excess of 15 degrees initial, otherwise its fine. in the summertime I can floor it in 5th gear @ 1500 RPM and it will not ping until 3500rpm.

 

I drive my car every day in stop and go traffic (pizza delivery) and run 92 octane and I have not killed a piston yet. I CAN use 89 octane for driving around town, but I have to be light on the throttle (nothing more than about 3/4). The car uses some oil, but thats because it leaks from every seal under the hood! it does not smoke, nor does it run lumpy. I am, however, afraid to do a compression check, lol.

 

A lot of my ping problems will go away when I switch fuel systems.

 

Mack

[z-ya]

I'm running a Megasquirt on my F54/N47 setup. It's really a great setup as you can move each RPM and load point (and of course adjust injector opening time) to match the engines fuel requirements. I was able to get the mixture to a safe 13:1 (+- 0.5) throughout the entire RPM band.

 

Richening it up more than 13:1 didn't stop the detonation when I tried more than 26 deg max advance. Again, maybe race fuel would have cured it, but I want to run street gas to save $. So I just backed off the timing to 26.

[Mack]

DAW>>>> no, I havent done any of the richening tricks yet. I tried (a) POT once, but that was when my ignition module was out. I really should go back and fiddle with it. I have a 5K POT so, it could be fun to toy around with that.

 

On a side note, Z-YA, are you running a Z N47 or a Maxima N47? Im curious about the "quench" factor! not to start any wars or anything.....

 

McAdam

[z-ya]

Oh no, that quench word again. I am running an N47 from a 280ZX. So I gues I am quenchless!.

 

Pete