If you install a cam with 4 degrees ground in, and dont mess with the timing chain position (like with the Cloyes True Rollers) and install straight up, does this affect your base timing value?

Lets say you have a cam (08-302-8 comp cam) that has a 4 degree advance ground in, and your factory stock timing calls for 6BTDC, should you set your Spark Reference Angle - Base Timing at 2degrees?

 

No no no lol. Cam position and ecm timing are completely unrelated. You are thinking of two way different things

 

The term "installed straight up" has two meanings depending on the person. Some think straight up means "match the dots" on the timing gears. Ie: how you would install a stock cam and how most people install a cam. Where as, IMO, the correct term means matching your ICL with your LSA. If you cam has an ICL of 109* and LSA of 113* this means the cam has 4* of advance "ground in". If you install this "straight up" you would retard the cam 4* (on an adjustable timing sprocket) to make your ICL 113*, which matches your LSA.

As for setting your base or "initial" timing this is a really good method: Get the engine up to operating temperature and set timing to a known good setting (say 6* BTDC). Advance the distributor 2* and turn the engine off. If you watch your datalog or temp gauge you will see after a few minutes the temp will spike. Now try and start the car. If it still starts easy, then advance another 2* and repeat the process until the car hard starts or windmills , then back up 2*. Now your initial timing is set.

 

<No no no lol. Cam position and ecm timing are completely unrelated. You are thinking of two way different things>

You can see how I <newb> got confused - the bin has 5.98 in it for base timing, and i installed the timing chain dot-to-dot, not advanced or retarded, so I thought you had to compensate somewhere if you wanted the base timing to remain stock.

<As for setting your base or "initial" timing this is a really good method>

I am going to try that method and let you know the results. I think now is a good time ...

 

The chip has built in start retard and is programmable so do not just give base timing advance until its hard to start. That would work for a non comp controlled distributor but for ecm controlled its not correct.

Just set it to 6 deg with est disconnected. Tune from there. Base timing ref really doesnt matter imo. Your overall commanded timing does. The main table will add in spark once est is connected and that really has control on idle quality and driving performance.

You just set base ref to the lowest timing that engine can run at. Some hot street motors will not idle with 6 deg base and may need 8, 10, 12 or more. Basically i back off timing til motor stumbles and then add 2 deg. Whatever that ends up being i make bin value the same

Spark timing and cam valve event timing are two separate unrelated values. Cam timing, aka dot to dot, or straight up or ICL numbers control valve motion with respect to crank rotation and piston motion. Spark timing by ecm and the base ref angle all have to do with firing the plugs with respect to piston motion/crank rotation. They both work together to make power but do not determine/influence each other

 

Well, I went through Morgsie's procedure and ended up at 8, maybe because I'm at 7K elevation.

Now after reading Orr's perspective, I really should go back out there and go the other way till it stumbles then add in two degrees. I feel like a pinball

 

Your motor should do handle more than 8 but it may not be necessary. I would just leave it somewhere in the 6-10 range