Hi Aldo, your static (initial) timing @10 degree's sounds O.K. to start with. You can easily experiment with that part of the timing now that you have access to the timing light. If you are continuing to use 94 octane as your base fuel you may want to advance the timing a little at a time to achieve your goal of maximum output. I would set it at 14 degree's and keep going up 2 degree's at a time until you hear pre-ignition. Your part throttle timing of 53-54 is real close to max but you might be able to start that earlier by adjusting the vacuum advance. Each engine is unique to the amount of advance it can handle and it is based on many variables. I agree with the other members, the 98 octane should not have made such a noticeable improvement unless the state of tune was too lean in fuel and/or too much advance in timing to begin with. One disadvantage that you are working with is the fact that you don't know what the compression ratio is, this is a function of the amount of pressure that is built up in the cylinders and is directly related to the style of pistons, size of the head chambers, thickness of the head gasket, and bore and stroke of the engine. Not that you need to know the ratio, it just helps to have a good base to tune to.

 

You may already know this but your mid-throttle value of 54 degrees looks like you added your mechanical advance and your vacuum advance together. While with no load on the engine, you may approach that value, when actually driving with a load on the engine, the vacuum will drop off somewhat.

 

Hi Aldo, you did a great job pat yourself on the back for being a quick study, as 78 buckshot said each engine is a little different but now that you have the bacis downyou can experiment.
Try to bring up the initial timing just a little at a time.
Change or adjust the vacuum to get about 16*.

PS I use 93 oct paid $3.37 today.

Most of all, just enjoy your ride. PG.

 

thanks to everybody!
I would have never made the necessary jobs on my Corvette without the help of this Forum's members...

the vacuum advance ( adjustable) of my Street Fire distributor is at limit... I have measured 17-18 hg vacuum at manifold out and with this vacuum I can get not less than 20-21° from the vacuum advance. So unless I replace the vacuum advance diaphragm , I can lower the vac adv just 2-3° and increase the initial advance of same amount. Not a great difference I think.

I think I'll stay with my timing setting for a while. I'm satisfied of my engine now, when using the hi oct gas. I have now the mid-throttle response I wanted.the hp at high RPM are more than I can actually use.

I have to work on suspensions and steering now , because I still can't handle safely my corvette's power.When handling will be brought to the best setting possible according to my budget, then i'll go back to my engine tuning ( carb and timing again)

I'm waiting today for a package from the US with lot of good stuff : front springs, steering control valve, various suspensions parts-arms, bushing, tie rods....