I assume that if you advance your cam by 4 degrees that you should back your timing off by 4.  Or is there a difference??

My truck has not been zero decked, & during my valve to piston clay check during the ecz-g install last month i measured almost .090 quench between the head & piston outside the combustion chamber with an old head gasket torqued to spec, measured at .045 with digital callipers.

I thought that engines with too much quench would tolerate less advance?

I am running 25 at a fast idle of 950, & total timing of 38 @ 3500 -4000 with about 5 degrees of vacuum pot.

Cam timing might require an adjustment to the ignition timing though it will not necessarily need to change by the same amount. I would start at 10 degrees. Work your way up or down from there.



Check your timing with the vacuum line disconnected from the vacuum canister. Plug the vacuum line so you do not have a vacuum leak while you are checking the timing. You should also set the initial timing with that line disconnected and plugged.


Lawrenceville, GA

Add this to what Charlie as said.

In general, total ignition timing doesn’t change based on cam phasing as both rely on the positioning to the piston to determine their effectiveness.  If the cam is phased in the extreme directions, then altering the initial ignition timing can make a difference in regards to idling characteristics but there isn’t a set rule for this.

 

But in regards to what I believe you are asking, if you advance the camshaft 4° in the engine without removing the distributor, then yes, you would need to back the ignition timing up 4° to put it back where it was.

 

Rule of thumb for optimum quench is to maintain 0.060” or less.  Anything more than this can increase the propensity for detonation if the compression ratio is high enough or the fuel octane is too low.

Lorena, Texas (South of Waco)

Sounds like you need to deck your block. If it is not yet assembled it would be money well spent. The excesive deck clearance and lowered compression will probably not run very well.

Replacement pistons are .015" lower than original. Factory deck was .025" (more or less) with .025" head gasket. That's about .050" while you're probably .085-.090".

With a 3.800" bore  you add .18cc for every 1/1000" of deck. With the additional .040" you will add 7cc to your combustion chamber. This will lower your compression nearly 1 point but it won't be less detonation tolerant. A lose-lose situtation.

Minimum deck clearance should be .035" or pistons can hit the head due to piston rock ect. We usually shoot for .045" .

http://ford-y-block.com 

20 miles east of San Diego, 20 miles north of Mexico

Another thing to consider is that today's gasoline is formulated for fuel injected engines and for low exhaust emissions. In other words it is next to junk. This is especially true of high ethanol gasoline. Bad for detonation and driveability. Pete

This upgrade was just that...

Pan, rear main, timing chain, heads, & all gaskets.  I have relatively low mileage on the engine, so taking it all the way down just not feesable from a budgetary standpoint.  I probably could have had Tim or another y block man build me an engine for what I have in the heads, & all the associated parts to go along with this upgrade & only spent a small amount more!

The deck wasn't something I was aware of when I did the original build.  It will have to wait until next time... Hopefully I can!