Thread: Decking Block/Head and Timing...How to Re-Adjust Timing??

So both cams need advanced 2* or only one?

Your distributor needs to be advanced not the cams.

2 deg off timing because of a shaved block and head would mean cam timing is off 1*

1 deg of cam timing will equal 2 deg of actual ignition timing being off.

So in other words if you wanted everything to be lined up back to perfect the proper way would be to get a timing wheel but assuming that both cams are off 1 deg retarded you would move the cams 1 deg and your ignition timing should be the same right where you left it. Either way you would need to set base timing to ensure.

Your confusing cam timing with crank/ignition timing.

This is the part that confuses me. By 'advanced' do you mean setting base timing to 17* or just making sure it's at 15* and realizing the bolt on the distrubtor will look like it's advanced more than middle. It's currently at 15* base timing and the bolt is moved to the 'advanced' side of the distributor.

This is an old pic, but this is what my distributor looked like both before and after the rebuild @ 15* base timing:





So you're saying here I get adjustable cam gears and advance both exhaust and intake cams by 1*?

All of the above is sort of right.

When you deck the block or machine the surface of the head you move the crank closer to the camshaft. When you do that you decrease the distance from the crankshaft sprocket to the cam sprocket. This will cause the camshaft to be "retarded" relative to the original specification. (I recall reading on here or maybe the old board that every .020" = 1 deg.) I guess that I would say that at .020" I wouldn't worry too much. If it exceeds that you would probably want to try and compensate for it. The distributor timing just needs to be set as it always is. The timing light will tell you when the spark is firing relative to crankshaft rotation so if you like to run 18 deg, set the timing at 18 deg.

Coheed,

Yes if the cams are 1 deg retarded due to the shaved block and head then yes you would advance both cams 1 deg to bring them back to where they are supposed to be.

As far as timing goes, remember 1deg of cam movement is equal to 2 deg of crank movement. So if your cams are off 1 deg your actual ignition timing would be retarded by 2 deg.

Dont confuse the two. Yes its only 1 deg of distributor rotation but 1 deg of distributor rotation has 2 deg of ignition timing affect as far as being relative to the crank.

So to simplify, if you adjust your base timing by moving the distributor, every 1/2 deg of movement advanced or retarded will equal 1* ignition timing change. Simple as that.

To the OP, I think your making a bigger deal out of this whole thing than is necessary. I would not worry about the cams being off 1 deg. Your not even going to notice any power difference or anything at that if thats even the case. You would need a timing wheel and dial indicator to actually properly dial back in cam timing back to factory. Again ive never done this in any motor ive had decked and put back together. Its really not enough to worry about. Just set your base timing following the fsm procedure using the distributor and be done with it.

hahaha. Wow man. I feel dumb.

I've taken a 3 month hiatus and this confused me... wow.

Hmm, this is what I wanted to hear. I was thinking if it was worth 10whp I'd get the gears because they are only $120, but if it's not even worth a couple whp then not worth the money.

-G

BTW,

This is exactly why they make different thickness headgaskets.

The stock headgasket is .9mm thick, most aftermarket headgaskets start at 1.1mm and this is to take into account resurface work. Then there is 1.3, 1.5, 1.8 all of which are common thicknesses with most aftermarket gaskets. Its not meant for lowering compression. Its to make up for removal of material from the block and/or head. Simple as that.

Ya, I originally got the VET head gasket for a light resurface job and then we found detonation so that increased the decking required. I don't really know what compression I'm at now hah...

-G

unfortunately there is not many options for the VE for headgaskets and thicknesses other than the Cometic gaskets, which I would rather pass on as well. Again youll be fine. Just get your base ignition timing set and be done and dont worry about the cams.