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

Hey,

So, I had my block and head resurfaced for a rebuild. I've read that when you mill the block/head it can retard the timing. My question is, how do you know where to adjust timing to get it back to 15*. Do you just advance the timing until you see 15* on the dial or is it more complicated than that?

Thanks!

Depends on how much is taken off the block. Put it this way the factory headgasket is .9mm thick. Most aftermarket gaskets start at 1.1mm thick I think mostly because they assume your going to have the head and block resurfaced during a build.

There is a how to on how to adjust timing. You need to put the car into timing mode and then adjust the distributor with a timing light until your at 15* base timing. Not hard to do you just need to do it following the procedure.

Ahh, so basically all you have to do is advance the timing until you get to 15*. I thought it might have been a little more involved like it would show 15* but really be retarded and some calculations involved.

Good to know!

So why do people recommend cam gears after decking when they can just advance timing using the distributor? I thought maybe more was involved here...

Most people dont use cam gears unless they are running cams that require them. Not because of the decking of the block.

If off enough your cams could be off a degree or so and they are saying to use them to redegree the cam back in to where they should be. But again I havent seen one far enough off to matter.

Seems to be some sort of myth or misinformation then on the intertubes about needing cam gears after getting the block/head decked. Not that I'm surprised!

-G

Can someone please explain to me the difference between adjusting base timing and using cam gears? Do the cam gears just allow you to adjust either gear independently and base timing will adjust both of them? Is base timing only when the spark plugs fire and has nothing to do with how the cams physically rotate?

I keep reading that decking the block requires cam gears...do these cars just not have the ability to adjust base timing? Could I set timing to 16* which would maybe fix any need for timing or would I need to physically do it w/cam gears? Still confused about this stuff...

My block/head were decked quite a bit. Over twice what FSM recommends as a max. Car does kinda feel like the timing is retarded a bit but it's right on at 15*.

-G

The base timing is ignition timing relative to tdc. Your cam timing is mechanical ie if the vertical distance between the crank and cam are not the same but the chain is the same length it could get out of mechanical time. However I think that's why the enhanced riming chain tensioner is longer with finer teeth. I thin you'd have to shave a lot off to get out of mechanical time. Most machine shops will only take like .020 off the head and like .010 off the block.

I know .014 inches was taken from the block. Unknown on the head. Probably a lot less like .006 inches. So a total of about .020 inches.

Oddly enough, my base timing on this car has always needed a lot of advancing(in relation to position of distributor bolt) and the timing chain sounds loose at idle. It's still like that, even after the engine rebuild. Makes me think the block/head have already been resurfaced or something before I got it resurfaced again. Perhaps cam gears are needed on my setup? I'm running S4 cams as well, not sure if that makes this better/worse. What do you guys think?

-G

I shaved head and block, timing on cams should be advanced 2* to compensate apparently. My dizzy in the middle of adjustment is about 13*.

It is recommended to get cam gears, but it is far from a requirement.