Timing question.

[YungICY]

I pulled the head off my motor last night and I'm just about done putting it back together.



I know when I time it, the crank and the cam both need to be lined up on tdc but what about the tfi distributor? If memory serves me right it gets timed to 10* btdc. That would mean that with the crank at tdc the rotor would be 10* past plug terminal 1 correct?





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[adsm08]

No, BTDC is before top dead, if you time it past the post it will have no power.

 

[YungICY]

So if the crank is at tdc the dizzy rotor should be 10* btdc? Thus making it fire on the down stroke?


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[adsm08]

No, you want the spark to fire on the up stroke.

If you fire on the compression stroke, while the piston is coming up, that is before top dead (BTDC). If you fire after the piston gets to the top, and is going down on the power stroke, that is after top dead (ATDC).

Now what you said you should line the rotor up at 10* past the post on the cap I take that to mean 10* farther along the rotation.


Anyway, the better way to do it is to set the cam timing, put all that back together, then set the crank so the pointer is at 10* BTDC and put the rotor in line with the post.

 

[Mikel89us]

You can't time it by eye, it has to be done while running with a timing light

 

[Mikel89us]

And adsm, if you put the rotor after the post while the crank is at tdc, that is an advanced setting because the plug has already fired and the rotor has gone past the post.

 

[YungICY]

Yeah I think we both misunderstood each other there. Mikel89us got it. What's the trick to getting the belt back onto the tensioner? My thumbs can push and harder haha.



And I just got it close by eye so when I get it all back together I can check it on the timing covers marks and adjust from there.


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[YungICY]

So I'm getting a major oil leak on the back side of the engine on the drivers side where the head meets the block. My new head gasket is set in place correctly, and the new head bolts are torqued down correctly. What other issues could cause this problem?


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[adsm08]

And adsm, if you put the rotor after the post while the crank is at tdc, that is an advanced setting because the plug has already fired and the rotor has gone past the post.

I know. That is what I was saying. Icy asked if he should set the crank to TDC and then set the rotor 10* past the post. I told him to line the crank mark for 10* BTDC with the pointer and then set the rotor at the post. Just like I have done for every engine I have spiked a dis in for the last 5 years. It has been a long time since I was more than 2* off on first start up.

 

[adsm08]

So if the crank is at tdc the dizzy rotor should be 10* btdc? Thus making it fire on the down stroke?


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No no no and no. Before top dead is before the piston hits the top of it's travel coming up. After top dead is after the piston has started to go back down. You keep describing after top dead center and calling it before top dead.

 

[Mikel89us]

gotcha, but those rotors arent exact, you really need to use a timing light

 

[adsm08]

Oh yeah, you still need a timing light for fine tuning it, no doubt about that. But if you don't happen to have a timing light handy spiking the dis that way will at least get it driveable so you can go get one.

The way he was going to try doing it would give it even less power than the unimpressive amount it produces when setup correctly. I have driving 2.9's that were severely retarded and they couldn't get out of their own way. I'm betting a 2.3 on a 20* retard like that could be outrun by a tumbleweed.

 

[Mark_88]

I'm betting a 2.3 on a 20* retard like that could be outrun by a tumbleweed.

Is that what they are? I thought they were skinny kids with afros...some of them even seem to be laughing at me...

Anyway, I think your oil leak might be the valve cover. The rear is always a problem area if you don't get it down right and you should use a similar tightening sequence on the valve cover as you do on the head bolts.

As for timing, mine has always been done by the marks initially and then adjusted through the distributor. It has always worked for me that way and I've only used a timing light on it once...only to find out that you need to remove the vacuum line (on a carbed engine and spout connector on FI) to set timing with a light.

Speaking of timing...going to have to have a look at that some day soon myself...gotta try passing some of those tumbleheads...

 

[Kenneth S]

As to the oil leak on the drivers side rear the there is a oil passage that transverses at the rear head bolt on the driver side rear, if it is leaking at the head gasket it's self usually means something got between either the block, or head when you were putting the head on (it doesn't take much). But make sure that the oil pressure sensor isn't leaking first because it's in the same area.

 

[YungICY]

I got it all back together and working properly.



And out here in the southern Utah desert those tumble weeds move quick. Some of them are hard to keep up with on a good day.



It was leaking out of the head gasket. I pulled it back off and I had missed some of the old gasket right next to that oil passage on the back corner.



I timed it like adsm suggested. I timed the cam and crank to tdc then rolled it back a bit it 10* btdc and lined up the dizzy cap and rotor. I haven't used a timing light on it yet, but its running great and I'm probably not any more than 1 or 2* off for timing.



Now what would cause a thick layer of white powder type build up on the exhaust valves? All of the exhaust valves were covered with it but it wasn't anywhere else in there.


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