camber and cam sprocket

[Travis]

I'm new to the forum but not so new to datsuns i was wonder if you guys might have so input on weither its better to set the cam sprocket to #2 or #1 location after doing a complete rebuild on a l20b. its got everything new and of course the head and block were resufaced, so i lost a little material which would make a differance on chain length. secoundly is there any way to adjust camber after doing a reindex on the front end as explained by bleach on his page. thanks for any input.

[Travis]

sorry i forgot to add its a 79 620 if it matters

[datzenmike]

Factory setting is #2 but with head trim this acts like slack so try the #2 and the notch in the sprocket should be just on or slightly to the right of the horizontal etch mark on the cam thrust plate behind it, like this:

 

http://i138.photobucket.com/albums/q251/datzenmike/L%20Z%20Heads%20and%20Motors/motorLcamtiming.jpg[/img]"].

 

If not move to the #3 hole and check again.

Edited February 25, 2009 by datzenmike

[Travis]

I would truely love to but the after market sprocket i got has no notch. i know im an idot but it came with the whole set. maybe i'll just have to go buy a new sprocket because i refuse to put the old one back on. the beauty of it is that it only take about 10 mins to swap back and forth.

[datzenmike]

Post your location on your signature before ppeters comes home and sees your post.:D

[copacetickid]

nice pic of the cam sprocket ;)

 

Mine's on the first notch still, and my block was decked and the head resurfaced. I haven't noticed any ill effects from it, so it may not matter too much (then again, I may not be attuned to the engine enough to know if there was a minor issue with the cam timing). There's a fair amount of play when attaching that locator plate onto the first cam tower, so it's not an exact science.

 

If I could do it over again though, I would put it on #2.

[HRH]

Personally I don't like the aftermarket gears. I reused an OLD original sprocket that looks like it could take a hit from a Sherman tank. Works great!

 

http://www.mattalbertson.net/camgear.htm

[Travis]

well heres what it looks like on #2. Iguess i'll run with it thanks

[Creepy Cruiser]

I'm kind old school here, lol, but after decking the block and milling the head we would run cam tower spacers to take up the slack in the chain. Is that still the thing to do, or is there a better way now a days?

[HRH]

That's the only way I know of to correct chain slack on L motors. Is that you Todd, or is there another guy in Spokane with a functional hearse? :D It's Matt at NAPA.

[hang_510]

I'm kind old school here,

Is that still the thing to do, or is there a better way now a days?

 

old (school) but not dead :lol:

 

 

nothing better as of today

[datsunaholic]

My '74 (which has an L20B) was set at #1 when I got it. Since I never pulled the valve cover until the head gasket let go about a year and a half ago, I never noticed it was on #1. The truck always had a backfire problem- going down hills it would spit and pop, and when shutting off the engine it would give a pretty good "bang" on occasion.

 

Anyhow, when the head gasket let go I noticed it was on #1 upon disassembly and the timing mark was quite a way off. I repositioned it to #2 on reassembly and haven't had any backfiring since. Improved the gas mileage dramatically as well.

[Creepy Cruiser]

That's the only way I know of to correct chain slack on L motors. Is that you Todd, or is there another guy in Spokane with a functional hearse? :D It's Matt at NAPA.

 

Yep it's me, "The long haired freak", lol.

 

I was woundering how long it would take you to figure out it was me, lol.

[copacetickid]

When I had all the work done on my motor, I asked the machinist about spacers for the cam towers and he said that the amount of metal that they were taking off is negligible in terms of timing chain slack, so I shouldn't bother. He said it was something like a thousandth of an inch total (between the block and head resurfacing), so if that's true, I tend to agree with him.

 

I still don't know what the actual observable effects are of cam timing that's too late...

[datzenmike]

 

This is what you should see with crank at TDC. If they took 1 or 15 thou of the head, as long as you have this (above) the cam is properly timed no matter which hole 1, 2 or 3 is used. Keep in mind that for every mm taken off, 2 mm of slack is introduced to the chain. Even with a tight new chain you may not be able to get this setting even in the #3 hole. Shims of the same thickness as what was milled off can be placed under the cam towers to raise it back up the the original height.

 

If your chain is stretched or head milled and the V mark is not to the right of the horizontal mark, your cam... and valve timing will be retarded. This results in late closing valve events. A possible advantage at very high RPMs but it ruins low speed intake vacuum and thus idle and drive ability. It will run like shit where you drive it 99.9% of the time.

[HRH]

I seem to remember cylinder head service saying cam tower shims coming in increments of .015". That said, if you mill .030 off the head, you'll need two shims per cam tower to achieve factory correct height, which is a damn good idea for a tight chain. I always mill my heads according to that. .030,.060,.090.

 

Typically don't go over .030, though I know a fellow Datsun racer who does .060.

 

The only time it's negligible is when you're doing a cleaning clearance on the head, where they only take off .002 to straighten and get the crap off. That of course, wouldn't need a shim.