Head gaskets for 4cyl engine combos

[datzenmike]

Follow the cam manufacturer's suggestions for setting. Yes TDC and 360⁰ are the same just the number of cylinders changes. The stock cam sprocket is adjustable in 4⁰ increments for adjusting out chain stretch, sprocket wear and if the head is milled. L16/18 are set on the number 1 position, L20B are on number 2 from the factory. L16/18 have 2 and 3 or two possible future adjustments if needed. Not anywhere close to a precise adjustment for after market setting. You'll need an adjustable cam sprocket for that precise a setting of cam timing.

 

https://www.datsun-garage.com/products/full-adjustable-cam-pulley-sprocket-gear-1968-1973-510-1970-83-240z-260z-280z-280zx

 

 

https://jdm-car-parts.com/en-ca/products/l4-l6-high-performance-adjustable-cam-pulley-by-kameari?variant=12296726773881

 

[Stoffregen Motorsports]

Yes, cam position should be set, but a degree wheel is not always needed. Setting up the degree wheel takes a bit of time, and for all the fuss, it's not always worth it. You can set the cam timing using the split overlap method. This method only requires that you know exactly where TDC is (verified by actual piston travel, not just by the pointer on the front cover). The only special tool required for this method is a brake dial indicator. I use a brake rotor runout gauge setup with the dial indicator mounted on a flexible arm. There is a vise grip on the end of the arm, which you clamp onto a head bolt, then set the tip of the dial indicator on the rear valve retainers for measurement.

 

Though tough to find online, there are a couple articles describing the split overlap method online. I think Isky has a basic rundown on their website.

 

Typically, am L motor likes to be a tad advanced. In general terms, setting the cam "straight up" means that the measurement take at the intake valve is identical to the measurement taken at the exhaust valve. Loosening the cam bolt and rocking the motor backwards (to the rear of the dowel hole) will advance the cam. I like to drill out the hole in the cam sprocket and use cam degree bushings, like in a SBC. The amount of advance varies from cam to cam, but it's usually in the .010" range, meaning, if you have .100" travel on the exhaust valve, there should be .110" measured at the intake valve.

 

I may have just caused a ton of confusion, but degreeing the cam this way takes a ton less time, and can be done on an assembled motor, without degree marks on the crank damper/pulley, thus, allowing for easier cam timing adjustments after the engine is built.

[JumboFett]

1 hour ago, Stoffregen Motorsports said:

Yes, cam position should be set, but a degree wheel is not always needed. Setting up the degree wheel takes a bit of time, and for all the fuss, it's not always worth it. You can set the cam timing using the split overlap method. This method only requires that you know exactly where TDC is (verified by actual piston travel, not just by the pointer on the front cover). The only special tool required for this method is a brake dial indicator. I use a brake rotor runout gauge setup with the dial indicator mounted on a flexible arm. There is a vise grip on the end of the arm, which you clamp onto a head bolt, then set the tip of the dial indicator on the rear valve retainers for measurement.

 

Though tough to find online, there are a couple articles describing the split overlap method online. I think Isky has a basic rundown on their website.

 

Typically, am L motor likes to be a tad advanced. In general terms, setting the cam "straight up" means that the measurement take at the intake valve is identical to the measurement taken at the exhaust valve. Loosening the cam bolt and rocking the motor backwards (to the rear of the dowel hole) will advance the cam. I like to drill out the hole in the cam sprocket and use cam degree bushings, like in a SBC. The amount of advance varies from cam to cam, but it's usually in the .010" range, meaning, if you have .100" travel on the exhaust valve, there should be .110" measured at the intake valve.

 

I may have just caused a ton of confusion, but degreeing the cam this way takes a ton less time, and can be done on an assembled motor, without degree marks on the crank damper/pulley, thus, allowing for easier cam timing adjustments after the engine is built.

When I had the engine apart I verified TDC using my dial indicator, then after I put the head on marked TDC on the pulley and the timing plate, so I’m confident their in alignment. Nevertheless, I trusted the advice of placing the cam dowel on the 2nd sprocket hole, though I was told that would advance the cam 4°, which is what I wanted. Because I was advised not to worry about degreeing the cam I trusted the process and set it there. What I was hoping to see was the cam sprocket cutout just slightly ahead of the static timing mark, but it was dead on. I tried placing it on the 1st and 3rd marks, but there was no difference, so I put it back to the 2nd hole and it’s been there since.

I’ve heard horror stories about those adjustable cam sprockets, so I’ll probably stay away from them, but the cam bushings sound promising, so I’ll keep those in mind for the future high compression engine. Right now I’m working with an 8.5:1 motor with a much better flowing head and a slightly more aggressive cam profile, so my margin for error is wide. Still, I wish I had more adjustment options when I had it apart so I could tighten my IVC angle ABDC in order to maximize cranking pressure. Confirming ICL according to the reported cam specs is all well and good, but I’m most interested in when my intake valve closes, which will become especially important in any serious future engine plans. 
And of course… Thank you both for your help!

[Stoffregen Motorsports]

Here's the Isky split overlap tutorial - https://www.iskycams.com/cam-degreeing.html

 

This might confuse things a bit, but I just found a video of a guy using a similar method for checking cam timing. The principle is the same as the split overlap method using a dial indicator, but he doesn't go that far.

 

 

 

[JumboFett]

31 minutes ago, Stoffregen Motorsports said:

Here's the Isky split overlap tutorial - https://www.iskycams.com/cam-degreeing.html

 

This might confuse things a bit, but I just found a video of a guy using a similar method for checking cam timing. The principle is the same as the split overlap method using a dial indicator, but he doesn't go that far.

 

 

 

Good video! I’m guessing the application that would work for our engines is measuring off the valve retainer? Obviously there’s no lifter, but would there be another spot on these OHC engines?

Edited December 14, 2023 by JumboFett

[Stoffregen Motorsports]

Yes, the spring retainer. The split overlap method works as he describes, but you put the dial indicator on the #4 cylinder intake valve and zero it, then bring it to TDC, and record that measurement. Without moving the crank, move the dial indicator to the exhaust valve and zero it, then turn the motor until the dial indicator stops moving. The difference between the two numbers is your split overlap advance/retard.