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Discussion Starter #1
Hey, so I’m in the process of rebuilding the engine (for track use) after some minor alterations to the ports (only the recommendations in the race manual) and looking for some advice on the head gasket thickness I should go for. I was thinking of going middle ground to be on the safe side. Any thoughts/recommendations other than needing to make sure the squish value is higher than 0.65mm and the piston to valve clearance?

Also, the race manual gives value timing info for the slots bolt holes, but the combo in the table doesn’t show both the standard in/ex cams together, according to the part numbers (or I’m being massively special and totally missed something). Any advice on the inlet timing if using the slotted holes and 106 degree on the exhaust?
 

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As far as head gasket goes, get it as close to that .65mm number you can with the gasket. I wouldn't run anything approaching .020" or less clearance (.51mm) under any circumstances, but up to that point benefits will be realized. .65mm (.0255") is reasonable and safe for these motors. Compression gain would be mostly unnoticed, but the other benefits are real.

Cam numbers aren't my specialty, though if Gaz chimes in I would listen to what he has to offer. It may help if you state your desire/intended purpose for the motor: Steet/drag/circuit/dyno queen/etc.
 

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Discussion Starter #3
As far as head gasket goes, get it as close to that .65mm number you can with the gasket. I wouldn't run anything approaching .020" or less clearance (.51mm) under any circumstances, but up to that point benefits will be realized. .65mm (.0255") is reasonable and safe for these motors. Compression gain would be mostly unnoticed, but the other benefits are real.

Cam numbers aren't my specialty, though if Gaz chimes in I would listen to what he has to offer. It may help if you state your desire/intended purpose for the motor: Steet/drag/circuit/dyno queen/etc.
Awesome! Thanks for the heads up. I’ll have a better idea this weekend on squish value. I’ve just found out it’s currently got a .75mm in there but it was brought as a salvage so I have no idea how it performed. It needs replacing at this point anyway so getting one to suit the desired squish makes sense.

I’m looking to use on circuit if i ever get it built!
 

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Awesome! Thanks for the heads up. I’ll have a better idea this weekend on squish value. I’ve just found out it’s currently got a .75mm in there but it was brought as a salvage so I have no idea how it performed. It needs replacing at this point anyway so getting one to suit the desired squish makes sense.

I’m looking to use on circuit if i ever get it built!
Watching this, exactly where I'm at. I have been told 108/110 (in/ex) but cannot confirm if those are the magic numbers.
 

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Always measure deck height with aftermarket pistons... most tend to raise the piston crown above the pin slightly more than stock, and any material decked off the block to bring it into square will raise the effective height as well. A .75 gasket is super conservative for a stock motor/stock pistons, but you may find it is baby bear for aftermarket pistons.... no way to know without measuring!
 

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Discussion Starter #6
Watching this, exactly where I'm at. I have been told 108/110 (in/ex) but cannot confirm if those are the magic numbers.
From this it looks like 106 for the exhaust using standard cams (with slotted bolt holes), but it doesn't show an option for the inlet with standard cam, only the kit inlet (49118-0728).

It's just that one magic number. I'm wondering if its the same as the standard - 105.5.......
446415
 

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Discussion Starter #7
Always measure deck height with aftermarket pistons... most tend to raise the piston crown above the pin slightly more than stock, and any material decked off the block to bring it into square will raise the effective height as well. A .75 gasket is super conservative for a stock motor/stock pistons, but you may find it is baby bear for aftermarket pistons.... no way to know without measuring!
Thankfully its standard pistons and I'm hoping it no head adjustment ...for the minute at least. It'll keep it relatively simple ish. Just need the torque wrench to arrive so i can confirm the squish depth.
 

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Any assistance on the inlet timing for circuit use?
I also have that race manual. I noticed that the difference btw the std 0860 inlet and the kit 0728 inlet is 0.2mm in lift, same duration. The 0728 figures are 110/106. The advice I was given here by an engine builder who is also a fast racer was 110/108 for oem inlet. Those are the figures I'll be using when I do mine as long as the v/p clearance spot on.
 

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Discussion Starter #10
I also have that race manual. I noticed that the difference btw the std 0860 inlet and the kit 0728 inlet is 0.2mm in lift, same duration. The 0728 figures are 110/106. The advice I was given here by an engine builder who is also a fast racer was 110/108 for oem inlet. Those are the figures I'll be using when I do mine as long as the v/p clearance spot on.
Awesome, thanks man!
 

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Discussion Starter #11
Just out of curiosity has anyone done dyno runs with varied cam timing to see how it affects the power and torque curve? Marginal or huge difference in performance? Nothing specific and no timing secrets necessary 😉
 
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