Topic: Choosing MLS head gasket thickness - squish clearance

[macvit7906]

Hoping to be pointed in the right direction here and verify I'm measuring correctly.

1975 cb750F
836cc wiseco kit, stage 4 ported head by M Rieck.

I’m measuring my squish clearance in order to figure out the thickness of MLS gasket to order. I was told to shoot for 0.04" squish.

I zero my gauge at the top of the sleeve. I have a piston in the cylinder without a base gasket.
When at top dead center, the piston does not go over the deck of sleeve. As best as I can measure it is .005-.01” below the sleeve at the edge of the piston near the wrist pin.

When searching the forum I found an example, but the piston goes above the sleeve by a little bit.

My base gasket reads .019” thick.
If I go with a 0.04” thick MLS head gasket that gives me .019 + .008 (piston is below the sleeve) + .04 = 0.067 clearance. Is that too much?

The thinest MLS gasket I can find is from dynoman at 0.03” thick giving my about 0.06” squish at most. Is that ok?

To show you how I’m measuring I took a pic below.

[PeWe]

Base gasket fiber or RCS (rubber coated steel)?
Fiber will compress when head is tightened, RCS not.
RSC available in different thicknesses too.  0.010" and 0.020".
Also important to verify valve to piston clearance with cam to be used.
Use a cam with relatively high duration and high lift like DP/RC295, Megacycle 125-75 for a good street bike.
Longer duration = more overlap= less compression= less power except on higher rev.

[macvit7906]

Base gasket fiber or RCS (rubber coated steel)?
Fiber will compress when head is tightened, RCS not.
RSC available in different thicknesses too.  0.010" and 0.020".
Also important to verify valve to piston clearance with cam to be used.
Use a cam with relatively high duration and high lift like DP/RC295, Megacycle 125-75 for a good street bike.
Longer duration = more overlap= less compression= less power except on higher rev.

Thanks
Base gasket is fiber I believe. Do you know where to get a 0.01" thick base gasket?

Camshaft to be used is cycleX CX-1 (webcam 41)

I was told to shoot for 0.04" squish clearance but it seems the closest I can get is 0.06", is this ok?

[PeWe]

I'm sure you'll get enough dynamic compression with that very mild cam.
MLS 0.04" will most likely work fine. Important to verify that the rivets will not sit where head and cylinder mating surfaces are.
I had that in my K6. I hammered rivets flat and drilled small dents where rivets hit cylinder and head. 8mm drill, just touch it 0.5-1mm down. Worked fine.

Possible to remove rivets too if hitting mating surfaces. I preferred to let the MLS layers to sit together.
I used 2 o-rings for oil transport up to head with MLS. 836cc as well as 1005cc with no leaks.

RCS base gasket need case surface without scratches.

If you use a cam with more duration and  overlap you need more compression.
I tested my DP315 cam with various valve lash. It must have double lash than other hot cams to reduce overlap and increase compression. Rather big difference when measure compression and during road tests.

Why not using 41A?  Stage 4 head means good valves and springs made for hotter cams
RC295 is my favourite cam profile.
Dynoman sell it as DP295. I found my on eBay as used unknown cam. Found RC295 scratched under its washer. Data matched RC295 cam data when I timed it.

[macvit7906]

I'm sure you'll get enough dynamic compression with that very mild cam.
MLS 0.04" will most likely work fine. Important to verify that the rivets will not sit where head and cylinder mating surfaces are.
I had that in my K6. I hammered rivets flat and drilled small dents where rivets hit cylinder and head. 8mm drill, just touch it 0.5-1mm down. Worked fine.

Possible to remove rivets too if hitting mating surfaces. I preferred to let the MLS layers to sit together.
I used 2 o-rings for oil transport up to head with MLS. 836cc as well as 1005cc with no leaks.

RCS base gasket need case surface without scratches.

If you use a cam with more duration and  overlap you need more compression.
I tested my DP315 cam with various valve lash. It must have double lash than other hot cams to reduce overlap and increase compression. Rather big difference when measure compression and during road tests.

Why not using 41A?  Stage 4 head means good valves and springs made for hotter cams
RC295 is my favourite cam profile.
Dynoman sell it as DP295. I found my on eBay as used unknown cam. Found RC295 scratched under its washer. Data matched RC295 cam data when I timed it.

Thanks for the help PeWe!

[macvit7906]

I'm sure you'll get enough dynamic compression with that very mild cam.
MLS 0.04" will most likely work fine. Important to verify that the rivets will not sit where head and cylinder mating surfaces are.
I had that in my K6. I hammered rivets flat and drilled small dents where rivets hit cylinder and head. 8mm drill, just touch it 0.5-1mm down. Worked fine.

Possible to remove rivets too if hitting mating surfaces. I preferred to let the MLS layers to sit together.
I used 2 o-rings for oil transport up to head with MLS. 836cc as well as 1005cc with no leaks.

RCS base gasket need case surface without scratches.

If you use a cam with more duration and  overlap you need more compression.
I tested my DP315 cam with various valve lash. It must have double lash than other hot cams to reduce overlap and increase compression. Rather big difference when measure compression and during road tests.

Why not using 41A?  Stage 4 head means good valves and springs made for hotter cams
RC295 is my favourite cam profile.
Dynoman sell it as DP295. I found my on eBay as used unknown cam. Found RC295 scratched under its washer. Data matched RC295 cam data when I timed it.

Found out today the rivets are too thick. I'm hesitant to drill the head/cylinders.

Can I just cut off the rivest and keep the MLS layers in the same orientation?