Copper Head Gaskets

[pilothyer]

First off this is an engine that will be used in a Porsche 914 for spirited pleasure driving.
In my 2056 build I am using a Raby/Webb cam 9550 (new but old) I am shooting for a C/R of 8.0:1. I have Ham heads with 58.4 cc combustion chambers, 96mm KeithBlack pistons, 71 stroke crank, H-beam new rods. with the Victor/Reinz Gasket set I am using the standard cylinder base shims.I am accurately measuring .044" deck height. I need to add .040" to get the total deck height of .084" in order to hit my required C/R of 8.0:1. I have on hand new .040 copper head gaskets specifically for the heads with the 96mm cylinders. They are a nice snug fit in the heads with no over hang into the cylinders. I am told I can expect the copper gaskets to compress to about .020" (heat cycle and retorque) C/R goes to 8.4:1. I could live with that I suppose. I would rather not have to use premium gasoline or have heat issues and I would like to have good longevity.
I am looking for input on this from builders that have used copper head gaskets. Opinions on use them or not, will they crush that much. or should I just use cylinder shims of the proper thickness to achieve .084"deck height and just use the stock head gaskets. I am not trying to start a debate on use or don't use head gaskets. I am well aware of the VW Bulletin about that. I am just asking the collective about copper head gasket use or not.

[wreck]

I just did an inspection /cam change on a 2600cc with 0.040 copper gaskets . I use higher head torque than stock (30ftlb) . my gaskets only "crushed" by 0.002" . to 0.038 " generally the deck shouldn't be more than 0.060" . over that you loose efficiency and the engine runs warmer . do you have any info on the cam , i.e duration @ 0.050 and intake closing degree's . you can then work out the dynamic ratio.


https://uempistons.com/p-27-compression ... lator.html

[pilothyer]

NEW RABY/WEBB CAM #9550. (9550 SUPER KIT)
LIFT: INTAKE .426”
LIFT EXHAUST .426”
DURATION INTAKE 262 DEG.
DURATION EXHAUST 267 DEG.
INTAKE DURATION @ 0.050” 224 DEG.
EXHAUST DURATION @0.050” 229 DEG.
LOBE CENTER 108 DEG.

[wreck]

even with a 0.040 head gasket and a 0.010 deck from shiming the cylinder giving a good safe deck of 0.050 will give you 8.6 to 1 static and with that cam ,based on using the web valve timing for a #73 grind that has similar numbers ,the dynamic compression is only 7.4 which is quite safe for pump fuel . do a little research on dynamic compression and what fuel octane you want to run .

some people don't like copper gaskets and would recommend spacing the cylinder to give the required deck and don't run the copper gasket .

[pilothyer]

Thanks for your reply and help. I was more concerned about hitting that static C/R of 8.0:1, but further research found information from the man who the cam was ground for, Jake Raby. He was responding to someone building a 2056 just like mine, and he stated that a static C/R for that cam (9550) was 8.5:1 for sea level and up to but no more than 9.0:1 for higher elevations. That information give me a bit more room to play with.