Stock Rb26-dett Head Chamber Volume?

[Chris Wilson]

What's the stock head chamber volume for a virgin stock head please? Thanks.

[Dale FZ1]

As I see things, you have a nominal vs actual volume. They could be the same, might be different. It should be measured if you are trying to select correct parts to achieve a target CR.

That aside, I believe the chambers for a 25 and 26 are the same. Mine measured at 65cc consistently.

Searching recently, I saw a comment from Sydneykid in an old thread that he had seen ~64cc. Nothing wrong with my gear, so it's reasonable to expect some variation.

Hope that helps.

[Angus Smart]

search on your uk forum's

i forget who but a guy rebuilding his motor with plenty of photos on there has the mesurements.

my internet is capped still so i cant do a great deal.

[The Dan]

You can always measure it yourself.

Get yourself a sheet of perspex. cut it out so it cn be bolted down through 4 of the head bolt holes. Drill a small hole in the centre of the perspex. Seal the perspex against the cylinder head after it has been shaved. Measure the amount of fluid you put in the hole to fill up the chamber. Use a blank syringe as it has the cc's on the side of it.

[Chris Wilson]

You can always measure it yourself.

Get yourself a sheet of perspex. cut it out so it cn be bolted down through 4 of the head bolt holes. Drill a small hole in the centre of the perspex. Seal the perspex against the cylinder head after it has been shaved. Measure the amount of fluid you put in the hole to fill up the chamber. Use a blank syringe as it has the cc's on the side of it.

Thanks, I am about to do just that, it's a brand new head that has been ported, and a bit of chamber tidying done. I'll post up the volumes, just needed a guide as to what a stock head chamber volume is. I have the piston crown volume from Tomei, so I can then, with the bore (86.5) see where we stand with a stock gasket fitted. Thanks

[rb26s13]

vaguely remember someone saying it was 62 or 64cc's

[Chris Wilson]

Measured a stock head today and it was 63 cc +- 1.5 cc across all six chambers. My new ported head is 65.5 cc on all +- 1cc. With Tomei cooling channel pistons with stock valve reliefs, a 0.9 mm thick, 87 mm opening gasket and stock deck height on 86.5 mm bores on a stock stroke crank I get 8.61 to 1 CR, which is what I was after.

Thanks