Datsun Roadster Forum-311s.org

My question to the group is , I bought this 67.5 spl311 three years ago without the previous owner knowing much about the build. What I do know is that it has an h20 block and head with a r16 valve cover. The motor has a lot of torque very fun to drive and fast. I assume there is really no way of knowing what the internals have without pulling the valve cover and head ? Also was thinking about installing a five speed. Any advantage and or disadvantages of doing such? Also would like to know if a 1600 Isky cam 5162cc racing will fit an h20 ? My block # is 816659, head has a #2 near front and 8613A on side.

I don't know R/H engines personally, but I'm pretty sure they use the same cam. Compression ratio may be different, as perhaps the crank (3 main vs 5?). Anyway the cam will likely fit. However, you would want to know the specs on that cam before deciding to run it, as it may not put the power band where you want it, or may be less suited to work well with all the other systems (intake, exhaust, carbs, ignition, etc) than what you have. Call Isky and they will be able to tell you what it is, that's the place to start. Race is not always fun on the street.

On the cam it will work in the H20 I beleive but you really need to get more details on it before deciding if it make sense to swap or not, I would call IskY and try to get more details about the grind , power range etc. If it really is a “racing” cam and tuned let’s say for a high revving 12:1+ CR 3 main R engine it will just be a dog in your engine and you will need to pull it out again.

Is the head an H20 or is it an R16 head ? (Look at the markings on the head if not sure )

Personally I like the 4 speed a lot behind my R16 I don’t do a ton of long distance but even when I do it cruise at ~3700 at 70mph on stock tire size which is not that bad compared to 3100 in my U20 5sp car both cars on 3.9 rears. With a lightened flywheel and 2l clutch it’s just a fun combo. That’s not counting the crazy prices of 5speeds nowadays

Irrelephant

Thanks to all who replied with the helpful information. Much appreciated.