the camshaft and the no.82??

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its a stock camshaft or competition camshaft??

someone??

As there appears to be no ramp for the mechanical fuel pump, this appears to be a race cam, as you'd need an electric fuel pump. Tomei have a graph of the specifications of their cams on their web site, you might want to have a look & compare the measurements with what you have. It's definitely a late model cam, post 1973, where the distributor was moved from alongside number 1 cylinder to alongside no 3 cylinder & the fuel pump casting was modified to give clearance for the distributor.

i see....so i have to use an electric pump..hmmm..what kind of pump i need...if u can guide me much appreciated..for the time being im thinking to have an electric pump from honda 689....any other option??

i will check for comparison about the camshaft...thanx alot mate...

I'd say if the Honda pump was of a reasonable flow rate & low pressure it should work. The way I've seen a flow rate tested was to get a 2 litre container & fill it using the fuel pump. I think that if it takes more than a minute to fill the 2 litre container it's not enough. A small square Facet fuel pump that was available here in Australia was what I used, as Facet is European (British) you should be able to get something similar.

If my Combustion Ratio is 9.4:1 how much do i need to machine head to have 10.4:1 ???

There isn't an easy answer to that Gandalf - but there is a way to find it. Basically, you do the same 'maths' to work out the compression ratio, but let's say currentlu you have 24cc in the chamber in the head. Well do the calculation again (there is a quicker way, but this one is easier to explain in text) but use 23cc then 22cc and keep working until you get to 10.4:1 as the answer. Let's say when you went to 21cc you got 10.4:1 - just for example.

Then put the head upside down again, and completely level, and smear a thin smear of grease around the edges of the valves to prevent leakage, then measure out 21cc of kerosene (or water with some detergent in it, or food dye or something) and put the 21cc into the chamber, then look at how far up the fluid level comes, that's how much you need to take it off.

VERY VERY VERY roughly, you'll be looking at probably 10thou (imperial) per 1cc reduction on a closed chamber head of this size (that's going by my memory of mini heads which were actually similar shaped and sized combustion chambers (*well the 998 12g295 cooper heads were, the 12g940 1275cc heads were similar chamber diameter but not as deep)

The other option would be to measure the cc carefully now, get 10 thou machined off the head (make sure they can actually machine it that accurately, a lot of machinists will just take whatever amount of metal needed to clean it up, so make sure you are telling them you need to do it exactly to get the compression ratio right). After 10thou (0.010") is taken off, re-measure the chamber volume, re-calculate comp ratio and work out how many more cc you need, and then work out how many were taken off by 10 thou and add up what you will need.)

If 10.4 is the goal, personally, I'd aim for around 10.1-10.2 incase they take one cut too far. You can always shave another few thou off, but it's more of a problem if you go too far and need to _lower_ the compression ratio.

I would say it is risky to cut the head that much. Even if succesful your valve train will be out of whack and won't less the normal life.

Use flat-top pistons with Nismo thin gasket and you get 10.0:1. You still need to mill the head to get 10.5:1.

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This is just the standard small port, small valve cylinder head. It will be great for a low power economy engine, or you can spend a bundle on it with port enlargement & larger valves to make it about equal with an original stock A15 head, which would be prefered if it isn't the California smog version.

Try to find a serviceable A14 or A15 head without the air injection feature & this will go a long way towards improving performance as it comes with bigger ports & valves than the A12 head.

Using the A12 head will be like running a race with your fist in your mouth, neither you nor your engine will be able to breathe properly.

The standard compression ratio for many A series engines is about 9.5 to 1. For street use, about 10 to 1 is a good number, particularly with declining octane ratings or rising prices for high octane fuel.

I would prefer buying a GX head instead of a A15 head.....looking for one GX head, anyone have one?