m40 tuning update

[ejoeyward]

so my head is stripped. iv been quoted <200 quid for 3 angle valve job, guides replaced and head skim, which i thought was a good price from sabre head in Wisbech, Cambs. just waiting for my dremmel bits to turn up then its time to polish inside and out, port matching of which i need to take about 2mm off of each side on the exhaust ports.

To the block now and im doubting to strip it at the moment, i was going to do it at a later date, when i have my custom pistons made, but when i was removing the head, i fount the piston faces had A LOT of carbon on them.

finally do you think it is possible for me to knife edge a crankshaft. i have electronic calipers to measure everything and pin striping tape to tape it up. so it will all be even. but is there still a chance i will knock it out of balance even it if its measured to within a few thousandths.

btw i am pretty anal when doing some thing like this my ports are going to polished with 4000+ grit wet and dry

[broadie]

Stick some bg44k in the fuel tank that will clean the pistons up.

[ejoeyward]

Stick some bg44k in the fuel tank that will clean the pistons up.

just thought while i could get to them maybe some gunk and a pressure wash may do it

[Speedtouch]

That may do it, although you'll probably need to gently scrape them with a sharp piece of wood, say.

[broadie]

Nail polish remover!

[rotta]

interested in seeing how beneficial all the head work will be ive been considering it myself, are you going to still use a single throttle/intake or itbs ect? big cam? chip?

Rotta,

[NoTurbo]

Metric Mechanic in the US sell a kit to convert the head from 7mm valves to 6mm valves. They also have and better valve assembly with springs, tappets etc all of this helps to create a lower weight on the rotating assembly and allows for higher lift cams.

[ejoeyward]

update 3
polshing has been done inside and out, waiting for my carbide bits to turn up so i can rib the floor of the intake ports. Block is painted kawasaki green and the engine bay is bmw cosmos black. the next bit is the expensive of the valve guides and 3 angle valve job

interested in seeing how beneficial all the head work will be ive been considering it myself, are you going to still use a single throttle/intake or itbs ect? big cam? chip?

Rotta,

il be using twin 45 webers and iv used a m10 intake manifold. im going for a big cam probs a rally style (280-285ish) to give equal amounts of top and bottom power

[NoTurbo]

What size valves are you going for? Will you be grinding out and replacing the valve seats?

[ejoeyward]

im using the standard size valves and replacing the guides and doing a 3 angle valve job

[NoTurbo]

Any reason you are not going bigger?

I would have thought that at least on the inlet side there is scope to increase diameter.

[ejoeyward]

i dont want to lose out on the venturi effect