i'm getting my cam back tommorow, wondering what would be the best size valves to fit. i know most people fit the L18 valves and just cut down the valves, it's a 42mm intake and i think a 35mm exaust valve. is this the size to go for or should i stick with stock valves?

I think you will hinder performance with 42mm inlets. That's so huge that much of the incoming charge may be shrouded by the cylinder wall essentially ruining the fuel/air mix distribution into the cylinder.

But I can't be certain. I had 38's on my GX head and I thought that was huge.......42 is something else. Wait for a second opinion though as I'm probably off the mark.

35 for an exhaust should certianly help things along.

i'm using an h75 head and as far as the wiki is a 37mm intake and 30mm exaust. do you think i should just do the exaust as i don't see why spend the money for a 1mm bigger valve on the intake side?

Okay yeah maybe it'll be okay I was thinking of a 42mm intake in reference to a GX head (which is a big jump). Maybe bump up to 40?

42 sounds huge, but I guess it depends on the capacity of the engine as well as the cylinder bore size, obviously with bigger bores you increase the gap between valve head and cylinder wall. As for it being too big and interfering the flow I guess I was wrong.

Is 42mm the L-seires size? Gylezy runs those then on his A15 and that goes hard.

Chris

yes, it's from the l16/l18 engine. the engine is a stock a14, just doing cam which is a tr68 290 degree which i know is hectic but it works like hell, had one in my gx as well, then just proper compression and light flywheel for now. i will be upgrading to an a15 very much later.

Ahh okay, I'll guess you'll be okay the A15 is just a stroked A14 isn't it? So the big valve shouldn't matter as Gylezy has had great success with it. I think I even recommended the L-Series valves to him.

Hectic? I run a 322 cam (dur. adv). But it was all I had so that's what I run. I know what you mean about hectic, this bloody thing is like driving a golf-cart until you kick it in the guts, then it just goes ape-shit.

Chris

especially when you had a few beers, get home and check the tacho at last placed revved and it shows 10k.... couldn't believe it so i reset and did it again :) i'll check into the valve situation, maybe i can get a 40mm just to be safe as the bore is still standard

Yeah good luck with it all. I'm off.

Cheers.

You can´t use 40mm intake valves with std 76mm bore, the valves will hit the cylinderwalls! A well ported head with std valves will make enough power with a standard bottom end!

Riaan, if you build that Monster, I have to see it, was having that in mind for a14 turbo, but don't have the money to get around to it.

Ps; I like Monsters