primary cam lobes on b16

[gnx1987]

Took my rocker cover off today to do the valve clearances and noticed that both the primary lobes (both intake and exhaust) have different lift (possibly duration as well but didn't bother to check) to each other. Why aren't they just the same?

[bennjamin]

if they were the same duration/lift - surely that would defeat the purpose in having secondary lobes/profile ?

[wynode]

You have a DOHC VTEC engine ?

If yes, then that is the idea!

[gnx1987]

I knew at least someone would miss read the question. Read again! PRIMARY LOBES not the vtec lobe. Both the PRIMARY lobes are different. I spose you could say that all three lobes have different lift and duration. Why is this?

[KB]

My Guesstimate is so air comes into cylinder at slightly different times to promote a swirling effect in the combustion chamber causing better fuel/air mix. Or maybe one valve lets in air slightly earlyer to push some zorst gasses out. Hmmm

Maybe you got ultra rare B16C1 that has 3 stage Vtec.

[94integragsi]

there a b16c1????? what is it???

[tRipitaka]

eg7 sirIII engine..

[wynode]

My Guesstimate is so air comes into cylinder at slightly different times to promote a swirling effect in the combustion chamber causing better fuel/air mix..

That would be my guess too. The VTEC-E engine does a similar thing and only opens one valve fully (the other one opens very slightly pre VTEC) in order to promote better swirl.

[bennjamin]

my guess x 3,

What is the point of the same clearences on the exhaust cam side ?( as gnx1987 tells us) Promote an equal effect in the exhuast pulse ?

[gnx1987]

That swirling effect sounds reasonable. I doubt it's the b16c1 though cause james (blkcrx) reckons I've got one of the earliest VTEC motors judging by the ECU even though the papers I got with the car say 92 CRX. Anyone know how I can tell what the engine is out of or if it's original. No requests to look at VIN numbers and stuff cause the more I find out about the car the dodgier (how do you spell that?) it's history seems.