38deg timing And Retard Cam What are the pros and cons

[MiniBike.Life]

Hi guys so I have a 212 with racing head 32/28 valves, 60lb dual springs with 1.2 roller rockers. I’m currently running 38deg timing. What or what can happen if I retard my adjustable billet cam say 2deg retard. Will it conflict with anything?

 

[ole4]

It certainly could, advancing/retarding timing changes the valve to piston clearance near TDC. Retarding cam causes less exhaust clearance and the exhaust is the critical V to P clearance. What compression and what style chamber are you running? Unless your running alky why are you running 38 degrees ignition advance? Is this on a minibike? Retarding the cam basically reduces low end and can increase high rpm power.

 

[MiniBike.Life]

I’m sorry I should be more clear of my engine mods. It’s a 212 bored to 72mm on stock crank. Using clone head milled to .065” ported/polished. I’m also running alky and yes it’s going on a MiniBike

 

[ole4]

OK I do not run alky but I do know it is pretty detonation proof and you usually bump up timing when switching from gas. I was curious of head chamber as a 14cc head or the ZH8 type of head has a lot of squish area which reduces timing requirements vs something like a hemi with very little squish area. If you had adequate ex clearance before ie more than .070 then you should not have any issues with a 2 degree change.

 

[65ShelbyClone]

Retarding cam timing will shift the power curve higher in the rev range. 1° very roughly moves it 50-100rpm. It's used more for fine-tuning an engine combination and power delivery and not so much for realizing big gains.

 

[MiniBike.Life]

Retarding cam timing will shift the power curve higher in the rev range. 1° very roughly moves it 50-100rpm. It's used more for fine-tuning an engine combination and power delivery and not so much for realizing big gains.

Thanks you for your advice and info. That’s what I’m exactly trying to do on fine tuning my bike set up for a 1/4 mile run