advancing cam timing on a briggs flat head

[oldfatguy]

has any one ever tried advancing the cam shaft one tooth ? I'm working on mildly built briggs and stock the valves open and close at TDC "top dead center which means the piston is at the very top of the stroke " .
By advancing the cam one tooth the intake valve starts to open just before TDC and is fully open as the piston moves down.This also lets the exhaust valve start to open just before BDC. I was thinking that opening the intake valve sooner would allow more fuel to be drawn in and opening the exhaust valve at the bottom of the power stroke will use part of the fuel burn to force exhaust out of the engine this should improve the air flow through the engine .Has any one else experimented with this ? I also realised that the Easy Spin feature was opening the valves at the beginning of the compression stroke,a little grinding and filing of the cam fixed that

 

[DreyeIce]

i tried advancing 1 tooth ahead and 1 tooth behind, but i couldent get it to run very good or at all,

but i did once ignore the stock timing mark, and try my own setup where i stamped a mark in the gear where i had it, and it ran alright, but the stock was the best,

maybe an aftermarket cam would be best for what you want,

 

[oldfatguy]

thanks ,I was curious if it would work or not .this saves my from wasting time on it and having to take it apart again.

 

[robby12]

i retarded the cam on my 5hp flat head and it ran way better it had more top end power

 

[DreyeIce]

my tests were done ona 3hp briggs and a 4hp tec, basically same results for both in my situations,,,

 

[65ShelbyClone]

The problem is that one tooth on the cam represents a huge amount of crankshaft rotation. Usually cams aren't advanced or retarded beyond 10°. More than that often results in the engine losing power or running noticeably worse, not better. If you want to find out exactly how much a tooth will shift the timing, divide 360° by the number of cam teeth and multiply by two.

As the terms suggest, advancing the cam timing moves the torque peak earlier in the rpm range. Retarding it brings the torque in later.

 

[Lockasiam]

I might be like 10 years late, but I did a full rebuild on a 5 hp flattie and I accidentally got the timing mark off 1 tooth and it ran real crappy. Hope I helped