Chris58 wrote: ↑Sun Feb 10, 2019 8:56 pmTo degree your cams you need to be able to turn them in relation to the crank. If you were to move the cam one tooth on the chain, you would be way too far out of time.VT1000r wrote: ↑Sun Feb 10, 2019 9:29 amthanks for sharing that, that may be what I end up doing but what do you mean by file out the cam sprocketChris58 wrote: ↑Fri Feb 08, 2019 4:17 am I agree that only changing intakes can have a good advantage. In most cases I would think you are likely to end up with a mid range power increase with a bit more overlap than stock.
I just wouldn't recommend it to the OP because hes on a budget and it can get costly very quickly to get it done properly (as I have found out from installing stage 2 mega cycles)
I think it may be worth bringing up that you can degree your stock cams to move the power a bit higher or lower in the rev range. Just file out the cam sprockets, and get a degree wheel.
Ive been doing lots of cam figuring lately, Here is some info to reference for anyone willing to experiment:
These are listed from most important to least. ICV has the most direct effect on performance, then IVO, EVC, EVO.
IVC (Intake valve Closing) - Anywhere from 30deg to 70deg ABDC. The later it closes the higher rpm your peak hp will be, air momentum keeps filling the cylinder ABDC at high rpms..But at low rpm some air will be pushed back through the intake valves lowering compression. high compression pistons can help with this.
Sooner closing will trap the charge, giving better compression at low to mid rpm, but you will lose out on peak hp.
IVO - Anywhere from 5deg to 25deg BTDC. If it opens early there is more time for cylinder filling and more overlap (more scavenging) for top end power, but at idle exhaust gases may be pushed into the intake (reversion) causing a lumpy idle. Late opening will give a nice idle and better low end performance.
EVC - Anywhere from 5deg to 25deg ATDC. Earlier closing will reduce overlap and give better mileage, but will not allow the engine to breathe. Late closing will give more overlap which can waste some fuel out the tail pipe but will allow exhaust velocity to scavenge a fresh charge in the intakes.
EVO - Anywhere from 30deg to 60deg BBDC. This happens on the power stroke, the sooner it opens compression is let out which leads to less torque, but this is what initiates the scavenge effect (good for peak power). late closing = longer compression = low end torque
Overlap - can typically be anywhere from 15deg to 60deg
Lobe Separation angle - The value of crankshaft degrees between the intake and exhaust at their highest points in relation to TDC. The tighter the LSA the more overlap and vise versa. LSA can be from around 100deg to 115deg. A 104-106 LSA is considered a lumpy idle top end number , 107-110 midrange power , 110 - 115 low end power.
There is a formula to figure this out once you've picked your degree values. if its not the LSA you were looking for, then adjust accordingly.
Keep in mind that when you change an opening time of a valve it will also change the closing time and vise versa, you can only change a stock cam so much... maybe a few degrees one way or the other. To get the best of both worlds, you need a new cam profile.
there is more to consider than just this, but that's a good start..
Cheers
Slotting the bolt holes allows the cam to be adjusted on the sprocket without having to jump an entire tooth.
To do this you will need to remove the cam sproket, then use a file or small die grinder to slot the bolt holes so that you can adjust the cam on the sprocket a few degrees each way.. This is ok to do on a storm, as the sprockets are not centered by the bolts, the bolts just lock it in position.
If you dont have experience with valve timing you will want to do some research before starting. It is a procedure that has to be done properly and with accuracy.
There are many online tutorials for different engines, the same principle applys to each engine.
Do you have to torque the sprocket bolts to a higher ft lbs after slotting them, or will they move at all if you just tighten it to normal spec running the engine with them slotted?