Will I need compression releases if I go with the andrews 57h or the feuling 543,579?

 

sorry mate, not sure...
mine has them but i think that was because of the compression of the 106, not the cams themselves

 

Kinda late to the thread but the compression releases become more necessary with higher compression builds. You are planning a 103" build, so while you are at it you will have the oppurtunity to set the compression where you want it. The cams you chose will help determine what you need for compression and whether or not to get compression releases installed.

Big difference between Andrews 57 and Feuling 574s, give us some more info on where in the rpm range you want your cams to "hit" and do you ride 2 up a lot ?

 

What about SE 204's or 254's? I am really happy with the 204's. They come on a little later but hold the torque for a long time.

You are on the right track with Andrews....Also check out Woods.

 

I 99% ride solo. I would like the cams to hit around 2800 to 5500. I dont mind downshifting so I dont really want a cam like the 255 (thats y they're in the classified sec) Thanks again to everyone, this is very helpful.

 

Based on what you have said, I would forget the MR 103s(too early on the rpms), pass on the 574s unless you want to up the compression quite a bit(~ 10.5:1), run the Andrews 57s if you keep compression around 9.8 - 10.2:1, or run the Andrews 54s at around 10.2 - 10.4:1.

Not sure what the SE 103" kit brings your compression to, but you may have to have your cylinder heads decked a bit(pretty inexpensive) to get the compression perfect. You should also use .030" Cometic head gaskets that will get you a compression bump too.

Could probably avoid compression releases with the 57s, but would get them for all the rest. Would also get new lifters and adjustible pushrods - I like S&S here, but the SE tapered prs have a good rep too.

 

hey Pilot, why do you say that? Just curious, my S&S106 puts me at 10:1 and they seem to perform well... Feuling's website says they're a good bolt in for 96 and 103s - not arguing, trying to learn

I will admit I'm not sure of the comparison so I don't actually know if 10 and 10.5 are considered close for this type of things...

 

I like to spend a lot of time playing with the Big Boyz TC Compression calculator. When using the calculator you start by putting all the normal data in like bore and stroke, head gasket thickness, cylinder head volume, etc.

I always try to put in info that is normal(average/common) to the build being discussed, then you put in the cam - but the only thing that counts is the intake closing of the cam. After all this is entered you look at the corrected compression and cold cranking pressure(I just look at sea level, unless I know the person lives in Denver or something) and see if the numbers look good.

I think for a good build where you get excellent performance for your build but not too difficult of a bike to tune, you should be looking at ~ 190 - 200 psi cold cranking compression. Much higher than that the tune becomes more critical which may be fine for a tuner/builder but probably not for the average rider. If you undershoot the 190 - 200 CCP, well you are leaving performance on the table.

Now to "tweak" your CCP, you can adjust the head gasket thickness but I usually just put in .030" because that is a nice performance thickness on most builds, so this leaves the ccs of the cylinder heads - normally adjusted by "decking".

Anyway after all this tweaking, cams like 574s have a intake close of 45 degrees, not too different from my Tman 590s that close at 44 degrees. When you throw these cams in and adjust the numbers to get the CCP right, the Static Pressure will go up to around 10.5 which is what I targeted on my build. TR of Tman wanted me to push closer to 10.8 which would produce bigger hp/tq but living in Texas, with all the heat, I decided to stay around 10.5 to help simplify any tuning issues.

Now if you run at say 180 - 185 CCP, your bike will run fine and probably feel great compared to before the cam install but it could have felt even better/stronger at 190 - 200 CCP.


Dang, I'm warn out....

 

Many thanks for the great info. I already have the cometic .30 gasket. Ive been slowly collecting parts so I can do the teardown this winter. I also just got a thundermax to go on before the build just waiting for it to arrive. I see woods cam out with a new cam tw999-6a looks interesting.

 

Those cams have an intake close of 46 degrees and fairly long duration numbers. IMO if you want to run cams with late intake closing, longer durations, and higher lifts(~ .560 and up) I would do headwork. Bigger cams, higher compression just leads you to headwork...and a dyno tune, not autotune stuff.