compression

[turner]

I understand what you are saying Perf, but a 113 lobe seperation angle cam will have less cranking compression than a 108 lobe seperation angle cam. The smaller the lsa., the more cranking compression it will have, and more cylinder pressure.I guess i am confused.

[turner]

Perf. Isn't lobe seperation ground into the cam?(cant be changed). So the smaller lsa, the more the cylinder pressure, cranking compression and effective compression?Wider will be less cylinder pressure, cranking compression, and efective compression.Maybe i need to do more research. LOL. Just trying to figure out where i am going wrong.

[perfconn]

Turner,
You are right that the lobe seperation is a permanant thing and can't be changed without regrinding the cam and then you usually can't change it more than one degree.Think of the lobe seperation as two different lobes setting side by side. The further apart you move them(lobe seperation) apart the less overlap you will have.The overlap bleeds off compression and the more overlap you have the less comprssion you have,both on cranking and running.

[dirty white boy]

Turner,
You are right that the lobe seperation is a permanant thing and can't be changed without regrinding the cam and then you usually can't change it more than one degree.Think of the lobe seperation as two different lobes setting side by side. The further apart you move them(lobe seperation) apart the less overlap you will have.The overlap bleeds off compression and the more overlap you have the less comprssion you have,both on cranking and running.

the amount of over lap is effected by the size of the lobes too,..the bigger the cam,..the more lobe separation you'll need to achieve the same cylinder filling...or cylinder pressure,..lotta verabiles to a good cam profile!!

[perfconn]

Sure nuff.Thats the reason you can't expect a cheap cam from a dude that grinds half a dozen cams a year in his basement to give you the performance that the large companies that do lots of r&d do.

[DaveBauerSS6]

just got new motor from engine builder. 4 valve relieve flat top pistons, 450 lift cam, 993 heads. it has 205 pounds of compression. our rules say 175 max. what are some things that i can do to make less compression?

What size is the motor?

[dirtman45]

Like I said way back.... call a major cam company, i.e. Isky or Crane and ask them. They will steer you right. I have specific contact people at both and they know cams inside and out.

Stop guessing.

[dirt fox]

I tightened the number one cylinder valves down a half turn and checked it with 4 differant gauges and its dead on 175. Hope the tracks gauge is the same. Thanks fore all the help

[perfconn]

With 175# compression I doubt the valves are standing open.

[sj valley dave]

Call Mike Jones @ Jones Cam Designs 704-489-2449..He will work with the combo you have...