How much Cam split?

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08-31-2009, 12:11 PM
30-A Rider

How much Cam split?

Guys I am gathering parts for my BBC build. Its a 454 .030 over block. 10:1 compression. Intake is an Edelbrock RPM air gap. Have not purchased/decided on a carb as of yet. Trans is a TH400 and will have approx 3200 stall. Rear gear 3.73. Car is a 66 Chevelle and will be 90% street and is not a daily driver.

Heads are GM 049 castings that have had port work and 2.19/1.88 Ss vavles installed by a reputable builder. Flow sheet was provided with heads and reads as follows:

28" 4.350 Bore

Good Port Bad Port
2 162 2 162
3 228 3 222
4 286 4 270
5 311 5 302
5.5 313 5.5 311
6 313 6 318

I have not decided on a cam as of yet but Im leaning heavily towards a hydraulic roller camshaft. My question is how much split should I look to utilize in a cam I choose? I hope I have provided enough information for some insight/advice.

Thanks for any replies in advance,
Scott
09-01-2009, 11:29 AM
30-A Rider

Pat, Tech, nobody has an opinion or wants to share thier knowledge?
09-01-2009, 12:20 PM
skids72

My opinion is not nearly as valuable as the others mentioned and I figured pat would be on this one... my feeling is that you will want a 112 to 114 LSA for street use but I am far from the expert in this regard.

2 cents is about all it's worth,

-Chris
09-01-2009, 02:02 PM
pat mccarthy

you could run a 112 but i would lean more to a 110to108 if your at 10to1 a 230/238@050.621/.621 lc 110 or 234/242 @050.585/.585 lc 112+AV.4 ON 106 or 234/242@050.621/621 lc108+AV.2 ON 106 .you could run abit more dur i used the 238/246 @050 .621/621 on 108 and have used it at 112 on a 396 stick car you can move out theLC if your goin to spray it. here is big as i would go for your build 246/254 @050 .621/621 LC108 AV +2. on 106 if you could get to 10.5 CR and have 3200+stall they are all the Erson Cams HR ENERGY PLUS CAMS with new lobe all BUT the 585 lift cam
09-01-2009, 04:32 PM
vara4

Pat; do you think his stall will be big enough with that cam?
Kurt
09-01-2009, 04:36 PM
pat mccarthy

Quote:

Originally Posted by vara4

Pat; do you think his stall will be big enough with that cam?
Kurt

what cam ? they all will work smaller dur @ 050 will work better if stall is not what he think he has
09-01-2009, 04:49 PM
vara4

Pat: I was talking about the one you said was as big as you would go.
{here is big as i would go for your build 246/254 @050 .621/621 LC108 AV +2. on 106 if you could get to 10.5 CR and have 3200+stall they are all the Erson Cams HR ENERGY PLUS CAMS with new lobe all BUT the 585 lift cam}.
09-01-2009, 05:31 PM
pat mccarthy

Quote:

Originally Posted by vara4

Pat: I was talking about the one you said was as big as you would go.
{here is big as i would go for your build 246/254 @050 .621/621 LC108 AV +2. on 106 if you could get to 10.5 CR and have 3200+stall they are all the Erson Cams HR ENERGY PLUS CAMS with new lobe all BUT the 585 lift cam}.

WELLLLLLLL the book said it should work3000to3500stall i have that cam in a 4/7 swap 496 guy never said any thing about the stall just the back tires:LOL: but sounds very good**)
09-02-2009, 08:53 AM
30-A Rider

Actually the cam specs I was leaning towards is as follows:

292/300
241/249 @ .050
625/625
110 LSA

I just didnt know how much split is required for the cam with the perfromance of the heads. I was under the impression that a motor utilizing for example a good set of AFR head will not need as much split because the exhaust flows so well...and on factory casting the exhaust falls short of the intake and therefore using a larger split helps. Then I was also under the impression that if you were using a 5000 rpm limit street car not really much need for a split, where as if your gonna spin a motor for 7000 rpm and the purpose of the motor is HP then a great split is required. Again this was what I understood but wanted the experts opinions, thats why I started the thread.
09-02-2009, 04:17 PM
pat mccarthy

Quote:

Originally Posted by 30-A Rider

Actually the cam specs I was leaning towards is as follows:

292/300
241/249 @ .050
625/625
110 LSA

I just didnt know how much split is required for the cam with the perfromance of the heads. I was under the impression that a motor utilizing for example a good set of AFR head will not need as much split because the exhaust flows so well...and on factory casting the exhaust falls short of the intake and therefore using a larger split helps. Then I was also under the impression that if you were using a 5000 rpm limit street car not really much need for a split, where as if your gonna spin a motor for 7000 rpm and the purpose of the motor is HP then a great split is required. Again this was what I understood but wanted the experts opinions, thats why I started the thread.

i really do not look at it that way
09-02-2009, 06:17 PM
techinspector1

When the post involves a BBC, I usually don't answer it at all. Pat McCarthy knows waaayyyy more about them than I do, so I defer to him.

I will join in on this one, but only to post a tutorial from Iskenderian so that you have a contrarian point of view. You know me, always the contrarian.:LOL:

Please scroll down and read Tech Tip 2003 here.....
http://www.iskycams.com/techtips.php
09-02-2009, 07:22 PM
Dave Severson

[QUOTE=techinspector1;362002] You know me, always the contrarian.:LOL:

QUOTE]

Oh man, no way!!!!! Heck, I always figured you were mild and easy going like me!!!!!!!!!!!!!:whacked::whacked::whacked:
09-02-2009, 07:33 PM
pat mccarthy

[QUOTE=Dave Severson;362010]

Quote:

Originally Posted by techinspector1

You know me, always the contrarian.:LOL:

QUOTE]

Oh man, no way!!!!! Heck, I always figured you were mild and easy going like me!!!!!!!!!!!!!:whacked::whacked::whacked:

hey string the pot dave when you should be building chevy headers :3dSMILE:
09-02-2009, 07:36 PM
Dave Severson

[QUOTE=pat mccarthy;362012]

Quote:

Originally Posted by Dave Severson

hey string the pot dave when you should be building chevy headers :3dSMILE:

Awwwwww come on, even slaves get a water break!!!!!:LOL::LOL::LOL:
09-02-2009, 07:41 PM
jerry clayton

building headers?????? I forgot---I got two sets to do before I get to work on my car---if I could only find my welding helmut---and magnifiers
09-02-2009, 07:59 PM
pat mccarthy

Quote:

Originally Posted by jerry clayton

building headers?????? I forgot---I got two sets to do before I get to work on my car---if I could only find my welding helmut---and magnifiers

that not bad i need to build 10 engines before i can ever think of building my headers :D
09-03-2009, 01:10 PM
30-A Rider

Quote:

Originally Posted by techinspector1

When the post involves a BBC, I usually don't answer it at all. Pat McCarthy knows waaayyyy more about them than I do, so I defer to him.

I will join in on this one, but only to post a tutorial from Iskenderian so that you have a contrarian point of view. You know me, always the contrarian.:LOL:

Please scroll down and read Tech Tip 2003 here.....
http://www.iskycams.com/techtips.php

Thanks for the link Tech. I actually had read that article before and always remembered it. I have gotten all sorts of answers on this ranging from Hardold Berkshire (Ultradyne Cams, and Lunati Cams developer) , Joe Sherman etc. So I posed the question on here to get some opinions. Appretiate the strait forward post sir.