Help with picking roller cam for Vortec 355 - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 10-30-2011, 07:32 PM
zildjian4life218's Avatar
Listen and Learn
 
Last wiki edit: DIY junkyard electrical fan controller
Last journal entry: SBC 305 Twin Turbo
Last photo:
Join Date: Dec 2008
Location: WNY/Rochester, New York
Age: 25
Posts: 1,512
Wiki Edits: 7

Thanks: 41
Thanked 6 Times in 6 Posts
Help with picking roller cam for Vortec 355

Hey I was wondering if someone could give me a couple pointers on what to look for when picking out a cam to best suite a given set of cylinder heads and power goals. I know cylinder pressure, head flow, converter stall, gearing, and weight all matter a lot when choosing a camshaft. I was hoping you guys could give me some insight on what determining factors will effect my power goals.

I currently have a 355ci late model sbc with hypeurtectic pistons and eagle rods. It also has vortec heads that i ported a little. On top of that is a performer rpm vortec intake with a 650cfm edelbrock carb. The current cam is a performer rpm hyd flat tappet has gone flat. multiple lifters are scored and lost their convex shape. So I would like to take the winter months here and pull the cam out and replace it with a hydraulic roller. I have a complete setup from a vortec engine, wishbone, hardware, and lifters that I could use but I heard that too much lift will cause the lifter to rotate in the bore which would not be good. I have also heard of people buying GMPP lifters because they handle rpm better or something? http://www.summitracing.com/parts/NA...5&autoview=sku
Is there any fix to the lift issue? I imagine not running a small base circle cam would be the first and obvious answer but idk if cams grinders do take the base circle down even a little to cause the lifter issue.

One thing I noticed about the vortec heads is the intake flows best at .5 and the exhaust flows better at .6 so should i get a cam where the intake lift is close to .500" and the exhaust lift will be close to .600 or maybe run 1.6 rocker arms on the exhaust? I also plan on buying a set of full roller self aligning rocker arms for this motor over the winter so I can go with whatever ratio will best suite my needs.

My end goals are I would like to get my car in the 12s for sure....... faster is always better. Drive train will hold. The title says it weights 3200ish with the original v6. So at least 320whp will get me there but the more the better right? lol Please any and all input is appreciated. I am still learning from all you guys on here so like i said any input is well appreciated. Thanks!
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 10-30-2011, 10:14 PM
Registered User
 
Join Date: Nov 2009
Location: Charleston
Posts: 227
Wiki Edits: 0

Thanks: 0
Thanked 3 Times in 3 Posts
Not REALLY a Chevy guy but......

whoever told you that roller lifter will rotate if the lift is too high...??? In a FoMoCo they use a "dog-bone" style link to keep the roller lifters from rotating. Chevys have a link bar type device that prevents rotation. I guess you could get a cam with sooo much lift it would push the lifters out of the hole! but I doubt they would/could rotate!
Unless you run a stroker crank there is no need to wonder about a small base circle camshaft.
A roller cam allows... more lift and duration than a flat-tappet cam. Whats "wild"in a FT is pretty tame in a roller! I would not be afraid to run a roller cam with 230-240 duration (figure + 5 or 10 degrees more on the exhaust side)@050. LSA of 110*or 108*(if you like it choppy!) 112* is pretty smooth. No need to run a lot of lift on a street mostly engine. Lift in the 510-520 range should work nicely... Check with Chevy guys....seems like the Vortec heads DO limit how much lift you can run.
Compression of 9.5:1 to 10:1 is good for street and this cam. IF you use less duration and more LSA then drop the compression some to avoid spark knock. Will make less power too!
May need a custom ground cam if using these numbers but.....there are cam co. (like Delta and others) that will do a custom cam cheaper than a "shelf item" from Comp or the others. They give great advice too!
6sally6
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 10-30-2011, 10:22 PM
zildjian4life218's Avatar
Listen and Learn
 
Last wiki edit: DIY junkyard electrical fan controller
Last journal entry: SBC 305 Twin Turbo
Last photo:
Join Date: Dec 2008
Location: WNY/Rochester, New York
Age: 25
Posts: 1,512
Wiki Edits: 7

Thanks: 41
Thanked 6 Times in 6 Posts
Quote:
Originally Posted by 6sally6
whoever told you that roller lifter will rotate if the lift is too high...??? In a FoMoCo they use a "dog-bone" style link to keep the roller lifters from rotating. Chevys have a link bar type device that prevents rotation. I guess you could get a cam with sooo much lift it would push the lifters out of the hole! but I doubt they would/could rotate!
Unless you run a stroker crank there is no need to wonder about a small base circle camshaft.
A roller cam allows... more lift and duration than a flat-tappet cam. Whats "wild"in a FT is pretty tame in a roller! I would not be afraid to run a roller cam with 230-240 duration (figure + 5 or 10 degrees more on the exhaust side)@050. LSA of 110*or 108*(if you like it choppy!) 112* is pretty smooth. No need to run a lot of lift on a street mostly engine. Lift in the 510-520 range should work nicely... Check with Chevy guys....seems like the Vortec heads DO limit how much lift you can run.
Compression of 9.5:1 to 10:1 is good for street and this cam. IF you use less duration and more LSA then drop the compression some to avoid spark knock. Will make less power too!
May need a custom ground cam if using these numbers but.....there are cam co. (like Delta and others) that will do a custom cam cheaper than a "shelf item" from Comp or the others. They give great advice too!
6sally6

Thanks for the clarification on the lift issue. I guess the issue is the small base circle and the lifter dropping too far down that it will fall out of the dog-bone but since I'm not running a stroker crank I don't have to worry about it. I have milled the valve guides to accept around .600" lift. I have the article from hotrod and bought the tools from comp to do the job. I like the choppy idle so I would def prefer the 108* or 110* LSA. My current cam is I believe 236* Duration at .050" so I could def keept it at that or higher. My machinist told me to have one custom ground also because the price is cheaper and its more suited to my exact needs as opposed to an off the shelf piece.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 10-31-2011, 07:08 AM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 28
Posts: 8,236
Wiki Edits: 0

Thanks: 12
Thanked 220 Times in 205 Posts
I would go with about a 225/230 duration on a 108 LSA, installed 4 degrees advanced, try to get around .550" lift on the intake and the same or a little less on the exhaust. run 1.6 rockers if you're getting new ones, and if you're buying new lifters I'd go with the limited travel ones from Comp.

Stock Vortec heads do not do well with more duration than what I posted, they go into choke. They're great for a factory head but they still only have a 170cc port volume so there's no sense in camming for peak power at 6,000 RPM when your heads can't support it- ESPECIALLY if its a street driven car.

With a proper engine build to match these heads and cam are still good for over 320hp at the wheels.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 10-31-2011, 07:33 AM
zildjian4life218's Avatar
Listen and Learn
 
Last wiki edit: DIY junkyard electrical fan controller
Last journal entry: SBC 305 Twin Turbo
Last photo:
Join Date: Dec 2008
Location: WNY/Rochester, New York
Age: 25
Posts: 1,512
Wiki Edits: 7

Thanks: 41
Thanked 6 Times in 6 Posts
Quote:
Originally Posted by ap72
I would go with about a 225/230 duration on a 108 LSA, installed 4 degrees advanced, try to get around .550" lift on the intake and the same or a little less on the exhaust. run 1.6 rockers if you're getting new ones, and if you're buying new lifters I'd go with the limited travel ones from Comp.

Stock Vortec heads do not do well with more duration than what I posted, they go into choke. They're great for a factory head but they still only have a 170cc port volume so there's no sense in camming for peak power at 6,000 RPM when your heads can't support it- ESPECIALLY if its a street driven car.

With a proper engine build to match these heads and cam are still good for over 320hp at the wheels.
If the exhaust ports flow better at .600" lift why wouldn't I want I want the exhaust lift to come closer to that? also I don't want to buy new lifters if I don't have to. Will the stock ones work?
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 10-31-2011, 08:24 AM
zildjian4life218's Avatar
Listen and Learn
 
Last wiki edit: DIY junkyard electrical fan controller
Last journal entry: SBC 305 Twin Turbo
Last photo:
Join Date: Dec 2008
Location: WNY/Rochester, New York
Age: 25
Posts: 1,512
Wiki Edits: 7

Thanks: 41
Thanked 6 Times in 6 Posts
Also I forgot to add I have 2800 stall converter in the car now. What do you guys think my motor makes right now? I was hoping around 400 at the crank but I opened desktop dyno and put in all the specs for my current setup and its saying closer to 350hp at the crank.

Last edited by zildjian4life218; 10-31-2011 at 08:39 AM.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 10-31-2011, 10:00 AM
zildjian4life218's Avatar
Listen and Learn
 
Last wiki edit: DIY junkyard electrical fan controller
Last journal entry: SBC 305 Twin Turbo
Last photo:
Join Date: Dec 2008
Location: WNY/Rochester, New York
Age: 25
Posts: 1,512
Wiki Edits: 7

Thanks: 41
Thanked 6 Times in 6 Posts
Okay so I apparently messed up the valve timing when I originally did the desktop dyno program for my current motor. And yes I know this is just a ball park figure. So after fixing everything to what edelbrock has http://www.edelbrock.com/automotive_...7102&submit=go
I got a peak of about 350hp at 6000rpm and around 340tq at 5000.
Now with the howards cam 110325-10
http://howardscams.com/index.php/com...ategory_id=371
I get about 415hp at 5500rpm and 420tq at 4500. Wow! quite the difference lol.
I did notice Summits website was way off compared to what Howard has on their site but either way this would be a serious improvement. Any input?
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 10-31-2011, 10:23 AM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 28
Posts: 8,236
Wiki Edits: 0

Thanks: 12
Thanked 220 Times in 205 Posts
Quote:
Originally Posted by zildjian4life218
If the exhaust ports flow better at .600" lift why wouldn't I want I want the exhaust lift to come closer to that? also I don't want to buy new lifters if I don't have to. Will the stock ones work?
With the right cam the stock ones will work fine, but it appears you want to overcam it.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 10-31-2011, 10:26 AM
zildjian4life218's Avatar
Listen and Learn
 
Last wiki edit: DIY junkyard electrical fan controller
Last journal entry: SBC 305 Twin Turbo
Last photo:
Join Date: Dec 2008
Location: WNY/Rochester, New York
Age: 25
Posts: 1,512
Wiki Edits: 7

Thanks: 41
Thanked 6 Times in 6 Posts
Quote:
Originally Posted by ap72
With the right cam the stock ones will work fine, but it appears you want to overcam it.
What do you mean? I don't want to overcam it. that would be pointless im just not sure exactly what I need. Do I have too much lift or duration or both?
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 10-31-2011, 10:33 AM
zildjian4life218's Avatar
Listen and Learn
 
Last wiki edit: DIY junkyard electrical fan controller
Last journal entry: SBC 305 Twin Turbo
Last photo:
Join Date: Dec 2008
Location: WNY/Rochester, New York
Age: 25
Posts: 1,512
Wiki Edits: 7

Thanks: 41
Thanked 6 Times in 6 Posts
Quote:
Originally Posted by ap72
I would go with about a 225/230 duration on a 108 LSA, try to get around .550" lift on the intake and the same or a little less on the exhaust.
I chose 225/233 and .525/.530 @ 1.5 on 108. Thats pretty damn close to what you said.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 10-31-2011, 11:49 AM
Registered User
 
Last photo:
Join Date: Nov 2006
Location: Woodstock
Posts: 794
Wiki Edits: 0

Thanks: 2
Thanked 64 Times in 58 Posts
Quote:
Originally Posted by zildjian4life218
If the exhaust ports flow better at .600" lift why wouldn't I want I want the exhaust lift to come closer to that? also I don't want to buy new lifters if I don't have to. Will the stock ones work?
Its not worth the extra strain placed upon the valvetrain to lift the exhaust vales and extra 0.100" (0.500" up to 0.600") to gain an extra 4 cfm.

You can run Comp Cams 26915 or 26918 Beehives or PAC Beehives and run a Comp Cam 787 retainers and 648 locks and run 0.550" lift.

Here are some actual measurements as installed on stock L31 Vortec 350 heads.
http://www.pacificp.com/forum/viewto...&highlight=787

320rwhp is roughly a warm stock LS1 output.

peace
Hog
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 10-31-2011, 12:13 PM
zildjian4life218's Avatar
Listen and Learn
 
Last wiki edit: DIY junkyard electrical fan controller
Last journal entry: SBC 305 Twin Turbo
Last photo:
Join Date: Dec 2008
Location: WNY/Rochester, New York
Age: 25
Posts: 1,512
Wiki Edits: 7

Thanks: 41
Thanked 6 Times in 6 Posts
Quote:
Originally Posted by Hogg
Its not worth the extra strain placed upon the valvetrain to lift the exhaust vales and extra 0.100" (0.500" up to 0.600") to gain an extra 4 cfm.

You can run Comp Cams 26915 or 26918 Beehives or PAC Beehives and run a Comp Cam 787 retainers and 648 locks and run 0.550" lift.

Here are some actual measurements as installed on stock L31 Vortec 350 heads.
http://www.pacificp.com/forum/viewto...&highlight=787

320rwhp is roughly a warm stock LS1 output.

peace
Hog
Ah ok that makes perfect sense. I have already machined down the valve guides so the lift isn't an issue. When I assembled them I had almost .600" between the seal and the retainer.
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 10-31-2011, 12:21 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 28
Posts: 8,236
Wiki Edits: 0

Thanks: 12
Thanked 220 Times in 205 Posts
Quote:
Originally Posted by zildjian4life218
Ah ok that makes perfect sense. I have already machined down the valve guides so the lift isn't an issue. When I assembled them I had almost .600" between the seal and the retainer.
I was just saying that you seemed to be wanting to put a bigger cam than you needed, and as already mentioned going overkill may net you a few extra hp, but at the cost of valvetrain longevity. The cam you chose will probably work very well for your application, what brand did you go with?
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 10-31-2011, 12:26 PM
zildjian4life218's Avatar
Listen and Learn
 
Last wiki edit: DIY junkyard electrical fan controller
Last journal entry: SBC 305 Twin Turbo
Last photo:
Join Date: Dec 2008
Location: WNY/Rochester, New York
Age: 25
Posts: 1,512
Wiki Edits: 7

Thanks: 41
Thanked 6 Times in 6 Posts
Quote:
Originally Posted by ap72
I was just saying that you seemed to be wanting to put a bigger cam than you needed, and as already mentioned going overkill may net you a few extra hp, but at the cost of valvetrain longevity. The cam you chose will probably work very well for your application, what brand did you go with?

I haven't picked one out for sure yet but the one I saw that looked to match my goals best was a howards roller 110325-10. Should I still go with 1.6 rockers?
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 10-31-2011, 12:30 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 28
Posts: 8,236
Wiki Edits: 0

Thanks: 12
Thanked 220 Times in 205 Posts
Quote:
Originally Posted by zildjian4life218
I haven't picked one out for sure yet but the one I saw that looked to match my goals best was a howards roller 110325-10. Should I still go with 1.6 rockers?
change that -10 to a -08. 1.6 rockers will help on your intake but won't do much on the exhaust.

Its another area where you have to consider the cost/benefit, you could possibly pick up 10hp by running 1.6 rockers but you'd also need valvesprings that can handle that lift and last.
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Roller Rockers to use with Vortec heads??? GUITAR1989 Engine 5 06-02-2011 05:24 PM
vortec roller cam help footjoy Engine 3 03-31-2008 11:04 AM
vortec heads & hyd.roller cams BourgD Introduce Yourself 1 07-22-2007 12:29 AM
best roller cam for vortec heads 11secmudtrk Engine 6 01-18-2005 09:38 PM
Vortec - roller rockers? dev Engine 2 09-20-2004 05:05 AM


All times are GMT -6. The time now is 03:36 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.