Engine sbc combanation - 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 05-27-2010, 09:52 AM
Registered User
 
Join Date: May 2010
Location: Batesville MS
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Engine sbc combanation

Hey i have a question i am building a engine, or getting parts together. I bought a Comp Cams Big Mutha Thumpr 299THR7. The rpm range is 2500 to 6500. Valve lift on the intake is 0.533 and 0.519 on the exhaust. The engine i have is a 350 board 40,and came factory with roller cam,im going to use 3.750 crank. Just wondering what would be the lowest runner i could use with this cam would a afr 195 work,or would it perform better with GM fast burn heads? Those are the 2 heads im wanting to run, but cant make my mind up on which of them to use. The compression ratio will be about 10:5. If any body has any head recommendation it would be appreciated, or advice on this cam shaft. Ive heard good stuff about the thumper line, but also heard bad. THanks for reading
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 05-27-2010, 09:55 AM
Registered User
 
Join Date: May 2010
Location: Batesville MS
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
RPM range is not 6500 its 6200 at max
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 05-27-2010, 01:32 PM
my87Z's Avatar
Veteran/Firefighter-EMT-I CRT
 
Join Date: Mar 2009
Location: maryland
Age: 30
Posts: 1,685
Wiki Edits: 0

Thanks: 6
Thanked 11 Times in 11 Posts
i dont know who you have heard good things from about the comp thumper cams but i have never heard anything but bad about them, "they're all show and no go" they are a cam designed to give you the solid cam sound but with out the actuall power behind it. the AFR 195's would be a decent fit, so would a set of DART iron eagle Platinum 200cc, or RHS pro action 200cc, the Brodix ik200's are nice as well, since you are building a 385 that cam's rpm range will be little lower to say about 2200-5900 and with this rpm range i wouldn't go with less than a 190cc intake runner on the heads, and i would stick with a dual plane intake. IMHO i would look for another cam
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 05-27-2010, 01:41 PM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 12,257
Wiki Edits: 326

Thanks: 604
Thanked 768 Times in 658 Posts
Don, I don't think there are too many board members here who would choose a Thumpr cam. It's considered by some to be a "poser" cam, one that a 16 year old kid might choose. Maybe he wanted the thump because it sounds like a race car motor and he didn't know any better from a performance standpoint.

If you like the sound, great, go for it. If you want performance, there are better choices.

I personally would not use a 10.5:1 static compression ratio in a street motor. 9.5:1 would be plenty in my opinion and would be easier to prevent detonation with crummy fuel.

Runner selection, in my opinion, should be 195-210 for a 383/385 SBC, depending on static compression ratio.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 05-27-2010, 01:45 PM
ericnova72's Avatar
More for Less Racer
 
Join Date: Jan 2007
Location: S.W. Lower Michigan
Age: 47
Posts: 7,672
Wiki Edits: 0

Thanks: 10
Thanked 149 Times in 137 Posts
Not to harp on you, but the cam should be close to the last thing you buy, not the first. You pick the cam to fit well with all the other parts, not buy the parts to fit the cam choice.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 05-28-2010, 12:13 AM
Registered User
 
Join Date: May 2010
Location: Batesville MS
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I thought this would be a good cam,and Ive already bought it. So i will have to use it. is the lobe separation thats the problem, or overlap. So these cams are pretty much for sound, i thought it would make good power. i should have posted and asked
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 05-28-2010, 12:18 AM
Registered User
 
Join Date: May 2010
Location: Batesville MS
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Should i try to sell the cam
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 05-28-2010, 07:43 AM
Registered User
 
Join Date: May 2010
Location: Batesville MS
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Its already shipped please read

The cam already shipped. I know you guys know whats good and whats not. I read on these post and the replies are crazy. This site has alot of intelligent people for sure, and i know you can help me understand. I don't care about the sound i care about performance, and it had good lift,and the rpm looked to be where i would want it. Is it the exhaust overlap that hurts it,and if so wouldn't it only decrees power at low rpm. I just got back into building engines. I was spending time boxing, and I didn't know the cam was just for sound, i would have never bought it,and i have kids,and not alot of money so when i get extra money i want it to be on quality parts not some cam that makes your car sound stronger than it is, i could care less about sound performance is important to me, please let me know what the problem is with the cam
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 05-28-2010, 07:56 AM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 59
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 595 Times in 545 Posts
Quote:
Originally Posted by don77camaro
i could care less about sound performance is important to me, please let me know what the problem is with the cam
The cam (as you've guessed) has an inordinate amount of exhaust duration, a narrow LSA and is made to have a race cam sound yet be usable on the street.

That said, all is not lost!

Depending on who you ordered it from, get on the blower to them and just tell them that you want to return the unused, unopened cam for an exchange on another different cam. Likely, they will give you a return authorization or something like that along with instructions on how to return it for credit/exchange/refund.

I know of no reputable dealer who wouldn't accept a return- you'll only have to eat the shipping charges but that's a better alternative to using a cam that's not what you want.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 05-28-2010, 08:02 AM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 59
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 595 Times in 545 Posts
It occurred to me that if you get ahold of the company who sold it to you, you may be able to just tell the deliverer to return it to the sender when it comes, if you or someone will be there. I would check w/them and see.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 05-28-2010, 02:50 PM
Registered User
 
Join Date: May 2010
Location: Batesville MS
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Hey im going to run the thumpr cam,and im going to degree it ,and run the recommended parts,and i have a friend at bb&t racing who has a engine dyno,and im going to do a swap and see the difference of horsepwer, im going to see if an extreme energy roller will make more than this cam, or if any one knows of a cam with close to same lift on intake and exhaust that would like to see which would do better. The heads are afr 195cc
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 05-28-2010, 02:52 PM
Registered User
 
Join Date: May 2010
Location: Batesville MS
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I really want to see some actual dyno runs for the thumper cam with adv. duration of 299
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 05-28-2010, 03:43 PM
ericnova72's Avatar
More for Less Racer
 
Join Date: Jan 2007
Location: S.W. Lower Michigan
Age: 47
Posts: 7,672
Wiki Edits: 0

Thanks: 10
Thanked 149 Times in 137 Posts
I have seen on another board where engine builder Joe Sherman(maybe you know the name?, won the first Jeg's Engine Masters contest) has good results with the two biggest Thumpr cams in 383-406 street builds but doesn't recommend any of the smaller ones. IIRC seems like he is installing them 6-7 advanced.

You might try looking for his posts over at www.speedtalk.com in the engine forum, his handle is bigjoe1
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 05-29-2010, 02:38 AM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 12,257
Wiki Edits: 326

Thanks: 604
Thanked 768 Times in 658 Posts
Quote:
Originally Posted by ericnova72
I have seen on another board where engine builder Joe Sherman has good results with the two biggest Thumpr cams in 383-406 street builds. IIRC seems like he is installing them 6-7 advanced.
See, just when you think you know the facts on something, along comes new information. Thanks Eric, I'll be more careful in my description of these cams in the future.
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 05-31-2010, 07:54 PM
Registered User
 
Join Date: May 2010
Location: Batesville MS
Posts: 30
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by ericnova72
I have seen on another board where engine builder Joe Sherman(maybe you know the name?, won the first Jeg's Engine Masters contest) has good results with the two biggest Thumpr cams in 383-406 street builds but doesn't recommend any of the smaller ones. IIRC seems like he is installing them 6-7 advanced.

You might try looking for his posts over at www.speedtalk.com in the engine forum, his handle is bigjoe1
Thanks im going to check that out for sure
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
350 SBC marine engine sluggish? daeble Engine 17 02-21-2010 05:26 AM
SF oil???? n-gin Engine 6 07-09-2008 01:37 PM
SBC - Engine dies after hard acceleration CuttyGMachine Engine 9 07-07-2008 01:39 PM
Engine Running Hot 327 SBC EazyDuzIt102 Engine 2 08-15-2006 12:12 AM
Figured I'd ask here SBC INFO ENGINE COMBO SITE??? DeathByGreaser Hotrodders' Lounge 3 08-25-2003 11:33 PM


All times are GMT -6. The time now is 03:20 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.