Marine cam in 454 - 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> Hotrodding Basics
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 03-27-2009, 02:01 PM
Member
 
Join Date: Nov 2001
Posts: 447
Wiki Edits: 0

Thanks: 0
Thanked 11 Times in 10 Posts
Marine cam in 454

Looking for advice, I am currently building a 454 for street use, Its a 73 truck engine with oval port 206/172 valves, .030 flat tops so the compression should be low. I have a complete Comp cams Xtreme marine 288H cam kit. (cam, lifters, springs, retainers, locks, timing chain) The kit has been sitting on the shelf for a couple of years since I sold my boat. I hate to not to use it for something. According to spec card it's got .570in/575 exh with 244/254@.50 duration with 112 degree lobe seperation. It says this cam is for rpm range of 2500-6500. Intake is a early non-egr quadrajet intake with adapter and holley 750 mechanical secondaries (will fit under stock hood). I really don't see why this won't work in street engine. Am I missing something. From the specs I don't see why the marine cam won't work for street use. Feedback from some of the BBC experts would be nice. Drive train will be a t-400 with rear 3:50 gears. I have not yet purchased a converter, figure about a 2800 stall? This will be street driven 68 Impala with occasional strip use.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 03-27-2009, 02:29 PM
richard stewart 3rd's Avatar
Registered User
 

Last journal entry: 351W rebuild
Last photo:
Join Date: Jan 2006
Location: tremont, pa.
Age: 69
Posts: 2,217
Wiki Edits: 0

Thanks: 13
Thanked 15 Times in 14 Posts
Hi
A lot of marine cams are very similar to an RV cam
I don't think you'll have any problems with it. I'd be more
concerned about the head flow, what castings do you have?
Good luck,
Rich
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 03-27-2009, 03:32 PM
Member
 
Join Date: Nov 2001
Posts: 447
Wiki Edits: 0

Thanks: 0
Thanked 11 Times in 10 Posts
Casting number on heads are 336781, I believe it to have 118 cc chambers. I think I screwed up and posted this on the basic hotrodding forum when it should be on the engine forum.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 03-27-2009, 03:56 PM
richard stewart 3rd's Avatar
Registered User
 

Last journal entry: 351W rebuild
Last photo:
Join Date: Jan 2006
Location: tremont, pa.
Age: 69
Posts: 2,217
Wiki Edits: 0

Thanks: 13
Thanked 15 Times in 14 Posts
Hi,
The info you have on the heads is correct, & what you should be using if using stock heads.
Flat tops are around .030 down, have you had it decked? the compression as you said will be low,
do you remember how to figure CR, if not here's a link to a CR calculator.

http://www.csgnetwork.com/compcalc.html

http://www.rbracing-rsr.com/compstaticcalc.html
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 03-27-2009, 04:08 PM
BOBCRMAN@aol.com's Avatar
Member
 
Last photo:
Join Date: May 2002
Location: Holly, michigan
Posts: 8,084
Wiki Edits: 0

Thanks: 23
Thanked 257 Times in 241 Posts
Most 781 heads in fairly stock condition. Will require a lot of work for with that much lift. You will have to use the kits springs/retainers and remove the rotators.. Probably invest in some .050 UP locks. Be sure to get installed height on the springs correct. These stock heads have very SHORT valve springs. Also, that cam needs more compression.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 03-28-2009, 10:02 AM
Registered User
 
Last photo:
Join Date: Sep 2007
Location: Mississippi
Posts: 357
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Also, I don't believe it was mentioned. Some marine engines rotate in the opposite direction from automotive engines. Make sure your cam is not one of these.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 03-28-2009, 10:32 AM
Member
 
Join Date: Nov 2001
Posts: 447
Wiki Edits: 0

Thanks: 0
Thanked 11 Times in 10 Posts
Excellent point on engine rotation. I checked and it is for a standard rotation. This will mainly be a street driven vehicle, the 68 Impala is a heavy car, Hopefully it will have good torque to get that weight moving.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 03-29-2009, 09:34 PM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 12,564
Wiki Edits: 326

Thanks: 698
Thanked 878 Times in 746 Posts
Yours is a perfect application for Rhoads Lifters.....
http://www.rhoadslifters.com/
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 03-30-2009, 11:47 AM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,537
Wiki Edits: 0

Thanks: 3
Thanked 331 Times in 328 Posts
This cam is very simular to the comp 292H magnum.
It has a rough idle and reduced manifold vacuum. It needs 9.5 or more compression ratio, 10:1 to 10.5:1 is idea for 92 octane gas A loose converter and a stiff rear gear. (3400-4000 stall and 4.10-4.30 gears 4.56's is not too much,edpecially with a tall tire) for your Impala. Use a Performer RPM Hi rise dual plane manifold
Do not use with a low stall converter or low gears or low compression or a stock Qjet manifold.
A modifed distributor advance curve is required.
This is the wrong cam for a low compression ratio engine.
(unless you're going to bolt on a supercharger)
If you want to use a 2800stall converter and 3.50 gears, use a comp 280H magum or smaller cam. If the cr is lower than 8.8:1 use a cam with 218@.050 in and 230 exhaust or less. EG Comp 275DEH pn 11-109-3
or a Crane Powermax H-272-2 pn 113941
You must upgrade the stock valve springs.
454 flat top pistons and 73 smog heads gets you 7.8:1
Al the Rhoads lifters will do is make this over cammed low cr mutt into a annoying, noisey over cammed low cr mutt.

If you want the big cam to work, change the pistons in the motor. (25cc dome)

Last edited by F-BIRD'88; 03-30-2009 at 12:09 PM.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 03-30-2009, 12:24 PM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 12,564
Wiki Edits: 326

Thanks: 698
Thanked 878 Times in 746 Posts
I've used Rhoads Lifters in a BBC and they worked well to make the cam effectively smaller. Sometimes you just have to work with what you've got.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 03-30-2009, 12:30 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 29
Posts: 8,678
Wiki Edits: 0

Thanks: 17
Thanked 281 Times in 261 Posts
change the cam. The rest of your build calls for a smaller cam so it would make the most sense to change that rather than everything else to match your cam. You can probably use the rest of the kit, just need a differenet 'shaft. An "RV" grind or even something slightly smaller is needed.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 03-30-2009, 12:35 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 29
Posts: 8,678
Wiki Edits: 0

Thanks: 17
Thanked 281 Times in 261 Posts
I just pulled out the ol' clearance catalog from Comp. Products. They have a few cams on clearance for $50 that would do a MUCH better job. I figure $50 is a price anyone can afford. You still need to run tight quench and mill the heads some if you can to gain some sort of compression.

Comp. Products #- 1-920-233-5228 ask them about BBC hyd. cams that are on their "broom sheet". In your case the smaller the better (within reason).
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 03-30-2009, 01:06 PM
Member
 
Last photo:
Join Date: Dec 2004
Location: San Antonio, Texas
Age: 50
Posts: 4,021
Wiki Edits: 0

Thanks: 0
Thanked 23 Times in 23 Posts
cam is way to big and cr is way to low for a cam any bigger than stock.

I would use a compcam 268H or 270H and change the flat tops to a dome piston. Go for 9.25:1 cr.

781 heads are good. you will need to get rid of the exhaust spinners with stronger springs.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 03-30-2009, 02:49 PM
F-BIRD'88's Avatar
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,537
Wiki Edits: 0

Thanks: 3
Thanked 331 Times in 328 Posts
Quote:
Originally Posted by techinspector1
I've used Rhoads Lifters in a BBC and they worked well to make the cam effectively smaller. Sometimes you just have to work with what you've got.
buying the right camshaft for this motor is half the price of Rhoads crutch lifters
and a real fix.
http://store.summitracing.com/partde...1&autoview=sku
or
http://store.summitracing.com/partde...0&autoview=sku

Sometimes what you got is not what you need. Other than common sense.
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 03-30-2009, 02:57 PM
techinspector1's Avatar
Senior Curmudgeon
 
Last wiki edit: DynoSim combinations Last photo:
Join Date: Oct 2005
Location: Hemet, California, USA
Age: 72
Posts: 12,564
Wiki Edits: 326

Thanks: 698
Thanked 878 Times in 746 Posts
There is a time and place for everything. If they were so horrible, they wouldn't still be sold 25 years after I first used them. I totally understand what you and others have to say about them and that's OK. You have your opinion and I have mine. No harm, no foul.

It was 1983. I was building a 454 for my friend's 4X4 truck. He wanted more cam than I knew he needed, so I decided to try the variable duration lifters. In that case, they worked perfectly for what he wanted to do, effectively extending the operating range of the camshaft so that it worked effectively at low and high r's.
Reply With Quote Quick reply to this message

Recent Hotrodding Basics 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
Cam tight on insertion 70bird Engine 12 12-27-2008 07:51 PM
Wiped out a cam lobe :( 66GMC Engine 25 04-28-2008 05:49 PM
Cam button length/clearance..? mrdreex Engine 1 04-12-2008 10:17 PM
ls-7 454 cam opinions bamacj Engine 8 01-14-2007 07:30 PM
mild cam for a 454 boss350 Engine 4 11-23-2006 06:19 PM


All times are GMT -6. The time now is 02:23 AM.


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.