my 355 after cam swap sluggish help - 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 10-16-2012, 07:17 PM
Registered User
 
Join Date: Oct 2012
Posts: 7
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
my 355 after cam swap sluggish help

I have a 355 with lunati 285 235@50 510 lift 108degree lobe sep edelbrock performer eps intake 305 heads runnin very sluggish cant figure out why it seems to take very long time to get any speed at all edelbrock 600 carb could this be my problem is not enough carb??? LOST if anyone could give me any ideas would greatly appreciate it i know the 308 gear isnt helping but truck was alot quicker before cam intake and headets thanks for the help

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 10-16-2012, 07:31 PM
Registered User
 
Join Date: Jan 2012
Posts: 10
Wiki Edits: 0

Thanks: 4
Thanked 0 Times in 0 Posts
sounds like the ignition timing is slow or if you have vacuum advance it may not be responding properly...you will loose vacuum sometimes when you change cams..and if this all checks out ok you will need to put the cam in at a 106 lobe center...
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 10-16-2012, 07:38 PM
Registered User
 
Join Date: Apr 2007
Posts: 9,535
Wiki Edits: 0

Thanks: 14
Thanked 201 Times in 159 Posts
Quote:
Originally Posted by chvy285 View Post
I have a 355 with lunati 285 235@50 510 lift 108degree lobe sep edelbrock performer eps intake 305 heads runnin very sluggish cant figure out why it seems to take very long time to get any speed at all edelbrock 600 carb could this be my problem is not enough carb??? LOST if anyone could give me any ideas would greatly appreciate it i know the 308 gear isnt helping but truck was alot quicker before cam intake and headets thanks for the help
This can be a lead in to a lot of tuning issues but this is a pretty big cam that has moved the power band way up the rev range. For sure the 3.08 gearing isn't helping because the engine's power band and the gearing to get up to it no longer match. The 305 heads unless you put in 350 valves and did some porting aren't helping either as about the time the engine revs to the cam's power band unmolested 305 heads are out of breath. You may also be looking at detonation with these small chamber heads, they have the spark plug way off to one side with a lot of compression on a 350, the plug location brings the slow burn of large chamber heads with a lot of compression. This will put the point of maximum pressure late in the power cycle where it isn't effectively pushing the piston and creats a situation where the piston has moved so far down the bore that the quench function is no longer a viable method of damping the excess temperatures that cause detonation of the unburnt mixture ahead of the flame front. More advance that comes in quickly will help getting the peak cylinder pressure earlier but will increase any detonation tendency. There are some cures for that of which richening the mixture is the quickest without backing down the advance. The 600 cfm carb won't be the best at feeding the engine where it has to go for max power on this cam, but that's probably the last issue to chase as it will do well enough to at least tickle your fancy for power but won't satisfy it.

Bogie
Reply With Quote Quick reply to this message
 
  #4 (permalink)  
Old 10-16-2012, 09:53 PM
vinniekq2's Avatar
Registered User
 
Join Date: Jun 2012
Location: BC,Canada
Age: 59
Posts: 11,607
Wiki Edits: 0

Thanks: 690
Thanked 1,323 Times in 1,229 Posts
with all the parts you have in the engine,its the cam thats a little big.The carb could be a little bigger.The heads could use some work. Im sure with some tuning it will improve.Is that a hydraulic flat tappet cam. when the engine reaches 2500 rpm does it get a lot better?
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 10-17-2012, 05:46 AM
Registered User
 
Join Date: Oct 2012
Posts: 7
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
355 slow

Thanks to everyone who answered it seems the cam is to big for the stock 305 headsand my 308 gear it seems a head swap to maybe a good set of double humps and a lot more gear would be a huge help as i am really new to all this i never realized u could overcam one that easily this is in a 1983white gmc swb also runnin a 10/31/50 tire also seems to be killin it what would be a good tire size lookin for at least a 410white gear now
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 10-17-2012, 08:41 AM
Registered User
 
Join Date: Oct 2012
Posts: 7
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
It starts pullin around 2700 pretty hard but nothin like it shouldat the top if first gear its pullin hard if u hold it to around 5500 before shiftin when u shift it barks tires just takes forever to get it there was just very disapointed in the petformance but i am new at this and learning some things i am learning are turning out to be expensive lessons lol
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 10-17-2012, 09:03 AM
Member
 

Last journal entry: was hoping for better than this
Last photo:
Join Date: Mar 2012
Posts: 256
Wiki Edits: 0

Thanks: 16
Thanked 20 Times in 20 Posts
if it's an 67-72 p/u they are not heavy by p/u standards my long bed is 3890. lb
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 10-18-2012, 04:56 PM
Registered User
 
Join Date: Oct 2012
Posts: 7
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I installed a cloyce heavy duty double roller timing chain and gear at first had it all out of whack and had to tear it all down and reset it i had it set on wrong timing mark and wouldnt hit a lick
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:
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:
Insurance
Please select your insurance company (Optional)

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
1986 355 swap to zz383 help 400fbird Engine 3 07-09-2012 03:19 PM
355 Cam suggestions KMAY Engine 20 02-24-2011 12:11 PM
Help me cam my 355 down a little!! hotrodf1 Engine 13 11-27-2006 10:03 AM
355 cam ray bob Engine 2 02-09-2006 07:33 PM
Cam for a 355 Dans83Olds Engine 14 10-08-2003 06:16 PM


All times are GMT -6. The time now is 12:43 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.