bucking while cruising. - 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 05-30-2010, 03:40 PM
Registered User
 
Last photo:
Join Date: Mar 2010
Location: USA
Posts: 218
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
bucking while cruising.

I just did a thorough test to try to get the conditions of when the car bucks. Ive noticed that it will buck in all gears except for 6th. Also it will stop bucking in all other gears if the rpms are over 2000. Its done this with the holley 750 i have now and the edelbrock 750 i had before. I did not do this when i had the automatic in it. What are some things that could make the car buck so much? Also could it just be the cam?

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 05-30-2010, 06:59 PM
Registered User
 
Join Date: Dec 2004
Location: San Jose Ca
Age: 62
Posts: 472
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
More info what are we dealing with,motor ,car,gears etc.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 05-30-2010, 07:32 PM
Registered User
 
Last photo:
Join Date: Mar 2010
Location: USA
Posts: 218
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
87 Trans am

383 stroker

t56

3.42 posi rear end
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 05-30-2010, 07:36 PM
Registered User
 
Join Date: Dec 2004
Location: San Jose Ca
Age: 62
Posts: 472
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Cam,dist ,timing,static and total ,comp ratio,cylinder heads.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 05-30-2010, 07:55 PM
Registered User
 
Last photo:
Join Date: Mar 2010
Location: USA
Posts: 218
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by SDLuck
Cam,dist ,timing,static and total ,comp ratio,cylinder heads.
Comp camshaft 510/520 lift 230/236 Duration 112 LSA

Msd HEI distributor with accel high output coil

14 initial 36 all in at 3k

didnt build engine so i didnt check it myself, but person who did said its at 10:1 compression

PBM Aluminum Heads, 220cc runners 2.02 and 1.60 valves 58cc chambers
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 05-30-2010, 09:29 PM
Registered User
 
Join Date: Dec 2004
Location: San Jose Ca
Age: 62
Posts: 472
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
58 cc heads mean dished pistons to get the compression that low .What is cranking compression?
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 05-30-2010, 09:30 PM
406 bug's Avatar
9.82 @ 139mph
 
Last wiki edit: Finding vacuum leaks Last photo:
Join Date: Nov 2007
Location: phoenix, arizona
Posts: 582
Wiki Edits: 1

Thanks: 0
Thanked 1 Time in 1 Post
I would concentrate on the rear gear 3.42. when you changed to manual I would have maybe changed the gear . 220 runners too much for that mtr.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 05-30-2010, 09:47 PM
Registered User
 
Last photo:
Join Date: Mar 2010
Location: USA
Posts: 218
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by 406 bug
I would concentrate on the rear gear 3.42. when you changed to manual I would have maybe changed the gear . 220 runners too much for that mtr.
The rear end and transmission are from a fourth gen firebird. Its a good match to each other.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 05-30-2010, 10:19 PM
406 bug's Avatar
9.82 @ 139mph
 
Last wiki edit: Finding vacuum leaks Last photo:
Join Date: Nov 2007
Location: phoenix, arizona
Posts: 582
Wiki Edits: 1

Thanks: 0
Thanked 1 Time in 1 Post
Quote:
Originally Posted by stroker444
The rear end and transmission are from a fourth gen firebird. Its a good match to each other.
does the Firebird use the same rear gear for both the Auto and manual trans?

The reason I think you need more gear (lower) is because of the fact you mentioned all is fine above 2k. Your rear./ trans may be a good match to each other as you say, but maybe not that good of a match with your eng.
I just think you may need additional r's at the lower speeds..
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 05-30-2010, 10:47 PM
Registered User
 
Last photo:
Join Date: Mar 2010
Location: USA
Posts: 218
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by 406 bug
does the Firebird use the same rear gear for both the Auto and manual trans?

The reason I think you need more gear (lower) is because of the fact you mentioned all is fine above 2k. Your rear./ trans may be a good match to each other as you say, but maybe not that good of a match with your eng.
I just think you may need additional r's at the lower speeds..
It could be. The rear end is from an ls1 with a t56 and the transmission is for an lt1. You see lots of guys in 4th gen firebirds with a bigger cam and etc with the same powertrain i have. There really isnt much difference between an lt1 and sbc.

On acceleration and decelleration theres no jerking whatsoever, smooth as can be (except for the tires spinning! jk), its only when im doing part throttle the engine bucks. When i had to much vacuum advance it made it alot worse, but now im running low total mechanical so it shouldnt be that. Also in 4th gear which is direct gear, its the worst. It feels like im slamming on the brakes quickly then letting off.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 05-31-2010, 07:39 AM
Registered User
 
Join Date: Dec 2009
Location: illinois
Posts: 375
Wiki Edits: 0

Thanks: 1
Thanked 32 Times in 32 Posts
You Might Want To Check Your Power Valve. If The Diaphram Is Blown It Will Make Make You Pig Rich At Partial Throttle. Ask Me How I Know.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 05-31-2010, 08:57 AM
1BAD80's Avatar
The Smell of Nitro in the morn
 
Last wiki edit: How to adjust valves Last photo:
Join Date: Jun 2001
Location: Mich
Posts: 2,423
Wiki Edits: 2

Thanks: 0
Thanked 3 Times in 2 Posts
Change the power valve to a lower number, if it is blown it would be flooding out.

If expect a blown power valve, use this simple test.
TEST: At idle turn your idle mixture screws
(found on the side of the metering block) all the way in.
If your engine dies the power valve is not blown.
__________________
Luv the smell of NITRO in the morning.
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 05-31-2010, 11:06 AM
Registered User
 
Last photo:
Join Date: Mar 2010
Location: USA
Posts: 218
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by 1BAD80
Change the power valve to a lower number, if it is blown it would be flooding out.

If expect a blown power valve, use this simple test.
TEST: At idle turn your idle mixture screws
(found on the side of the metering block) all the way in.
If your engine dies the power valve is not blown.
Would the powervave really have any effect? Its all under 2000 when the engine is running off the idle circuit anyway
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 05-31-2010, 11:11 AM
1BAD80's Avatar
The Smell of Nitro in the morn
 
Last wiki edit: How to adjust valves Last photo:
Join Date: Jun 2001
Location: Mich
Posts: 2,423
Wiki Edits: 2

Thanks: 0
Thanked 3 Times in 2 Posts
Well it helped mine, what do you have to loose except the bucking.
It feels like the torque converter going in & out.
I like a lower PV anyways, I run 3.5 in my carbs now.
__________________
Luv the smell of NITRO in the morning.
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 05-31-2010, 11:35 AM
Registered User
 
Last photo:
Join Date: Mar 2010
Location: USA
Posts: 218
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by 1BAD80
Well it helped mine, what do you have to loose except the bucking.
It feels like the torque converter going in & out.
I like a lower PV anyways, I run 3.5 in my carbs now.
Alrighty, ill give it a try. Im pulling about 10-12 vacuum right now. When choosing the powervalve do i just take the lowest vacuum i get at idle, then take half of THAT for the valve?
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:

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
Effects of Axle ratio change on cruising RPM Regal Beagle Transmission - Rearend 14 06-27-2008 01:17 AM
Front face of tire dismounted from wheel while cruising !!!!!!!! Calderone Hotrodding Basics 7 06-05-2008 05:20 PM
SNEAK PEAK!!! 2009 Camaro Convertible Cruising on Woodward! Video first time ever! powermelissa Hotrodders' Lounge 1 08-18-2007 09:19 PM
1988 Camry cruising issues ChevelleSS_LS6 General Rodding Tech 6 08-11-2007 06:41 AM
Almost cruising time. HemmiGremmie Hotrodders' Lounge 5 06-10-2003 01:08 PM


All times are GMT -6. The time now is 03:08 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.