Quardajet Lag at the light - 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 07-18-2010, 10:33 AM
Registered User
 
Join Date: Jul 2010
Location: michigan
Posts: 5
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quardajet Lag at the light

Hi guys,

Hopefully a basic question that will be easy to resolve. I just rebuilt my q jet and while it idles better and is more responsive, there is still a lag when at the light and I go to full throttle. When coasting along and I go full throttle the secondaries are loud and the truck will move, so I am assuming this an adjustment that is easy to resolve?

This is on a late 70's 350 with HEI and a 17058213 Q jet. I reset the idle mixture screws to 1 3/4 as they were before, have not touched the idle speed nor timing.

I was thinking start with the carb and get it best as possible but not sure where to start. Advice?

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 07-18-2010, 11:13 AM
DoubleVision's Avatar
Not Considered a Senior Member
 
Last photo:
Join Date: Oct 2002
Location: Heart Of Dixie
Age: 40
Posts: 10,654
Wiki Edits: 0

Thanks: 15
Thanked 58 Times in 55 Posts
You will need to adjust the secondary upper throttle flaps. They are controlled by a tension spring. This will show you how it`s done:
http://www.73-87.com/7387garage/drivetrain/myqjet.htm
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 07-18-2010, 06:49 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
sounds like you need more accelerator pump.

get a performance accelerator pump rod from summit racing or cut about 1/4" off the stock rod end.

set the idle air mixture to the highest vacuum which is typically the highest rpm with a set idle screw position.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 07-19-2010, 04:01 PM
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 597 Times in 546 Posts
Quote:
Originally Posted by 57vroom
Hi guys,

Hopefully a basic question that will be easy to resolve. I just rebuilt my q jet and while it idles better and is more responsive, there is still a lag when at the light and I go to full throttle. When coasting along and I go full throttle the secondaries are loud and the truck will move, so I am assuming this an adjustment that is easy to resolve?

This is on a late 70's 350 with HEI and a 17058213 Q jet. I reset the idle mixture screws to 1 3/4 as they were before, have not touched the idle speed nor timing.

I was thinking start with the carb and get it best as possible but not sure where to start. Advice?
If you have a vacuum gage, use it to adjust the idle mixture screws to give the highest vacuum at idle, w/the screws turned out about the same amount. Gently rev the engine between adjustments and allow the engine to come back to idle, then note the reading. If you don't have a vacuum gage, use an accurate tach and go for the highest RPM at idle.

If you don't have the vacuum advance hooked up to a manifold vacuum source, you should give it a try.

When you use manifold vacuum for the advance (if not done already) the idle speed and vacuum reading will increase. Use the curb idle screw to lower the idle back down.

You should use about 36 total timing (not including vacuum advance), all in by around 2500-3000 RPM, depending on weight, gears, fuel, etc. This is adjusted by the springs atop the mechanical advance mechanism under the rotor.

After doing the above, see if the bog has been cured or lessened.

If not, either the accelerator pump shot, the secondary air valve- or both- may need attention.

You should see a stream of fuel come from the accelerator pump discharge ports as soon as the throttle is opened. There are two holes to choose from on the accelerator pump arm. The innermost hole gives a larger shot.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 07-20-2010, 08:02 PM
Registered User
 
Join Date: Jul 2010
Location: michigan
Posts: 5
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Thanks for the quick responses, you guys are great! This might be a baisc question as it related to the timing, but how do I get that many degrees? The extent of my experience here was on the old point style distributor where you just turn the cap to get a value of X. Is HEI different? Sure hoping my 1973 timing light/ analyzer is going to suffice on this endeavor....
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 07-21-2010, 09:03 AM
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
yes, just turn the distributor to get the timing you need (hei or points style).

however, you will need timing tape on the balancer or use a timing light with a degree knob to see the total timing number on the balancer.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 07-21-2010, 09:15 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 597 Times in 546 Posts
If you don't have a degreed damper or a dial back timing light, you can easily make a temporary TIMING TAPE.

To set the total timing, disconnect the vacuum advance and plug the line from the vacuum source. Then, increase the RPM until you see no more timing advance- this timing reading is the total timing.

If it is less than 36-38, turn the distributor body CCW until you see the correct reading.

Return to an idle and see what the initial timing is. You'd like there to be at least 10-12 if the engine is stock. Another thing you can do is to connect the vacuum advance to a manifold vacuum source. If it is now on a ported vacuum source, this will cause the idle speed to increase. Just readjust the curb idle screw to give the correct idle speed and see how it drives like this.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 07-21-2010, 10:08 AM
adantessr's Avatar
'23 T-Bucket Pickup
 
Last wiki edit: Troubleshooting ignition Last photo:
Join Date: Jun 2010
Location: South Charleston , WV
Age: 62
Posts: 1,549
Wiki Edits: 3

Thanks: 43
Thanked 17 Times in 15 Posts
Quote:
Originally Posted by cobalt327
If you don't have a degreed damper or a dial back timing light, you can easily make a temporary TIMING TAPE.

To set the total timing, disconnect the vacuum advance and plug the line from the vacuum source. Then, increase the RPM until you see no more timing advance- this timing reading is the total timing.

If it is less than 36-38, turn the distributor body CCW until you see the correct reading.

Return to an idle and see what the initial timing is. You'd like there to be at least 10-12 if the engine is stock. Another thing you can do is to connect the vacuum advance to a manifold vacuum source. If it is now on a ported vacuum source, this will cause the idle speed to increase. Just readjust the curb idle screw to give the correct idle speed and see how it drives like this.
cobalt327 . Even though my T-bucket runs like a scalded dog on take-off , I am going to do what you mention here just because I have the time .(read retired) BTW . I wish I had a Q-jet on my T-bucket just 'cause I love the HUGE secondaries . But it runs great with the 1405 Edelbrock so I guess I'll keep my money .
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 07-21-2010, 10:12 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 597 Times in 546 Posts
Quote:
Originally Posted by adantessr
cobalt327 . Even though my T-bucket runs like a scalded dog on take-off , I am going to do what you mention here just because I have the time .(read retired) BTW . I wish I had a Q-jet on my T-bucket just 'cause I love the HUGE secondaries . But it runs great with the 1405 Edelbrock so I guess I'll keep my money .
You know what they say about fixing things that ain't broke... lol

But seriously, the closer to stock the cam is, the less the whole ported vs. manifold vacuum for the vacuum advance matters, IMO. I'd only suggest it IF the engine wasn't responding well to "normal" tuning procedures.
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
GEN Light On with IGN Key OFF strausbo Electrical 10 09-06-2009 06:59 PM
oil warning light romaro Engine 3 09-15-2006 09:31 PM
Trust the timing light or the timing pointer? lluciano77 Engine 6 03-06-2004 01:35 AM
Light Problems like crazy ponybuster Electrical 7 10-14-2003 12:12 PM
a little humor to get through the evening antirice Hotrodders' Lounge 7 08-28-2003 08:36 AM


All times are GMT -6. The time now is 06:51 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.