Hot Rod Forum : Hotrodders Bulletin Board - Reply to Topic
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> is back fireing normal for cold motor
User Name
Password
lost password?   |   register now

Thread: is back fireing normal for cold motor Reply to Thread
Title:
  
Message:
Trackback:
Send Trackbacks to (Separate multiple URLs with spaces) :

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.



Additional Options
Miscellaneous Options

Topic Review (Newest First)
08-06-2011 02:05 PM
63chevy when i start it up it doesnt backfire
then when i put in d and drive out onto the street it cough and sputters
alittle when it's cold (120/140 degree).
but when it is above 200 deg its fine
08-06-2011 01:37 PM
ericnova72 OK, Holley type/style carb. The advice I gave is still correct. All chanfging the jets will do is decrease fuel mileage.

This is assuming the backfire is when you are opening the throttle, not a steady cruise backfire.

You're not giving a ton of info on the exact symtoms and total conditions when it happens. Be specific.
08-06-2011 01:32 PM
63chevy quick fuel (i didnt get holley ,this one was lighter just have a heavy van trying not to add alot of weight)
08-06-2011 01:22 PM
ericnova72 Super Street what? Made by who?
08-06-2011 01:12 PM
63chevy its a super street
08-06-2011 01:10 PM
ericnova72
Quote:
Originally Posted by 63chevy
i un hooked the choke simply i dont drive it when its really cold
ok so your saying bigger jets/smaller or main valve in carb??
No, not bigger jets or power valve changes. Change the accelerator pump nozzles(shooters) to a larger size, and you may possibly also need to put on larger pump cams(the plastic cam that moves the accelerator pump arm when you open the throttle).

This is a Holley carb we are talking about? You said 830 cfm and that is a Holley size, so I just assumed.
08-06-2011 12:57 PM
63chevy i un hooked the choke simply i dont drive it when its really cold
ok so your saying bigger jets/smaller or main valve in carb??
08-06-2011 12:54 PM
ericnova72 If the carb doesn't have a working choke, it will backfire when cold, usually when you try to accelerate(any opening change in the throttle blade position). This is quite normal.

Increasing the size of the accelerator pump shot will lessen or remove the tendancy for it to backfire. Experiment with larger pump shooters(nozzle) or/and larger pump cams on a Holley carb.
08-06-2011 12:40 PM
63chevy
is back fireing normal for cold motor

hi i have a 1963 pannel van(4160lbs)
i resently have a machine shop build a motor
for me ,blue print balanced,and bored

469 (454)
roller cam howard 0 lash
10.5 pistons
598 horsepower
582 tork
400th
830 cfm
373 rear end grear
vac plugged on carb and distrib.
i had the timing at 38 degr.
now it's 34 deg runs better and cooler now
when its cold it back fires a little (very little)

driving down road when under 180' (temp) it does it
when 200deg it runs fine fine
and the oil temp is at 70 psi when temp is at 200 it drops to
40 ( in has a high per pump.)
any thoughts thanks

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


All times are GMT -6. The time now is 06:07 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.