New/old 350 problems...someone help me!!! - 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 09-06-2006, 10:23 PM
Warrant's Avatar
72 Nova, 65 Rambler, 37 Chevy
 
Last photo:
Join Date: Dec 2005
Location: Utah
Age: 24
Posts: 337
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
New/old 350 problems...someone help me!!!

I got my car running again!!! just replaced 250 and glide with 350/350 in 72 nova.

But I got some serious problems

Here's what I got going: 100000mile 350 with great rings and bearings....everything cleaned and retorqed...great oil pressure, 882 heads with new seat surfaces and seals...doesn't smoke at all, 8.5CR, weiand action+ intake, 750 qjet, 224* .465" 114LS summit cam, 15/8 ceramic headers, HEI ignition with MSD coil and Accel wires, stock plugs, th350 with 2000 stall and transgo soft shift repair kit, 3.08 open rear.

It is real boggy and slow off the line...I cant even break the tire loose and it seems the converter is working...can rev it to 1800 1900 braking....sometimes it will backfire out the carb (wrecked my air cleaner...toasted it) sometimes it will die or sputter....sometimes fuel comes squirting out of the carb...this all happens when floored sometimes when starting off slow.

At idle or idling in gear...sometimes it will fluctuate rpm... rev up 200-300 rpm and back down continuously. Also idling in neutral...I floor it and let up real fast it'll backfire...or hesitate....and rpms drop real slow.

I checked all vacuum...timing is set...mechanical and vacuum advanced working....PVC valve working with breather on other valve cover(or should I seal other side?) Transmission modulator vacuum hooked up...everything else is plugged. Vacuum guage says 11 inches...

It pulls really really hard past 2500-3000 RPM....rolling at 30-40 mph and I downshift into 1st...Ill be to 90 real quick. But off the line its a dog log...sputtering dieing spittin poppin blowin flames.

Also on WOT at about 5000 rpm and past somtimes it will jump and sputter and die out...just like its not getting fuel or ignition problem? Could this be my origanal 5/16" 6 popper fuel line?

Could this be associated with my trans problems(rebuilt Th350 downshift problems)

Badly tuned carb? converter problem?

Im guessing not enough compression for my cam, Too tall of rear gear, or bad carb... Or all of them.

What do you guys think?

Last edited by Warrant; 09-06-2006 at 10:36 PM.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 09-07-2006, 08:04 AM
DoubleVision's Avatar
Not Considered a Senior Member
 
Last photo:
Join Date: Oct 2002
Location: Heart Of Dixie
Age: 40
Posts: 10,643
Wiki Edits: 0

Thanks: 13
Thanked 56 Times in 53 Posts
Did you convert the ignition over to a 12 volt source? point ignitions that came stock on your nova ran on 6 volts, HEI`s require 12, if the HEI doesn`t get 12, it`ll still run, but it`ll run like crapola.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 09-07-2006, 09:48 AM
Mustangsaly's Avatar
Member
 
Last photo:
Join Date: Jan 2005
Location: Nebraska
Posts: 1,071
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
isn't a 72 nova a 12v system ? maybe it's not a 72 nova we are talking about. I think or think that a 72 could be points. not trying to be a smart ***** just curious.








Mustangsaly
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 09-07-2006, 11:11 AM
larryblack's Avatar
Certified Lead Foot
 
Last photo:
Join Date: Jan 2003
Location: Houston, TX again
Age: 62
Posts: 519
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
72 nova's were points type and had a ballast resistor wire to the coil. That gives 6 volts to the HEI if it was not replaced with a straight wire. This is what doublevision is refering to.

The slow off the line is probably due to having a really high gear in the axle.

Most of the other problems make me believe you have a carb problem too.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 09-07-2006, 03:09 PM
Warrant's Avatar
72 Nova, 65 Rambler, 37 Chevy
 
Last photo:
Join Date: Dec 2005
Location: Utah
Age: 24
Posts: 337
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
yup I have a full 12 volts to the HEI....It is a 72 nova...and it did have a pink 6 volt resistor wire to the coil...which was replaced.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 09-07-2006, 04:52 PM
Mustangsaly's Avatar
Member
 
Last photo:
Join Date: Jan 2005
Location: Nebraska
Posts: 1,071
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by larryblack
72 nova's were points type and had a ballast resistor wire to the coil. That gives 6 volts to the HEI if it was not replaced with a straight wire. This is what doublevision is refering to.

The slow off the line is probably due to having a really high gear in the axle.

Most of the other problems make me believe you have a carb problem too.

thanks I learned something,





Mustangsaly
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 09-07-2006, 10:14 PM
57 Chevy's Avatar
Registered User
 
Join Date: Dec 2005
Location: Montana
Posts: 156
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
A Q Jet has a vacuum operated secondary air valve in the top of the air horn. It is held closed with an adjustable spring and the amount of tension controls the opening rate. Set too weak and it flops open when the throttle opens, (bog) too tight and it will never open. Get the right size allen wrench and a small screwdriver. The allen wrench to loosen the screw under the shaft on the right side of the secondary air horn. Back the screw off until you get "O" tension, the air valve will barely close, then tighten it 7/8 turn clockwise and tighten the allen while holding the screw in place. If you tighten over one full turn, the spring may distort.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 09-07-2006, 10:24 PM
Warrant's Avatar
72 Nova, 65 Rambler, 37 Chevy
 
Last photo:
Join Date: Dec 2005
Location: Utah
Age: 24
Posts: 337
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I see, but when the air filter is off...and I rev it up in idle....the secondary's air valve will open up. In gear from stop to WOT they will open at about 3000-3500 I beleive. I can certainly feel them open when on WOT runs...boogy below 2500-3000 and really pulls past that, shift to 2nd they'll shut again and open soon after.

I checked a spark plug today...black...I had a buddy of mine tune it up...was at 11 in. of vacuum...now we got it up to 13-14 inches. Revs better, doesnt hesitate off idle when floored...still very slow tho...with my converter...rev it up to 1800-1900 still cant get the tire to spin...and their not that big either. In a little bit of gravel I got it to break loose...boggy at first but as soon as it lost all traction it reved up 4000-5000 and just spun like crazy lettin off the break.

Also after we tuned it up...I went on a WOT run....the tires chirped as I shifted into 2nd.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 09-11-2006, 11:08 PM
Warrant's Avatar
72 Nova, 65 Rambler, 37 Chevy
 
Last photo:
Join Date: Dec 2005
Location: Utah
Age: 24
Posts: 337
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Any one esle's input?

I fixed alot of the backfireing and hesitation. But somtimes it will still pop spit backfire and die when I bring it up to on the converter and luanch. Also I noticed that fuel will leak out of what looks to be the choke shaft while pumping the carb.

And somtimes its real quick and shifting into 2nd the tires will churp...somtimes its just poopy. And still slow low end

usualy tt runs our of air or fuel? just past 5000. But once I got it to 5600 and shifted to 2nd and thats when the tire churps.

Could a bad carb couse all this?
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 09-12-2006, 12:18 AM
Member
 
Join Date: Aug 2003
Location: California
Posts: 903
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Warrant,

Hook up the vacuum gauge again and try this and let me know what the reading are.....Let the engine idle and what is the vacuum reading? Now using your hands cover the air inlet of the carb. Do not choke the engine off just restrict the flow of air a little bit, what is the vacuum reading now? Did the RPM drop or did it go up like 3 to 4 hundred RPM's.

Waiting
Scholman
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 09-12-2006, 05:38 PM
Warrant's Avatar
72 Nova, 65 Rambler, 37 Chevy
 
Last photo:
Join Date: Dec 2005
Location: Utah
Age: 24
Posts: 337
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Scholman, off the manifold...where powerbrakes are usualy takin off of, it read a little over 11 in. idling at about 550RPM. When I restrict some air the vacuum hardly moves...it moves down slighty to a lowest of 10...and thats really restricting...anymore and the egnine dies.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 09-12-2006, 05:43 PM
Member
 
Join Date: Aug 2003
Location: California
Posts: 903
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Warrant,

This test tells me that there is an internal fuel leak in the carb or the float setting is too high. Also advance the timing until you get 16-18 inches of vacuum.

Good Luck
Scholman
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 09-12-2006, 09:35 PM
Warrant's Avatar
72 Nova, 65 Rambler, 37 Chevy
 
Last photo:
Join Date: Dec 2005
Location: Utah
Age: 24
Posts: 337
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Well I changed the carb today to a Holley vacuum secondary...seemed like it ran alittle better off the line...still hesitated some...All in all I think the quadrajet actually ran better, So I think that rules out carb problem.

My knowledgeable Friends have concluded that the converter is too tight. The cam after all is rated for 2200-5200RPM and Im stalling at around 1900, guess I just cant get the Rpms up. And were guessing rear gears and compression may be contributing to the problem too.

Im going order something along the lines of a 10 in. 2500 stall and 3.73 gear. And Ill go from their.


Scholman, Having only 11 inches now, I would think I would have to advance off the timing marks to get too 16-18 in. With only 8.5 CR should I still be ok of detonation? Also will that improve low end drastically?

Thanks a ton.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 09-19-2006, 03:20 PM
Warrant's Avatar
72 Nova, 65 Rambler, 37 Chevy
 
Last photo:
Join Date: Dec 2005
Location: Utah
Age: 24
Posts: 337
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Well I advanced the cam - I have it advanced 15* initial, Im not sure what the total is...the engine has more power down low and runs better/quieter...still cant spin a tire tho Vacumm now is around 14-15 inches. When the engine starts it makes a "knocking noise" almost like when a car runs out of gas in the movies...

Should I advance it even more? it doesnt detonate yet. Will higher octane be needed when advanced alot more?

Thanks
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 09-19-2006, 05:58 PM
Member
 
Join Date: Aug 2003
Location: California
Posts: 903
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
Warrant,

More advance please! (I hope you ment the distributor and not the cam.)
You may need more octane but until the vacuum gets up near 18 inches I think you are ok.
What has me worried is the noise when you start the engine up. Does this knocking go away right after it starts running or do you hear it for a few seconds?
I read your first post again and you mention that this is a used or should I say a seasoned engine and I am worried that the oil pressure is going a way. You say it has great oil pressure but what is great? PSI at idle? PSI at 2000 RPM?

Scholman
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
DEBATE: Which heads are better?....Chevy 350, Pontiac 350, Olds 350 or Plymouth 350. Steve-0321 Hotrodding Basics 21 11-26-2007 12:44 AM
Idleing problems with a 350 sbc Eric327 Engine 7 12-29-2005 12:21 AM
SBC 350 Crank Balancer Problems bjam2 Engine 8 05-04-2004 07:36 PM
350 Problems.. Meangreen Engine 9 06-17-2003 08:02 AM
chevy 350 problems Thacolbster Engine 9 01-05-2003 03:15 PM


All times are GMT -6. The time now is 01:23 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.