What is a good street carb? - Page 10 - 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
  #136 (permalink)  
Old 07-10-2013, 01:40 PM
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
To much fuel pressure is pushing the gas past the floats.
You will never be able to adjust the idle until it's fixed.
Get the higher pressure float needles, stock are good for only 5 psi max or get a fuel regulator.

No need to change the power valve unless it's ripped and causing the flooding problem.
It will not starve at higher rpm's either with less pressure. I'm running quad's with only 5 psi, it's the Flow that really count's

I like setting the float to where the gas just trickles out when I bounce the front end a little.
Make sure you have around .015 gap on the accelerator pump arm when fully open ( check when shut off)

Change your oil once you get this fixed.
I recommend fixing the advance unit since this is not a race only car
set the timing to 12* initial and 36* total

    Advertisement
__________________
Luv the smell of NITRO in the morning.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #137 (permalink)  
Old 07-10-2013, 02:27 PM
Registered User
 
Last photo:
Join Date: Jul 2010
Location: New Jersey
Posts: 630
Wiki Edits: 0

Thanks: 8
Thanked 8 Times in 7 Posts
Quote:
Originally Posted by 1BAD80 View Post
I recommend fixing the advance unit since this is not a race only car
set the timing to 12* initial and 36* total

Actually, it kinda is a race car that I drive on the street. The cam is a .600 lift. Look at the first 2 pages for the engine specs. The distributor is fixed at 36*. As for the Needle and seats , I am running the 110's and believe that my float level is fine just under the sight glass. (unless it is changing when I drive.)


Another culprit I suspect due to the idle adjustment screws not really doing much, is the Idle Air Bleeds. Im thinking of installing larger ones to lean out the idle circuit this way I can lower the Idle adjustment screw. As of right now I believe I am ideling off of the primary metering block and too much of the idle transfer slot is exposed. The issue is when I try and close the primary throttle blades to get it to idle off the idle circuit, the car will not stay running, it gets too rich. Then I wind up almost fully closing the idle adjustment screws, and the car idle picks up, but then starves and dies out. I cant seem to find a happy mid way point between the idle adjustment screw and the idle mixture screws..Leading me to believe I need larger Idle air bleeds..
Reply With Quote Quick reply to this message
  #138 (permalink)  
Old 07-10-2013, 03:10 PM
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
You are trying to have the best of two worlds so you need to tune in the whole combination for both.
The 850 is a big carb for that motor and just changing the bleed screws/seats won't help it either.
No reason that can't idle at 650 rpm when tuned in.

quote: idles good at around 850-950, timing set to 32-34 degrees fixed worse when it gets some heat, because when cold it needs to be rich.

Borrow a smaller carb like a 750 and you will notice a difference.

You can always change the carb & distributor when you go racing but then again why.
It's combination, combination, combination and tuned in combination .

Like I said before along with the other's in this posting fix the timing, locking the advance out don't help on the street.

F-BIRD'88-ap62-Techinspector gave some very good info and are some of the best on this site, along with many others I did not name.
__________________
Luv the smell of NITRO in the morning.
Reply With Quote Quick reply to this message
  #139 (permalink)  
Old 07-10-2013, 11:26 PM
Registered User
 
Last photo:
Join Date: Jul 2010
Location: New Jersey
Posts: 630
Wiki Edits: 0

Thanks: 8
Thanked 8 Times in 7 Posts
Quote:
Originally Posted by 1BAD80 View Post
You are trying to have the best of two worlds so you need to tune in the whole combination for both.
This is exactly what I am trying to do...But i cant seem to get the specific answers for my specific combination.
I took the previous advise:
-Timing
-New plugs
-Float level
-Needle and seats
-powervalve replaced (3.5)
-Jets down 2 sizes
-Idle transfer slot Not over exposed ( car wont idle unless I expose it more)
-idle mixture screws- not responsive
-fuel pressure 6 psi

It seems as if I am ideling off the main circut and dumping fuel as I drive, the RPMS's occasionally hang up, and when I come to a light sometimes it idles fair, some times it dies from being too rich.

The carb is running overly rich and I want to know how to fix it, I cant get a straight answer..I covered the basics as advised, but something is just off in the carb itself. I feel that because sometimes it runs ok and sometimes it runs like crap.

Quote:
Originally Posted by 1BAD80 View Post
The 850 is a big carb for that motor and just changing the bleed screws/seats won't help it either.
Every calculator I do for my motor tells me 850 or a 950, even on Holleys website with the interactive carb selector. 383 stroker motor+ 7500 rpms.If I go any smaller will i hurt the motor running lean?


Quote:
Originally Posted by 1BAD80 View Post
No reason that can't idle at 650 rpm when tuned in.
So how exactly do I tune it in at this point? What is dumping fuel into my engine on the carb? What do I check and how? What if the float level is inconsistent and rising as Im driving?
Reply With Quote Quick reply to this message
  #140 (permalink)  
Old 07-10-2013, 11:42 PM
vinniekq2's Avatar
Registered User
 
Join Date: Jun 2012
Location: BC,Canada
Age: 57
Posts: 8,802
Wiki Edits: 0

Thanks: 380
Thanked 879 Times in 839 Posts
D,rat,look back at all the posts that the members contributed.Look at the decisions you made,then you will see why most of us bailed on you.

re 1bad80 telling you to get a smaller carb,lol.
Reply With Quote Quick reply to this message
  #141 (permalink)  
Old 07-11-2013, 12:02 AM
Registered User
 
Last photo:
Join Date: Jul 2010
Location: New Jersey
Posts: 630
Wiki Edits: 0

Thanks: 8
Thanked 8 Times in 7 Posts
Quote:
Originally Posted by vinniekq2 View Post
D,rat,look back at all the posts that the members contributed.Look at the decisions you made,then you will see why most of us bailed on you.

re 1bad80 telling you to get a smaller carb,lol.
I did everything everone told me to do. still runs like ****. Thanks then. I guesl I have to look elsewhere for the advice I need.
Reply With Quote Quick reply to this message
  #142 (permalink)  
Old 07-11-2013, 12:11 AM
vinniekq2's Avatar
Registered User
 
Join Date: Jun 2012
Location: BC,Canada
Age: 57
Posts: 8,802
Wiki Edits: 0

Thanks: 380
Thanked 879 Times in 839 Posts
You might want to check how you were? I dont know.I think you went a little off,maybe Im wrong.
You might get lucky if you start another thread.I wish you good luck
Reply With Quote Quick reply to this message
  #143 (permalink)  
Old 07-11-2013, 11:56 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
Get a 750 carb or try some annular booster's in the carb you have
fix the advance on the distributor to work again for the street
__________________
Luv the smell of NITRO in the morning.
Reply With Quote Quick reply to this message
  #144 (permalink)  
Old 07-11-2013, 12:19 PM
Registered User
 
Last photo:
Join Date: Jul 2010
Location: New Jersey
Posts: 630
Wiki Edits: 0

Thanks: 8
Thanked 8 Times in 7 Posts
Quote:
Originally Posted by 1BAD80 View Post
fix the advance on the distributor to work again for the street
So your saying that my issue is the fact that I dont have a vacuum advance distributor?
Reply With Quote Quick reply to this message
  #145 (permalink)  
Old 07-11-2013, 02:56 PM
Registered User
 
Last photo:
Join Date: Jul 2010
Location: New Jersey
Posts: 630
Wiki Edits: 0

Thanks: 8
Thanked 8 Times in 7 Posts
Quote:
Originally Posted by F-BIRD'88 View Post
Get another carb. Get a holley 750 cfm DP. That carb is not a 850. it is a modded 650.
Do not buy a avenger carb. Get a 750 that is not fubared. (doesn't have to be new)

This engine with this cam in it will never be happy driving around at always less than 3000 rpm.
And there is no telling what was done to your race moded 650.

A 750 is a better choice anyway.

inactive idle screws//dribbling venturiis at idle... The throttles are too far open at idle. needs more air flow at idle yet less thottle angle at idle. ( T slot exposure at idle) so it needs a air bleed. I never drill throttle blades. It is easier to use the 3/8" PCV port as a "idle eze" extra air port to get the tiny little bit of extra air flow needed so the throttle are positioned at idle.
Use a pepcock valve to adjust the air flow rate of the bleed. Then install a equal fixed orrifice as required to ge tthat same idle speed and correct pri and sec throttle position at idle ( T slot exposure)
This will get the throttles sorted out but will not correct the idle circuit metering if it was modified.
Thats in the metering block(s).
The 650 based carbs never work that great on these motors any way.

Your race specific modded 650 based holley is never going to be that good on this motor on the street
in the way you want to drive it.
Start with a holley 750. Consider taming down the camshaft, if all you want to do with this car is putt putt around and cruise at low rpm.
A solid "street roller" cam with duration of 238 to 244@.050 on 110-112LSA +/-.600" lift will rock in this car and drive much nicer.
With a different 750cfm based carb. and it will still GLH.
I was toying with the idea of a cam swap but someone on the thread said it would screw up my compression ratio and cause detonation Is that true?

I want to change the cam, and intake manifold for sure, the way this car is now id WAAAAAAAY to aggressive for me. I also might swap out the Jerico, the darn thing sounds like a dump truck shifting anything less than WOT..

I do have a nice little 355 10.3:1 with a lunatti Cam .517/543 lift 239*/240* sitting in my garage. It was the last engine my dad ever built before he died of cancer, and I have been toying with the idea of throwing it in. I will have to lower the steering rack about an inch to fit a conventional Oil pan, or if it is not too much work I can convert my dads engine to a dry sump. That motor should make the car go decent. drop a nice 750 cfm on that too... Would that be all round better street motor?


But I am with you on this whole "modified race carb" that seems to be tinkered with beyond belief..

On a side note, I did lower the fuel pressure to about 5.5, and change the power valve to a 2.5, and it seems a little bit better but not much...I still leave the car smelling like raw fuel...LOL..My wife wont come near me..(perhaps thats not a bad thing..)
Reply With Quote Quick reply to this message
  #146 (permalink)  
Old 07-12-2013, 12:51 PM
Registered User
 
Last photo:
Join Date: Jul 2010
Location: New Jersey
Posts: 630
Wiki Edits: 0

Thanks: 8
Thanked 8 Times in 7 Posts
Quote:
Originally Posted by F-BIRD'88 View Post
Did you get that Racemaster full race (on/off) clutch sorted out?
Yup, I wound up with nice Centerforce single disc sprung hub with a standard 33lb flywheel, no lightweight crap.. Very easy to drive.

Which cam do you have in mind? and what should I check with my Valve train to see what needs to go with it? Also, what about a better matched intake?

This is the cam in there now.

The push rods say 7.800 and a part number of 0408 on them
The rocker arms are Crower and say 1.50/.150 RH on them
Attached Thumbnails
Click image for larger version

Name:	cam.JPG
Views:	54
Size:	1.21 MB
ID:	75595  

Last edited by Dajerseyrat; 07-12-2013 at 01:04 PM.
Reply With Quote Quick reply to this message
  #147 (permalink)  
Old 07-12-2013, 02:32 PM
Registered User
 
Last photo:
Join Date: Jul 2010
Location: New Jersey
Posts: 630
Wiki Edits: 0

Thanks: 8
Thanked 8 Times in 7 Posts
Quote:
Originally Posted by F-BIRD'88 View Post
I am working on a few things for you.
Bullet Racing Cams custom grind. 243-249 @.050" .427" lobes 112LSA .640" lift w 1.5 rockers.
It will need snotty valve springs and the rocker stud tie bar is just right.
This is a snotty street cam. But shorter duration and less valve overlap but really moves the valves . and a Ton of Mojo. it is no wimp cam but will drive MUCH BETTER.
I am getting details for you. The valve spring setup WILL matter.
Tell me about the intake manifold you got.
Tell me about what intake you might be interested in trying. That intake may not need to go...but
You can try new things. I hate that 650 carb.
What are the gear ratios on that Jerico trans?
The intake is some custom cast aluminum welded and epoxy job..The gears in the Jerico are
1-308
2-193
3-134
4-1 to 1

Rear end is a 308
Reply With Quote Quick reply to this message
  #148 (permalink)  
Old 07-12-2013, 06:30 PM
Registered User
 
Last photo:
Join Date: Jul 2010
Location: New Jersey
Posts: 630
Wiki Edits: 0

Thanks: 8
Thanked 8 Times in 7 Posts
Quote:
Originally Posted by F-BIRD'88 View Post
I am getting a picture now of why this car is such a pig to drive.
It seems to be geared for top end speed right?
Reply With Quote Quick reply to this message
  #149 (permalink)  
Old 07-12-2013, 07:52 PM
Registered User
 
Last photo:
Join Date: Jul 2010
Location: New Jersey
Posts: 630
Wiki Edits: 0

Thanks: 8
Thanked 8 Times in 7 Posts
Quote:
Originally Posted by F-BIRD'88 View Post
A set of 4.10's 4.30's would fix a lot.
Is this trans staying or....?
Not sure..If I wind up selling the engine and trans combo, I may go with a fuel injected LSX engine and 6 speed. But who knows..For now the set up is staying the way it is. I may swap a cam or the engine to my 355 over the winter, but that will require some fabrication and altering the position of the steering rack.
Reply With Quote Quick reply to this message
  #150 (permalink)  
Old 07-12-2013, 07:55 PM
Registered User
 
Last photo:
Join Date: Jul 2010
Location: New Jersey
Posts: 630
Wiki Edits: 0

Thanks: 8
Thanked 8 Times in 7 Posts
Quote:
Originally Posted by F-BIRD'88 View Post
Ya the3 gearing and gear spread are way off for a street machine with that cam.
Needs 4.56's. A 5 speed trans would be sweet. Rear ratio x first gear ratio should be in the 10.5:1 to 11.50:1 zone. The 3.08"s are killing it... bad ratio spread too. That 260-264 107LSA cam wants to rev.

What is/does the plenum of the intake look like,, with the carb off. There may be a problem there
Fuel distribution at low rpm. Some one off custom racey intakes make good WOT power but suck at low speeds.
Often the plenum is too smooth for its own good.
Measure the carb vernturii ...

The carb needs a tweek so it can idle with the throttles positioned correctly at idle.
When the throttles are too far open when its at idle, its gets all screwed up (fouls plugs)

Adding air bleed thru the PCV port on the car base corrects this. (easier to do than drilling throttles blades)
These 650 carbs were origionally made to employ a PCV valve. When the PCV valve is eliminated they get screwed up.
The cam makes it even worse. But its fix able.
You need to add a air bleed that does the same air leak as a PCV valve did. Then fine tune that as required.
This allows correct throttle T slot exposure at idle and correct idle circuit function.
Some people drill the primary throttles to get this extra bit of idle air leak/flow. I don't. I get it thru the 3/8" PCV port on the base. I suggest you do the same. This also trims/dials in the idle circuit AFR.
Hard to do over the internet.

When you say measure the venturi, do you have an illustration of exactly what points to measure from? Do you also need the baseplate openings? I removed some of the smaller jets from the blocks but they were not stamped. Also this carb appears to not have removable idle air bleeds like a Holley would..
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
Good street racing motor SBC 350 Hotrodding Basics 4 10-09-2011 04:18 PM
Good Gear For The Street wormy5 Transmission - Rearend 10 01-27-2009 12:54 AM
Is all of this be Good for the street ? chevy350_Camd Engine 9 01-14-2008 10:36 PM
a good street cam 75jeep Engine 5 12-21-2004 08:51 PM
is this a good street engine? Mike_82 Engine 5 03-19-2004 10:31 PM


All times are GMT -6. The time now is 11:22 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2015, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.