Go Back   American Sedan Forum > Main American Sedan Categories > American Sedan General

Reply
 
Thread Tools Display Modes
  #1  
Old 03-15-2007, 06:38 PM
Scott Davie
Guest
 
Posts: n/a
Default Race ready Carb

I'm looking for info on race ready carb to buy or should I send mine to a carb guy to have rebuilt or do it myself? Does anyone have someone they use that is good?
Reply With Quote
  #2  
Old 03-15-2007, 06:47 PM
t4wallace t4wallace is offline
Senior Member
 
Join Date: Nov 2004
Location: White Lake, Michigan
Posts: 1,430
Default

Quote:
Originally Posted by Scott Davie
I'm looking for info on race ready carb to buy or should I send mine to a carb guy to have rebuilt or do it myself? Does anyone have someone they use that is good?
Scott -- there were some race-ready carbs for sale here on the forum some time ago. David Melley had one and so did Raybob. You might PM them and see if they're still available, although I think Raybob does not play here anymore.
__________________
Tom Wallace
Great Lakes, Detroit Region
Hoosier Tire
Reply With Quote
  #3  
Old 03-15-2007, 10:46 PM
smithpr smithpr is offline
Senior Member
 
Join Date: Dec 2004
Posts: 572
Default

Scott:

Based on the dyno testing of a bunch of different carbs there is no and I mean no power to be gained from a modified card. The Fords might be a little different because of their higher level of performance but I would go to summitt racing an order a new 600 CFM card and see what that does.

Philip
Reply With Quote
  #4  
Old 03-15-2007, 11:53 PM
socalta
Guest
 
Posts: n/a
Default

Does that include changes to the floats, jets or are you referring to more advanced ...$1,000 carb type work?

Last edited by socalta; 03-16-2007 at 12:23 AM.
Reply With Quote
  #5  
Old 03-16-2007, 07:46 AM
jimwheeler jimwheeler is offline
Senior Member
 
Join Date: Oct 2004
Location: Kansas City
Posts: 5,275
Default

I would, at a minimum, change the floats to road race floats. Other than that, I agree with Philip.
wheel
Reply With Quote
  #6  
Old 03-16-2007, 09:22 AM
smithpr smithpr is offline
Senior Member
 
Join Date: Dec 2004
Posts: 572
Default

I am talking about the $1000 plus carbs. Just to be clear. You will need to tune any carb to the car and the track on any given day. We change jets at least once everyweekend and sometimes once or twice per day.

I have a lamda sensor so that it is very easy to know what to do. You would be surprised by how much the engine tune changes during the day.

In addition, accelerator pump cams, and float levels need to be adjusted.

Philip
Reply With Quote
  #7  
Old 03-16-2007, 12:28 PM
kbsmith1 kbsmith1 is offline
Senior Member
 
Join Date: Jan 2006
Location: Hillsboro, OR
Posts: 772
Default to race carb, or not to race carb

Like Philip I use a stock carb, and even stock floats. I bought
it from summit new in box, and haven't done anything to it
except remove choke mechanism (not air-horn though). I jet
it on a chassis dyno at the beginning of the season, so that under
full high end load it is running slightly rich. You have to set float
levels of course.

I don't change jets often at all, only down a size or so on really
hot days. I have dual EGTs, one in #1, one in #8 header tubes,
and try to run so that temp 2" or so from cylinder head is 1350-1400 at high end in top gear, if I see
over 1400 then I jet richer, and if lower than 1300, then I jet leaner.

Getting the jetting right affects HP most based on the dyno work
that I've done.
__________________
Kevin Smith
1993 Firebird AS #03 Oregon Region SCCA & ICSCC
Reply With Quote
  #8  
Old 03-16-2007, 03:33 PM
Walther
Guest
 
Posts: n/a
Default

I would tend to agree with ALL the responses. Based on the limitations of the engine, regardless of the make, the lack of volumetric efficiency simply does not warrant the expenditure of a "race-ready" carb. You will not benefir from it. Even if you do note a dyno increase, it will be minimal and you will be disappointed after the amount you spend. Normal carb adjustments during the weekend on a stock type 4776 is all you should need. Center squirter sizes should remain constant on the accelerator circuit, with tuning done on the accelerator cam. Jetting changes should not vary more than 2-3% on any one given weekend. Depending on the track, you may also want to consider removing and plugging the power-valve since the lack of vacuum signature on most AS motors may cause the valve to open and close erratically. If you do..jet it up 8%. So purchase reusable gaskets, a jet board, and a Holley "trick-kit" and you should be fine.
Reply With Quote
  #9  
Old 03-16-2007, 03:42 PM
smithpr smithpr is offline
Senior Member
 
Join Date: Dec 2004
Posts: 572
Default

I agree with all comments.

It looks like the Carb guys are not going to like this discussion. No more $1,000 carbs.

Philip
Reply With Quote
  #10  
Old 03-16-2007, 06:42 PM
kbsmith1 kbsmith1 is offline
Senior Member
 
Join Date: Jan 2006
Location: Hillsboro, OR
Posts: 772
Default accel pump shot

Has anybody modified their own accelerator pump cam? I
bought Holley's pump cam assortment, and none of them work
better than the stock pump cam. I spent an hour playing with
these during chassis dyno time, and all seem to provide too
much initial pump shot, causing a very rich condition, and slight
initial bog at anything below 3000 RPM. Not terribly important,
but it irritated me, so I wanted to try to tune it out.
__________________
Kevin Smith
1993 Firebird AS #03 Oregon Region SCCA & ICSCC
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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

Forum Jump


All times are GMT -4. The time now is 01:14 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2022, vBulletin Solutions, Inc.