Hot Rod Forum : Hotrodders Bulletin Board

Hot Rod Forum : Hotrodders Bulletin Board (http://www.hotrodders.com/forum/)
-   Engine (http://www.hotrodders.com/forum/engine/)
-   -   Barry Grant Carb Help (http://www.hotrodders.com/forum/barry-grant-carb-help-224227.html)

Daubers 09-21-2012 09:46 AM

Barry Grant Carb Help
 
2 Attachment(s)
Hey guys, I recently acquired a 67 Nova that was set up for the track, and I am in the process of making it more streetable. It has a Barry Grant 800 Carb on it. Right now the jets in it have been bumped up to I believe 78. I have been searching to find specs on my carb to find what the stock jetting was so I can get them in and have a starting point for tuning, i cannot find anything on the carb at all and i don't have a model #. Below is a pic to help identify. Thanks!

http://i1114.photobucket.com/albums/...-46-24_581.jpg

vinniekq2 09-21-2012 09:58 AM

Take the bowls off and look at what you have for jets and power valves.If you have a problem,what is it?why are you changing anything?Do you or someone you know have a jet board(spare jets)

Daubers 09-21-2012 10:31 AM

2 Attachment(s)
Quote:

Originally Posted by vinniekq2 (Post 1592567)
Take the bowls off and look at what you have for jets and power valves.If you have a problem,what is it?why are you changing anything?Do you or someone you know have a jet board(spare jets)

I will confirm tonight, I was told they were 78's. Right now it is simply getting too much fuel dumped in, and get's prominent as I adjust the timing. Would like to get it down to a nice idle, not needing 1600 rpms to keep it from stalling out.

Also i do not have access to a jet board.

vinniekq2 09-21-2012 10:36 AM

make sure your static timing is 16 degrees or so at idle.what coil are you using? I dont see a multi spark unit in your photo?what cam are you using?
when changing jets,go up or down 2 sizes at a time until fine tuning.

cdminter59 09-21-2012 10:44 AM

Barry Grant Carb help
 
Here is the website for Demon carburetors. Click on Tech Support. Demon Fuel Systems - Tech Support

Daubers 09-22-2012 04:19 PM

2 Attachment(s)
Quote:

Originally Posted by cdminter59 (Post 1592582)
Here is the website for Demon carburetors. Click on Tech Support. Demon Fuel Systems - Tech Support

Thanks for the link, but it is not a Demon carb, its older than that. On their site you have to chose what model is on the carb and mine does not have one, it only has hand engraved numbers. Anyone know of any reference to decipher them to know what I have?

It says:
BG
477983
11586

Thanks!

painted jester 09-22-2012 04:53 PM

Barry built custom Holleys for racing !!! What you have is a custom built Holley by Barry Grant Built around the engine for max performance.

Changing jets wont match the engine build or Idle normal to that cam and compression some builds Idle at 2500 rpm and some at 600rpm perticular to the build. The jetting and power valve are set for the characteristics of that particular eng. unless some one bought it and put it on that eng that it wasn't set up for!!!

His Holleys were great performing carbs he knew his stuff! your lucky to have one!!!

Jester

To make it more streetable you may want to start with a cam change and then tune the carb in!

vinniekq2 09-22-2012 05:03 PM

4779 is a holley 750.It does look like a holley carb.BG carbs use a.n. fittings

painted jester 09-22-2012 05:06 PM

Whats the blue print on the engine? Surly you have the print? The 4779 is the holley # hand etched its a 750 modefied! as vinny posted

Jester

painted jester 09-22-2012 05:19 PM

The holley choke horn has been milled off thus you have an increase in CFM as you were told by the last owner stating it was 800 it actualy may be more!!!The Holley list # was on the horn Thats why he etched it on the carb! Barrys a member on this forum or was there have been many changes in the last few months you might try to private message him or maybe he'll see your thread and chime in.

Jester

painted jester 09-22-2012 06:43 PM

I called a few other carb builders in detroit and received some good info on the #s and the jets. original jets were #74 prim & #84 sec.

The scribed # of #4779-S3 There never was a #4779 8-3!

There were 3 stages #4779S1 ,#4779S2 ,and #4779S3

The S1 was a reworked 750 with the chock horn intact.flowed about 800 for sportsmen class just had a little work.

The S2 was a reworked 750 with the chock horn milled off and flowed about 850

The S3 Which you have is a horn off radius ed and flowed with jet tubes a completely reworked drag carb that flows well over 950 CFM
The other #'s are inconsequential I hope this helps you know what you have:thumbup:

Jester

vinniekq2 09-22-2012 06:50 PM

PJ are the venturis ported?

painted jester 09-22-2012 07:04 PM

Quote:

Originally Posted by vinniekq2 (Post 1592949)
PJ are the venturis ported?

Vinnie he may not know what ported venturie's look like? Unless you know his ability ?

Jester

painted jester 09-22-2012 08:45 PM

There was 1 more B.G. Holley its number was 4779S with no #'s after the S, That one is a check legal sportsman class carb.

Jester

I just found it here with more info you may like to see on the B.G. Holleys 4779S's


http://www.chevelles.com/forums/showthread.php?t=212629

ap72 09-22-2012 08:50 PM

for tuning on the street it is VERY IMPORTANT to tune with the pvcr's for WOT and jets ONLY FOR CRUISE. So many people think the jets are for WOT and they ARE NOT.


All times are GMT -6. The time now is 07:13 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.