13B holley 600 cfm 1850
08-27-07, 09:53 PM
#26
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Your car is running out of fuel.
Couple of issues that I see.
1. Fuel pressure should be 7PSI not 6PSI at the carb. Set the pressure higher and then reset the float level so that the fuel is even with the bottom of the sight hole.
2. Take the screw out of the secondary linkage and let the vacuum diapham do what it is supposed to do. Your car is falling on it's face at high RPM in 3rd and 4th because the secondaries are open but there is no enrichment - no extra fuel. You have a lean condition. You don't notice it as much in 1st and 2nd because of your gearing but the problem is there in those gears too.
Here is the deal, you should never "feel" the secondaries open on a Holley 4bbl with vacuum secondaries. When "you" feel a surge in speed at high RPM what you are feeling is the fuel metering signal "catch up" with the increase in air volume, not the fact that the secondary butterflys just opened. In reality they have been open a long time and were causing a lean condition that was slowing you down.
A properly tuned vacuum secondary carb will open the secondaries when the engine demands it. Opening is controlled by the secondary spring. You can install a softer spring for an earlier opening point or a stiffer spring for a later opening point. My guess is you will need a later opening point. The spring that came in the carb would be a good starting point. Holley sells a kit with different color codes springs - get one. By the way, don't shorten these springs because it makes them stiffer.
Another useful addition is 3150 kit that includes a secondary metering and a longer transfer tube. This will allow you to change jetting in the secondary side just like the primary side. I would keep the side hung floats that came with your carb beacuse they orient the pivot of the foats so they swing fore and aft. This will help you avoid fuel starvation in corners.
I have no idea if you primary jetting is correct and you didn't specify the opening point of your power vlave. Others may be able to help you with that.
Get a Holley tuning book, they are invaluable.
Couple of issues that I see.
1. Fuel pressure should be 7PSI not 6PSI at the carb. Set the pressure higher and then reset the float level so that the fuel is even with the bottom of the sight hole.
2. Take the screw out of the secondary linkage and let the vacuum diapham do what it is supposed to do. Your car is falling on it's face at high RPM in 3rd and 4th because the secondaries are open but there is no enrichment - no extra fuel. You have a lean condition. You don't notice it as much in 1st and 2nd because of your gearing but the problem is there in those gears too.
Here is the deal, you should never "feel" the secondaries open on a Holley 4bbl with vacuum secondaries. When "you" feel a surge in speed at high RPM what you are feeling is the fuel metering signal "catch up" with the increase in air volume, not the fact that the secondary butterflys just opened. In reality they have been open a long time and were causing a lean condition that was slowing you down.
A properly tuned vacuum secondary carb will open the secondaries when the engine demands it. Opening is controlled by the secondary spring. You can install a softer spring for an earlier opening point or a stiffer spring for a later opening point. My guess is you will need a later opening point. The spring that came in the carb would be a good starting point. Holley sells a kit with different color codes springs - get one. By the way, don't shorten these springs because it makes them stiffer.
Another useful addition is 3150 kit that includes a secondary metering and a longer transfer tube. This will allow you to change jetting in the secondary side just like the primary side. I would keep the side hung floats that came with your carb beacuse they orient the pivot of the foats so they swing fore and aft. This will help you avoid fuel starvation in corners.
I have no idea if you primary jetting is correct and you didn't specify the opening point of your power vlave. Others may be able to help you with that.
Get a Holley tuning book, they are invaluable.
08-27-07, 11:18 PM
#29
Thank you for all this very useful information, I now feel I'm getting some where, I can't wait till tomorrow to take the dam screw off my secondaries and open up the car and see what results I get,. I don't now the specs on my power valve but I'm thinking to replaced with a plug, because I use to get a lot of back fire before i install the RB muffler, and i think it may be blown after reading some of the threads on this forum. By the way I have the spring set from holley, I just need to located. Thank you for taking the time to out line all this good information.
What a power valve does is provide enrichment on demand based on vacuum. As you accelerate engine vacuum falls. When it reaches a certain point the power valve will open. Since it will only open at WOT a power valve provides a little more fuel economy that running without one.
Power valves come in various values - the higher the number the sooner they open. So a 5.0 power valve opens before a 4.0 etc. A stock Holley 1850 probably has a 6.5 power valve. This is a common number for a V8 engine.
If you decide to remove the power valve anyway you will need to increase your primary jet size 2-4 sizes to accomodate for the loss of high speed enrichment.
To determine the value of the power valve that you need hook up a vacuum gauge and drive your car. Determine the vacuum that your engine has at a steady cruise in the 60-70mph range in 5th gear. Purchase a power valve that is one inch of mercury lower than your cruising vacuum. This way it will only open when you need it.
Good luck.....I am thinking about doing a holley or edelbrock on a 13B myself so keep us posted.
08-28-07, 06:54 PM
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Updates, I remove the screw from the secondaries and change the spring on the vacuum to yellow, take the car for a test drive and the car bugs out like is not getting enough gas at 6k rpm on first gear. this engine just demands gas. I went threw this when I first install the holley and started with 55 jets and work my way up to 63 jets. now what I'm thinking is this engine may have been ported, because I got it out of a car that I purchase at the auction total and the engine was rebuild already If this is the case I may need to go up to 66 wish I use before and the car did not flooded or may be even higher. If this car is not flooding with 66 do you guys think the engine has been ported? I been told thaat a stock engine needs nothing higher than 55 jets on the primaries. Thank you
08-28-07, 09:22 PM
#33
On a 600 cfm Holley, they came stock with 66 primarys, and a secondary metering plate equivalent to 67 jets. These are the jets I am running in a stock port 12A. You cant run the same jet sizes in a 600 cfm that Racing Beat puts in there 465 cfm Holley, which is 52 primarys and a secondary metering plate equivalant to 55 jets.
08-28-07, 10:14 PM
#35
66 jets in the primary sid and 68's in the secondary side is what I ran on a 600 Holley on a 302. That should be a good ball park for your car. Keep in mind that jetting has to match the volume of air that the carburetor can flow. For example the same 302 with a 750 vac secondary carb used 68's on the primary side and 70's on the secondary side. I also ran a Holley 500 2bbl on the same car and it needed 72 jets to work - a Holley 500 has two monster venturies!
Keep tuning with a focus on idle, throttle response and then high RPM performance. Keep an eye on the basics like timing - as others suggested - and the coloration on the plugs.
Keep tuning with a focus on idle, throttle response and then high RPM performance. Keep an eye on the basics like timing - as others suggested - and the coloration on the plugs.
08-29-07, 11:11 AM
#36
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Timing #'s
RB recomends
20L
13T
With your set up @ Idle W/Vacuum Advance Disconnected.
You can also do the Paul Yaw way of the 6 degree split @ 4000RPM.
I prefer to run mine this way and never have any Ping or other Problems.
L@8BTC and12ATC is a 77-83 12A Street Porting w/ Holley or Weber Application (Not for your Set-Up). Sorry Above Post.
Might not fix your fuel issue but maybe the timing is where the problem lies. (Just be careful not to advace to Far).
Let your ears do the talking!!!
I chased this same Gremlin for awhile and found out I was way off!
Just a Thought for Ya. Then you could type in Timing in the search function on this site and find what works and not in your application.
sgieldon
steve
20L
13T
With your set up @ Idle W/Vacuum Advance Disconnected.
You can also do the Paul Yaw way of the 6 degree split @ 4000RPM.
I prefer to run mine this way and never have any Ping or other Problems.
L@8BTC and12ATC is a 77-83 12A Street Porting w/ Holley or Weber Application (Not for your Set-Up). Sorry Above Post.
Might not fix your fuel issue but maybe the timing is where the problem lies. (Just be careful not to advace to Far).
Let your ears do the talking!!!
I chased this same Gremlin for awhile and found out I was way off!
Just a Thought for Ya. Then you could type in Timing in the search function on this site and find what works and not in your application.
sgieldon
steve
Last edited by sgieldon; 08-29-07 at 11:19 AM. Reason: new info
09-01-07, 03:33 PM
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Hello, I got the problem iron out, it turn out that the 63 jets were actually to big and the timing wold have to be set to L30* for the engine to burn the gas but still get hesitation (flooding) at high rpm's, so I did was I lower the timing to L10* and T 12* with 58 jets on the primary and what a difference that made all the way around, I'm getting smother acceleration and no hesitation at high rpm's The bug is totally gone. Thank you all for all the help.
