Are my float levels too high? - Carb flooding

[sccachallenger]

Congratulations!
You can disconnect the secondaries to make sure that the primary side isn't too lean.
The secondaries can be tuned by swapping to lighter or heavier springs, see if that helps.
No jets on the secondaries! there may be an aftermarket conversion metering block with replaceable jets, if Holley doesn't offer one.
Holley might still sell metering plates with different sized holes, for tuning purposes.
Experienced tuners with number drills will sometimes drill the passages larger.
Not sure I'd recommend  that for you, try everything else first!
Glad to hear progress is being made.

[rollo1504]

Hey,

Ok I can disconnect the secondaries but how do I recognize then if the primary side is too lean?  I mean if the sec are disconnected then I will always be too lean at WOT or not?

A shipment will arrive in the next 2 weeks with a huge amount of holley stuff

... new carb
... set of jets
... set of nozzles
... new sec vac diaphragm
... set of pump cams
... new fuel lines
... new fuel pump

... I am in contact with Mr. Firecore (Ron) to get a new distributor and spark plugs

and many other things...

Can't wait as I then really can try things out :-)

Regards

Roland

[sccachallenger]

if it pulls cleanly through the rpm range, you can rule them out as being the problem.
Then concentrate on the secondaries.
Please,please,please, only change one thing or new part at a time, you want to be sure what hurt or helped.

[rollo1504]

if it pulls cleanly through the rpm range, you can rule them out as being the problem.
Then concentrate on the secondaries.
Please,please,please, only change one thing or new part at a time, you want to be sure what hurt or helped.

Promised.... I will only change one thing at a time... :-)

I am the type of hobby mechanic who always wants to know whats going on so I will take the time for it....

And concerning the bunch of spare/tuning parts which will arrive soon...... I live in AUSTRIA and ordering just one part also takes so much time and costs to come over to my home in Europe and because of this I have prepared myself through getting much information and then ordered a bunch of parts.....

Roland

[rollo1504]

if it pulls cleanly through the rpm range, you can rule them out as being the problem.
Then concentrate on the secondaries.
Please,please,please, only change one thing or new part at a time, you want to be sure what hurt or helped.

Shall I test it like just push the pedal halfway down? Or must it be tested with WOT?

Just questioning because if it is needed to be tested at WOT with secondaries disconnected and it pulls cleanly through the rpm range why would the secondaries be needed then? :-)

Thanks

[XH29N0G]

Can you describe again the behavior that makes you think it is lean at WOT?

I get the impression from what you wrote that if you depress the throttle, there is a hesitation.  I just don't know if it is a hesitation that happens right after the throttle is depressed or if it accelerates for a few seconds and then hesitates (which is what I thought the first time I looked at your description). 

Or are you suggesting that it is lean for some other reason? 

I always have to remind myself that I can tinker with carburetors for ever, but if I keep looking at how they perform with an ever more critical eye, I will always find someplace where they are not perfect.  Sometimes the limit that is reached is inherent in the design.

[rollo1504]

Hey,

It does NOT hesitate if throttle is depressed.... Thats fine...

I hesitates after around 2 seconds at WOT.... I suppose it is because there are no jets in the secondaries?.....

So after reading through many other topics I think my problem is the "missing" jets in the secondaries, or the secondaries are opening too early or too late, or the power valve .....

Everything else is pretty good at the moment....

Regards

[XH29N0G]

Double check to make sure you do not have a metering plate.  Something like that shown at http://www.jegs.com/p/Holley/Holley-Secondary-Metering-Plates/761696/10002/-1

The 2 second delay (starting off fine, then after 2 seconds hesitating, and then picking back up again) is not something I have experience with.  Hopefully someone else will recognize this behavior.  It seems a little late for the pump shot to make a difference.  I wonder if it has something to do with the secondaries opening - like the initial push is with the primaries opening and the pump shot covering them, and then later the vacuum allows the secondaries to open a little too fast to cover the transition to the main circuit.  

I suppose bigger jets could cover up something like this but if it were me, I would want to hear from someone who knows the answer.  

My suggestion is to start a new thread that asks if people have seen this type of behavior and know the answer.  I think you have some good answers here, but it is possible that people have stopped scanning this thread - so a new one on that specific topic may bring a more specific answer.

[rollo1504]

The 2 second delay (starting off fine, then after 2 seconds hesitating, and then picking back up again) is not something I have experience with.  

Hey!

As far as I can remember I DID NOT SAY "... and then picking back up again".

Starting off fine, then after 2 seconds engine begins to stumble and continues stumbling as long as pedal is at WOT.

Sorry if I said something different....

Regards

Roland

[XH29N0G]

Most likely I misread or misunderstood.  Apologies.

The important thing is to make sure they know what the symptoms are.  I am responding because I am trying help, but my responses have reached the point of speculation But someone else here might have the answer that will provide a solution to what you are seeing.

So stumble and continue to stumble (it isn't knocking is it?).  If it truly is lean, then I would be careful because I believe that can lead to much bigger problems.

[rollo1504]

Don't worry...

I really appreciate your help and suggestions/thoughts :-)

Hahahaha that would be the next question if it is stumbling or knocking.... Are there somewhere youtube videos or something similar which explains me what really knocking is?

I have found several youtube videos but I cannot really determine HOW knocking sounds.....

Nevermind.... Right now I am in contact with Ron to get a new distributor, firecore coils and wires. Further new NGK sparks will be installed and hopefully Ron will guide me to set the correct timing curve for my application....

Thanks though dude

[sccachallenger]

I would  suggest wide open to at least 5000rpms to test.
It should not accelerate as rapidly on just the primaries, but shouldn't miss or stumble.
With the secondaries working, you'll get there faster and your problem may return.
You should also check your fuel pressure, a big block at WOT will probably need more fuel than many stock pumps can provide.
Many stock fuel systems are fine for normal driving but can't supply enough volume at WOT for a full 1/4 mile.
Glad you're checking one thing at a time!

[69wannabe]

Really can't go wrong with the firecore ignition set up. I have never been a fan of the holley 600 carb's. I have had a couple of good one's and several bad one's but you may want to check fuel pressure, sounds like you may have a weak fuel pump or maybe the pump pushrod is worn. Are you running a 383 engine?? I'm assuming you are with a 600 holley. I ran a 670 holley street avenger on my 383 and with some minor jetting it ran pretty good!! Never liked the 600's when they went to the sealed fuel bowl so you had to pull the bowl to set the float level, most of the center hung float bowls had the external adjusting needle and seat's. Reading the spark plugs once you get it up and running good will tell you if you need more or less fuel. Getting one tuned in is a process but it's not rocket science......

[rollo1504]

Thank you all for your inputs....

I will check all that step by step...

The stock fuel pump was replaced by a new stock fuel pump BUT the pushrod was NOT checked during replacing the pump.

I really wanna renew the whole fuel line "system"

Actually a new tank is already installed. Have 3/8 fuel sending unit already at home but not installed yet. Fuel lines will also be upgraded to 3/8 as well as the edelrock fuel pump recommended by Ron which provides constant 6 PSI and where no fuel pressure regulator is not needed. Also the fuel line pump to carb will be upgraded to 3/8 and a fuel pressure gauge near carb will be installed.

Firecore parts like distributor, coil and spark plugs are provided by Ron and already on the way to Austria.

Meanwhile another package with lots of "tuning" parts from Holley will arrive to be able to test with different jets, nozzles etc.
Finally a holley street avenger 770 cfm 4bbl vac sec will be installed.

As soon as all parts have arrived I will continue as follows:

- Install new fuel sending unit 3/8"
- Install new fuel lines 3/8" from tank to pump
- Install new mechanical fuel pump with "internal 6 psi regulator" AND check pushrod if worn out and replace if necessary <<< --- Is there a special trick to get the pushrod out from the engine???
- Install new fuel lines 3/8" from pump to carb
- Install fuel pressure gauge near carb
-->> Testing
- Install new distributor and coil from Ron
- Set timing
-->> Testing
- Begin step by step testing by changing spring, jets, nozzles

Pretty sure I will find it out. Will just take some time... :-)

Maybe with some luck I will find out HOW knocking sounds to determine if engine knocks or not.... :-)

Thanks guys

Roland

[rollo1504]

Really can't go wrong with the firecore ignition set up. I have never been a fan of the holley 600 carb's. I have had a couple of good one's and several bad one's but you may want to check fuel pressure, sounds like you may have a weak fuel pump or maybe the pump pushrod is worn. Are you running a 383 engine?? I'm assuming you are with a 600 holley. I ran a 670 holley street avenger on my 383 and with some minor jetting it ran pretty good!! Never liked the 600's when they went to the sealed fuel bowl so you had to pull the bowl to set the float level, most of the center hung float bowls had the external adjusting needle and seat's. Reading the spark plugs once you get it up and running good will tell you if you need more or less fuel. Getting one tuned in is a process but it's not rocket science......

I am running a stock 400 big block engine...

Regards

[XH29N0G]

I changed the fuel pump and fuel pump rod on my 1970 383 and it was not difficult. I had to remove the fuel pump and drop out a plug from the block that has a hex fitting.  I copied this image from the web that shows it.

Before doing that, I would check the pressure with a gauge.  I had to buy a gauge and plumb it in to the line with a T fitting.  I only had to test at idle to see I had a problem.  Some people have taped it with a tube to the windshield (don't bring it into the cabin) to see while running to see it under load.  

If you have fuel pressure, I would see what happens with your other tests and changes.  If you like swapping things, go ahead, but if those aren't the parts that are broke, then maybe you don't want to fix them.  

For the 770, I would post a question on here and also ask to carburetor company what would be a good starting jet setting to use.  I had a 670 on my 383 and it came very lean and backfired through the carburetor.  I do not know if that is typical, but I wish I had asked.

As far as being able to identify knocking, it is a little difficult and I did not find listening to youtube videos super helpful.  they were helpful a little.  What you will notice is a change in the tone of the engine and what sounds like metallic rattling.  You do not want it.  I missed what the compression was on your engine.  Compression can make a difference.  My guess is that once you get the firecore set up right and with the help of people like Ron and others here you will be in good shape ignition-wise and probably not have too many issues with knock.  I think they can also advise on a starting set up for the carburetor.



     

[rollo1504]

I changed the fuel pump and fuel pump rod on my 1970 383 and it was not difficult. I had to remove the fuel pump and drop out a plug from the block that has a hex fitting.  I copied this image from the web that shows it.

Before doing that, I would check the pressure with a gauge.  I had to buy a gauge and plumb it in to the line with a T fitting.  I only had to test at idle to see I had a problem.  Some people have taped it with a tube to the windshield (don't bring it into the cabin) to see while running to see it under load.  

If you have fuel pressure, I would see what happens with your other tests and changes.  If you like swapping things, go ahead, but if those aren't the parts that are broke, then maybe you don't want to fix them.  

For the 770, I would post a question on here and also ask to carburetor company what would be a good starting jet setting to use.  I had a 670 on my 383 and it came very lean and backfired through the carburetor.  I do not know if that is typical, but I wish I had asked.

As far as being able to identify knocking, it is a little difficult and I did not find listening to youtube videos super helpful.  they were helpful a little.  What you will notice is a change in the tone of the engine and what sounds like metallic rattling.  You do not want it.  I missed what the compression was on your engine.  Compression can make a difference.  My guess is that once you get the firecore set up right and with the help of people like Ron and others here you will be in good shape ignition-wise and probably not have too many issues with knock.  I think they can also advise on a starting set up for the carburetor.



     

Not sure if the 400 engine has this plug with a hex fitting but will check that out...
I already heard about taping a gauge to the windshield idea. I have the gauge and the hose, just the T-fitting is missing but will get one of those and check it out if fuel pressure drops below 6 psi if under load...

Thanks for the hint concerning questioning carb company concerning good starting jet setting....

Mmmh... Concerning "knocking".... Does the engine knocking come up when timing is set too advanced and ignition is too early and works "against" pistons as they still haven't reached TDC? During setting the timing the very first time I recognized some detonations... Is detonation the same as knocking? If YES, then I know how "knocking" sounds...

[XH29N0G]

Yes detonation and knocking (a little like a diesel) can be interchanged (or at least I do and also preignition and pinging).  There is another thing (run on when the engine is turned off) that can also happen but that is different.  Yes it happens when the timing is too far advanced, too hot spark plugs, or when the fuel is too lean.  My understanding is that it has to do with heat in the combustion chamber causing the fuel to ignite too early.  I think we mean the same thing.  If I have messed up the terminology, someone will correct it.

[rollo1504]

I know what too early ignition means but didn't yet how knocking sounds....

Nevermind.... if the new dist is here I will adjust the mechanical, advanced and total timing correctly for my application with support by Ron...

As many other guys here in this forum reported Ron as great guy with great knowledge I am pretty sure concerning setting the correct timing curve for my application he will also provide some help to me and I will set it as it should...

Will be back as soon as I have news for you...

Thanks for all the support

Roland

[69wannabe]

I changed the fuel pump and fuel pump rod on my 1970 383 and it was not difficult. I had to remove the fuel pump and drop out a plug from the block that has a hex fitting.  I copied this image from the web that shows it.

Before doing that, I would check the pressure with a gauge.  I had to buy a gauge and plumb it in to the line with a T fitting.  I only had to test at idle to see I had a problem.  Some people have taped it with a tube to the windshield (don't bring it into the cabin) to see while running to see it under load.  

If you have fuel pressure, I would see what happens with your other tests and changes.  If you like swapping things, go ahead, but if those aren't the parts that are broke, then maybe you don't want to fix them.  

For the 770, I would post a question on here and also ask to carburetor company what would be a good starting jet setting to use.  I had a 670 on my 383 and it came very lean and backfired through the carburetor.  I do not know if that is typical, but I wish I had asked.

As far as being able to identify knocking, it is a little difficult and I did not find listening to youtube videos super helpful.  they were helpful a little.  What you will notice is a change in the tone of the engine and what sounds like metallic rattling.  You do not want it.  I missed what the compression was on your engine.  Compression can make a difference.  My guess is that once you get the firecore set up right and with the help of people like Ron and others here you will be in good shape ignition-wise and probably not have too many issues with knock.  I think they can also advise on a starting set up for the carburetor.



     

Yep, the 670 street avenger was lean on my 383 too, I think I jetted it up 4 jet sizes in the front and 2 jet sizes in the back and stayed with the 6.5 power valve. After jetting it up it ran out pretty good, a 770 maybe rich on a stock 400 but once you got the initial timing pulled up around 16 or 18 it should run it good from there. I have seen alot of holley 750's on 383's that ran out good so that 770 maybe a good choice for it. I didn't know how to set the distributor up on my 383 way back then so my initial was only about 12 or 14 BTDC. Thanks to the guy's on here I know how to set my distributor up now and limit my total advance so I can run some good initial timing. You are on the right track with the firecore ignition and the holley carb and fuel pump pre set at 6psi. That is pretty much the set up I have and so far it works good.....

[rollo1504]

Thanks for your reply!

And which diameter does your fuel line have? 5/16 or 3/8?

Roland

[69wannabe]

Thanks for your reply!

And which diameter does your fuel line have? 5/16 or 3/8?

Roland

I am running 3/8 from the tank to the pump and 3/8 from the pump to the carb. Before I went with the stroker kit in my 440 I ran the 5/16 line from the tank to the pump and the 3/8 from the pump to the carb with no problems......

[rollo1504]

Hey guys!

Disconnected the secondaries and engine beautifully pulls up the rpm's without any stumbling...

So I think the secondaries are opening too early or too late..... Still have not received my spring set to test yet....

But I really suppose that engine stumbles as there are no jets in the secondaries........

Shipment with set of jets, springs, a metering block for the secondaries will arrive in 2 weeks... Then I will have the possibility to test all sort of things out...
But after the test from yesterday I can say that the primary side is OK I think because engine does not hesitate stand off and pulls nicely up the rpms  near WOT but then stumbles....

So total timing and a 2nd metering block will improve the situation... We will see...

Will keep you up to date guys...

Thanks for all your help

Roland

[rollo1504]

Hey Folks!

It's been a long time since my last post but had a lot of work to do around my house but now the oddysee can continue....

Whats the actual status:

- Received Firecore Parts from Ron and installed them (Coil, Spark Plug Wires, NGK Sparks, Distributor)
> Engine is now idling very smooth

- Installed the vac sec quick change spring kit and installed a stronger spring
> Now engine pulls through the RPM ranges without stumbling and actually it makes a lot of fun driving her

- What problems still persist:
a) If engine is shut off after driving around and I let the car in park after some minutes I still can see that fuel is dropping out from the secondary throttle shaft on both sides of the shaft - One drop every 3 minutes which stopps after 15 minutes..... Still do not know whats going on.... Any suggestions ?

b) If I play with the pedal and push it from off idle to WOT it hesitates for a very very small time -> Jets to small or accerlator pump? Not sure. If I drive off with 50-70% pedal down it does NOT hesitate...

Thanks for any comments....

Regards from Austria

[XH29N0G]

Glad to hear progress has been made.

- What problems still persist:
a) If engine is shut off after driving around and I let the car in park after some minutes I still can see that fuel is drop :rotz:ping out from the secondary throttle shaft on both sides of the shaft - One drop every 3 minutes which stopps after 15 minutes..... Still do not know whats going on.... Any suggestions ?

b) If I play with the pedal and push it from off idle to WOT it hesitates for a very very small time -> Jets to small or accerlator pump? Not sure. If I drive off with 50-70% pedal down it does NOT hesitate...

Thanks for any comments....

Regards from Austria

Concerning point (a) see if others have any ideas.  My understanding is that the throttle shafts are not directly connected to any particular gas filled reservoir in the metering blocks that could leak to them.  Is there gas leaking onto the blades of the throttle shaft, or from the gasket between metering blocks or fuel bowl and the main body?

Concerning point (b) If it is the Jets, then it will be lean at WOT and high RPM.  Have you checked the plugs to see if they give symptoms of being lean?  Usually, once the jets are set, hesitation with the pedal push to WOT is the accelerator pump system (make sure it squirts as soon as it is touched)  If that is the case, change the accelerator pump cams (what color is on there now).  I would think something like an orange cam is a good place to start.  You can also work on the squirters (nozzles) on the accelerator pump, but I would start with the cam.  What Nozzle is on the carburetor?