Holly carb help

[Josh A]

As for the dizzy, its what it had when i bought the car so it was already welded locked out so I just threw it back in as i dont have another. So I'll get that on my list to get another one.
So open the primaries some more and close down the secondaries. I was not even into the transfer slot on the secondary side so I figured leaving the fronts square and using the rear for more air was doable for my scenario.
I'll pull the front bowl off and inspect the pv and seal again i suppose.

 

[MoparDave]

As for the dizzy, its what it had when i bought the car so it was already welded locked out so I just threw it back in as i dont have another. So I'll get that on my list to get another one.
So open the primaries some more and close down the secondaries. I was not even into the transfer slot on the secondary side so I figured leaving the fronts square and using the rear for more air was doable for my scenario.
I'll pull the front bowl off and inspect the pv and seal again i suppose.

If pv was blown it would be rich at idle. Drop the pv size so it opens later, and drop to 35 squirter on front to see if less pump shot will help.

 

[92b]

I still fail to see how the power valve can affect idle. It's on the power circuit. But I won't argue it here. Don't wanna sidetrack. Yall carry on.

A loose power valve or leaky gasket can short circuit the fuel side to the manifold vacuum side. Not saying that is the op's problem.

 

[Rat Bastid]

A loose power valve or leaky gasket can short circuit the fuel side to the manifold vacuum side.

True. But that’s pretty rare. Just like the infamous “blown” power valve.

 

[MOPAROFFICIAL]

I still fail to see how the power valve can affect idle. It's on the power circuit. But I won't argue it here. Don't wanna sidetrack. Yall carry on.

He says its when he tips the throttle.
So is he in the idle circuit anymore.,no
It's a 10.5 pv, too high but wtevr
If its blown or dried up....it a will leak and psi will push the fuel through the mains-rich...if its dried up and not working...he may have fiddled the pump shot to compensate a lean spot and any amount of throttle movement will piss gas out the shooter and show as rich. on the a/f meter the pump shot shows as a rich blip...its pissing and no mixed as well as the booster does under the psi drop.
He does say the thing cleans up under wot or did he say it's still piggy? I'll have a look...but if it's just the low speed...pumps are pissin pretty good for a non working Pv is my guess. Let's wait n see

 

[92b]

True. But that’s pretty rare. Just like the infamous “blown” power valve.

True it's rare and in my opinion power valves get the blamed for more than their fair share of problems. Not just a theoretical situation though. There is a register for the gasket on the power valve to keep it centered. I've seen the gasket hanging down where it shouldn't be at times. I've seen torn gaskets and power valves that look like somebody just forgot to tighten. Sometimes they leak. Easy to check and sounds like the Op checked it already.

 

[Josh A]

This is definitely a light throttle application stuff I'm having my issues with being rich be it lower speed or high speed constant cruising. If I go straight from idle to full throttle carb seems on point, afr is good and it just wants to blaze the tires thru 1st 2nd.
Maybe after i checked the pv something happened to it or maybe the gasket was bad out of the box perhaps

 

[RustyRatRod]

He says its when he tips the throttle.
So is he in the idle circuit anymore.,no
It's a 10.5 pv, too high but wtevr
If its blown or dried up....it a will leak and psi will push the fuel through the mains-rich...if its dried up and not working...he may have fiddled the pump shot to compensate a lean spot and any amount of throttle movement will piss gas out the shooter and show as rich. on the a/f meter the pump shot shows as a rich blip...its pissing and no mixed as well as the booster does under the psi drop.
He does say the thing cleans up under wot or did he say it's still piggy? I'll have a look...but if it's just the low speed...pumps are pissin pretty good for a non working Pv is my guess. Let's wait n see

Gotchya. Ok. I unnerstand now. Thank you drive through.

 

[AJ/FormS]

I'll tell you what I for sure know, because I spent nearly a year with that cam.
You cannot run 36* of Idle timing, on the street, and here is why;

1) there is no reason to idle that cam over 800rpm, unless your oil-pressure is low, and then you have other issues.
2) The higher you idle it, the more idle-power she will make, and the harder she will bang into gear and the more rpm-drop you will get, and you will end up with two feet on the brake pedal.
3) at the current setting; your engine has way too much power BECAUSE;
A) of the 36*Idle-Timing, and
B) the high idle rpm, and
C) all the fuel she is inhaling, thru the 4-corner idle system.
4) IMO, that cam is not big enough to require a 4-corner idle system. Mine sure didn't need it.

Humor me;
set the Idle-timing to 14*,
set the T-slot exposure to like I said; a little taller than wide
Set the Primary mixture screws to, in the range of 3/4 to 1 turn.
Make sure the fuel-level is correct and stable
Then get your idle-air bypass worked out, to set your idle-speed to ~800, but DO NOT CHANGE the T-Slot exposure! Set your idle speed with bypass air.
You will know that you are getting close by:
A) when the rpm drop from Neutral to in-gear is ~100rpm or less, and
b) it doesn't want to explode the L/R band or over-running sprag, and
C) when you roll into the throttle, you do not get a hesitation, a sag, or nose-over. and
D) she tics over in gear at 650/700ish, and you can hold her back with just a lil toe on the brake-pedal.

Now; because of the small amount of Idle-advance;
1) to get the off-idle power back, you will need to use two strategies; You will need a two-stage advance curve with a kink in it at around 2800 +/- 200; very fast at the start, then slowing right down to keep your VERY HIGH compression ratio engine out of detonation. and
2) you will need a lot of vacuum advance at Part-Throttle to clean up the exhaust, and make her peppy again, and fuel-efficient at cruising speed. BTW, this cam sucks gas big-time and the more you advance it the worse it gets. This is partly because of the very modest duration of the power cycle. Because I already had 11.3 Scr and big cylinder pressure, I ended up running this cam at a few degrees retarded, but to no avail; with 3.55s it just sucked.

Right now, your engine is getting 36* under all circumstances.You are getting away with 36* of Power-Timing because of the 3000TC. So under power that may be fine (unless it detonates). But at rpms less than stall and under part throttle, there may be times your engine is wanting 40 to 50 degrees, but all your current system is allowing,is the 36*.
Mine liked at least 20* MORE under various circumstances; up to 60* of cruise timing at 2800rpm!
But at 3000 and Cruising, yours might like 56* for best torque and then can be leaned out for a modicum of fuel economy. The only way to get those high numbers (40 to 50) is with a good working modified vacuum advance system.

>>Lets say your engine likes 44* at 2000 just accelerating normally; and lets say your idle-timing is 14*@800; and lets say she does Not begin advancing until 1000 rpm. So that means, from 1000 to 2000rpm, the advance systems have to bring in 44 less 14=30degrees. Make a note of that.
>I said to install a 20* cam into your distributor. At 14* of idle timing, then, your Power Timing will be; 14 + 20=34* leaving you a 2* window to play with at some future date.
> I said to modify your V-can to 22* ( I think I did) that means the very maxim cruise timing can be is 34 +22=56* after the Advance is all in, which is perfect for your 3.91s.
> Lets go back to Cruise timing at 2000rpm. We already know that the V-can will be bring in up to 22*, so 30less 22= 8 degrees required in the mechanical.
so then 8 degrees from 1000 to 2000 is .8* per 100rpm , which is easy to get with One light spring and One HD spring that has a long-loop on one end. These are the stock 318 smogger springs.
So that's how I get 44* at 2000rpm for cruising on. But as you roll on the throttle, the 22* of vacuum advance will diminish and eventually disappear. Thus you might think that leaves you with just 14*plus 8= 22*, but simultaneously, your engine rpm is climbing to it's stall so picking up about .8* per 100rpm, so by 3000 it has climbed to 22* plus another 8, is 30 degrees, IMO, this is perfect to stay out of detonation. Then from 3000, to 3400/3600, the final 4* will come in.
> I would try this for a few weeks monitoring for detonation. I guarantee you that on the street, you can NOT feel the difference by azz-dyno of 34* or 36*. So don't be in a rush to dial those last two degrees in; ESPECIALLY with cylinder pressure over say 170psi. You are just looking for trouble on pump-gas with pressure higher than that.
Please note;
Unchecked detonation will destroy your engine and must be avoided at all costs, especially with cast pistons, hypers included.
Ok I've said my piece.
BTW, I am not insisting that you have to do it my way, as some members occasionally mention. I only care about your engine surviving detonation. So you are free to follow whatever advice you get. But if she drops the skirts into the pan, or holes a piston, maybe on the next go-round, you will tame it down.
Happy Hot-Rodding,
lol

 

[mderoy340]

To clean up the cruise and off idle you need to get the idle circuit correct. IMO the IFRs are to big and you need to go down .001 at a time. If I were you I would use a .032 IFR in the bottom position and a .067 IAB as a starting point. Reset the idle mixture screws after motor is at operating temp. If you look closely your rear throttle bores have a .021 hole just below the t-slot to. Set the front t-slot squared up and use the rear to fine tune.

 

[Mattax]

This is definitely a light throttle application stuff I'm having my issues with being rich be it lower speed or high speed constant cruising. If I go straight from idle to full throttle carb seems on point, afr is good and it just wants to blaze the tires thru 1st 2nd.
Maybe after i checked the pv something happened to it or maybe the gasket was bad out of the box perhaps

At light throttle and lower than interstate speed cruise the manifold vacuum is higher than stopped with idle in drive.
The idle or more correctly low speed circuit is manifold vacuum dependent.

Four corner idle will let you correct for this on a combination with poor idle vacuum (under 9" or so).
Use the locked distributor to figure out a good idle in gear tune. Then you'll know how it ought to be set up when youy unlock it or get another.
Step by step make changes in timing, primary throttle, and idle mix. If needed crack the secondaries a bit more. When the carb is off for setting the transfer slots, see if the secondary slots are as low as the primaries. They often are not, in which case can't go bu the amount exposed as a reference on the secondaries. Their job is mostly to provide some transfer juice when the secondaries open.

 

[Josh A]

To clean up the cruise and off idle you need to get the idle circuit correct. IMO the IFRs are to big and you need to go down .001 at a time. If I were you I would use a .032 IFR in the bottom position and a .067 IAB as a starting point. Reset the idle mixture screws after motor is at operating temp. If you look closely your rear throttle bores have a .021 hole just below the t-slot to. Set the front t-slot squared up and use the rear to fine tune.

Sence my carb has a pressed bleeds and restrictors Is this where I would try using small wire in the restrictors in the metering blocks i refered to earlier?

 

[mderoy340]

Sence my carb has a pressed bleeds and restrictors Is this where I would try using small wire in the restrictors in the metering blocks i refered to earlier?

You can do it with wire. The primary metering block is really the one you want to concentrate on since this is the circuit you are cruising on. If this is a newer carb the IFR is most likely in the upper position which is not as stable for flow.
Here's a good read that explains how to tune:
Carb Tunning

 

[Professor Fate]

Sence my carb has a pressed bleeds and restrictors Is this where I would try using small wire in the restrictors in the metering blocks i refered to earlier?

*I believe* you're getting overly fixated on the carb "at this point".
As Mattax stated, get your IDLE (in gear) timing/speed /mixture sorted out first.
Then get your distributor advance set up correctly. After that, you can figure out tuning the carb, the requirements of which will change once you get proper ignition advance.

 

[Josh A]

*I believe* you're getting overly fixated on the carb "at this point".
As Mattax stated, get your IDLE (in gear) timing/speed /mixture sorted out first.
Then get your distributor advance set up correctly. After that, you can figure out tuning the carb, the requirements of which will change once you get proper ignition advance.

Your right

 

[MOPAROFFICIAL]

Your right

You don't need to have an advance ....and locked out is not only for fuel injection.

More clearly ....the timing locked @36 a is not the cause for the rich condition you have. You can tune for both with or without a curve. Understand that having a curve would bring the timing down at the lower rpms from the 36 now and then steadily raise to the 36...at some rpm, day 2800-3000 where it stalls at, 3500
Less timing is gonna clean up the plugs? No fkn way.lol get the idle back on the primary side and not the secondary like you say you have it idling on.
What I'm trying to figure out is how you mostly drive this car and why was it the way you got it.

 

[MOPAROFFICIAL]

Your right

You don't need to have an advance ....and locked out is not only for fuel injection.

More clearly ....the timing locked @36 a is not the cause for the rich condition you have. You can tune for both with or without a curve. Understand that having a curve would bring the timing down at the lower rpms from the 36 now and then steadily raise to the 36...at some rpm, say 2800-3000 or where it stalls at, 3500
Less timing is gonna clean up the plugs? No fkn way.lol get the idle back on the primary side and not the secondary like you say you have it idling on.
What I'm trying to figure out is how you mostly drive this car and why was it the way you got it.

 

[Josh A]

You don't need to have an advance ....and locked out is not only for fuel injection.

More clearly ....the timing locked @36 a is not the cause for the rich condition you have. You can tune for both with or without a curve. Understand that having a curve would bring the timing down at the lower rpms from the 36 now and then steadily raise to the 36...at some rpm, day 2800-3000 where it stalls at, 3500
Less timing is gonna clean up the plugs? No fkn way.lol get the idle back on the primary side and not the secondary like you say you have it idling on.
What I'm trying to figure out is how you mostly drive this car and why was it the way you got it.

The car was a gutted bracket car that they only ran on the track when i got it off my father in law. And i want to have a street/strip car so when i was putting it back together i was trying to use as much of what parts I could to save money for other things that needed fixed.
Hopefully Sunday I can get time to work on it. Ill check the pv again, and i plan on closing down the sec and opening up the pri a little more. Do I just split it between the 2 to get the idle or favor the pri a little more enough to still have adjustment in my corner screws?

 

[MOPAROFFICIAL]

The car was a gutted bracket car that they only ran on the track when i got it off my father in law. And i want to have a street/strip car so when i was putting it back together i was trying to use as much of what parts I could to save money for other things that needed fixed.
Hopefully Sunday I can get time to work on it. Ill check the pv again, and i plan on closing down the sec and opening up the pri a little more. Do I just split it between the 2 to get the idle or favor the pri a little more enough to still have adjustment in my corner screws?

Set them to the transfer slots first, .020 exposed or to what looks like a square. 'You can google the holley site for this' . Then set the idle screws abou 1/2 to 3/4 turn out both primary n secondary. Ideally you want the idle screws out the same amount all 4 corners and the blades open the same amount all 4.. but if you have tmo lower idle speed...close the secondaries some, little at a time.. 'The holley red book is a must have for beginners and details a lot of this crap'. I use a digital timging light and watch the rpms on the light...open the idle screws till the rpm reaches its highest ,and only up to and never beyond....from there fire it up n set the timing to 20 and let run....till warm... then advance the timing to 24....tshut it off then try n start it...from there advance 2 degrees at a time.. each time shutting it off and restarting it till the starter fights/kicks back....once it does... go back 2 degrees. That's roughly the initial timing it wants. Now note the timing and then reset it back to 20 btdc/Advance. Now Before you worry about part throttle/wot ...check the vacuum at idle 'for now' and then check the condition of the PV and its rating which should roughly be half if the vac reading you get with trans mission in gear brakes on ...again ..once you get the idle dialed...ex if 8 then 3.5-4.5 for automatic in I choose only about 2" below reading for stick cars or big stall.
Once the PV is in the realm... we can almost drive it. Go back and adjust the timing to the 36 total....like you had and drive it...but 1st jet down the carburetors primary jets 2 sizes at a time till the engine surges at cruise '60mph+'....then go back up 2 jet sizes. That's your primary...now set the secondary 7-9 jets bigger than the primary 'assuming it has only 1 pv, if 2 pv's then square jet it' and then drive it and raise the timing till it pings under wot....then go back 2-4 dgrees... that's your total timing...curve depends on the spread and you'll still need to read the plugs for secondary wot and jet accordingly. The pump shot can be tuned once the primary jetting and pv are set...then the same for the sec
....then mod the distributor to limit mechanical advance/end up with the initial & total you found it liked. Hope what I'm saying is clear...I'm bbq'n ....and that means beer o'clock!!

 

[Mattax]

I both agree and disagree with your post (above). LOL I'll break it down after addressing your question to me and Dr Fate.

Less timing is gonna clean up the plugs? No fkn way.lol

Who said the plugs are carbon fouled?
Josh has only said the AFR numbers on his meter show richer than he was shooting for.
Even if they were showing overly rich at idle, are you saying increasing initial even more than 36* will clean them up? ?????

the timing locked @36 a is not the cause for the rich condition you have.

By itself, basically agree

Set them to the transfer slots first, .020 exposed or to what looks like a square.

Agree. Primary side anyway.

Then set the idle screws abou 1/2 to 3/4 turn out both primary n secondary. Ideally you want the idle screws out the same amount all 4 corners and the blades open the same amount all 4

Basically disagree. Its fine to begin with 3/4 out with a four corner that has strong idle, BUT there is no magic number of turns out that is right. Adjust each one as needed for best power. Important thing is that the engine responds to adjustment. As far as the secondary throttle positions go, it depends on the carb. Again no reason they must be the same as the primaries unless doing a 1:1 linkage.

but if you have tmo lower idle speed...close the secondaries some, little at a time

I agree that they can be tweaked further open or shut to help idle conditions. But if the t-slots are not as long as the primaries, then its best if the t-slots don't show.

'The holley red book is a must have for beginners and details a lot of this crap'

I agree that Urich's 4150/60 is an excellent introduction.

I use a digital timging light and watch the rpms on the light...open the idle screws till the rpm reaches its highest ,and only up to and never beyond....from there fire it up n set the timing to 20 and let run....till warm... then advance the timing to 24....tshut it off then try n start it...from there advance 2 degrees at a time.. each time shutting it off and restarting it till the starter fights/kicks back....once it does... go back 2 degrees. That's roughly the initial timing it wants

I know this is a popular approach in some circles. I personally disagree with it. In my view initial timing should be chosen based on building the most power in gear at slow idle. Obviously that can not apply when a locked timing is chosen for racing.

the PV and its rating which should roughly be half if the vac reading you get with trans mission in gear brakes on ...again ..once you get the idle dialed...ex if 8 then 3.5-4.5 for automatic in I choose only about 2" below reading for stick cars or big stall

Disagree.
As long as the PVCR is much smaller than the main jets PV will have little effect idle. But in general what Mark shows in the video here holds true.
Quick fuel carb fuel pressure too high? Rich idle...
PV opening has been covered in detail before so can refer back to that thread you're interested in why rather than make a big sidetrack in this one.
Power Valve Selection: The Definitive Answer

but 1st jet down the carburetors primary jets 2 sizes at a time till the engine surges at cruise '60mph+'....then go back up 2 jet sizes.

Agree

 

[MOPAROFFICIAL]

I both agree and disagree with your post (above). LOL I'll break it down after addressing your question to me and Dr Fate.


Who said the plugs are carbon fouled?
Josh has only said the AFR numbers on his meter show richer than he was shooting for.
Even if they were showing overly rich at idle, are you saying increasing initial even more than 36* will clean them up? ?????

By itself, basically agree

Agree. Primary side anyway.

Basically disagree. Its fine to begin with 3/4 out with a four corner that has strong idle, BUT there is no magic number of turns out that is right. Adjust each one as needed for best power. Important thing is that the engine responds to adjustment. As far as the secondary throttle positions go, it depends on the carb. Again no reason they must be the same as the primaries unless doing a 1:1 linkage.

I agree that they can be tweaked further open or shut to help idle conditions. But if the t-slots are not as long as the primaries, then its best if the t-slots don't show.

I agree that Urich's 4150/60 is an excellent introduction.


I know this is a popular approach in some circles. I personally disagree with it. In my view initial timing should be chosen based on building the most power in gear at slow idle. Obviously that can not apply when a locked timing is chosen for racing.

Disagree.
As long as the PVCR is much smaller than the main jets PV will have little effect idle. But in general what Mark shows in the video here holds true.
Quick fuel carb fuel pressure too high? Rich idle...
PV opening has been covered in detail before so can refer back to that thread you're interested in why rather than make a big sidetrack in this one. 1
Power Valve Selection: The Definitive Answer

Agree

Sounds like you're saying I said the pv effects idle/mains.? I said to use the vac at idle as a starting point for choosing the pv.
@36 at idle...the blades are probably barely open even @1100 rpm... again its 36 btdc.. he is not in the mains by a long shot...yet the afr is rich....is it floats high, have the bleeds been changed...who knows..
I also stated to use the timing lights tach as reference to ultimately how many turns out the idle screws should end up or how rich by watching the rpms climb. If you don't do it that way, that's your preference. I've done it for years. He is also idling on the secondary circuit...but no ones addressing that besides me. Okay...??
I don't run around accepting the carb guru title like some rat turds, but I've known how to tune for decades and if you rode in my cars.. you would instantly know that.
I remember the 1st chassis dyno test, the fuel ratio I dialed myself with test drives and a timing light in my 20's
..only funk was a momentary blip from the secondary shooter 'one bigger than what I had in the carb box'...afr was sweet, near perfect. Made 392 hp with stock x heads n a .528 cam 750 holley.
Everything I said to do is to get him to clear waters where he more fine tune. Even after a few beers that still pretty damn good advice...but If anyone thought I was saying 'this is exactly what it wants' they're mistaken and imo only looking to be better than someone else.
I gave all the advice I need to give at this point.

Good luck OP.

 

[Hysteric]

A poor ignition can create the appearance of a an overly rich mixture. Make sure that's it operating as it should and that the alternator is providing enough voltage to it.

 

[toolmanmike]

Jeezz WTF is up with you guys. I booted Ratbastid for being a ***. It is best to just back away instead of pissing people off, pushing buttons, or using the red X.