Holley 1000 HP- won't idle in drive

[buick64203]

Im trying to get my new Holley 1000 HP carb dialed in. This is on my 71 455. The cam is a 308S

The car idles just fine in neutral at 1000 rpm. Floats are set so that they just trickle out as the engine shakes. All 4 mixture screws are out 1 1/2 turns.

I first thought that the transfer slots were too exposed on the primary side. So I adjusted the secondary butterflies. As the idle came up, I adjusted the primary down. So now the idle screw is maybe one turn out. But when I put it in drive, the car just dies out. Almost feels like the engine drowns. Now I only have about 4" of vacuum at an idle. The old 850 I had idled fine in drive, but as I recall, I had a 3.5 in that one. Did I just answer my own question?

The new carb setup is:

Primary jets- 84
Secondary jets- 92

Primary power valve- 4.5
No secondary power valve

Primary/ secondary nozzles 32

[71stagegs]

CALLING THE WIZARD

[skylark]

4" of vacuum with a 4.5 power valve sounds like the problem to me. If there isn't enough vacuum to hold that valve shut, wouldn't it just dump fuel?

[DaWildcat]

Im trying to get my new Holley 1000 HP carb dialed in. This is on my 71 455. The cam is a 308S

The car idles just fine in neutral at 1000 rpm. Floats are set so that they just trickle out as the engine shakes. All 4 mixture screws are out 1 1/2 turns.

I first thought that the transfer slots were too exposed on the primary side. So I adjusted the secondary butterflies. As the idle came up, I adjusted the primary down. So now the idle screw is maybe one turn out. But when I put it in drive, the car just dies out. Almost feels like the engine drowns. Now I only have about 4" of vacuum at an idle. The old 850 I had idled fine in drive, but as I recall, I had a 3.5 in that one. Did I just answer my own question?

The new carb setup is:

Primary jets- 84
Secondary jets- 92

Primary power valve- 4.5
No secondary power valve

Primary/ secondary nozzles 32

I think you did. Below 4" vacuum the power valve is opening, putting the mixture over the deep end. That little trickle of fuel from the boosters is an indication of this. There should be no fuel flow from the booster discharge tubes at idle...if so, you should look at float level, fuel pressure, power valve(s) or all of the above.

If you're trying to run vac advance you may be having a timing problem if the vac is too weak to keep the diaphragm pulled in all the way, causing you to lose some advance.

I run the 308S as well and run power valves about 1 number lower than the vacuum reading I get in drive. It's still so close to the ragged edge that if it weren't for high stall on the switch pitch, the engine would die.

Devon

[BuickBuddy]

In gear I bet your vacuum drops to 3.. Get a lower power valve.:idea2:

[70aqua_custom]

Jason, I have a very similar combo and had the same problem. The key for my idle was to lock the timing @34* BTDC and set all 4 idle screws @2.25 turns out, a little on the rich side. It now idles around 1200-1400 in neutral and around 900 in gear with no stalling whatsoever. I always shut it down in gear to prevent dieseling. I have the same power valves and vac in gear I think was around 4.5". As the idle speed goes down, the vac goes down. Are you reading the 4" as it's about to stall or at 1000 RPM?

[buick64203]

We'll give a 3.5 a try and see what's what after that. I got the 850 to idle nice, Im sure I can this one to do the same. The vacuum reading was when it was idling at around 1000 rpm. Im sure its a bit lower in gear. I hope the 1000 is going to be as streetable as the 850 was:pray:

You guys think Im in the ball park as far as jet sizes go?:Do No: Dave- how do you have yours setup?

On a side note- How do you guys test your power valves? I bought the coolest power valve tester from Moroso. Works with a mity-vac. No more guessing.

[BuickBuddy]

We'll give a 3.5 a try and see what's what after that. I got the 850 to idle nice, Im sure I can this one to do the same. The vacuum reading was when it was idling at around 1000 rpm. Im sure its a bit lower in gear. I hope the 1000 is going to be as streetable as the 850 was:pray:

You guys think Im in the ball park as far as jet sizes go?:Do No: Dave- how do you have yours setup?

On a side note- How do you guys test your power valves? I bought the coolest power valve tester from Moroso. Works with a mity-vac. No more guessing.

I had 12-15 inches of vacuum so the 6.5 that came in it worked fine.. Plugged the rear one and 84-94 front and rear jets.

Idle screws are out 1 1/2 turns.. Brown accelerator cam which is the biggest. Remember accelerator pump shot relative to cam color from lightest to heaviest are as follows. White, Blue, Red, Orange, Black, Green, Pink and Brown

One thing you may have to do is tighten up the accelerator spring a bit and bend the tab down so it's tight against the cam. When I mashed the gas the spring would squish to much and I'd get a stumble.. Not enough gas in the shot. That fixed it.

I'm going to have to start over with the new motor..:rant:

[LARRY70GS]

The secret to taming a big cam on the street is to run as much initial timing as you can. That gives you the most vacuum and best idle. 20* + is best. locked out timing with a start retard is even better.

[Stg'd 2Discover]

I run the same cam with a Proform 950. With that cam you definately need a lot of initial advance. Lately I've run 28 degrees initial with a total of 34. Did this by reducing the slot size on the HEI. Your Vac readings shoud be a tad higher at 5-7 inches. I get around 6".

I can also idle at 900 in gear in high stall mode.

An MSD starter saver module cuts it back 20 deg during cranking.




Tom

[buick64203]

Just wanted to follow up on this. I managed to get the car out of the garage over the weekend and replace the 4.5 PV wit ha 3.5. No change.


Now, I have a PV plug and #92 jets in the rear. What advantage is there to a PV plug as opposed to just putting a PV back in? Im thinking of replacing the PV plug with another 3.5, then bringing the jet sizes down. Any suggestion on what size jets I should put in? I was thinking on 84s

[BuickBuddy]

Just wanted to follow up on this. I managed to get the car out of the garage over the weekend and replace the 4.5 PV wit ha 3.5. No change.


Now, I have a PV plug and #92 jets in the rear. What advantage is there to a PV plug as opposed to just putting a PV back in? Im thinking of replacing the PV plug with another 3.5, then bringing the jet sizes down. Any suggestion on what size jets I should put in? I was thinking on 84s

84's all the way round was the way mine came from Holley. It ran great on the street.

[bills2x4cat]

I would definetly lock the timing out! Fixed the same prob on two separate cars by locking out the timing. If you dont want to lock it out to see if that fixes it at least pop a couple of STIFF advance springs on there and see if it goes away. Im guessing you have fairly weak advance springs in there. What happens is when you are in neutral the rpms are up a little and the weights are actually starting to advance the timing already. Advanced ign timing equals higher idle rpms. When you put it in gear your rpms drop a little, causing the distributor to slow down and the weights retract. This then retards the ignition timing and retarding timing slows down you idle speed, and in your case causing it to go too low and stalling the engine.
Even if this doesnt fix you prob keep this advice in the back of your head for a rainy day. Good LUCK!! :TU:

[sailbrd]

I agree that the power valve and timing should be worked on.

I am surprised at how many turns you guys are running on the idle screws. With the 4 corner system you usually start at 1 turn out and work from there. Johnny Angel had a thread on idle with the 1000HP. He found out he had a defective carb. http://www.v8buick.com/showthread.php?t=144491&highlight=1000+holley

[bills2x4cat]

Let us know what the fix was. Were dying to know!! :pray:

[buick64203]

The car had an 850 DP on it previously and it idled fine in drive. Idled at about 1000 rpm in neutral and about 800 or so in drive. No other changes were made with the rebuild So there's no reason for me to think at this point that the problem is somewhere other than the carb. Distributor and timing are the same.

I'm planning on tearing the carb back apart this weekend and make the changes. The 3.5 PV and 84s ought to do it. From what Ive read, the PV plug is more for drag racing. it tends to give an excessive rich mixture at low idle conditions.

Stay tuned!

[tt455]

Hey Jason,what happened with this? Did you figure it out.I found this on power valves.

http://www.youtube.com/watch?v=6vKlAnKdcB4

[buick64203]

Jason, what's the carb part# ? 80514-1 ? Chris


Chris, Im sorry I didnt see this post until now. Im not sure of the number. I assume its on the throttle body?


Tom- Thats a neat video. I never thought to look to Youtube for tuning tips:Dou:

I havent had a chance to take the car back out. Its either been too cold, raining or Ive been too busy to do anything. But Im pretty confident removing the plug will fix the stupid thing.

I'll get to it soon. Its on the list....the never ending list of stuff I have to take care of

[buick64203]

Success!!!

It was a gorgeous day today. Good carb tuning weather. I took the carb off, and installed a 3.5 PV in the rear and 85 jets. Re installed carb and did a bit of fine tuning on the mixture screws. Just swapping in the PV, the car ran leaner at idle.

Now idles in neutral at 900-1000 and it will idle in gear at 700. I think thats as good as it gets folks.

Chris- the list is 80514. Stamped HP. I bought the carb from a Allstate Carb & Fuel Injection. They custom built as per my specs from parts

[70aqua_custom]

Success!!!

It was a gorgeous day today. Good carb tuning weather. I took the carb off, and installed a 3.5 PV in the rear and 85 jets. Re installed carb and did a bit of fine tuning on the mixture screws. Just swapping in the PV, the car ran leaner at idle.

Now idles in neutral at 900-1000 and it will idle in gear at 700. I think thats as good as it gets folks.


Jason, Yours now idles better than mine :TU: I'd like to get mine to idle lower like yours. I don't understand how installing a PV in the secondary side leans out the idle. I googled it and read a bunch of stuff but nothing on that. Can you explain the logic or point me to where you read about this?

[staged67gspwr]

Jason what PV are you running in the front?

Thanks

[DaWildcat]

Jason, Yours now idles better than mine :TU: I'd like to get mine to idle lower like yours. I don't understand how installing a PV in the secondary side leans out the idle. I googled it and read a bunch of stuff but nothing on that. Can you explain the logic or point me to where you read about this?

If the power valve he was previously running had an opening vac point higher than his actual manifold vac at idle, the valve would have been open, unneccesarily enrichening the idle mix. The correct choice of pv should mean it stays closed at idle (or just block it), thus not affecting idle mix. I'm guessing this was the case based on Jason's comment.

Devon

[buick64203]

Andy- let me preface this by saying that I'm no Holley expert. And I consider Holley tuning a "black art" so to speak! Most of my knowledge came the hard way. I do plan on playing 20 questions with my carb guy on Monday.

But from what Ive read, a power valve block off will make for an extrememly rich low idle condition. For a drag car with a 1500 rpm idle that does a 1/4 mile at a time, that may not be an issue. Maybe one of the Holley gurus can explain to us what applications a plug is for. I dont see a use for it myself other than for drag use only.

But with the carb set up that way (PV block off), it seemed to idle fine in neutral (1000 rpm), but die out in drive. From sitting in the driver seat, it died out slowly. It felt like someone was pouring fuel down the carb, drowning it out. I playing with the secondary butterfly adjustments, mixture screws etc to no avail.

PV's keep the mixture lean, until the vacuum drops to below the rating of the valve. Once below the vacuum rating, the PV richens up the mixure. For example, a blown PV will make the idle extremely rich. So, my theory was to remove the plug and install a 3.5 PV in the secondaries. And it seemed to work. Im sure someone else can explain this better than me. I think 2.5 PV's all around would of been better with the vacuum as it is, but im not messing with it again.

What I should of done was to put it on my 5 gas analyser before and after just to see the HC difference

So, the final setup is

84 jets and a 3.5 in the primaries
85 jets and 3.5 in the secondaries

Mixture screws turned out 2 turns on all 4 corners. 5" of vacuum in neutral ( I didnt check in drive)

The car now idles in gear at 700 with a 308S cam. :beer

[LARRY70GS]

Jason,
Glad to hear you got it worked out. I don't know what AED does to their carbs, but I have no PV in the back, and a 4.5 up front. Jetting is 80/92. It idles very nicely and even returned over 13 MPG on a trip to and from Marcus Dairy.

[TORQUED455]

Nicely done, Jason! :beer

[staged67gspwr]

So it wouldnt be a problem to run a PV at the rear also?


Thanks

[staged67gspwr]

I would not just go and remove your power valve. The fact that some people may not have a power valve in the rear of there carb doesn't mean you should get rid of yours. I'm a big fan of NOT altering your carb from factory spec's. If it was built and engineered by Holley, AED etc it was calibrated as a combo. Chances are if you have to change the jets more then 3 or 4 jet sizes one way or the other you have the wrong carb for your combo. Power valves are meant to be adjustable, set up to work with your manifold vacuum. But if your carb came with them leave them in there. Just to give you an idea on how removing the power valve effects your carb, you would have jet up 8-10 jet sizes to compensate for removing it. I've seen people try to re-engineer there carbs before, eg: I've seen it many times at track where guys block of there power valve and can't understand why the thing keeps loading up and fouling plugs as there idling around the track. If your carb was engineered with a power valve leave it alone, there is NO gain in removing it. The big thing is to buy the right carb to fit your combo. Chris



Chris,Jason did remove the power valve,he removed the rear plug and replaced it with a power valve.

Thanks

[staged67gspwr]

George, I'm going to work on a 67 project for the afternoon, I will ask the owner if I can post some pic's. I think you will really like this car:TU: Chris



:TU: :TU:

[TORQUED455]

Chris,

It would seem like removing the rear PV and installing a plug, in conjunction with rear jet extensions and rear jetting 8-10 over "stock" would be done to eliminate a lean-bog condition on hard launches. The cause is the rear PV and jets being "uncovered" with fuel. How else can you combat this on a Holley?

After thinking about it a little more, I don't see how plugging the rear PV could ever effect the idle mixture, unless the PV is blown.

[DaWildcat]

After thinking about it a little more, I don't see how plugging the rear PV could ever effect the idle mixture, unless the PV is blown.

Should have had no effect. I'm guessing something else was up, maybe a leaking metering block gasket that got fixed when it was put back together.

Devon

[buick64203]

The carb thats on my car is basically a "put together" carb from Allstate. In other words, Allstate built my carb from parts as per my specification. I do remember telling them I was very interested in straight line performance and was willing to give up some driveability. In hindsight, that may not have been the best thing to have told them. I do tend to drive the car on the street occasionally (when its not holding down the garage floor)

The carb has aftermarket red anodized metering blocks. I did notice they installed jet extensions in the rear when I had it apart. You guys have me wondering now if removing the plug and installing the PV corrected the problem or not. Its a possibility that I fixed it without knowing it as Devon suggested. While I hesitate to start fiddling with it again, I feel compelled to re install the plug and the #92 jets just to see if the problem re-appears. I tend to belive that the secondary side was loading up. Maybe if Im bored I'll screw with it again.

Here's the link to Allstates website. They are very good. They did an excellent job restoring my 7040246 Q-Jet. They do cad plating and re coloring. It looked almost too good to run gas though....almost:grin:



http://www.allcarbs.com/index.html

[LARRY70GS]

Hey Jason,
If you want, you can install my AED 1000 HO carb and drive around with it for awhile. See if you notice a difference. I'm not using it right now, but will in the future I'm sure. Let me know.

[LARRY70GS]

Larry, what carb do you use? Is it a 1000hp with 4 corner idle? Chris

Not an out of the box 1000HP, but similar. AED builds there own carbs from Holley parts. It does have a 4 corner idle. Take a look here. It is the 1000HO

http://www.aedperformance.com/HO.htm

Here are the specs:

http://www.v8buick.com/attachment.php?attachmentid=87174&d=1169934555

Some Pictures:

http://www.v8buick.com/attachment.php?attachmentid=87080&d=1169854507

http://www.v8buick.com/attachment.php?attachmentid=87117&d=1169899894

http://www.v8buick.com/attachment.php?attachmentid=87082&d=1169854507

Jason had his engine dyno'd with my carburetor.

[TORQUED455]

I decided to check the innards of my 1000 HP carb a week or 2 ago, because of this thread. I had purchased it used and the owner said it had stock jetting as the bowls had never been off.

What I found was 78 front and 82 rear jets, rear jet extensions and 6.5 PV's in the front and rear. The front had a 30cc pump and 35 discharge nozzle, and the rear had a 50cc pump and 35 squirter. So much for being stock.

What I did was jet up to 84/92 (retained the jet extensions), lowered the front PV to a 3.5 and plugged the rear. I added a 50cc front accelerator pump kit with the brown cam installed in the #2 position.

What this accomplished was a significantly better idle (TA510 cam) -- it will now idle in gear, hot restarts are much better, and it has much better throttle response. There is no adverse part-throttle driveability w/o a secondary power valve.

Along with JW's billet fuel pump, -8 line and RobbMc's 1/2" sender, I feel much more confident about getting enough fuel to the engine this year at the track. :Comp:

[BADDABUICK]

Hi Guys I am having a problem with my HP 1000 it won't idle in park much under 1000 rpms and it makes your eyes water like crazy,could it be a blown power vavle.i turned the idle screws to one turn out and it did help with the richness .if i try to adjust the idle down under it dies .thanks for the help.:beers2: