Slant Six Forum :: Holley 350 carb (7448) problems

Anybody know where to get different gauges of tiny wire to tune the PVCRs?

Quote:

Anybody know where to get different gauges of tiny wire to tune the PVCRs?

I have lots of guitar strings in different gauges I can send you pieces of, free of charge...as long as you post the results! PM me.

I would get a lean surge at idle and my plugs were running fairly white. I upped it to #63 or 64, can't remmeber, and it fixed that, but it's still on the ever-so-slightly lean side it seems.

What I am thinking is to see how much vacuum Im pulling at idle and jet down until it runs lean a couple inches less vac. than idle.

It's my understanding that mains jets have little to no effect on air/fuel ratio at idle. Fuel ratio of the idle circuit is adjusted with the mixture screws and the main circuit is adjusted by changing jets.
I've never heard of a lean surge at idle?? I thought if you don't have enough fuel at idle the engine stalls. eg. if you screw in the mixture screws till the engine leans out.
When I had a 350 on my Slant it had 63 jets, 65 PV and 31 shooter. That carb ran very well, and my Slant is a very warm build.

Author:	Dart270 [ Mon Oct 19, 2009 2:19 pm ]
Post subject:
Too much messing around and I'll just have to EFI this thing too!! Lou

Author:	Rick Covalt [ Mon Oct 19, 2009 2:28 pm ]
Post subject:	THe Answer
Come on Lou, You know the answer. Bolt on a 500 Edelbrock and away with that Holley!! Good luck finding the problem. Rick

Author:	radarsonwheels [ Mon Oct 19, 2009 3:20 pm ]
Post subject:	Brass is not necessary
Holley sells a power valve plug. I just took an old one and plugged it up with JB weld. With the PV plugged I was able to get a reasonably good tune in terms of drivability but my wideband is showing lots of problems/potential for improvement. The gas mileage is poor- about 12mpg with this setup and the best I can say for the tune is that it doesn't ping. There is no reason except laziness that I haven't figured out the PV circuit. What I am thinking is to see how much vacuum Im pulling at idle and jet down until it runs lean a couple inches less vac. than idle. Then I can lean out the PVCRs until it stops overcorrecting and hits the 12.5 sweet spot at WOT. Anybody know where to get different gauges of tiny wire to tune the PVCRs? If you want to just eliminate the PV I'll let you know what jets I'm running. It is pretty rich most of the time, but the power is good under load. It'd be a shame though and at that point it makes more sense to just put the one barrel back on.

Author:	emsvitil [ Mon Oct 19, 2009 3:29 pm ]
Post subject:	Re: Brass is not necessary
Quote: Anybody know where to get different gauges of tiny wire to tune the PVCRs? Strip out the strands from electric wires. (some have fine strands, some thicker, and phone/ethernet cable is solid) Measure the diameter with your caliper.

Author:	the_shadow [ Mon Oct 19, 2009 4:10 pm ]
Post subject:
Quote: Anybody know where to get different gauges of tiny wire to tune the PVCRs? I have lots of guitar strings in different gauges I can send you pieces of, free of charge...as long as you post the results! PM me.

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Holley 350 carb (7448) problems https://slantsix.org/forum/viewtopic.php?t=37563	Page 2 of 3

Author:	emsvitil [ Mon Oct 19, 2009 4:45 pm ]
Post subject:
Quote: Quote: Anybody know where to get different gauges of tiny wire to tune the PVCRs? I have lots of guitar strings in different gauges I can send you pieces of, free of charge...as long as you post the results! PM me. Wouldn't guitar strings look bigger to fuel flow because they're wire wrapped? (more turbulent flow due to the wrapping)

Author:	radarsonwheels [ Mon Oct 19, 2009 5:14 pm ]
Post subject:	answers, and more questions
I was originally told to use stainless piano wire. Seems like the best idea, but piano wire is expensive and I don't have a piano tuner in the family... I am a bass player and I know you are thinking 'round wound' strings where the core that holds the tension is wound with usually nickel wire to give it the mass it needs to vibrate at the proper frequencies. I don't think any round wound string would work. I was thinking more about the cores of the wires, or the smaller strings on the guitar (electric or steel string) that are thinner. I never was much of a guitar player, but the string sets are usually described and sold based on the thickness of the bottom (high E) string, the thinnest of the six. A 'shredder' or high speed left hand metal guitarist will often use '9s' while Dick Dale- high speed right hand guitarist looking for less floppiness and more sustain will use maybe '14s' I don't know if the numbers represent a wire gauge or an inch measurement in thousands or what, but I'm thinking it might be my first stop on the PVCR tuning express. I've been searching the 'net all day for pvcr tuning info and I have heard here and there that there is a kit using mikuni motorcycle air bleeds/jets because they're small enough but no one seems to sell this kit. Most people are drilling the restrictions out or throwing out the metering block when they go too far, so this is somewhat of a new frontier for the average tuner...

Author:	the_shadow [ Mon Oct 19, 2009 5:21 pm ]
Post subject:
No, only larger guitar strings are wrapped, the smaller ones aren't and would work perfect. They are gauged by their diameter in thousandths of an inch. Guitar strings aren't usually wound until .018+ and there's options either way at that gauge. PM ME radarsonwheels if you want some

Author:	SV162 [ Mon Oct 19, 2009 5:48 pm ]
Post subject:
Quote: I would get a lean surge at idle and my plugs were running fairly white. I upped it to #63 or 64, can't remmeber, and it fixed that, but it's still on the ever-so-slightly lean side it seems. It's my understanding that mains jets have little to no effect on air/fuel ratio at idle. Fuel ratio of the idle circuit is adjusted with the mixture screws and the main circuit is adjusted by changing jets. I've never heard of a lean surge at idle?? I thought if you don't have enough fuel at idle the engine stalls. eg. if you screw in the mixture screws till the engine leans out. When I had a 350 on my Slant it had 63 jets, 65 PV and 31 shooter. That carb ran very well, and my Slant is a very warm build.

Author:	DusterIdiot [ Mon Oct 19, 2009 6:46 pm ]
Post subject:	Yep...a few basics
Quote: What I am thinking is to see how much vacuum Im pulling at idle and jet down until it runs lean a couple inches less vac. than idle. The idle circuit on a Holley (and most carb) is separate from the main circuit... The idle circuit fuel is set up by the idle mix screws on the side of the metering block... those and the air bleed to the "outside" of the air horn will control how lean or rich your idle and transition slot are (yes, that long slot about 1/8" past the little idle hole when the throttle plates are closed). A few things that will affect your carb tuneability: The high speed air bleeds (the ones next to the "shooter"), these determine "when" the mains come on line... instead of using a big pump shot, you can sick a bent wire into here and cause your mains to come on quicker... if too quick you will have to visit a hobby shop and get a drill set to and open them up to get it to come on later (most are set for about 1800-2100 rpm depending on the engine they calibrate them to...Chevy 350 in many cases) PV- you want to dial this in so it comes on just above the "intercept" point aka. when you hit the go pedal to pass a truck on the highway but aren't looking to get the attention of the police (1/2-3/4 pedal)...you should be looking at the vacc. reading... most moderate slants will use a 10.5-8.5 PV...period...they unfortunately don't make a 12.5...which would be nice for the short stick engine builder...the dual enrichment PV's are great for highway only use and heavy vehicles with lower power engines (1980 Mirada with a 225...or the 1975 Duster...)...these tend to 'eel over' when at the track as your engine demands some of the enrichement but doesn't get all of it until the vacc. gauge hits the goose egg... Mains are a spark plug reading affair to see how close they are...bad part is if the vacc. reading due to a lean out is low, it might open the PV or Vacc. secondaries making you look around for "another problem". When you can get you primaries jetted up properly and your plugs are a tan color (or green for us oxygenated gas swilling states), then work toward dialing your PV or shooters in if you stil have a "bog" during take off from a light... This isn't the final word, but it's enough to get things going... -D.Idiot

Author:	the_shadow [ Mon Oct 19, 2009 6:51 pm ]
Post subject:
Quote: It's my understanding that mains jets have little to no effect on air/fuel ratio at idle. Fuel ratio of the idle circuit is adjusted with the mixture screws and the main circuit is adjusted by changing jets. I've never heard of a lean surge at idle?? I thought if you don't have enough fuel at idle the engine stalls. eg. if you screw in the mixture screws till the engine leans out. When I had a 350 on my Slant it had 63 jets, 65 PV and 31 shooter. That carb ran very well, and my Slant is a very warm build. Correct, I didn't type that correctly, I meant a lean surge at cruise, not idle.

Author:	coconuteater64 [ Mon Oct 19, 2009 9:01 pm ]
Post subject:
Just a quick thought here, anybody know the stock fuel pressure for a slant six fuel pump?

Author:	Aggressive Ted [ Tue Oct 20, 2009 1:28 pm ]
Post subject:
Mine puts out 6 lbs.

Author:	coconuteater64 [ Tue Oct 20, 2009 7:47 pm ]
Post subject:
OK, I was just wondering if maybe the fuel pump was overpowering the needle valve. IIRC, Holley recommends no more than 8 pounds, preferably less. I noticed that mine does run a tad better now that I installed a heat shield under the carburetor. So at least there's that.

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Author:	Dart270 [ Tue Oct 20, 2009 8:24 pm ]
Post subject:
Mine has a stable and well adjusted float level, so no fuel pressure issues for me. Lou