CRG Discussion Forum

Camaro Research Group Discussion => Maintenance => Topic started by: Henry Cloutier on October 15, 2020, 11:42:46 PM

Title: Power Valves
Post by: Henry Cloutier on October 15, 2020, 11:42:46 PM
Hi all,

I'm in process of rebuilding the Holley 4053 on the Camaro. I am to the point of installing new power valves. The ones removed are marked 6.5 and I wasn't having any running issues so am planning on installing the same rating however the renew kit came with four marked 6.5. Two have 2 slots and two have 4 slots. The ones removed have 2 holes each primary and secondary. I'm assuming the 4 slot valve supplies twice the fuel as the 2 slot valve and therefore should be installed on the secondary side, or is 2 slots good on both sides? The Z is a weekend warrior and isn't driven daily but does know where the straight line country roads are. I do need to satisfy my need for speed every now and again :-)

Thanks in advance for the help,

Hank
Title: Re: Power Valves
Post by: firstgenaddict on October 16, 2020, 01:11:50 AM
I just looked in my tune up tool box and I have a mixture of double and quadruple slot PV's - I have built a lot of carbs over my life and honestly I have never paid attention to the number of slots in the PV's.
Title: Re: Power Valves
Post by: z28z11 on October 16, 2020, 01:32:04 AM
Original 4053's were equipped with a 25R-591A-65AS primary power valve, which is a 6.5 - secondary power valve was a 35R-591A-85AS, which is an 8.5 valve. Gaskets are also different between the drilled valves and the slotted valves - failure to use the proper gaskets in each case can cause fuel leaks around the valve -

Regards,
Steve
Title: Re: Power Valves
Post by: firstgenaddict on October 16, 2020, 02:11:14 AM
I didn't have any drilled valves,
I will state that I do check that the gasket is in the correct position when I install the valves and I place the gasket on the PV then hold the JET PLATE with the power valve hole pointing towards the ground then raise the PV to the plate and screw in so the gasket does not become oriented "wrong".
Title: Re: Power Valves
Post by: z28z11 on October 16, 2020, 03:16:57 AM
I have seen both gaskets shown below in kits, important to use the gasket visible on the right for the slotted power valve. I think Holley only furnishes the slotted power valve nowadays, but this is a "just in case" note. If the valves supplied in the OP's rebuild kit are correct, are the 4 slot valves marked 8.5 ?

Regards,
Steve
Title: Re: Power Valves
Post by: Henry Cloutier on October 16, 2020, 02:24:05 PM
Hi everyone,
 Thanks for the info you all have provided. My mistake last night (perhaps one to many Bud's), The removed valves are slotted not drilled and both are 8.5. I had to get the magnifier out to verify. Hopefully the picture attached; it shows 2 and 4 window 6.5 valves. I've been researching for a couple hrs now reading threads, articles etc. Steve is correct with 6.5 primary and 8.5 secondary from the factory. This was apparently done as the engineers feared there may be a lean droop during the transition from primary onto the secondary's. The 4 window valves as near as I can tell are termed "Quick Response Hi Flow valves." They are most often refenced when "Alcohol" is used for the primary fuel source. They are also slightly taller than the 2 slot valves.
 I'm thinking to return the carb back to stock configuration of valves; 6.5 2 slot for primary and 8.5 2 slot for secondary. Any thoughts are very much appreciated! And whoever was in this carb last time double stacked the PV gaskets on both!

Hank     
Title: Re: Power Valves
Post by: rszmjt on October 16, 2020, 02:38:19 PM
I think the original Holley PV had holes instead of slots, I haven’t seen those supplied in many years, except for in some after market cheaper generic brand rebuild kits. I have some hole type PV from Holley kits dating back to the mid 70,s. Personally I like Holley branded kits and parts. We tried some after market branded accel pumps and PV /needle & seats but they seem to fail quick & the pump diaphragms seem to petrify , I think the ethylene in today’s fuel cause this.
General rule for PV selection is it should be rated at 1/2 of idle vacumn with a vacumn gauge . Eg if you have 13” manifold vacumn use a 6.5 PV
Title: Re: Power Valves
Post by: z28z11 on October 16, 2020, 03:09:42 PM

 I'm thinking to return the carb back to stock configuration of valves; 6.5 2 slot for primary and 8.5 2 slot for secondary. Any thoughts are very much appreciated! And whoever was in this carb last time double stacked the PV gaskets on both!

Hank     

I would use the original 6.5/8.5 combo as it was specced, and a single gasket for the slotted valve configuration - should not be a reason to use two, one should be sufficient. The worst problem I ever had with my 4053 was an off-idle bog, a known aggravation, easily corrected by upping the diameter of the accelerator nozzles or changing the pump cam to allow a longer duration pump shot. 302's with stock compression, cam and heads are thirsty, even when jetting and timing
are dialed in. Another suggestion - if you ever sneeze the carb, prudent to replace the power valves (pretty sensitive to backfiring).

Regards,
Steve

Title: Re: Power Valves
Post by: rszmjt on October 16, 2020, 05:59:10 PM
You can also test the power valve operation by turning mixture screws in slowly, it it stumbles and try’s to quit running PV is OK
Title: Re: Power Valves
Post by: Henry Cloutier on October 16, 2020, 09:02:32 PM
Thank you for the great responses. Based on what you all have provided I have a much better understanding of PV's and associated issues with them. When the Z was delivered in July I pulled her into the garage and there was a distinct fuel smell lasting a few days. My first thought was float levels to high so I went about trying to adjust them along with the mixture screws and wanted to check the timing to see where it was sitting. The engine ran fine, pulled really well thru the gears(although I didn't get above 5000rpm on the first outing) idled a little rough but I also knew the car had sat for extended time periods. Left side mixture screw reacted normally but the right side needed to be almost bottomed out for the engine to sustain idle. Front float was to high but did adjust correctly. The rear float didn't want to adjust without much coaxing (and a small fire) but finally got it to respond. Initial timing sitting @ about 8 degrees. Still the fuel smell after driving and then both inlet fittings began to leak and I could smell fuel while driving. That was pretty much the last straw so off the carb came for a rebuild. Course some caveman before me worked on this last as the fuel line fittings are severely over torqued resulting in damage to them and the inlet fittings during their removal. So here we are to right now and now it seems the issue of which of the plethora of PV's to install is solved I can continue on with the re-assy. Thanks to everyone!  :)

Henry
       
Title: Re: Power Valves
Post by: rszmjt on October 16, 2020, 11:01:17 PM
Henry, as far as the fuel line problem, make sure it doesn’t have stainless repo lines, they do not work well and cause lots of leakage problems like you are describing. I always use just the OEM style plain plated steel lines as the stainless offers no conformity to the inlet fittings, plus the expansion rate of stainless always seems to make them seep.

Mike
Title: Re: Power Valves
Post by: Henry Cloutier on October 16, 2020, 11:31:20 PM
Hi Mike,

I guess I'll just say oh crap as the replacements I ordered are stainless. I didn't figure they would cause a problem cause I've seen many different vehicles thru the years sporting stainless lines. I am becoming aware however of vastly different levels of quality when shopping parts for the classics.  Aahhh the saga continues...

Thanks for the info!

H
Title: Re: Power Valves
Post by: z28z11 on October 17, 2020, 12:42:35 AM
Henry, as far as the fuel line problem, make sure it doesn’t have stainless repo lines, they do not work well and cause lots of leakage problems like you are describing. I always use just the OEM style plain plated steel lines as the stainless offers no conformity to the inlet fittings, plus the expansion rate of stainless always seems to make them seep.

Mike

Mike,

Perfectly correct. It takes a lot more torque to seat the stainless inverted flares, as the SS is usually not anywhere near as ductile as the OE steel versions - that extends to reproduction brake lines as well.

Regards,
Steve
Title: Re: Power Valves
Post by: firstgenaddict on October 17, 2020, 01:54:28 AM
I had issues with the Stainless flared tube not being concentric and would not seal well.
I ended up doing the following...
I "LAP" them in...
With the carb off the car, apply a dab of grease or oil to the flared tube end... hand tighten the fitting, spin the entire tube around and around in the fitting, tighten a little more, spin a couple of times, tighten slightly and spin... repeat with EACH connection and they should seat without leaking.
 
Title: Re: Power Valves
Post by: Henry Cloutier on October 17, 2020, 12:16:16 PM
Hello James,

I'll give the lapping a try. The fittings aren't installed yet so I should be able to accomplish this on the bench.

Thanks,

Hank
Title: Re: Power Valves
Post by: rszmjt on October 17, 2020, 02:09:16 PM
I Hope the lapping works for you, it’s a good idea, I’ve never tried that. When I worked at the Corvette/Camaro Restoration shop for 20 years we tried many sets of stainless lines brake & fuel from different vendors, but never had a lot of success with them. They always seemed to leak or sweat. We finally quit buying them and only ordered and Recomended original type lines. Most of the time they were nut & bolt restorations and stainless looked wrong anyway. Fuel is bad enough but brake fluid takes paint off, a lot of customers were not very happy when that happened. Good Luck & keep us updated.
Cheers.
Mike
Title: Re: Power Valves
Post by: Henry Cloutier on October 17, 2020, 08:12:39 PM
Thanks Mike,

Will do on the updates. I need her running again. I thought the stainless would look a little more attractive which is why I picked it. I knew when I bought the car she needed a little TLC so here I am. It's been awhile since I owned the 68 and for sure have not kept up with the classics. Trial by fire as they say so I learn from you all every chance I get. I had a timeline in my head what should come first, second etc, so now with the fuel leaks experienced needed to change the order. Much to do yet, 1 step at a time!

Thanks for all info provided and look forward to much more!

Hank
Title: Re: Power Valves
Post by: Henry Cloutier on October 22, 2020, 03:51:06 PM
Hi everyone,

First thanks for all the info already provided! The Z is back together and I have issues I didn't have before. The idle is more stable and the engine seems a little cleaner in its response except the is now a stumble every time gas is applied. Its fine right off idle but at any cruise speed if the gas is applied the is a stumble. Cruise is about 2200-2300 rpm. I had one backfire occur during the test drive. I checked for vacuum leaks and could not find any. I'm wondering if the power valve is incorrect now as the primary one taken out was an 8.5 and I put a 6.5. The jetting is currently 69's primary and 73's secondary. I also think the engine doesn't pull as hard as before the carb was taken off.
Any ideas are greatly appreciated!

Hank
Title: Re: Power Valves
Post by: z28z11 on October 22, 2020, 04:17:25 PM
Starving for gas off-idle, open up the accelerator pump squirters as much as you can. and/or change the pump cam to a more aggressive ramp. 30cc standard pump is sufficient, it just needs to deliver more gas at the initial opening of the throttle. As I mentioned before, a more common problem with the 4053/302 combo than you would think.

Have MacNeish rebuild/recurve your distributor while you're at it - timing should keep up with the carb. If you're running an original 1111480, advance springs are likely shot or may have been changed, bushings wear, things do get sloppy with age -

Regards,
Steve
Title: Re: Power Valves
Post by: Henry Cloutier on October 22, 2020, 04:49:11 PM
Hi Steve,

My initial thought was/is accel pump except it wasn't doing this before. All I changed was the diaphragm during the rebuild. There were three diaphragms to choose from so I picked the one which looked closest to the one removed. The others not installed had much more stroke to them. That and new  power valves as mentioned. The stumble doesn't happen off idle but once the throttle blades are cracked and the throttle is pushed it stumbles.
Thanks for helping!
Hank   
Title: Re: Power Valves
Post by: Henry Cloutier on October 22, 2020, 05:16:48 PM

I rechecked what came in the kit and figured out what they sent. Two shallow and two deep diaphragms obviously for single or double pumpers. Silly me... I wonder if rebuilding this carb uncovered issues previously masked by other things?... I honestly don't know what accel pump cam is on it now. It was not removed during the cleaning.

Thank you for helping!

Hank
Title: Re: Power Valves
Post by: rszmjt on October 22, 2020, 10:05:01 PM
The kits come with 30 cc diaphragms and 50 cc. R4053 carbs use the 30 cc. The green diaphragm is a GFLT type used for alcohol, I use them a lot because today’s ethanol based fuel seems to petrify the stock rubber diaphragm.

As suggested the dist may need a recurve, the stock GM advance curve is brutal, you might want to try bumping initial timing to 10-12, also make sure vacuum advance is OK.

Mike
Title: Re: Power Valves
Post by: rszmjt on October 22, 2020, 10:16:34 PM
Stock jetting is 68/76 BTW, typically it’s 1 jet size leaner per 1,000 ft altitude
Title: Re: Power Valves
Post by: Henry Cloutier on October 22, 2020, 10:31:39 PM
Thanks for the jetting, Someone in the Z's previous life has re-jetted, why they went up on the primary side and down on the secondary side makes no sense to me. I was used to the other way around back in the day. Wichita altitude is 1300 ft. prior to rebuilding the carb the z was running fine, no stumble or accel problems I just couldn't live with the fuel leaks any longer. I've already had one fire, definitely don't need another.

Hank
Title: Re: Power Valves
Post by: Henry Cloutier on October 22, 2020, 11:58:27 PM

Hey Steve,

Who is MacNeish? I have no doubt the distributor needs some attention.

Thanks,

Hank
Title: Re: Power Valves
Post by: z28z11 on October 23, 2020, 01:34:52 AM

Hey Steve,

Who is MacNeish? I have no doubt the distributor needs some attention.

Thanks,

Hank

Hank,

Jerry MacNeish, authors the "Definitive Facts" books for 67-69 Z28's and 1969 SS 396 First Gens. Web site for his company "Camaro Hi-Performance" is z28camaro.com . Surprised you've not seen his books (as a Z owner) -

Steve
Title: Re: Power Valves
Post by: Henry Cloutier on October 23, 2020, 11:37:25 AM
 Hi Steve,
Thanks for the info. I haven't run across his stuff and now that I know about him I'll for sure look him and company up. I've only owned the Z since mid July so I'm a rookie at it no doubt. i have wanted one ever since I was a kid. Closest I got back in my teen years was a 1968 Camaro with a 327, 4 speed Saginaw  and 10 bolt rear. Fortunately the 10 bolt was at least a posi rear. I drove the 68 well into my 20's until I finally sold it to a friend. By then it was far from stock. The engine had a Crane 510 solid lifter cam, angle plug fuelie heads,11.0/1 pistons, Offenhauser dual plane manifold equipped with a Holly 3 barrel carb. Headers which had to be shorted about 4 inches a tube since they were off a small block 1957 two door coupe (I had never welded before, man were the beads ugly) and a 4.11 rear gear/Muncie trans.
I knew when I purchased the Z she wasn't perfect and would need some work which I'm happy and excited to do. I'm retired now from 40 years in aviation maintenance and for sure have the time. Unfortunately The are no speed shops like there was back in the day to go visit and build those kinds of relationships. Fortunately this forum exists and I can and am learning from you all when ever possible. I realize I have a ways to go yet and am so appreciative of all the knowledge and advice the forum and everyone on it gives me!

Best regards,
Hank
       
Title: Re: Power Valves
Post by: PHAT69AMX on October 27, 2020, 04:20:11 AM
As to the original Question, imho no functional difference between 2-window and 4-window power valves.  Both are just to prevent the PV from being a fuel flow restriction.  Very early Power Valves with the round drilled holes in theory could be a fuel flow restriction, so the 2 & 4 window units were developed.
  The PV windows do NOT determine the amount of power valve enrichment.  That is determined by the PVCR's, Power Valve Channel Restrictions, which are drilled orifices in the metering block itself, one on each side of the cavity that the power valve screws into.
  Would imagine after the rebuild the Accelerator Pump Arm was re-adjusted?  If not that might cure that stumble.  The Accelerator Pump arm adjustment is directly affected by the idle screw adjustment.  Any time the Idle Speed Screw is changed, an adjustment to the Accelerator Pump may also be needed.  This is due to the Accel Pump Cam being mounted on the Bellcrank, change the idle speed screw, it moves the bellcrank, which moves the Cam, which can change pump arm adjustment.

  Imho, the Primary Idle Speed Screw Adjustment should be done on the bench and set to achieve proper primary transfer slot exposure below the butterfly blades, only a 'square' no more.  Then the accelerator pump and arm can also be adjusted on the bench.  No the tricky part.  Do NOT touch or adjust the Primary Idle Speed Screw again !  LOL  Leave it right there where it was set on the bench to give correct transfer slot exposure...

  The final idle speed once back on the car is done by way of the almost always overlooked Secondary Idle Speed Screw...  which is a pita... but it can remedy a number of tuning woes.
It is a very small flat blade screwdriver 'set screw' with a 'played locking action' is one way to put it.  It is recessed into the #10 iirc threaded hole in the baseplate.
This prevents the Primary Throttle Blade Butterflies from being too far opened at idle, messing up the Primary Accelerator Pump, over exposing the Primary Transfer Slots, and loosing all controlled of the idle mixture delivered by way of the Idle Mixture Screws...  The Idle Mixture Screws get their emulsion from the same circuit as the Transfer Slots.  The Transfer Slots are upstream of the Idle Mixture Screws.  Over expose the Transfer Slots and all the idle emulsion discharges through them and nothing go past the idle mixture screws and the mixture screws no longer ahve any effect.
Here is an image from a Holley document about it.

Title: Re: Power Valves
Post by: Henry Cloutier on October 27, 2020, 12:02:14 PM

Thank you so much for the adjustment info. I've done a lot of reading on Holley's in the last several days. Enough to know there seems to be a division in the adjustment and use of the secondary idle screw as a final adjustment. I have considered trying this and I did notice when the carb was on the bench the secondary's were in fact cracked open; since my only issues were fuel leaks and float adjustment sticking, I didn't change secondary butterfly adjustment figuring they must be alright as adjusted. Cleaned everything up with Gumout and re-assembled. I sure didn't expect the problem created by only replacing gaskets, a diaphragm and PV's. Although I fully understand the possibility the stumble was somehow masked by the way the carb was before I tend to believe the theory if it wasn't broke before I worked on it and now it's broke, I did something to upset the operational balance. Thank you for clearing up the flow question regarding the PV's as I'm finally beginning to piece all the info provided together! I have received and installed new 8.5 PV and re-installed the front bowl. I did notice the accel pump adjusted differently this time; before there was not enough length in the bolt/spring/capture nut to get anywhere close to the .015 desired at full travel. The clearance before was probably .060"-.080." Now it adjusts correctly so I am wondering if perhaps the geometry of the accel pump linkage was changed enough to create the stumble. There is freezing rain, ice and snow here for a couple days so we are parked for awhile. If the stumble is still present I'll probably remove the carb and go back thru it paying more attention to the secondary idle adjustment screw and how much it is actually open. I've also considered the accel pump system is no longer supplying the appropriate amount of fuel following the clean and reseal and was somehow masked by the way the carb was thus requiring a larger nozzle or more aggressive cam. Thanks to you and the group for putting up with my questions and silliness, I will fix this!       
Title: Re: Power Valves
Post by: Kelley W King on October 27, 2020, 07:31:36 PM
just my 2 cents, if it ran ok before I would put the PV you took out back and drive it before changing other things. It appears the only change you made other than gaskets. Maybe the "new" one is defective. Also while you are in there check the gaskets for holes that do not line up or are not there.
Title: Re: Power Valves
Post by: Henry Cloutier on October 27, 2020, 08:44:16 PM

Hi Kelley,
Somewhere in my now vacuum of a brain I had thought to do just that. Unfortunately I didn't have a new gasket to re-install the old one. I ordered a bunch of those along with the new PV all of which arrived yesterday. I elected to go with the new PV as apposed to the old one only because it was new (full well knowing new doesn't necessarily guarantee success). Admittedly I have been a little overwhelmed with all this so far. The carb is old, has been into before and I haven't done any of this for many years. All of that together probably equals something could go of the rails. I will fix it and I'm learning a ton along the way. That can't be a bad thing although frustrating at times.
 
Thanks for the input!     
Title: Re: Power Valves
Post by: PHAT69AMX on October 28, 2020, 08:10:38 AM
You're Welcome.
Be sure to lubricate the Needle Assy O-Rings with chapstick or something before screwing it into the bowl.
When reattaching the front and rear fuel bowls, 1st overly shorten the Accelerator Pump Arm Screw with the spring on it.  This prevents the Pump Arm from 'displacing' the Bowl downward when mounting the Bowl and Metering Block to the Main Body.  I stand the Holley vertical up on end when installing fuel bowls.  Install the 4 Bowl Screws but do not fully tighten.  The Bowl & Block assy can be 'wiggled around' in place with the screws almost tight.  "Centralize" this "slop", "midrange it" before then tightening the Bowl Mounting screws evenly in an "X" Pattern, Firm Hand Tight with a NutDriver.  Beforehand for the gaskets I get chapstick on my finger tips and liquefy it between the fingers and then apply it to the gaskets as only a thin film, avoiding any amount in the gasket holes.  "Midranged" Bowl mounting location promotes proper Accelerator pump geometry.  The bowl can be "mis-mounted" a considerable amount up, down, or sideways, due to the "slop" which adversely affects resulting Accelerator Pump geometry.

Imho the Secondary Idle Opening is whatever it want's to be.
The driving factor is the Primary Idle throttle opening must be correct relative to the transfer slots.
Primary is set on the bench, then not changed, unless closed further, which is unlikely.
Then once on the car all idle speed adjustments are made by way of the secondary idle speed screw.
Valve Adjustment, Initial Timing Advance, and Advance Curve must all be set 1st and not changed,
as changes to any of those will change the carb idle settings.
The Vacuum Secondary will also operate considerably better with sufficient secondary Idle opening.
The Vacuum secondary diaphragm is acted on by Venturi Vacuum, not manifold or ported.
Venturi Vacuum pick up ports are high up in the main body venturi bore just below the pinch point
and it has an opening to both the Primary and Secondary Bore on the passenger side.
So airflow on the primary side creates a venturi vacuum signal, BUT it must 1st overcome the "leak"
of the same common passage opening also on the Secondary side which has minimal to no air flow
creating basically no secondary Venturi Vacuum signal IF the secondary butterflies are almost or basically closed at "idle"...
Cracking the Secondaries more at idle increase "idle" air flow through the Secondaries,
which increases secondary Venturi Vacuum Signal, which reduces the "leak" the Primary has to overcome,
therefore resulting in a "better" more positive Vacuum Secondary actuation.

Put this is all just opinion, discussion, & bench racin', not at all intended as "gospel", or "the only way".
Title: Re: Power Valves
Post by: Henry Cloutier on October 28, 2020, 09:08:52 PM

Hello,
Very good information and this helps me understand the workings of the carb. Many people have jumped on this thread to assist me with the troubleshooting and possible avenues of repair. It's up to me disseminate all this info in order to get the Z running properly again. I very much appreciate all the help and guidance provided! I'm almost ready to start her up and check for leaks, course now the weather has changed for the worse. I did install the  missing choke bimetallic spring assy. during the carb re-installation and now I need to figure out what the engine needs for the start sequence. Seems like I remember needing from previous experience to pump the gas 2-3 times before turning the key in this now cold weather pattern. More to come as I work thru this troubleshooting process.

Best regards,
Title: Re: Power Valves
Post by: Henry Cloutier on November 01, 2020, 09:49:40 PM

Hello everyone,
Happy November 1st! The Z is back up and running. The replacement of the PV appears to have cured the stumble.  The throttle response is clean and the engine accelerates smoothly thru the gears. I also finally was able to get to the initial timing setting. It was sitting at 8 degrees and I bumped it to 10 degrees. The engine liked the new setting, so much so I'll try bumping it to 12 degrees next time I'm under the hood. Thank you all for the valuable info and insight during this process. For sure I made some rookie mistakes during this carb rebuild/troubleshooting scenario which I will not let happen again.

Best regards,

Hank
Title: Re: Power Valves
Post by: Kelley W King on November 02, 2020, 01:25:19 PM
It is possible that your cam is not exactly a 302 spec cam or your carb has a port partially clogged. The different PV makes up for the situation. But when I have a Holley that runs well and does not leak I call that good.


















Title: Re: Power Valves
Post by: Henry Cloutier on November 03, 2020, 12:47:58 AM

Hi Kelley,

Agreed everything is possible and I don't have any previous maintenance records, My best guess is the cam is still OEM issue for the vehicle. All indications are this car had two owners last changing ownership in 1985. At that time the mileage was not quite 14k and I bought it with 31,832 showing. Numbers match on the motor and all appearances are the car car sat for extended periods of time, I'll never be sure. It is possible there is a plugged or clogged passage in the Holley...I cleaned everything as best I could using Gum out carb cleaner but for sure don't have the dip processes that would be available to those shops who do it for a living. She is running running better than when I started following the final changes so I am calling it good!

Best regards,

Hank
Title: Re: Power Valves
Post by: firstgenaddict on November 24, 2020, 04:52:05 PM

Hello,
Very good information and this helps me understand the workings of the carb. Many people have jumped on this thread to assist me with the troubleshooting and possible avenues of repair. It's up to me disseminate all this info in order to get the Z running properly again. I very much appreciate all the help and guidance provided! I'm almost ready to start her up and check for leaks, course now the weather has changed for the worse. I did install the  missing choke bimetallic spring assy. during the carb re-installation and now I need to figure out what the engine needs for the start sequence. Seems like I remember needing from previous experience to pump the gas 2-3 times before turning the key in this now cold weather pattern. More to come as I work thru this troubleshooting process.

Best regards,
Did you see how to set the choke correctly - adjust by bending the dogleg in the arm coming up to the carb from the bi metallic spring?

When you depress the accelerator it will set the choke HOWEVER if you hit the gas pedal at all after the car starts it will come down off the fast idle.
So I don't have to crank and crank and crank - If my car sits a week or longer I fill the fuel bowls and give a squirt down the primaries... press the accelerator once and fire it off.

FWIW The worst problems I have had ARE when I do not let the car fully warm up, it spits and sputters because of the long aluminum runners on the intake and fuel falling out in liquid form on the intake floor.
Title: Re: Power Valves
Post by: Henry Cloutier on November 24, 2020, 11:37:57 PM

Hi and the arm came with a bend in it from the kit. I needed to bend the fast idle arm to engage the fast idle cam. Choke plate closes to about a 1/4 "from fully closed and the idle speed comes up to about 1100-1200 rpm before I kick it down some. I've seen data suggesting the fast idle speed should be up around 2200 rpm which seems really fast to me. I'll probably give the fast idle arm another bump to increase it slightly but otherwise it all seems to be working nicely. For sure she's a little cantankerous until wormed up. I figured out not to back out of the garage until the temp gage is up off the peg and then gentle on the throttle the first few minutes of driving.

best regards,

Hank
Title: Re: Power Valves
Post by: firstgenaddict on November 25, 2020, 04:40:08 AM
Sounds like you have the arm adjusted right, yes the fast idle should be more than 1100-1200 -I believe 2200 is correct, it does seem high to me as well, however mine is in that area as it will cost me points in NCRS judging.
FWIW if the intake is REALLY cold it needs the engine speed to keep the fuel in mixture- try driving one straight off start and they wheeze, pop, and snort.