Inliners International Forums General Discussion Engines Mechanical Advance Weights

Does anyone know what the difference between mechanical advance weights with different numbers on them.

I have three stock distributors and one has '254' stamped on the weights and the other two have '106' stamped on them. The 254 weights came out of junkyard 292 (year unknown as it was originally a V8 truck) and the other two came out of junkyard 76 Nova's with 250s.

The 254 weights appear to be heavier than the 106 weights and they they are not shaped the same.

Jim,
Cannot help with the #'s.

I would recomend getting a Moroso/ Mr Gasket/ whatever HEI recurve kit. They are less than 15.00 from anywhere and the same as a V8 application. They come with weights, springs, and instructions to curve it right in just a few try's.

While you are at it get a adjustable vacuum can, also the same as V8.

Keep up the good work! Tom

The shape is a very complex subject. As the weights speed up, they fly away from the center post and increase the point plate advance.
However, the rate at which this occurs does not depend entirely on the spring tension vs. actual weight mass (which would be nearly linear). Instead, it's intentionally "shaped" by what exact curvature of the weight's nose is acting against the stop, which changes as the weights move.

Tom,
I did get a kit from Mr. Gasket, but the bushings and weights wouldn't fit on the pins under the rotor. I did install the lightest springs and it helped a bunch.

But, I'm concerned. Is it possible that inorder for me to be at 35 degrees total timing (base + mechanical) that I have to have the base timing set to 12 to 14 degrees advanced?
I ask because that is where I'm at now and it runs best there and my vacuum is highest there. I think my mileage is best there also, but I my idle is too high, 875-900 (which doesn't bother me.)

FYI - currently my mechanical advance is in full at aprrox 2400 rpms. My only dilemma is that I'm running 67mph at 2250 (the 33" tires are being replaced soon!)

Also, wondering if my vacuum is correct. When on a relatively flat road (low throttle demand) I'm running about 8-10 in of merc at 2300 rpm's. On a grade I can keep it at 6 in.

Is this an old Delco-Remy six cyl distro with really low value mechanical advance? I've got one on my Brand R engine. From the factory it would do 11 degrees mechanical advance total! No aftermarket available.

I hacked my distributor to get about 20 from it. Here's the description: http://wps.com/AMC/195.6OHV/Distributor/index.html



Your light-load-cruise vacuum sounds too low. Could be too low cruise rpm, even under-square motors from the 50's on should be over 2000 rpm at your target cruise. The motor may be OK with all that pumping but the low vacuum means you're probably driving the carb on enrichment circuits (eg. power valve) and that's bad for mileage. If you bring cruise RPM up you might find cruise vacuum goes up.

With light load/high vacuum, and correspondingly lean-ish mixture, then the vacuum advance unit will help the thin mixture. All this junk interacts, and it can be a bear to wrestle it into cooperation.

It might simply be that your 33" tires dropped cruise RPM and caused all your "tuneup" problems...

Jim,
12-14 base timing is ok , esp if it starts good. I like to see 34-36 timing mech+ base at WOT. On the highway rpm timing should be 40-45 or maybe even higher.
My engine on the highway vacuum runs at 10-12 on flat ground and around 5 inches on slight grades.
You have less motor,so it has to work harder , thus less vacuum.

More people need to hook up vacuum gauges.

Now, what carb are you running? If a Holley, get a power valve that opens around 3-4" vac and you will get much better economy.

x2 what tlowe said.
My 250-1v (or 250-4v right now) runs its best at 12 initial and 34 total, all in by 3000rpm. Add about 10-15 degrees vac advance to that for cruise and it's just about right. Mine is the pre-HEI distrib so the parts are different from v8 stuff.

Sort out the spark and vacuum spark before choosing a power valve. The valve should be closed under normal cruise, and only open on a significant grade.
Too low: no response when you accelerate slightly, engine runs lean under load.
Too high: you're at full rich nearly all the time, wastes gas.

tlowe,DeuceCoupe and Panic are correct.

35* total @ 2200-3000 RPM (As low an rpm as possible without detonation under load)(Mech + Initial)
10-15* vacuum (45-50* During cruise)

Ron

Tom,
I'm have a 390 Holley.
How do you check the timing when driving? I tried to get my son to get under the hood with the timing light, but he wouldn't do it. He claims he's claustrophobic. I told him he was being wimpy.

Just kidding. I assume your electronics monitor that on your El Camino.

I've done several things over the past week. Based on Panic and Tony P's advice, I ran my vac gauge into the cab and then drove it aprox 800 miles (I commute 118 miles a day). Changed the base setting at every fill up. I worked my way up to 37 degrees advance at 3K and my mileage has improved (but still not very good-14.5.) I took your advice and bought an adjustable vacuum advance. I drove it tonite and adjusted the base timing and vac cannister (about 12 times) and found that the highest vacuum is achieved at 41 degeees at 3K with vac can as loose as I can get it. But I only picked up 1 inch of merc and it doesn't start as easy as it was (I checked starting at every adjustment.)

I also did one other thing to the distributor. I ground out the stopping point on the mechanical advance in an attempt to get to full mechanical advance before 2500 rpm's. I was successful. It hits at 2300 and it eliminated my 'stutter' at 2200 and it improved acceleration and vacuum upto 3K.

You made me feel better about the vacuum readings at cruise speed because the best I could get was 12 inches of merc on a flat stretch nand all the local guys are V8 dudes and they all told me that I should be 15 to 18.


Panic and Tom,
I'm just under 5 inches of merc at mild throttle. Are you saying that I need a power valve that opens at less than this?


I'm going to turn the total timing back to 38 and leave the vac can as loose as possible. But I have to say that at 41 total timing was the first time I was able to leave a stretch of rubber on the road in second gear (33" inch tires and a posi! - thanks for the all the help so far)

If you have 5" and the valve is open, it's dumping gas. You need a 3.5 or so.
You may also have a different problem.
Have you already sized your main jet for best economy? It doesn't control acceleration, that's handled by the pump, then the PVCR.

I dug out my carb spec sheet (my carb guy supplies one with every carb he does) and low and behold I have a 6.5" power valve which menas it is open waaaay too much. I'll be changing to a 3.5" asap. I confirmed on Holley's site that they recommend 1-2" less than light acceleration vac pressure.

Hopefully problem solved. I let you know what happens to the mpg after getting it changed. Live and learn.

Thanks again Panic and Tony P for recommending the vac gauge. It helped me explain to all of you and understand what was going on! I would recommend it for all performance/mpg diagnosis.

which menas it is open waaaay too much

This may just be a choice of language, but the power valves do not regulate the amount of gas - they're just the on-off switch. A 6.5 releases the same amount of gas as a 3.5, the only difference is when.
He didn't specify the PVCR, because he didn't change it (IDK the size). You won't know if the size is correct until you select the main jet, which (as I said) controls all light throttle cruising. Then, WOT mixture is adjusted by changing the PVCR diameter, which requires a drill with the standard carb, or a new metering block.

Panic,

'way too much' means too soon and too long, basically when it it is unneeded.

I don't know exactly what 'PVCR' refers to.
The power valve feed holes for the front and rear are 'stock'.
The needle and seat for front and rear are .100
The accelerator pump is .30 cc
The shooter size is 25
The front jet size is a 59 (stock is listed as 51)
The rear jet size is 'Plate #31 stock'

All the other settings are listed as stock. My carb guy said to make sure to save the sheet for future mods to the carb.

If it isn't obvious yet, I'm no carb tuning specialist. I've never had a Holley until my carb guy built this one for me.
But, correct me if I'm wrong, currently my mileage is not as good as it could be due to the power valve opening under light acceleration, right? And, most likely the #59 jet is not the 'perfect' jet for mileage for my engine, but based on the performance I don't think that it is way off, do you think?

Previously I changed the spring for the vac secondary to get the secondaries to come in later. I did this because I thought they were coming in too soon casuing a light throttle response (bogging) problem. After the going to the second stiffest spring possible the bogging problem did improve dramatically. But was planning on having to change it again after I get the power valve situaton under control.

All advice always appreciated.

The Power valve Channel Restrictions (PVRC) are a part of tuning a Holley not known by many.
The power valve add's additional fuel above what the main jets can give. It is simple to tune them , but patience is key. Buy a numbered drill set. Find the one that is the same size as your PVRC. For example :to add 10% more PVCR flow. Calculate the area of the size bit you find to match existing hole. Now calculate 10% more area in size and find the corresponding bit. Use a hand operated grip to run the bit in. Now the PVCR will flow 10% more fuel.
Maybe you will want to start with less than 10% change, but you get the idea.
The goal is to run normal sized main jets for fuel economy and let the PV supply the fuel when really getting on it.

What list # is your 390 carb? It may not have PVCR in the rear, infact no power valve. Just a plate or jets?

The 390 CFM (list #8007) has .038" PVCR.
The normal sequence is to find the best main jet for mileage first.
Then, test the WOT the easiest way by using a larger main jet (yes, this will temporarily ruin mileage) so you don't have to modify the PVCR more than you need to.
Go up in main jet until your 1/4 mile speed does not increase (last change = no result).
Now reduce the size by 1 at a time and test.
When it starts going down, STOP. Add 1 to the jet number.
Now you have the total of MJ + PVCR "best power" area.
Calculate the MJ area: jet ID (not the size!)^2 * 1.5708. Example: .060" jet area is .00565"
Add the existing PVCR area: .038^2 * 1.5708 = .00227".
Total area is .00792".
Subtract the "best mileage" jet area, example .056" = .00493".
The result is the new PVCR area, .00299".
Divide by 1.5708, then take the square root.
The PVCR should be drilled to .043" (#57 drill).

Now, put the mileage MJ back in.

I would recommend a wide band O2 reader.
This will take out the guess work.

MBHD

Thanks for explanation guys, I get it!

I had heard of drilling out out a port in the metering block (PVCR) before, but really didn't understand the process due to my lack of knowledge and/or a poor explanaton. But now I see.
My carb guy made mention of this. He showed me a box of metering blocks (about 10-12 blocks) and they were all labelled with the size that they were drilled.

I've mostly read and heard about the 'trial and error' method(voodoo system) of carb tuning. Basically keep trying different combinations of this and that until you're happy, and when you are happy it's a mystery as to exactly what was done (VOODOO! - I hate it).

So, for the 1st step, I'll be changing jet size and monitoring mileage closely. Based on your experiences, do you guys think a #59 MJ is reasonably close jet size or should I start smaller or stock (my carb guy was real clear that most of 390's he rebuilds are not for inlines)? Or isn't there a good way to determine an appropriate MJ size due to too many variables?

Based on your low vacuum reading (and clean plugs?), I'd start with 1 or 2 sizes smaller than you have now - very carefully. If vacuum goes up, drop another size.

For safety, I'd leave the 6.5 PV in there for now to prevent a small MJ from producing any knock by accident.
You can't replace it until you know your final cruise vacuum anyway, when the test for MJ is complete.

There are differently configured 390 holleys. The 8007 is real good for use on 6 cyl. There is also a 6299 list which is better for 4 cyl apps. They are both configured different. May even be a few more made thru the years. That is why I asked about the list #.
I would put in the PV that is closer to the needed application. I doubt that any vacuum will be gained. Then the MJ can be tuned for correct cruise without the excess fuel from PV. Maybe start back to the stock jet size for a #8007 carb. If it runs good at cruise then start playing with the PVCR to gain fuel for getting on it. Tom

My data shows no PV for the 6299?

My 1992/1993 Holley book says the same thing. I own a dissasembled 6299 and just looked. It has a front PV, correct stamped plate with tiny PVCR. They are almost pin sized. Tom

It's an 8007. I ass u me d that there was only one 390, but whad da I know.

Panic, you answered my next question - should mess with the PV or MJ 1st. I'll get some specifics from my carb guy about how to change them. I guess I'll try a 51 1st as Tom said (it's as good a starting point as any), then increments of 2 to see what happens. And of course keep watching the the vac gauge and mileage and recording the info (I've made so many changes lately from timing, different weights and different modified rotors, I need a new notebook)
My carb guy told me that he changes the jets, if needed, after every run with his drag car based on plug appearance - it must be relatively simple, even for me.

Tom,
Thinking while I'm typing, I probably should put in a lower PV, 3.5 for now, as you recommend and that way my data won't be affected by the PV opening. I can change it after I get the MJ set right.

Panic,
Regarding the plugs, 1,2 ,5 & 6 look perfect, but 3 & 4 are carboned minorly. The 1st time I found this I readjusted the valves (1st time since rebuild), but after another 800 miles they looked pretty similar.

An update and of course a question.

Downed the PV to 3.5. It's too low for good acceleration, but it seems to work great for checking mileage. I think I will end up putting in a 4.5 or 5.5 based on cruising and acceleration vacuum levels.

I'm on the 3rd change of jets. I'm down to #53 jets from #59's, which is where I started. The mileage has gone from 12 to 16.5 mpg! A 37.5% increase :).

But with the #53's the plugs began turning a light shade of white (lean indicator). Question, is a light shade of white OK, or should I go back to #54's?
I think I'm ready to drill the PVCR's (after you guys let me know about the plug coloration) as described by Panic and T Lowe in previous posts. And then I have to adjust the secondaries, via a spring change, to come in a little quicker. They're currently coming too late (but I think that's OK while I'm checking mileage.)

FYI, with the #53's there is a noticeable difference in performance from the #59's - sluggish is an understatement! The performance has steadily decreased as the mileage has increased.


On another note, presently the carb jetting has taken a back seat to a brake issue. Over the July 4th weekend I towed a 2500lb boat and trailer and had to make a panic stop at 65 mph on an Intersate (people drive like idiots! ) It pushed up the schedule on the manual front drum conversion to power front discs. Hopefully it will be done within a week or so.

Looking for input - Thanks

When I was,, sort to speak,,guessing & reading plugs if too lean or rich,way back when,,one way I would check the cruising circuit,I would have the engine turn about 2000-2500 RPM range in neutral & hold it @ that RPM,if the engine was too lean,the idle would go down a bit & seem to run a bit rough.
Doing it this way,you do not need to drive your vehicle all over the place,change jets & drive again. (Saves time)

That was one of the best ways to check if your too lean on the cruise circuit(lack of proper terminology),@ least it was for me.
Hope that made sense

Now I just check the A/F ratio w/my LM1 from Innovate.

I also purchased an LC1 on Ebay,cheapest I found anywhere.
The LC1 is a set-up that stays in the car you want to keep it in w/a gauge to read."A stand alone kit"
Here is the lowest price anywhere & I got it even less than advertized.
http://cgi.ebay.com/ebaymotors/ws/eBayIS...RK%3AMEWAX%3AIT

If you are interested.I would highly recommend one if you want to get an accurate A/F ratio reading & take out the guesswork & much less time to jet properly.

MBHD
I just bought a boost controller from him also,great prices!

Re: 1,2 ,5 & 6 look perfect, but 3 & 4 are carboned minorly

This is pretty common for center-mounted 4 bbl. (the center pair has more demand because it's closer), but the real question is: is it also true at full throttle?
If you can get to it you can modify the floor of the manifold to reduce the amount of fuel entering the 3-4 with a shallow ditch across in front where the runner takes off from the plenum floor (and it's got to be squeaky-clean afterward). Use a Dremel and a 1/8" bit, and just drag it along the face of the 3-4 runner inlet.
This will allow even leaner jetting (they'll all run the same) by perhaps 1 jet size.

From your comparo of accel using 53 vs. 59, we know that you need more PVCR than you have. 59 may already be too rich, so try both ways at WOT for test.
Once you pin that down (using the wrong main jet to supply the extra fuel to calculate how much the PVCR has to go up) you can go back to the 53.

Jimw,
I would be OK with the light shade of white. Does the engine at highway speeds have any stumble or bumble to it?

Hank,
Checking the plugs while only in the driveway @ correct rpm is not using the carb circuits the same way as a load on the road. I think on the road is more correct way to do it. Agree on the WBO2.

Next get the PV to open when you need it.

Can you tell the secondaries are opening at a certain RPM?

The work you are doing will help many other people tune a 390 for great street use, keep it up. Tom

Hank,
Thanks for the LC-1 link.
The same guy (I mean, person, who knows??) lists an LM-1 kit too:

http://cgi.ebay.com/ebaymotors/Innovate-...eQ5fCarQ5fParts

It sounds like you have both an LM-1 and an LC-1. I have neither but am also tuning a Holley 390 (4150 List 6390) and other carbs and also tired of guessing.
I do have a computer (my older one even has a serial port) - which would you suggest, the LM-1 or the LC-1?

JimW and Tom,
I am also setting up a Holley 390, List 6390, a 4150 used on International Harvester's 392 v8. Hmmm. Anyway, Stock jetting is 50 pri, 51 sec, I am running slightly richer at 52 pri, 52 sec. PVCR's are .028" pri and .031" sec as I measured them. Currently, this carb and jetting are winning the carb shootout I am doing.

Tom, if you have a 6299 apart, can you use a wire or something and measure the PVCR? Also, the 6299 is said to have an "inverse power valve which closes when vacuum is low" (Urich and Fisher, "Holley Carburetors" 1972, pg52). I could never figure this out. Does your 6299 have this? Otherwise, I can't see where the 6299 is any different from any other Holley. I've heard of reverse IDLE but never seen a reverse Power Valve.

JimW, ditto, can you try to measure the PVCR in that 8007 next time it is apart? Des Hammill's book pg 22 says PVCR .038" but that sounds too big, maybe. Also, you said the metering plate is #31,I can't find that plate #, but the Holley charts I have for 8007 show either plate #34 or plate #59, both of them with .052" secondary main holes. If yours is a #31 plate, what size are the holes (in the bottom)?

Agree with Tom, maybe we can sort out more on the 390 Holley here.

As a side note, the first 390 Holley was also the first 4150 Holley, used on the 1957 Ford 312/245hp, List 1272-1273. I actually drove an original in the original car back around the mid-70s.

Duece,
I will check my 6299 carb.
Here is a tip if using a WBO2 sensor/ gauge. No engine runs perfect at stoich fuel mixture( 14.7 to 1). My engine has been using a WBO2 since going turbo and EFI. By no means does my engine run best for idle/ cruise even near 14 to 1 fuel mixture. And full boost requires much higher mixture. The WBO2 will be a quick and easy way of taking reference readings, Once the correct mixture is found for a certain RPM/ load the you will be able to reference that.

For instance:
Gm says to set idle timing at 8 degrees but Jimw found that 12 degrees worked best for him.
Books say cruise mixture for a (390) carb should need a 51 main jet, but running it shows that a 53 jet works better. While measuring the mixture with a WBO2 will show possibly a 12.75 mixture. Books say it should be 14.7. Whats up? There are too many factors that can change the desired mixture for your engine. Timing, compression, fuel, combustion chamber, quench to name a few. So each engine will need a different than stoich mixture.


I would suggest using the gauged unit.

This way is a quick & easy way to go & get you closer to where you need to be instead of trying different jets,go driving,try different jets then go driving again & so-on. Saves time.
You will know right away if you are too lean in the driveway & say 2500 RPM it will not want to say @ 2500 or will be missing & not running smooth.

I am not saying this is the way to get correct jetting period & no further jetting will be required.

It's just a quick & dirty way to to get close to being as lean as possible & work your way back up.Saving time.

It does not hurt your engine being lean & missing a bit a a few seconds @ 2500 in neutral.

All this testing @ 2500 RPM (no driving required) can get your carb adjusted quicker for running on the primary jets.
Thats all I am saying.

As far as which unit to use the LM1 or LC1?

Well,if you are going to adjust A/F ratios or monitor A/F ratios on different cars,get the LM1 along w/one of these http://cgi.ebay.com/ebaymotors/INNOVATE-...sQ5fAccessories

If you just want a permanant install on a particular vehicle,get the LC1.


MBHD

That is not what GM says 8 degrees for what works best for power or mileage.

GM sets it at a certain timing for less emissions.

My moms 73 Nova 250 L6,,, GM set timing low for emissions.

I used to advance the timing to get better performance & better mileage.
The best mileage my Moms car ever got on road trips was 16 MPG,after I adjusted/advanced the timing it got 2-3 more MPG.

When I left the timing advanced & forgeting it was advanced,, I smog tested it,,,well, it failed emissions/smog test.

Put the timing where GM stated it to set it at,,it passed.
Glad we don't need to smog all the old cars still.

MBHD

Duece,
Checked my 6299 carb , the PVCR is .021 or a #75 drill. They are small. The PV circuit looks the same as a 600 holley I have sitting here. The idle circuit is slightly different. For reference, the 500 2 bbl used on the 250 turbo dyno engine had a .070 PVCR, it could flow lots of fuel.

IIRC the 6299 was developed for the Pinto 2.0 liter OHC L4?

It did develop a minor stumble at low RPM's when I put in the #53's. I assumed it was due to lack of gas; there was no stumble with the #55's. AM I incorrect?

I have monitored the secondaries by doing the following :
by using a paperclip on the secondary rod and then pulling up the same hill just below my home at differnt rpm's in 3rd gear and monitoring the vacuum at the same time.
They aren't opening until vacuum is less than 2" and rpm's are above 2500. The higher the rpm's, it seemed the higher the vacuum reading would be when the secondaries will open.


To all to eliminate any confusion,

I found the plugs a light shade of white from normal driving. I have not run WOT for any period prior to finding them like this. This was the 1st time, with #53 jets, that plugs began turning white with 'normal' driving. I have been pulling the plugs to inspect them prior to each jet change to compare.

I intend to do what Hank and Panic advised before I change the PVCR and jets and PV and secondary spring.



It will be a week or two before I get it back on the road due to the front brake conversion.

Deuce,
I'm not sure of the PVCR's other than what has been posted here by those of you with a Holley manual. I have to determine their size prior to drilling, with no guesswork, inorder to deterine my original area for gas flow. That last sentence does sound right, but if you read Panic's post about determining how find the proper PVCR size, then I think you will understand what I mean. A+B=C+D, inorder to find D, then I must know the other three variables, one of which is the original PVCR size.

Yep, there will be a hesitation when stepping on the gas when your pri jets are a bit too small for best acceleration,,, but there are ways around this w/out having to up the the pri jets to get rid of this stumble.
A larger acclerator squirter,changing the cams for the squirter,& other ways.
Might be a good time to pick up a good Holley book for tunning so it could help you out w/the different settings,how to cure stumbles & so-on..

Now,,,Because ,when you were cruising around w/the 53 jets,you think it runs fine & the plugs look good,but you need to get rid of that stumble but want the mileage the 53's are getting you ,,what do you do? You can put the 54's back in & get rid of the stumble,or there are othere ways getting around this stumble w/out having to go richer on the pri jets.

I don't have all the answers,,,& sometimes it's hard to find a good or great carb guy locally.

I always liked the Carter AFB's or AVS's or the Newer Edelbrocks,,over Holleys,mainly because the Carters would just keep on running & running & not get a needle & seat plugged,spewing fuel all over the place,guess it was my luck,but I've seen many other friends have problems w/there Hollys @ one time or another.
Kinda tempermental to apoint.

I always got the best mileage w/other carbs than a Holley.

A properly set-up Quadrajet spreedbore carb will give you a bit of the best of both worlds,good mileage & great airflow when needed WOT.
An improperly set-up Quadrajet can suck up the fuel badly also.

The better Holley carbs will have four corner Idle settings IIRC?
Annular discharge,etc.

But I believe,,,those carbs will be the larger ones ,like a 750 or larger,just thinking off the top of my head.

Old Nascar Holley carbs are good for adjusting the mixtures @ 4 corner idle adjustments.,, cruise, top end etc.

Of course there are people that can mod your carb to do a lot of things it cannot do as it is right now.(Stock)

When buying a nice new carb w/all the bells & whistles, you would have spent $1200-$1500 ,@ that point, might as well go to EFI, I think anyways,unless you would be running in a race spec class & need to use carbs, no EFI,,,, I know a bit off topic but just saying ;-)


MBHD

Yes - the stumble is partially the pump cam, don't assume the 53 won't work until later in the game.

An update - FINALLY!

We're down to a #51 jet. The mileage has picked up about.3/mile to just under 17 mpg.

I've discovered two things. 1st, the stumble is occurring just before the power valve opens, whether driving or revving from idle (happens between 4" and 6" of vacuum - presently have a 3.5 PV). I will be changing to a 6.5 next depending on what you guys tell me about my second issue. 2nd, the secondaries are opening when revving the engine from idle.? Just as the stumble dissapates they start to open and they will continue opening until I release the throttle. I have the stiffest spring in the Holley 7 spring vacuum secondary spring kit installed.

Why is this happenning? I thought the secondaries would/should not open when revving the engine from idle? Is this a symptom of another issue or just a lack of gas due to the pump shot being too small, too low a PV, too small MJ's or a combination of any of the above.

I had thought the lack of power prior to the PV opening was just that, but maybe the secondaries are opening at approximately the same time as the PV. I will be checking with a paperclip today or tomorrow. When the vac get to 3-4" during acceleration I can feel the power increase.

As always, thanks for any input

Congrats on the increase!
I would try a 4.5 - 5.5 range PV. I always try to get best mileage,even if there is a slight hesitation for a driver,but for performance, having a hesitation is not a good option.
I think stock for most carbs is a 6.5? Just thinking off the top of my head.

I have a friend that when we were younger,I would try & get better mileage & performance on his street/race car.

I would change & install the smallest jets that would allow for the engine to cruise @ a steady pace, work great,good A/F ratio @ W.O.T.,,,the only problem the engine had was a slight hesitation when cruising @ a steady state of cruise/RPM, when appliying some throttle,not bad, but enough you could notice it.

Well, my friend could not stand that slight hesitation so he had installed two jets 2 sizes larger to get rid of this hesitation.

Sure he got rid of the hesitation,but mileage suffered & @ W.O.T. the A/F ratio were too rich.Which in turn would make his car slower.
This is the same friend that could not understand why I never lost a race (w/my Camro 254 CI L6 engine) when racing his 1966 V-8 Nova,having an engine from 327 CI,355 CI - 406 CI,,good times!
When running the smaller jets I installed, he engine would never hesitate,from idle or by loading up the converter,leaving off the brake for drag racing.

Like I stated before,I am no experet in tuning these carbs, but there are books to buy & people who know these carbs inside & out & know how to mod them for your needs.

Just incase you are stuck @ some point where you have a stumble & you still want the better mileage & you do not want to simply install the larger jets.Books & people are available,most times not free.


MBHD