Holley SA 670 tweaking. Need advice.

[Stanglover]

Interesting, always surprising when it's something simple, but as in this case nearly invisible.

So, is the P II OK, and it was all the cap?

It's possible the cap was cracked out of the box, and the problem only showed up after installing the high voltage coil. When I've found cracked caps it's generally been due to water intrusion, but when we don't expose these cars to water that doesn't happen, takes something else.

I'm glad you got it sorted out, always a good feeling.

Don, it seem to be all in the cap and the P II is still good. Just weird that the brand new one is no good. I tried it twice making sure and double sure it was installed correctly.

The cap that has the crack, has been on the car for the last 6 years without any noticeable issues until recently. Obviously I now know why I was having issues. The wires were replaced last year with 8mm copper wound type and are for sure better with the Pertronix Flamethrower coil. Time to go buy a better Pertronix cap I guess.

Yesterday, I took the car over to my friend with the hoist to replace the shift link bushings and get the shifter operating much smoother. With the new but standard cap, the car pulled better than it ever has, no bog, no hesitation, just a solid hard acceleration up to 5K rpms. Even chirped the tire (one wheeler peeler) in 2nd gear!! Whahooo!

Geoff.

 

[Stanglover]

Geoff,

If it were mine,I would start by trying to lean your engine out at idle.

if you have 18'' at idle you should easily be able to do that, watch the vacuum gauge while leaning and set the mixture where it just starts to lose a little vacuum, let the engine tell you what is best.

Your 13:1 at cruise is OK but you could be as lean as 14:1 with next to no load.

Surprised your tuner says 11.0 :1 is ok at WOT there should no reason to be richer than 12.5: 1 at any time period unless you are using a power adder or running boost.

Your primary jetting is NOT the issue here and guessing the power valve is not either, however the power valve restrictor could be.

I would want to watch your AFR while observing a vacuum gauge and see what your afr does when it is supposed to be opening.

When the power valve opens, you should see 12.5; 1 if it is richer than that you need to decrease the power valve restriction.  ideally when the power valve opens it should give you  the same as adding  of 10 jet sizes . in my opinion you are dealing with a accelerator pump issue, either too small of a shooter nozzle or too small of a accelerator pump cam.

You did not state if you are running vacuum advance and mechanical advance or just mechanical, it could make a difference, also gear ratio and rear tire diameter all play a role here.

Boilermaster

The 670 will provide enough air and fuel until you reach a certain rpm, but it is NOT the issue you are dealing with here.

+1 on Boilermaster's post, very sound advice. I'm not a fan of any of the street avenger carbs. They all run very rich out of the box. Confirm float levels and fuel pressure is correct. The idle channel restrictor (idle jet) and main jet size is too big. The idle insert restrictor needs to be removed and the hole drilled and tapped to accept restrictors with a smaller hole (like changeable jets). Doing this requires proper tools and attention to detail. Set the transition slot exposure to .020-.040 with the idle speed screw. If more than about .050 of the transition slot is exposed at idle the stumble may be caused not having enough of the slot left to support the transition from idle (not the accelerator pump calibration). Optimize mixture screw settings (1.0-2.0 turns out). Fine tuning can be done by changing the size of the idle air bleeds (idle air correctors) and the mixture screws. Check the transition and light cruise next (14.5-15.0). If the idle circuit is right, the light cruise should be right or close to it. Light cruise runs on the idle circuit until about 2500 RPM before the main circuit begins to pull fuel through the boosters. If the light cruise mixture ratio gets richer as RPM increases the idle air bleed is too small. If it gets leaner as RPM increases the idle air bleed is too big. 

I'd get the idle ratio to 14.0-15.0 range then get the transition/light cruise in the 14.0-15.0. This may require main jet and idle restrictors changes. After the idle and cruise are right move on to the accelerator pump circuit. You should not need a .035 discharge nozzle. If you go from near idle to WOT and the engine bogs and doesn't recover the nozzle is too small. If the it initially accelerates, then bogs, and then recovers the duration of the shot is too short and a different cam setting or different cam with a longer duration profile is needed. You do not need the black spring in the secondary. The purple or long yellow spring should work for you. The WOT throttle setting will likely require the Power Valve Channel Restrictor to be made adjustable (like the idle restrictor). You are looking for 12.8-13.4 at WOT.


All calibrations should be done with the engine at operating temperature and the O2 sensor installed in headers collector or reducer or H pipe before the crossover. Tailpipe sniffers are not accurate enough for fine tuning. None of the numbers are absolute hard numbers as there are many variables.


You light detonation may be due to having a spark plug that is a heat range too "Hot". Based on your build the plug for a Boss 351 should be close. I'd use NGKs as they are easier to read than the Autolite plugs. Inhope you get it squared away. Chuck

 Chuck thank you too for your very knowledgeable input. Information like that will be very useful to others I sure. Carbs are a huge mystery to many including myself.

Where I'm at right now and with some changes I made including installing Autolite 25 plugs (had them on hand, so thought I'd try them) I think I'm just going to let it be. The plugs read is a light brown whereas the 24's were a much darker brown after a hard drive.

I will change out the black spring on the secondary's and take your advice on spring choice. They're very easy to change, so no big problem if it doesn't give me better response. 

 I currently don't have that AFR available, but I can borrow it any time if needs be. I reset my idle mixture to about 1.5 turns out with the new, more accurate vacuum gauge I bought and it holds a steady 17"Hg idle (hot) and I'm sure the transfer slot is at about .020" curb idle is around 780 rpm. One other tweak I made was to open the 3/32nd holes in the primary T/plates to .113" (+.020") That enabled the transfer slot to be closed down and allowed the idle screws to be set where the motor idles very smoothly. Other than that, I'm not touching anything else. Like you said, these thing run rich out the box and a tuner at the local speed shop initially drilled the holes in the plates.

Besides, most of my "problems" turned out to be a cracked distributor cap. Who'd have thunk it!!!

I too am not really impressed with the Holley SA carb either, but for now it's what I have until I can justify spending another 5-600 bucks, but then what do I buy?

Geoff.

 

[7173Vert]

FINALLY, today I solved the problem!! I have gone through switching my gas to Shell 91 from another ethanol free premium brand, bad gas thoughts, to stripping and rebuilding the carb, to new plugs, to switching out my Pertronix II (only to find the brand new, never been out the box in the 3 years it sat on my shelf P II was defective and NFG) to FINALLY finding a hair line crack in the distributor cap. That's all it was!! So why didn't I think of that sooner?? What I figured out was the 50000 volt coil is too much for a stock cap. There are burn marks on the contacts, but nothing that would scream out at you. In checking, Pertronix have a cap FOR the Pertronix coils, so I think I'd better order one soon.

Thanks to all for your input, 

Geoff.

I only put Shell Ethanol Free 91 in my car's...

 

[Stanglover]

FINALLY, today I solved the problem!! I have gone through switching my gas to Shell 91 from another ethanol free premium brand, bad gas thoughts, to stripping and rebuilding the carb, to new plugs, to switching out my Pertronix II (only to find the brand new, never been out the box in the 3 years it sat on my shelf P II was defective and NFG) to FINALLY finding a hair line crack in the distributor cap. That's all it was!! So why didn't I think of that sooner?? What I figured out was the 50000 volt coil is too much for a stock cap. There are burn marks on the contacts, but nothing that would scream out at you. In checking, Pertronix have a cap FOR the Pertronix coils, so I think I'd better order one soon.

Thanks to all for your input, 

Geoff.

I only put Shell Ethanol Free 91 in my car's...

 I usually do too, but Canadian Tire in OUR area is also ethanol free, all grades. Most stations west of London, are ethanol free with the exception of UPI and PetroCanada. Unfortunately Petro-Can 94 now has 10% ethanol. What a rip off!! I wish it were mandatory for Ontario gas station to display the Ethanol content on the pumps so we would know when we're getting ripped off. 

In my case, I now know it was not the gas problem. I do get bad gas sometimes, but not that sort!! Ok enough!

 

[Stanglover]

Here's the culprit!! 

Just need to get a new and better cap than the one I currently have on the car. It looks like Pertronix only have caps for their own brand distributors which don't fit the factory dist, pity!

 

[jpaz]

Glad you found the culprit! Something so simple but very tough to find, good catch. Sure sounds like you have it tuned up and running great. Hopefully it stays that way.

 

[Stanglover]

Glad you found the culprit! Something so simple but very tough to find, good catch. Sure sounds like you have it tuned up and running great. Hopefully it stays that way.

 Yes it seems to have solved the problem for now....... until the new caps burns and cracks!! I guess one has to keep replacing them more often.

I sent this to Pertronix as well with the question "why not for factory distributors?"

While I was checking things out, I installed a brand new P II, only to find it was nfg. I can't take it back to the local store as I've had it 3 years in an unopened box, sitting on the shelf. I requested Pertronix take it back and replace it. I'm sure they'd like to know why a brand new module is faulty.

Geoff.

 

[jpaz]

So I guess I may have the same thing going on with my car too. All of a sudden my newly rebuilt engine has been running kind of crappy, but intermittently. I thought maybe I got some bad gas or something. Seemed like it was running rich so I checked my plugs and see what was going on. 5 out of 8 were carbon fouled, the other 3 looked great. So I cleaned the plugs and reinstalled them, and again it was still running crappy, so I brought it right back home. I started checking for any vacuum leaks or anything else that looked out of the ordinary but everything looked good.

I then remembered this thread and decided to check my distributor cap and sure enough, I found 2 small cracks! They were both on the inside and coming from 2 of the electrodes that were not allowing the plugs to fire correctly, I guess? Anyway, Thanks Geoff, this thread has probably save me hours of trying to figure this out! I still have to get a new cap and I’m getting new plugs too, but I’m pretty sure that this is the problem.

So now I’m trying to find a USA made cap locally, but didn’t find any today. I guess I may have to get the one I found on eBay that has to come all the way from Oregon and I’m in Michigan. Can’t believe it I live in the motor city and can’t find any here, oh well.

I just found out that Mac’s has the Made in USA one. Cap and rotor with shipping about 28 bucks. I might even get 2 of them so I have a spare.

 

[Stanglover]

So I guess I may have the same thing going on with my car too. All of a sudden my newly rebuilt engine has been running kind of crappy, but intermittently. I thought maybe I got some bad gas or something. Seemed like it was running rich so I checked my plugs and see what was going on. 5 out of 8 were carbon fouled, the other 3 looked great. So I cleaned the plugs and reinstalled them, and again it was still running crappy, so I brought it right back home. I started checking for any vacuum leaks or anything else that looked out of the ordinary but everything looked good.

I then remembered this thread and decided to check my distributor cap and sure enough, I found 2 small cracks! They were both on the inside and coming from 2 of the electrodes that were not allowing the plugs to fire correctly, I guess? Anyway, Thanks Geoff, this thread has probably save me hours of trying to figure this out! I still have to get a new cap and I’m getting new plugs too, but I’m pretty sure that this is the problem.

So now I’m trying to find a USA made cap locally, but didn’t find any today. I guess I may have to get the one I found on eBay that has to come all the way from Oregon and I’m in Michigan. Can’t believe it I live in the motor city and can’t find any here, oh well.

I just found out that Mac’s has the Made in USA one. Cap and rotor with shipping about 28 bucks. I might even get 2 of them so I have a spare.

 John, damn frustrating isn't it!! Anyway, I'm glad what I went through pointed you (and maybe others) in the right direction.

I found the ad sheet that came with the cap I either have on now or could be the one that failed, not sure, but it's listed as a "high performance cap with brass contacts" from a company called California Pony Cars, www.calponycars.com, 888-225-7669, Ontario California. (not Canada!!) Actually, I have no idea where I bought this from, could be RockAuto or NPD. I know I didn't order it directly and no idea if that company is still out there.

As for plugs, I stick with Autolite, but switched from 24's to 25's which are 1 step hotter. I also have a GOOD 8mm wire set which are copper wound over carbon center sold for the 351C. As you know I run Pertronix Ignitor II and Flamethrower coil on a full 12 V. Plug gap is .045" and plug read is a med brown. Just for S and giggles, I might drop the 24's back in and see what if any difference there is now I have a good cap...... for now anyways!

Funny thing happened last night. The last time I drove the car was on Saturday to and from a car show. After I got home and let the car cool, I pulled #1 plug. I had driven the car hard and fast, so was curious to see the plug read. So last night, I started the car to go to the weekly A&W Cruise-In and it ran like a bucket of bolts again. WTF! Turned out all I had NOT done was to make sure the #1 plug wire was pushed completely onto the plug.

Let us know the outcome,

Geoff.

PS, the link works!!

 

[jpaz]

I will definitely let you know what happens. It looks like I will have to order from Mac’s. I just tried another local place that usually sells good stuff but they don’t have anything else but the Standard brand (more Chinese junk). So I won’t know till next week.

 

[Stanglover]

I will definitely let you know what happens. It looks like I will have to order from Mac’s. I just tried another local place that usually sells good stuff but they don’t have anything else but the Standard brand (more Chinese junk). So I won’t know till next week.

 Brass contact are important imo especially if you have a high voltage coil. Even then, there's no guarantee!

 

[jpaz]

I will definitely let you know what happens. It looks like I will have to order from Mac’s. I just tried another local place that usually sells good stuff but they don’t have anything else but the Standard brand (more Chinese junk). So I won’t know till next week.

 Brass contact are important imo especially if you have a high voltage coil. Even then, there's no guarantee!

Ya, I actually called Mac’s to see if the cap they sell with the brass contacts is made in the USA. It is so I got 2 of them. They also have one with aluminum contacts that is made in USA too. The one I have on the car is the aluminum one and it does have a made in USA logo on the inside, but I ordered the brass.

 

[Stanglover]

I will definitely let you know what happens. It looks like I will have to order from Mac’s. I just tried another local place that usually sells good stuff but they don’t have anything else but the Standard brand (more Chinese junk). So I won’t know till next week.

 Brass contact are important imo especially if you have a high voltage coil. Even then, there's no guarantee!

Ya, I actually called Mac’s to see if the cap they sell with the brass contacts is made in the USA. It is so I got 2 of them. They also have one with aluminum contacts that is made in USA too. The one I have on the car is the aluminum one and it does have a made in USA logo on the inside, but I ordered the brass.

 Good choice imo. Always good to have spares as well these days.

Talking of spares, I just put together another SPA-T variable ratio Saginaw 800 PS box (gear) to have on the shelf in case the current one f's up. It will probably be on the shelf for as long as own the car, but!!!!

Geoff.

 

[jpaz]

Took a couple pics. I actually see 3 small cracks by the electrodes and my rotor doesn’t look to good either.

 

[Stanglover]

Time to replace both. I think we all tend to forget this little item and the trouble a small crack or burn can cause. It could easily leave you on the side of the road...… cursing of course.

Geoff.