Vacuum advance tuning

[Anonymous]

PLEASE unhook the vacuum advance until everything else is tuned correctly.

But why? From what everyone else has said, I do not have too much vac. advance. And contrary to what everyone says, the car performs much better with it hooked up. I've been going about 160 miles on a tank- or about $30 with the autolite - have not checked since I put this yf on. I really can't afford that big a gas bill as I'm not working- the vac. advance stay's hooked up! ( I did more checking today, and the hesitation problem is the same with/without the vac advance)

I've about had it with these parts store rebuilt YF's- $110 and they don't work properly :x I tried richening it up today but that did not help the hesitation. Time to start a thread on YF tuning......

 

[Anonymous]

Thor check out this string for some info. it may answer a couple things and why your getting confused.

http://fordsix.com/forum/viewtopic.php? ... highlight=

Hyprdrv

 

[Anonymous]

Thanks- that's a long thread! I'll read it when I get a chance. I'm convinced my 2nd rebuilt Carter YF is defective, so I'm going to probably step up to one rebuilt by Holley in hopes that it's better quality. I wish could just skip this mess and go to the aussie or argie head setup like I plan to eventually!

 

[JoeTrojan]

I had the SAME problem. Way too much advance from the carb, under laod. During garage tuning, everything looked great, normal advace with RPM, starting at 12BTDC initial advance. All was swell.

BUT, under load, she knocked, especially at higher RPMS.

I have a theory. All Spark COntrol Valves (SCV) are NOT created equal. I had a Holley 1940 w/SCV that I installed to replace my Autolite 1100 w/SCV.

The dizzy was the same.

After years of restoration, she knocked like a banshee when you took again the the road.

Point Dwell error was partly to blame. (BTW Pertronix II has crappy dwell for the load-o's in my opinion.

After endless tinkering with initial advance to reduce knock (I was down to setting idle timing to 0 deg...TDC!!

That is NO way to run an engine.

I contemplated sealing the venturi port in the carb throat to let vacuum fall to near zero under load. THis is a bit power robbing when you want it most...but it is much better than knocking like I was getting. I was too afraid of the epoxy, or whatever plug, getting sucked into the intake if it dislogded.

I also looked at teh SCV to see if there was a way to plug the port in the SCV "chamber." No good method.

Knowing that my Clifford Holley converter will SOMEDAY arrive (hear me Clifford?), I planned to dump the Load-o-matic Dizzy soon. I decided to install the Duraspark Dizzy, even with the 1940's funky 2-way vacuum via the SCV.

I also learned that the load-o-matic dizzy is MUCH more sensitive to vacuum than conventional dizzys seem to be.

I had tried drilliling a small hole in the vacuum diaphram, tapping in a screw to adjust the maximum travel the diaphram could go, thus limiting total advance. It was a little better, but that also prevented full advance.

THe manuals for the 65-66 load-o-matic call for a maximum advance, from the dizzy, of 12-15 degrees, based on year and transmission configuration. Combining that with the initial 12 degrees BTDC called for on my car ('stang with C4), you should have a total advance of slightly less that 30 degrees. My experience is that alittle more advance is fine, so long as the car is not under load 35-40 degrees total advance can run well in some cases; As currently tuned, I'm getting about 35 degrees with no complaints

THe best solution? Duraspark!

THere are dozens of threads and posts espousing the best COMPATIBLE distributor for your 6 banger. Mallory makes a beautiful, highly tunable, dizzy for our ford 200's. It is over $400.00 though! My duraspark, with cap, rotor, wires, harnesses, coil, and dizzy was less than $100.

It works great, and the vacuum adnvance from teh carb makes little difference, though I have it hooked up. THe mech advance is the best way to get proper RPM based advance. The vacuum advance helps the car be much more efficient and clean burning in situations other than performance conditions. Who really cares about that?

On the other hand, with a "normal" (non-SCV) carburetor, the vacuum advance, in conjuntion with the mech advance, are designed to give you the best of both worlds, with the certainty of not having funky carburetor induced excess advance under load.

I posted how I did my Duraspark swap in the following thread, with links to how-to photos...very simple and TOTALLY WORTH THE TIME!!!

http://fordsix.com/forum/viewtopic.php?t=21002

Good luck!

Joe

 

[Anonymous]

I didn't go back and read the whole string but I'll mention this, sorry if it's a repeat.
The Load-o-Matic is a low vacuum dizzy requiring 5-7 in of vacuum to make them opperate. These were dizzy's up to 67 with some of the 66/67 units being from Calif. with dual advance units. The Dual Dizzy's require high vacuum at the dizzy, 16-19 ins. Problem is most of the carbs that are being replaced are the high vacuum ones. Some carbs have a small plug that can switch them from low to high but probably 90% of them are high from rebuild shops. Ok, do you have a low vac L-o-M dizzy and do you have a matching low vacuum carb? Put a vacuum gauge on the carb port (not the manifold vacuum) and see if it only goes to the 5-7 in's of vacuum. If so you have a match, if not your pulling full vacuum or full dizzy advance under most of the curve as well as under partial throttle.
The other thing is the L-o-M dizzy is a small shaft (1/4" I think) vs. the dual advance dizzy (5/16" shaft) drive to the oil pump so you can't just drop a newer dizzy in without changing the oil pump to a later model with the bigger drive size. The end result is a lot of people with miss matched stuff out there and a lot of problems including over heating IMO.

Personaly I think there is a lot of problems resulting from this miss match as well as the old Load-o-Matic distributors. I can't tell you why but I think the L-o-M distributors are a problem in themselves but again I don't know what the reason. Maybe they don't advance far enough, maybe the low lead fuels are the cause of a later burn requiring more advance, I don't know but I find it interesting. Hope that helped and more feedback is generated. I'm still trying to figure the right jet size for my H/W carb on a mild cam 200. But that's another story...

Steve

 

[Anonymous]

THe manuals for the 65-66 load-o-matic call for a maximum advance, from the dizzy, of 12-15 degrees, based on year and transmission configuration.

Keep in mind that the shop manuals list the distributor specs in distributor rpm and degrees. You need to double the distributor degrees and rpms to convert them to crankshaft degrees and rpm. So the max advance is really 24 to 30 degrees.
Doug

 

[JoeTrojan]

I agree, the manual refers to bench specs.

It also makes sense that more advance will work, based on my observation that 35 degrees of TOTAL advance works great. (14 degrees initial advance and also 20+ degrees of dizzy advance.

Your input is well taken and well reasoned.

I have to look at my advance setup eith that valuale info in mind.

Joe

 

[JoeTrojan]

If you do this, you can run ANY carb and get very good performance. You can get a rebuilt/remanufactured dizzy for a bout $50. you have an electronics issue that you must dsolve in a myriad of ways...an electonic dizzy needs to be controlled to send spark to the coil.

Check out this site for Duraspark options : http://home.cfl.rr.com/mustangsix/Engine/duraspark.htm

Do not hesitate to switch to Duraspark. It is a world better. My next contemplation is the MSD 6A box.....could it make me as happy as the switch to Duraspark's electronic ignition does???? I'll let you know when I get it going.



Again - best of luck,

Joe

 

[Anonymous]

Problem is most of the carbs that are being replaced are the high vacuum ones. Some carbs have a small plug that can switch them from low to high but probably 90% of them are high from rebuild shops. Ok, do you have a low vac L-o-M dizzy and do you have a matching low vacuum carb?

This is part of the problem- I have a single advance '68 distributor, but the vacuum can is of the dual advance style off the distributor that was in the 200 when I got it (I'm using it because the cannister on my newer distributor would not come apart to put shims in to adjust advance, and I ruined it trying to do so). The retard vacuum inlet on the side is plugged. The carb I'm running at the moment is a '70 carter YF, but it's a rebuilt unit from the parts store and I've had all sorts of problems with it. I'm not changing to a differant distributor- this one is not very old and I bought it after asking around which was the best non-duraspark unit to get. I"m dealing with carb issues, frontend problems, turn signal not working - a swap over to electronic igntion is not on my list of to-do's. NOTHING that anybody has told me would be simple on this car has turned out that way!

This thread seem's to be continuing on without me- I haven't had time to play with this since before the holidays, and don't have time now as the car now has electrical problems so that's my priority at the moment. It never ends..... :roll: