Ping problem

[Anonymous]

Today I installed my new distributor. It was built with 24 degrees advance @ 3000 rpm. Yep, it made a nice improvement in acceleration and fuel mileage, over the replaced one. My inital timming setting is 10 degrees, for a total advance of 34 degrees. The gas I have been using is 89 octane. And I have found a small vacuume leak. I will have the vacuume leak fixed tomorrow.
My question is, the car pings at 60 mph, light load. I changed the inital advance to almost 2 degrees, and have eliminated the ping, but driving the car isn't as fun. After increasing the timming back to 10 degrees, should I increase the jet size in the carb, use 93 octane gas, both? What do you suggest? Gas is still cheaper than a new engine.
Thanks, Ken

 

[grocery getter]

fix the vacuum leak first. see how it runs, then go from there

 

[rbohm]

8) i agree, the vacuum leak will give you a lean fuel mixture, and that will cause pinging.

 

[The Plankster Prankster]

if it isn't fixed by fixing the vac leak, retard it to where it stops pinging, then start running the better fuel. they say that once you can hear it pinging, you have severe detonation, and even mild detonation can bring down an engine (i would know).

 

[ferros oxide]

Light load at high speed, the vacuum advance unit would be at maximum advance.
Start reducing the vacuum advance. You will see the linkage. restrict the movement. Small amounts at the start and see how it works.
Noel

 

[63comet]

Which distributor did you install, points or Duraspark?

 

[CobraSix]

I agree with the others...fix the vacuum leak first...it may solve your problems. Your dizzy isn't set up extreme so it shouldn't have made a change by itself.

 

[fordconvert]

I have worked on several cars where a physical limit on the vacuum advance did the trick without hurting the performance. For GM stuff all the 'performance' people make a cam/washer thing just for that purpose. I have just used regular washers under the mounting screws. I have never looked for such a thing for the Fords but would imagine they exist or could be easily made.

On my last EFI project I found that it started to ping at around 13.5:1 AFR and took all the way to around 11:1 AFR to make it stop. About 4* less timing at cruise let me run down to 15:1 with no apparent change in drivability or performance, if anything its better now but my precision butt dyno may not have been calibrated that day.

 

[CZLN6]

Howdy Ken And All:

I'd start with-
* Fixing all vacuum leaks, as already suggested.
* limiting the vacuum advance. FYI- vacuum advance goes in addition to your initial and centrifugal advance, again, as already suggested.
* If all else is right and tight, try a colder heat range spark plugs.
* make sure any carbon buildup is removed. Carbon is the most likely culprit of pre-ignition

Even if that solves the audible "ping", you would be wise to do regular plug readings, especially after highway cruise/high vacuum drives. The spark plugs will tell you if your carb is lean. You can, mostly likely, make the ping go away by reducing advance, but if the carb is too lean in the cruise range you could still be doing damage. Short of an A/F meter, plug readings are the next check. Listen to your Plugs!!

Keep us posted on your progress.

Adios, David

 

[60s Refugee]

Modern cars have a computer. It senses pre detonation and retards the spark as needed to control it. Vintage cars don't have that option. It is all about getting the timing right and if need be, up grading the octane. There are numerous devices that will change your timing as this thread has already outlined. In my years of tinkering I have found that ultimately it comes down to retarding the spark. Yes, this will cost you performance, but you either get it on top or on the bottom of your RPM range. In most cases you can't really have it both ways. I always set mine for the kind of driving I usually do. Right now my 200 six is set right at the factory setting. Oddly enough, I set it there using a vacuum gage and a tach, just like the guys at Pony suggest. The timing light verified the results.

Now...that will all change when the tri-power goes in! 8)

Harry

 

[Anonymous]

Thanks for the help. Yesterday I fixed the vacuum leak. At least I remounted the carb plate, and tighted the port for the master brake cylinder, on the manifold.
Today I drove the car, with no ping change, the vacuum leak seemed to be fixed.
I changed the jets from 54 to 57's. That change didn't make any real change, either. Now, what did make the ping go away is removing the vacuum line from the port side of the carb, plugging it off, and distributor.
I have an adjustable vacuum module on the old distributor, that I may swap out on the new distributor.
No more ping. Car runs great. I may add some more initial advance and rejet to a 55.
The holley I have is an old 300cfm carb, not a 350 or 500, so the jet size might make a little more sense.
I won't be able to work on the car for a few weeks, but at least I know it runs great.

If you are interested, here are my mods,
Head milled .070, 1.75 int 1.38 exh, mild port job and 2bbl direct mount plate. Header, DUI duraspark distributor, recurved 24deg @ 3000, Livewires, Summit Racing CD ignition plus their TFI coil, 5.0 dual inlet air cleaner with K&N air filter, (Soon to be a ram air mod). The rear end gears are 3.25.
Today the car is fun to drive and I am now ready to do fuel milage readings.
Once I get the drive train done, I plan to work on the interior then body.
Thanks for your help,
Ken

 

[Bort62]

Sounds like that confirms what was suggested above - that your vac advance is too aggressive.

Throw the adjustable can on there and crank it back a little. Your part throttle performance and economy will suffer w/o the vac advance.

 

[Anonymous]

Hey Bort62,
I had to quit working on the Mav, due to time. But I did get it to quit pinging. Tomorrow, I get my shoulder operated on, then a few weeks of recovery, then back on the Mav. I am thrilled with tonights findings with the vacuum advance being the problem. I will fix the problem and advance the timing. I hope to get the initial timing to 12 degrees, from what is now 8 degrees. Now, that should make this a lot of fun to drive.
Thanks,
Ken

 

[Bort62]

Good luck w/ the shoulder. Car will wait

 

[CobraSix]

Plan on more then a few weeks. I had surgery on my shoulder 2 years ago (torn labrum). 4 weeks in a sling 95% of the day (including at night), 4 weeks of half time in a sling, followed by 4 months of therapy to get back full range of motion. Spent the next 18 months regaining the strength.

 

[Bort62]

Plan on more then a few weeks. I had surgery on my shoulder 2 years ago (torn labrum). 4 weeks in a sling 95% of the day (including at night), 4 weeks of half time in a sling, followed by 4 months of therapy to get back full range of motion. Spent the next 18 months regaining the strength.

Shoulda just used some HGH

 

[CZLN6]

Howdy Ken and All:

Good luck on your surgery. Been there! Done that!!
I'm going in for total hip replacement surgery on Monday. I hope to farm out a couple of spring spruce up projects while I'm down.

Does your 300 cfm Holley have both ported and manifold vacuum source? Some early versions of the 2300s only had a full/manifold vacuum nipple. I don't know what a DUI distributor requires, but if you were using a manifold vacuum source with a distributor that was designed for a ported vacuum source you will get too much advance at high vacuum driving situations. Check it out.

You didn't mention what cam you're using. Is it still a stock cam? If so, high cylinder pressure could be contributing to spontaneous combustion, another kind of pre-ignition. What spark plug heat range are you using? How do your plugs look?

Good luck and

Adios, David

 

[addo]

Hope yours comes out OK, too!

 

[Anonymous]

Hey Folks,
My shoulder is recovering well.
David, the carb has port vacuum, which i did have hooked up to the vacuum canister. The other place I can hook up the vacuum is from the log. In a couple of weeks, I'll change out the adjustable canister and see what happens. The cam is the stock cam. The short block is all stock, except for the timming chain/gears.
Good luck with your hip replacement.
Thanks again for all your help,
Ken

 

[CobraSix]

HGH would have gotten me kicked from the Coast Guard.

However now I can. I might after too. This morning I managed to dislocate my left shoulder completely while lifting some weights. Oh well...at least it isn't surgery, but now I know I"m in for a line of weakened shoulders.