Thread: Timing Issue? I wish I could get this thing to stop pinging!

Tweet

submit

Real good questions Pat, I'll do my best to answer

Originally Posted by pat mccarthy

how much are you pulling for adv with vac hook up?

Current timing looks like this: 34* total advance, 10* initial, 14* mechanical, 10* vacuum adv w adj can
RPM - Advance
1000 - 12*
1250 - 16*
1500 - 23* - HUGE jump in curve, must be where the vac kicks in...
1750 - 29*
2000 - 32*+
2250 - 34* - All In

It still pinged a wee bit with light throttle from cruise and if I hammer it out of the hole - I did note that if I ramp up the throttle evenly it will not ping under either of these circumstances. FWIW I drove the piss out of it late last night but the air is much cooler at night, no wonder it behaved!

have you added a race fule to see if it go s away ?

Not yet, still working with 87 octane, not sure if the next step will be 89 or 91, trying to keep it cheap-pump gas friendly if possible. 95-97 octane race juice is available here but I think it is still over $5 a gallon

for plugs just a AC 44 or cross it over to auto lites

I am not sure if AC44 is correct for my application, it is a 14mm thread but only 7/16 reach and 13/16 wrench - I cannot fit a 13/16 socket on #1, #2, #7 and #8 cyls due to head bolts, the vortec heads need a 5/8 spark plug and the reach needs to be over .7" to get into the chamber from what i have found... but what the heck do I know?

The Autolite plug I found was a 605, the next colder is a 104 (5144) and the second colder is a 103 (5143) all three are resistor plugs

.you want to pull as much adv as you can off idle. use a justable vac adv to pull some out if needed and it needs to drop out under load .or go full mechanical adv .i start at getting it all in at 2800 and 32 to 36 total to start.

I am down around 8 to 10 degrees at idle to avoid pinging while under load. The adj vac can i have ADDS advance, so I have been retarding the initial timing and adding it back with the can. I was running with full mechanical advance but did not get more than 22* total and was all in below 2000 RPM. I will go to lighter springs in my dist to see if I can milk out more mechanical advance than 15 to 18 degrees

did you try ligter set up springs in the carb ?

I did put stiffer step up springs in to keep it a bit richer with good results so far, I am sure I will need to consider different metering rods/main jets ultimately, probably larger secondary mains too...

how much vac is it pulling when its pinging ?

Ah, the $64,000 question! I didn't get a chance to look but I did think ahead enough to run a vac gauge into the cab, I just couldn't get a look at it fast enough to see it happen - next time I take a passenger along as an observer!

Thanks for the help Pat!