The outside temp today was about 115 where I was. The truck was unloaded and running a bit hotter than normal, understandably. When I got on the freeway it pinged so badly I could hardly accelerate. The temp also went up, but I expected that being it was the first time to drive in such heat.

Any ideas on the pinging? Street driving at normal temps it seems fine.

 

I Googled this... "is msd ignition heat sensitive?". And found this and a few others...

MSD ignition suggestions... [Archive] - MallCrawlin.com Forums

I found this intersesting...

Ignition Coil - Tech - Terms & Definitions - Hot Rod Magazine

Jim

 

Mine also pings considerably more when it's hot out, and I have to be careful accelerating. Not sure how to address it quite yet, but wanted to let you know you weren't alone in it. It's with the Duraspark II ignition, and whatever Schucks/Oreilly's aftermarket performance coil is.

Normal days I can't get it to ping if I try.

 

I suspect your biggest problem with pinging is due to lack of EGR. Without EGR, timing and F/A ratio are much more critical. Check your initial timing, and check to see how much vacuum advance you get. I removed the EGR from my 300. Took a bit of tweaking to get rid of the ping. I found that my vacuum advance pulled in about 20 degrees more timing. I pulled and plugged the vacuum line to the distributor. I am getting ready to rebuild the distributor and will adjust the vacuum advance to give a lot less total advance.

 

Hey F100Jim,
That makes a lot of sense! I hadn't thought of that. Again, makes me wonder if reinstating a simple EGR setup is worth the trouble. Doesn't more advance on the highway mean more mpg?

 

My dist. was set up for 16 degrees initial, and 16 vacuum. I started with that much, but the starter kicked a bit, so I backed off a couple. I will check it again. I have to find a battery powered t. gun. Last time I checked it with the msd, I got zapped and tasted the fillings in my teeth! It's not a mistake I'll make again.

 

IIRC stock initial timing is between 6* and 10*. With my razuu Mallory box, ACCELL coil, recurved dizzy, Taylor wires, and NGK plugs, it's not happy unless it is set right at 8*. You might try backing off on the initial a degree or two at a time, drive and try.

 

The guy who recurved the dizzy told me to run 16 initial advance, and that there was 16 degree vacuum as well. I tried it and bumped it back.

It has run perfect for seven months at this timing. But on that hot (115 degrees) day, it pinged getting on the freeway. As soon as I got to streets, and temp dropped, it was fine once more.

"razuu Mallory box," I don't think I'm familiar with that model. lol

 

Less than technical description for a Mallory HyFire 6a

If your heat wave is hanging out for another day or two I'd say just add some premium gas to the tank...that may take care of it.

 

gas is formulated 3 or 4 times per season. the hotter it gets, the more it is changed, to keep it from vapor locking. get some octane booster, and add it when it is real hot out. this is especially true for gas-a-hol. hahahaha. the alcohol evaporates, and you are left with a less than desirable mix to burn

 

16 degrees sounds like a lot of initial advance, I would think more like 10 would be right.
I could be that you are running to lean. Gas with alcohol needs a little larger jet in the carb. or back the timing down to compensate. Move the timing a little at a time until it stops pinging.

 

Research has told me that 32 degrees total advance is what you want. Without the vacuum advance your mpg will suffer.

I may bump the initial advance back a couple of degrees. I guess I hesitate because it ran great set there for seven months. It was the heat that affected it. I think carrying a bottle of octane booster will help.

 

Heya F-250,
Personally, if it were me, I'd leave it alone since it works great all of the time. The only time to worry about having too much initial advance is if you have hard starts (kickback on the starter), or if it's pinging all the time. If it's only under certain circumstances (ie. hot outside), figure out a way to deal with the special case. Aka. tune it for how it'll run best 95% of the time.

In this case, I'd say a bottle of octane booster, or high octane fuel on hot days.

 

my egr was removed by a p.o. any ideas on where to get the pipe that goes between the exhaust manifols and the egr input? my local jy, had only 1 and it was rusted apart...

I ask because i get pinging under throttle with the dizzy hooked up to vacuum, and little to none with it disconnected.

I tried setting different timing, with mixed results, so i set it back to the stock 8 degrees. runs fine around town, but I would like to get back a few mpg cheaply...

 

LMC truck, bronco graveyard, the 'for sale' forum here, craigslist vehicle, ebay....