351C 2V Pinging--How to Stop It?

[410bruce]

Have an excellent running 2V Cleveland in a 1970 Cougar I recently acquired but it pings under a load pretty badly.
I have always heard these engines with the open chamber heads were detonation prone and from having owned a 1974 Montego with a bone stock 2V Cleveland that pinged under a load and now this one, I would tend to agree. When I say under a load, I'm not talking wide open, just partial throttle climbing a moderate hill.
Now, short of swapping heads in favor of the Aussie heads, 4V closed chamber or running race gas, is there any way to remedy this situation? Would polishing the chambers help?

This engine I have now has a Holley 750 vacuum secondary carb., Holley Street Master intake, long tube headers with dual exhaust out the back. The mufflers are very quiet chamber style.
It needed a fuel pump so when I removed it, I could see and feel the timing chain was worn out. So, replaced that as well, and when doing it, removed the pan to make removing the timing cover easier. While the pan was off, replaced the oil pump and pick-up with new Melling stuff, standard volume and pressure.

The bottom end looked stock. The timing set was the factory nylon deal so I believe the cam is stock. it idles very smooth.

Haven't checked the timing yet because my timing light is at work. Will do that in the next day or so. Have the distributor mounting soaking with PB blaster as it's stuck.

[Falcon67]

I'd start with testing 89 or 91 fuel to see if that helped.  On timing, I think you'd have to experiment with the mechanical advance curve.  If an open chamber 2V doesn't have 12~14 or so initial, it's pretty much a dog around a stop sign.  But then you really have to limit max mechanical.  Some of those distributors can have as much as 50 degrees.  Your limit is likely somewhere in the 34~38 range for total.  Should have to do that much work on a nominal 9.5:1 motor, but gas is pretty crappy these days.

[jayb]

Bruce, if you can't resolve it with timing and a change to a higher octane fuel, you might consider a water/methanol injection system.  It would be a lot of plumbing, but would likely solve the problem when it was adjusted properly.

[410bruce]

Thanks guys. This engine won't be in the car forever as it is an M code car which means it was originally equipped with the 300 horse 4V Cleveland.
Eventually I plan to build one for it but in the meantime while I work on the rest of the car, I would like this engine to run the best it can for as long as it can. As we all know, detonation isn't conducive to either one of those deals. 

[machoneman]

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[machoneman]

Check to see if the outer ring on your old balancer has slipped. Old, dried up elastomer between the hub and outer ring has deteriorated over time, meaning the markings on the outer have moved.

[cammerfe]

I'll +1 on Jay's comment on the water/alcohol spray. For a time, I ran a 427+.030 engine in my '67 Cougar and built the engine with mostly 'parts-on-hand' and what I could scrounge. I made use of pop-up pistons and when I finally did the math I had about 14-1 compression. It did have a tendency to crackle under moderate load so I made a spray set-up using a windshield-washer pump and a nozzle I created by crimping the end of a small tube that fit into the hose. I used an adjustable Hobbs switch to trigger it.

I found a 'deal' at a local drug store and bought several cases of isopropyl alcohol for about fifty cents a bottle. That worked until we took the engine out and put it in a circle-track car to run the half-mile oval at Toledo, Ohio. We held the one lap record with that car that entire season, but that's another story. We used av-gas in the race car.

KS

[Rory428]

I have never owned a 351C 2V, but in the mid-late 70s, I owned 2 different M code 70 MUstangs, a Sportsroof with Shaker, and a Mach 1, with no Shaker. Even with the available 100 octane leaded Chevron Supreme back then, these engines were very sensitive to pinging/detonation. For best power , it needed more timing, but it was a juggling act to get enough total timing, without pinging on a warm day. And pulling back timing really killed the power. The Sportsroof I drag raced pretty much every weekend, and also did a LOT of street racing in between. It was all stock, except I put a pair of Cyclone headers on it in 1976, and they were both FMX cars with 3.25 gears. Not sure how the 2V heads would compare, but with the big 4V heads, both cars were soft below about 3000 RPM, then wake up, but around 55-5600 RPM, the stock cam gave up. Compared to my later 428CJs, the 351C 4V was much more sensitive to weather conditions, when the temps would change from 70F to 85-90F, it was not uncommon for the 1/4 mile ETs to fall off by 1/2 second and 3-4 MPH.

[410bruce]

I have never owned a 351C 2V, but in the mid-late 70s, I owned 2 different M code 70 MUstangs, a Sportsroof with Shaker, and a Mach 1, with no Shaker. Even with the available 100 octane leaded Chevron Supreme back then, these engines were very sensitive to pinging/detonation. For best power , it needed more timing, but it was a juggling act to get enough total timing, without pinging on a warm day. And pulling back timing really killed the power. The Sportsroof I drag raced pretty much every weekend, and also did a LOT of street racing in between. It was all stock, except I put a pair of Cyclone headers on it in 1976, and they were both FMX cars with 3.25 gears. Not sure how the 2V heads would compare, but with the big 4V heads, both cars were soft below about 3000 RPM, then wake up, but around 55-5600 RPM, the stock cam gave up. Compared to my later 428CJs, the 351C 4V was much more sensitive to weather conditions, when the temps would change from 70F to 85-90F, it was not uncommon for the 1/4 mile ETs to fall off by 1/2 second and 3-4 MPH.

Wow, that's interesting, Rory, thanks for sharing. Never heard they were sensitive to weather changes. Also, the quench heads were supposed to be way better at detonation prevention, but evidently, not in your experience. That's disappointing to me.

My 2V engine has excellent off-idle and low RPM torque and throttle response--it feels "lively." I guess kind of opposite of the 4V engine. I tend to like low RPM torque and throttle response over high RPM power for the street. That's why I like FEs and big blocks in general.

Man, I might stick with a 2V engine then. Since it's a street car and I won't be racing it, I'd rather have the low RPM power the 2V heads provide. But if I can't overcome the pinging issue, there's always the option of throwing another style engine in it, like maybe an FE or even a 460. Being a 1970, either engine family would be correct for it.