As Spring/Summer rapidly approach in central TX, I feel I will no longer be able to get away with using the open element air cleaner I tossed on top of my 4100 carb after I did the intake swap last december.
Anyway, we had a nearly 80* day last week and she started to ping pretty hard during my afternoon commute. I've been running a fair amount of timing in the cool weather and had the carb jetted leaner as well, all for fuel economy of course. I richened the carb a bit to curb that issue, and of course I took a hit with the mpg's.

I am assuming that with an engine as prone to pinging as this one, sucking in hot air with an open element filter only serves to aggravate this issue.

I would like to use an air cleaner like the stock one with the cold air snorkel setup, however, I am not sure the base of it will clear the 4100, and I do not have it with me to check.. When I originally installed the open element filter, the performance (and economy) increase was noticeable- even with the stock 2 barrel.
I was contemplating visiting a pick n pull and grabbing another stock air cleaner to rob the snorkel from, and then cutting a hole/riveting it on to my old air cleaner to make a dual snorkel filter housing. I would like to think that would supply enough air to my engine to not restrict it too much, even with the 4 barrel carb and comp 268 cam.

Anyone have any better ideas?

 

I run 34-36 degrees BTC when all centrifugal advance is in max then reconnect vacuum. I run a 192 degree RS 333-192 T-stat for years now, super cool radiator, FlowKooler modded water pump impeller (disc added) and now, Edelbrock 1405 carb with Holley 12-803 FPR at 5.5 psi. Jetted like out the box, but I played with step up piston springs. She does have a mildish cam with stock springs, an old Crane Fireball stick and no EGR..

I've been down that road of advancing timing, manifold vac to distr, leaning out a Holley 1850 a little bit, and while I did increase MPG a little, always up to pinging and backing off thinking that was best ....
..... soon I had burnt a couple valves ..... so I went back conservative.

That was about 1990-91 ..... I went with Edelbrock carb just a few years ago.

No pinging even on hot days.

 

I fabbed up a dual snorkel air cleaner last year. Unless ya run a low profile breather on the driver side VC the "extra" snorkel will hit or its hose.

Alternatively, the snorkel could be mounted to face directly sideways but symmetry looks better.

Feed it with inlet hosing... even ram-aired from the core support.

Something is definitely amidst if it's pinging at only 80° ambient...2x.... timing and tuning seems to the direction to take.

 

Believe me, I know. This engine loves to do it like no other, on premium gasoline and cold plugs of all things.

I'll dig out the timing light and check yet again, But I'm fairly certain that it gets no more than 35* all in, which is around 3k.

I am truly at wit's end....

 

Really, I would love for someone to point out the obvious solution to my problem.
I have never been able to run regular gas in this thing without seriously retarding it, even when it was stock. I know the egr not being present doesn't help, but many people seem to be able to get away with it.
If I were to even put mid grade fuel in it I guarantee it would ping so hard you would be amazed it wasn't melting down, and its 30* outside right now.

I've tried everything, and it just won't stop. The only thing that makes a difference is retarding it to nearly 0*, which makes it quite the dog, or running premium and erring on the rich side.

I've never had this issue with FE's, SBF's or 460's.
Maybe I'll just swap in my 429.....

 

HIO Silver: That's a nice job on the dual-snorkel intake.

If you want the end result without the hard work, the '83-'85 Mustang GTs had a dual-snorkel intake from the factory, and there are used ones to be had. Doing it yourself is probably a bit cheaper though - those usually go for a little over $50 used, or over $100 if they're mint.

 

Could it be the thermostat? I'm not 100% sure its the right one now that I think about it, and I'm running out of thing to try. When on the highway the gauge usually sits around the "N" or "O" of "NORMAL" which I assumed meant all was working, but it does rise a bit when not in motion, and in the summer it will begin to overheat if idling. I have a shroud and a flex fan so airflow isn't the issue. But if the thermostat is the wrong one, won't it bypass a couple cylinders? Which would cause them to overheat and be prone to pinging?
Someone correct me if I'm wrong here.

 

Thanks!. .. it took all of about 20 minutes to fab up.

Stock gauges are notoriously inaccurate. I suggest going aftermarket to get real info that the Kentucky windage referring to "N O R M A L".

It could also be the engine's cooling passages being all clogged with scale and rust. It'll settle at the bottom of the block.....On my 70's FE, I pulled the pipe plugs down by the rail (one on each side) and nothing came out.... that is until I poked the innards with a small screwdriver was immediately greeted with a torrent of rusty yuck...

 

The cooling passages are in great shape. I checked when I went through it a while back, it always had antifreeze in it so corrosion was minimal.
Come to think of it, it usually doesn't start to ping until its been on the road a while....At least 10-20 minutes.... That does seem to lead towards a cooling issue.
I ordered a #197 thermostat from my local Napa, which I believe is the correct style thermostat for this application.

 

Is the plunger on the bottom of the stat supposed to completely block the bypass? Or does it just partially block it? The one I removed is the same as the one I replaced it with, however it was bent a little, like it had hit something. Maybe it was bound up, or getting caught on the outside of the bypass.

 

If it was bent it was bent from being dropped before being installed. There is no way it could bend from opening up in the t-stat housing.

 

Yes, the wrong thermostat, even the correct temp and diameter but one lacking the hat on bottom that acts to restrict the cast in bypass in the block more as it opens wil cause heating. The bypass is provided to allow coolant to move in the water pump even when the engine is cold or the t-stat shut to prevent cavitation (like spinning wheels in mud) but as the engine warms, you want that coolant to go through the radiator. If the T-stat doesn't restrict the bypass when hot, it can be open but a bunch of the coolant will simply go through the bypass into water pump and back into the engine never seeing a radiator.

https://www.ford-trucks.com/forums/8...ermostats.html

 

It certainly restricts the bypass, It just doesn't close it off completely.
Is that correct?

 

No, I don't think it ever completely seals it ..... just serves to restrict that avenue more as the T-stat opens so the coolant will go through the radiator to the water pump.