Mystery 318 wants 30* initial timing?? Pinging hard

[macdrew77]

So i've got this 318 I bought non running. Finally got it going and when setting timing by vacuum gauge it likes ~30 degree BTDC initial and like 45 all in. (vac advance is plugged for now). That seems crazy high, and with 87 octane in the tank on the test drive it was pinging hard. So I set it to 20 degree initial, 35 all in and it was still pinging. Should I go with what the engine wants? Or keep it to a restrained 20* or so? I'll get better gas in there soon, and i checked my plugs and they are running too hot. I'm afraid I'm gonna grenade something. Thanks for any advice. And yes, my timing mark is accurate, I triple checked with a piston stop.

 

[67Dart273]

Well if it pings it doesn't "want that much." "It might be" you have a slipped timing chain

There are certainly other causes of pinging......overheating, severe carbon build up, of course high compression, which is doubtful, and so on

 

[Mopar Tim]

Cooler plugs to start. might do the old brake fluid down the Carb to clean out the carbon. just get engine running slowly pour brake fluid down the carb while keeping the engine running at a fast idle. dont let engine die! It will smoke like heck so dont do it in a garage! It will clean the carbon out of the combustion chamber. IF it is a carbon build up problem. Small bottle should do it.

 

[rumblefish360]

20* is a bit much IMO. Stock to mild performance engines will like something around 10-15.

 

[macdrew77]

It idled rougher and rougher as you move it from high 20s down to around 15* initial timing, where I thought it was going to die.

 

[AJ/FormS]

Throw the vacuum gauge away............

It doesn't matter what the gauge says ;if it pings she wants less.
Sometimes ping can be doctored away, and then timing added back in.
I like to start with a compression test.

 

[MopaR&D]

Put it at 15* then you'll still have 30* initial + mechanical

 

[roccodart440]

I run premium in my lawnmower. Try a better gas and then retune.

Also, do a compression test.

 

[toolmanmike]

I have blasted carbon by trickling water down the carb. That works also as long as you just trickle it and not pour. Carbon blaster chemicals are also sold. What port is the vacuum advance hooked to? Un plug it at the distributor and plug the hose with a screw or golf tee when checking timing. It should be connected to a port higher up on the carb just above the throttle plates for a stock engine.

 

[Lelo Dart]

Get a couple of gallons of race gas in the tank and see what it does. 9-1+ is not going to like 87 octane.

 

[nm9stheham]

So what vacuum levels DO you have?

Is this 318 stock or modified? If modified, what mods/parts?

 

[macdrew77]

Thanks for all the suggestions.

So what vacuum levels DO you have?

Is this 318 stock or modified? If modified, what mods/parts?

It is modified. Internals unknown, supposedly rebuilt. It has 302 heads, 273 rockers, RPM intake, thermoquad 9800s, headers and dual exhaust. About 15" of Hg at idle

 

[Infecteddog]

Date on block? If it's a late '84+ block it's quite likely that it came with the 9:1 pistons- don't think they like 87 as they were stock.

 

[moper]

Did you take any cylinder pressure readings?

 

[AJ/FormS]

Get a couple of gallons of race gas in the tank and see what it does. 9-1+ is not going to like 87 octane.

I have run 87 on 10.7 for 15 years and 125,000 miles; with a Dcr of over 8.2. So I would hesitate to make a blanket statement.

OP, at 15 inches of idle vacuum, we really need the cylinder pressure results to formulate a picture

 

[nm9stheham]

With 15" of vacuum, then the cam is not going to be too awfully radical, and the DCR will likely be up there. So the pinging would not be a big surprise on that fuel especially. I'd surely try some 91/93 fuel as one next step.

I'd be backing up and looking for small vacuum leaks and working on improving the tuning, taking compression readings, and pulling a valve cover to at least measure lift, though cam duration would be of more interest. The point is to get a better idea of what you have. Also, I'd check end-to-end resistance on each plug wire.

Have you done the basic things like adjusting the idle mixture and checking float levels?

What plugs do you have and what ignition system?

 

[mguner]

Probably has a lot to do with what ever was left in the tank before you put newer fuel in it...

 

[RustyRatRod]

17 responses and no one has asked why in the HELL you're using a vacuum gauge to adjust timing.

Use the right tool, a timing light, or find another hobby. That's like using a hammer to get a phillips screw out.

Is the distributor plugged in the right way? And what are we workin on here? Is it a stock 318? What's it in? So far, as usual no details at all and we are expected to have a crystal ball.......but you want answers. Yeah, ok.

 

[318willrun]

It is modified. Internals unknown, supposedly rebuilt. It has 302 heads, 273 rockers, RPM intake, thermoquad 9800s, headers and dual exhaust. About 15" of Hg at idle

without knowing what's been done to it, and your getting "weird" symptoms, it's hard to say. 273 Rockers, Does it have hydraulic lifters on a solid cam??? Or solid lifters on a hydraulic cam??? I mean, the only place to start is a tear - down and find out what ya have.

 

[AJ/FormS]

I did! Post #6. I said throw it away.................
My dad used to set his timing like that, and swore by it. I was just 19, and already knew that was not right. But in those years early 70s we still had "real" gas, so I guess if his timing wasn't out by a bunch, he could still get away with it. He used to time all his cars by ear. I just looked the other way...............I wasn't going to argue with my DAD; I was still living at home, and wanted that to continue for a while!

 

[macdrew77]

17 responses and no one has asked why in the HELL you're using a vacuum gauge to adjust timing.

Use the right tool, a timing light, or find another hobby. That's like using a hammer to get a phillips screw out.

Is the distributor plugged in the right way? And what are we workin on here? Is it a stock 318? What's it in? So far, as usual no details at all and we are expected to have a crystal ball.......but you want answers. Yeah, ok.

Read previous posts for more info about my 318. I'm using a vacuum gauge, a timing light, a piston stop and all other tools at my disposal, thanks. I'm simply trying to figure out why my 318 loves so much initial timing. It seems to me, it would be happier with a locked dizzy. It's obvious the engine likes the advance at idle.

 

[macdrew77]

Have you done the basic things like adjusting the idle mixture and checking float levels?

What plugs do you have and what ignition system?

Thanks for the response, idle mixture screws are turned WAY out, and metering rod tree has been raised a fair amount. The engine needs these settings to idle. Float levels, everything else is at factory settings for 9800 TQ. Ignition is Chinese HE I conversion with autolite plugs that say 56 on them. I have colder denso 3257s on the way. New wires.

 

[AJ/FormS]

Well then your T-port sync has got to be off.Or the float level is too low, or the gas is sick.Or the carb is sick.
There is no good reason for your carb to be that messed up.Your teener appears to be very nearly stock.

Pour about a pint of that gas into a glass jam-jar.If it is any other color except clear to very very light yellow; it is "no good."If it is red it is waaaaay past it's "best before" date.Orange is only good for a 1984 Hyundai-Pony ( they burn almost anything).Dark yellow will burn in your Briggs lawn-mower, if you can get it started.
Spill about a teaspoon of it on a concrete surface, out of the wind. Take a piece of paper and light it on fire. Drop it onto the patch.
When it lights; if it produces a smokey flame and the flame dances up and down, nearly going out as the flame goes down, then that gas is "no good".If it goes out and you can still see a wet patch on the floor;it is "no good."

It may not be scientific, but this test has saved me hundreds of hours of diagnostic time, and saved customers thousands of dollars.Customers always say "I just put that gas in there;it's fresh". Well it might be fresh outta the jug that's been in your garage all winter! But If it's got color, it is "no good" for a carb equipped engine.

So what color is your gas?

 

[nm9stheham]

Ok, more good info.

Pull the coil's spark wire from the center of the distributor and place the open end about 3/8" from metal; crank the engine to see if a spark will jump that gap in open air with a good blue spark. If so, then the ignition is probably fine. (Don't just test across a spark plug gap in open air; that is not anywhere near a comparable situation to a real spark in a filled combustion chamber.) Just do this to eliminate a weak spark situation.

The mixture screws being way out sure sounds like too much air into the intake somewhere. See if all throttle plates are closing down close to closed just as a quick check. 15" vacuum is not bad unless this is at higher RPM than a normal idle range.

 

[macdrew77]

It may not be scientific, but this test has saved me hundreds of hours of diagnostic time, and saved customers thousands of dollars.Customers always say "I just put that gas in there;it's fresh". Well it might be fresh outta the jug that's been in your garage all winter! But If it's got color, it is "no good" for a carb equipped engine.

So what color is your gas?

Thanks for the great info. This is something I didn't pay much thought too. In the clear filter window the gas is clearly turning to orange. Ill have to drain it and fill up with some higher octane.