timing, stock 283

[bobbybelair]

Diameter of those 57 balancers was 6 1/8" I think. Just want to make sure I get the right timing tape so I better measure it in case.

[chevynut]

About 95% of the time or more, this "heat soak" problem is either timing related, or a bad starter. battery, or connections. The heat soak deal is overrated.

It wouldn't be hard to check out with a temporary fix. All you would need to do is put a long wire on the solenoid, cap it, then connect it to the battery when the problem occurs and see if it goes away. If it goes away, you need to figure out why the solenoid isn't getting enough current to it.

The solenoid needs 12V to it while cranking. If you have the typical smaller wires, ignition switch, neutral safety switch, and all that garbage ahead of the starter you can get voltage drop which only gets worse when the solenoid is hot and resistance increases. The idea of the remote solenoid is to switch the battery voltage directly to the starter solenoid, bypassing all that stuff.

[55mike]

I would make double-dog sure the timing mark (at 0 ) is at TDC on #1 cylinder. Often pointers are simply not correct. A method I've used is to pull #1 plug and on the compression stroke (you'll get a puff of air) gently place a wire (a short chunk of a coated coat hanger will work) in the plug hole and rock the engine back-forth (i used the balancer bolt and a long breaker bar) . You'll feel the piston move up then down on the wire. Take some time, work back and forth, then double check yourself. Mark the balancer as "0" when you've determined the top spot. Keep in mind the piston feel like it's staying at the top before it travels back down. I spent some time "splitting the difference" with the travel of the breaker bar until I was satisfied I found the sweet spot. I fully realize this is a shade tree method, but, like I said it will get you very close . As for initial timing I agree with Rick. 4 degrees is very conservative. On a stocker... I'd see how it does at about 8 degrees initial.

[bobbybelair]

OK, here is the story. I timed it for about 8* at estimated 1000 rpm. Still have the problem. I turned it down to about 4* and I was getting backfires out the carb. I kept turning it up til the advance is basically off the map - what sounds like small staccato backfires out the carb. Beginning to think the distributor is mistoothed.

Spark plug wire for number 1 is on the distributor cap at the right side of the dwell window. at idle and moderate cruising it runs fine.

[bobbybelair]

But I am pretty sure it is not out a tooth. Else it wouldn't idle and run ok at moderate driving levels. It runs ok at idle and normal driving across a fairly wide range of timings, from 6 to 8 to even more.

[bobbybelair]

I'm moving my timing/distributor thread back here for a current summary.

I put electronic points and a new coil (Pertronix both) in. Set timing at 10* initial, which is where it seems to run best. Starts easy and fast, hotter coil seems to be helping overall.

Car runs VERY well with normal driving, and under "solid" acceleration. Pushing it brings on the machinegun rattle (or ping?) nearing Powerglide shift to second. Downshifting to first will also cause the staccato rattle. At 50 and up in second gear, if pushed there may be a mild rattling (where it doesn't downshift so revs don't get so high).

Vacuum gauge test steady as a rock at 20. Blipping the throttle brings it down to near zero, rebounds to 25 and settles back to steady 20. Normal readings. Pulling off the hose to the Vacuum canister will make the vac gauge drop to 16 or so, "late timing" area of vac gauge. Vac gauge is tee-ed between bottom of wcfb 4 barrel and vac canister. Indicates to me the vacuum canister on the distributor is working, at least in some fashion.

Is it possible that the springs on the advance mechanism have become weak causing too much mechanical advance under load? This distributor was in the car in 1975 when I got it, and has some considerable miles put on it since, off and on (60k +). I haven't been able to check the total timing yet , trying to get my hands on a timing light, or maybe this weekend I will try to get a good measurement on the balancer diameter to scribe it, which is not so easy while in the car.

[chevynut]

But I am pretty sure it is not out a tooth.

There's no such thing as being "out a tooth" on the distributor. All that would do is make the distributor body sit in a different position, but the timing would be the same.

[chevynut]

I put electronic points and a new coil (Pertronix both) in. Set timing at 10* initial, which is where it seems to run best. Starts easy and fast, hotter coil seems to be helping overall.

Did that fix the hot start problem too? Or have you had a chance to get it that hot? Electronic ignition is the way to go, imo, but I personally don't think that was your hot starting problem.

Car runs VERY well with normal driving, and under "solid" acceleration. Pushing it brings on the machinegun rattle (or ping?) nearing Powerglide shift to second. Downshifting to first will also cause the staccato rattle. At 50 and up in second gear, if pushed there may be a mild rattling (where it doesn't downshift so revs don't get so high).

This is where it gets confusing to me. You say "pushing it" brings on the pinging...does that mean when under a heavy load or when RPM is high? When you downshift to first, is that coasting with your foot off the throttle?

Is it possible that the springs on the advance mechanism have become weak causing too much mechanical advance under load?

Mechanical advance works on RPM, not load. The faster the distributor turns the more advance you get up to a point. Can you somehow limit the mechanical advance temporarily to test it out? I doubt that's the problem.

I haven't been able to check the total timing yet , trying to get my hands on a timing light, or maybe this weekend I will try to get a good measurement on the balancer diameter to scribe it, which is not so easy while in the car.

So how have you been checking the timing without a timing light? And why do you think you need to know the balancer diameter? Do you know your static compression ratio of your engine?

If it was me I'd start a process of elimination. This sounds like preignition or detonation to me based on your description of the problem and not having heard it myself. But some of your description of the problem doesn't seem to fit, like the "downshifting" comment.

I would verify your initial timing and make sure the timing mark is correct s suggested. Then I'd quit messing with the timing. Next I'd try high octane fuel to see if it goes away or improves. If it's mechanical could it be a lifter not working properly at high RPM? Does this sound like it's coming from one cylinder or all cylinders?