Technical Myths … or old wife’s tales about engines

What about the firing pin spring. There was a time when most manufacturers recommended not leaving the gun cocked for an extended period. Of course dry firing is also not recommended, that’s why they sell snap caps and dummy rounds.

 

Adding to jnaki's post, in our small part of the country there were a few 283 & 348 equipped Chevrolets that were faster than the others. All of them came from a Utah dealer who recommended "drive back to Idaho as fast as you can get away with." From what I remember, none of them ever gave trouble, but the owners took extra good care of them ...

 

I’m sorry, I wasn’t listening.

 

Flatheads overheat.

 

Mine wasn't. '56 Ford 292 won every street drag race it had, $100 mostly, and $200 for the 'faster Chevys'.
I relied on 'racers' insurance'. I was 'cheating'...

 

Engine overhaul in a can...STP, Bardhal, Motor Honey etc. amazingly cures ALL your engine issues. Your oil pressure gauge would make you think it really worked.

 

Red engines make more horsepower

 

Owner of a shop I worked part time at (1995) had been open since '60. Should have known things.

But one day he saw me about to turn a brake rotor on the new brake machine...
"Mike, you DON'T want to turn a disc brake. Ever. Because when you do, and the piston pushes the pad onto the surface of the disc, well, the disc has to be out of round to push the piston back into the caliper. Otherwise, the brakes would be on all the time!"
I laughed out loud... The next day, I took the piston out of a caliper and showed him the square cross section of the 'O' ring. He got real quiet... Then he said, "Go ahead and turn those discs, we can charge the customer for that!"
True story. Here. Atwater.

 

I’m betting it did work…..for a few flippers lacking scruples.

 

Please tell me more.

 

I once had a guy tell me that Pontiac V8s in particular needed back pressure to run, and proceeded to tell me a tall tale about how the muffler fell off of his '56 Pontiac, and it wouldn't even go up the hill to his house because of it. I shudder to think how much power I lost when I replaced the stock mufflers with glasspacks!

 

Friday and Monday built car thing is true. When I worked for Buick we kept track of this for a few months out of curiosity. Cars which had a Friday or Monday build date had more strange things. Handful of screws or nuts in between panels. Pop cans or beer cans under carpeting or in doors. And other strange phenomena. Strike time was even worse.

 

Had a buddy that worked at GM in the late 60's, early 70's and he said the same thing.

He said he'd seen guys do stuff like that and as you stated Monday's and Fridays were worse.

.

 

We used to call stuff like that “a quart of oil pump”.

 

Hey HRJ,

Yes, we heard all of those stories about the additives. Even our local mechanic at the Mobil Gas Station shop sold them, but, did not guarantee results. How could he? Motor usage is varied with everyone having their own requirements and ways to drive daily. Let alone, drag racing...

But, for some reason, all of the top drag racers and folks that are now "names" in the drag racing history books used oil additives, like STP, Bardhal, and Wynn's Friction Proofing. When we were building our first 283 SBC motor with 6 Strombergs, we were given a case of STP as a gift from the guy we knew. It was an advertising ploy to give his shop credit if and when we started to break some records in the Gas Coupe and Sedan Classes.

When we started the rebuild of the original 283 SBC to the 292 SBC motor, Reath Automotive guys said they used STP and Wynn's Friction Proofing as an extra additive to all of their built motors. Our friend in Los Angeles said the same thing and gave us several cases of Wynn's Friction Proofing for our daily drivers and for our 671 SBC motor in the Willys Coupe. The 58 Impala always got a can of Wynn's added to every oil change and tune up session. The 292 SBC 671 supercharged motor always got the Wynn's Friction Proofing treatment.

Jnaki

We never had a problem with the additives and never had engine difficulties. They always ran to almost perfect tuning and gave us maximum power when we needed it. Did the Wynn's Friction Proofing work? Well, we never had to worry about engine breakage, despite the hard running we did during our Lion’s Dragstrip race days and every weekend on the local cruising scene all over So Cal.

The one thing I will say for sure is that a lone, slightly used can of STP was in the Impala trunk. We had just added some to the 292 671 SBC motor for one of our maintenance jobs. There was still some stuff left in the can. It was upright in the spare tire well, taped to the steel rim.

While we were working on the starter motor, my brother was underneath and asked me to lean in over the fender to hold the top of the starter until he could get all of the bolts out. It neeed a part and some adjustment to make it run right. So, here we were working on the Willys Coupe in the pits. As he took out the nuts, the starter dropped down and seeing my brother's face right underneath, I grabbed the starter and the weight straightened my bicep into the hot header pipe. It hurt a lot and it was still there until my brother got a grip on the falling starter.

So, now what? I had a 3rd degree burn on my right bicep about the size of Hedman Header Exhaust Pipe. The skin was gone and the surrounding skin was black. So, I went to the medical services and they gave me a gauze to wrap it and told me to go see my family doctor. I was not going to go home when we were still in the elimination runs. So I improvised and knew from First Aid Info that something was necessary to cover the wound to not get it infected.

I got the idea that the STP thick oil would be thick enough to coat the wound and keep out all of the bad bugs. So, I rolled up my sleeve and coated the wound with STP. Instantly, it cooled and I was walking around with a t-shirt sleeve rolled up as if I was a tough kid. It worked and on Monday I went to our family doctor and he said the wound is not infected and healing nicely, after he got the gooey stuff off. He applied his own burn ointment and did the same coverage as I had done at the dragstrip.

So, for the last 62 years, the scar disappeared a little each year and now, it is a faint outline of a large Hedman Header Exhaust Pipe burn. But, I am still alive and still kicking in our old age... YRMV

 

S = Stopped
T = The
P = Pain
@jnaki

 

Never, ever trust what a race team says they use. Far too often they get a discount on other stuff or cash and a pack of stickers for whatever product someone wants advertisement for, if it's oil they may also get a pallet of empty bottles to fill with the oil of their choice so people see the bottles used in the racing pits, not knowing the content is something else, probably from a completely different manufacturer.

So, in a way, race teams use of various products fit perfectly into this discussion - by being myths I mean. The same smoke and mirrors as any kind of advertisement.

 

I would have asked Dr. Granatelli for a written prescription!

@Dan Timberlake: 'Racers' Insurance: CHEAT. That ensured a lot of wins.
Great name, BTW.

 

Prolly get run offa GJ but:

"They don't build 'em like they used to."

Thank goodness they don't, because the old stuff was only good as compared to other old stuff.

Today's soccer mom SUVs/minivans are faster, get better fuel mileage, handle better and last longer than most muscle cars from the bad old days.

The 1930s/40s engines needed a valve job at 40k miles and were worn out at 80k miles. Most can't be rebuilt because they have cracks through the exhaust seats into the cylinders.

When we tear down a '50s or '60s engine with 100k miles on it, it's worn out and so filthy inside, it takes a day just to clean it enough to begin working on it. Then, pistons, valves, lifters, have to be replaced, cam, crank, rods remachined. Tear down a current GM LS or similar engine with 200k miles and it's clean inside and the crosshatch on the cylinders is usually still visible. Most could be reassembled with new rings, bearings and a valve job.

And don't get me started on snake oils - STP, Marvel Mystery, Wynn's, Bardhal, MolySlip, et al. I have a friend who was a chemical engineer at Chevron for forty years. He said, "All those crooks buy their feedstocks from us, put it in a small can for a lot of money. If it were any good, we could add it to all our oil for pennies instead of dollars."

And how do those guys get away with selling "Real Lead" (59.4 grams of Tetraethyl LEAD per Gallon) gasoline additives? Tetraethyl lead is a deadly poison which is illegal to sell or ship.

jack vines

 

This almost made sense to me, except that it refers to a pressurized line.

Vibrations in a suction line could work a bubble into the mix. The clothespin acts as a dampener. Less vibration

 

I go to, or used to go to a lot of big motorcycle meets and at most of the big ones there was always some guys with a chassis dyno that did dyno tuning. Well, that was were I would hang out to watch these guys do there magic…adjusting the timing , resetting the carb, etc.
If the bike had straight drag pipes, one of the first things he would do, was to put in a small set of baffles. The all said it was to create “ back pressure “ because Harleys need some back pressure, especially the Shovelheads!
Well, I could never wrap my head around why these engines need back pressure, when virtually every engine I had ever known liked headers, which reduces back pressure.
But , without fail, everytime those guys added baffles to straight drag pipes, they got a lot more horsepower! I watched this phenomenon many times in many states. Still can’t figure it out…..but I saw it!






Bones

 

That one is easy to explain.

The baffles add an anti-reversion function.

Short drag pipes, and ones that do not merge with other pipes do not scavenge well, or in some cases, at-all.

They are too big, and to short for the pressure waves to form.

 

Mothballs in the gas tank increase the octane rating!

 

Maybe, but it is hard to catch enough male moths to make a real difference!

 

Here's one, White horses eat more than black horses. The only time that is true is if you have more of the white horses.

 

As far as exhaust backpressure goes, when I was much younger, I has a BSA 441 single that I put a shorty muffler on. That bike just blew out the guts of that muffler in no time flat and power just died. I think getting it to 30 mph was a struggle. Replaced it with another shorty muffler and same result. Ran OK for a short stretch and blew out another one. That bike would not work without backpressure

 

Removing the muffler increases the cross-section of the exhaust system, giving it an inappropriate flow rate to establish scavenging.

It's not pressure, it is flow, creating timed pulses that pull the next exhaust pulse out of the chamber and exhaust.

When the potential flow rate is too high, exhaust pulses collide in the pipe, eventually stacking all the way back to the combustion chamber.

That is actual back pressure. Not anything that you want.

I can't tell you how many guys that have come to me and told me that as soon as they put the three inch dual flowmaster system on their 350 equipped Chevy pickup, that the truck began running like hammered dog crap. A dual 3-in system can support 739.66 horsepower, and has no place on a stock 350, or even a modified one.

 

I think an exhaust system can be best thought of like this:

If you have an escalator that is just wide enough for one person to go down in a row, and everybody is going down that escalator at a reasonable walking pace, in addition to the speed of the escalator you will all reach the bottom of that escalator at the same reasonable speed.

If you have an escalator that is wide enough for three people to stand on it, and you try to walk down that escalator at a reasonable pace, you will find people all over it standing still and not moving. If you're not careful you will collide with those people. If you are careful, those people will indeed slow your speed to the bottom of the escalator.

You want an exhaust system that is small enough to quickly move the entirety of an exhaust pulse down the system, at a rate that is just slightly higher than how it is expelled from the engine itself. When these conditions exist, that exhaust pulse creates a low pressure area behind it that sucks the next exhaust pulse out of the chamber and down the system.

If you have a system that is too big this does not happen.

In every instance where you increase the potential flow rate higher than what is necessary for the performance level of the engine, you decrease the performance level of the engine.

Properly tuning an exhaust system, be that for a race car, or for a high performance street car is a science. It does not involve guessing games. It involves engineering principles that have been proven out decades ago.

There is not one single competitive racer or race team out there that does not have access to an engineer, and dynos for testing.

There is a solid reason why 180°, and 360° headers exist, why there are equal length headers, and competitive drag racers spend a lot of time trying to find out exactly how long a collector should be.

Myths are persistent. But they are, nevertheless, myths.

 

I love the HAMB.

 

A thermostat slows down the flow, so there is enough “time” for heat to exchange in the radiator.

That time bit cracks me up. Slow flow is not good for heat exchange. Reynolds would be turning in his grave.

Cheers,
Harv