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Author Topic: Have you checked your tire pressure lately??  (Read 4124 times)

Steve M Smith

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Re: Have you checked your tire pressure lately??
« Reply #50 on: November 14, 2013, 02:46:09 am »

It is really the octothorpe (a fun word to use in casual conversation).

That is a great word.  Up there with interrobang:  http://en.wikipedia.org/wiki/Interrobang


Steve.
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Chris Hindle

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Re: Have you checked your tire pressure lately??
« Reply #51 on: November 14, 2013, 08:06:24 am »

Jeff / John,
as a retired engine builder / mechanic, the COUNTERWEIGHTS on the crank are there to offset the weight of the connecting rods and pistons. Period.
A "heavier" crank with "lighter con rods is just going to shake the fillings out of your teeth, and rip up the main bearings.
Been there, seen that.
Same with a lighter crank and heavier rods, except that this combo shakes more. (because the heavier part is further from the centerline of the crank).
I don't grok the math, but I have seen the results.
Chris.
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Ya, Whatever. Just throw a '57 on it, and get off my stage.

John Roberts {JR}

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Re: Have you checked your tire pressure lately??
« Reply #52 on: November 14, 2013, 09:41:00 am »

Jeff / John,
as a retired engine builder / mechanic, the COUNTERWEIGHTS on the crank are there to offset the weight of the connecting rods and pistons. Period.
A "heavier" crank with "lighter con rods is just going to shake the fillings out of your teeth, and rip up the main bearings.
Been there, seen that.
Same with a lighter crank and heavier rods, except that this combo shakes more. (because the heavier part is further from the centerline of the crank).
I don't grok the math, but I have seen the results.
Chris.
Thanx... That's probably why they call them "counter" weights.  8)

There could be some extra gamesmanship in NASCAR where they may not be allowed to add mass to the flywheel (because flywheels can become grenades if they fail at high RPM). So some extra mass gets added where they can. I don't expect much advantage from increasing the rotating mass but competitive racing is a matter of inches and feet over hundreds of miles.

Back in my day we would (pay a shop to) balance stock crankshafts, adding or grinding off metal to match the connecting rod, piston, counter weight precisely, especially when planning to take an old motor up to higher RPM range.  My sense was that less was better for connecting rod weight (and any reciprocating mass) inside the motor. For me even aluminum rods were too exotic (expensive). While of course the rods and pistons and crank work together as a system so need to match. I never got that fancy in my messing around. While I did break my share of Y block bottom ends by turning a 4,500 RPM design motor up to 7,000 RPM...   

JR
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Chris Hindle

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Re: Have you checked your tire pressure lately??
« Reply #53 on: November 14, 2013, 12:06:06 pm »

but competitive racing is a matter of inches and feet over hundreds of miles.

I think you'll find it's more of ounces and inches.....

and yes, when balancing a crank, it was always as a short block, with a pumped in oil supply.

Back in the olden days, after a "little work", I was able to get my 71 455HO to 7300 RPM regularly, with an occasional missed shift hitting 8000, where my rev limiter kicked in.
Did I mention I did a "little" work to that engine ?
(his was a street build, not a competitive racer)
Chris.
« Last Edit: November 14, 2013, 12:11:50 pm by Chris Hindle »
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John Roberts {JR}

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Re: Have you checked your tire pressure lately??
« Reply #54 on: November 14, 2013, 12:46:44 pm »

I think you'll find it's more of ounces and inches.....

and yes, when balancing a crank, it was always as a short block, with a pumped in oil supply.

Back in the olden days, after a "little work", I was able to get my 71 455HO to 7300 RPM regularly, with an occasional missed shift hitting 8000, where my rev limiter kicked in.
Did I mention I did a "little" work to that engine ?
;D ;D  "71 455 is old days???  I was working with mid '50s technology, where OHV was a relatively new technology.  I managed to put enough carb, intake valve size, and cam shaft  lift/duration (with dual springs on the valves to prevent float)  with  <300 ci displacement. So I had a motor more than willing to rev thousands of RPM past it's design target. I honestly don't know how high. One motor that I blew was after my tachometer was stolen, so I was shifting when it ran out of accleration... It was pulling especially good that night, until a connecting rod let loose, cut my pan in half, and punched holes in my block.  :'(

A rev limiter would be nice but a relatively advanced technology for street racers back then. I had to put a special ignition in my supercharged mustang to prevent detonation as pressure built up with increasing RPM. It had a rev limiter too and I rather enjoyed putting the 2000 RPM chip in it, whenever I had to leave it somewhere for service.  ;D ;D  [edit forgot to mention the special ignition retarded timing based on # of boost in the intake, [/edit]
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(his was a street build, not a competitive racer)
Chris.
My only taste of organized competition was running an actual extremely stock vehicle at the drags, one time when I went as a visitor but paid for a pit pass so was allowed to race. I only found out afterwards that I could have gotten $25 cash instead of the plastic trophy.


Irony is that my current daily driver is a 32 valve DOHC, fuel injected, 5 speed, with posi-traction. 50 years ago that much automotive technology wasn't even on my dream list.

 
JR
« Last Edit: November 15, 2013, 12:52:11 pm by John Roberts {JR} »
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Chris Hindle

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Re: Have you checked your tire pressure lately??
« Reply #55 on: November 14, 2013, 02:07:43 pm »

Irony is that my current daily driver is a 32 valve DOHC, fuel injected, 5 speed, with posi-traction. 50 years ago that much automotive technology wasn't even on my dream list.

Ain't dat da truth.
When I was working at a GM dealership through the 90's, the Quad-4 (DOHC, 4 valves per), Turbo'ed and inter-cooled Grand National, and Supercharged Bonnie were all street versions of technology I wished was (reasonably) available when I was "fixin up" my Trans-Am.
Not so much the fuel injection. I had a pretty good handle on jetting the carb. The Accel super-coil and a double point distributor driving an Accel electronic ignition box kept the spark happy at 7000+ RPM Try that with the box-stock delco or ford......

Kids today have no idea where this stuff really came from.........
That Grand National was a real bitch in the rain. Shoulda had wipers on the back glass, considering how easy it was to swap ends.......
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Ya, Whatever. Just throw a '57 on it, and get off my stage.

John Roberts {JR}

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Re: Have you checked your tire pressure lately??
« Reply #56 on: November 14, 2013, 03:20:53 pm »

IIRC Chevy offered limited production fuel injection in '57, and ford countered with Paxton superchargers to win at the race track and show rooms.  Somebody from the government probably put their foot down to nip that in the bud... but it keeps coming around.  Silly now we can buy 1000 HP mercedes stock.

=====
 
Don't mention rain... I totaled my supercharged '93 mustang Cobra into a guardrail on the interstate in the rain with only 22k miles on it. I was still dialing it in. It left us much too soon. RIP  :'(

===
I used to have a Mallory dual point distributor back in the day, and the extra dwell time helped squeak a little more spark out of the old school Kettering ignition system for higher RPM (the hard part was keeping the points closed a longer percentage of the time.). My older brother built a very early capacitor discharge ignition kit while I never saw him wind his 392 hemi above 5,000 rpm.   

JR

PS: Funny how there are parallels between big iron in cars and power amps...
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Bob Leonard

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Re: Have you checked your tire pressure lately??
« Reply #57 on: November 14, 2013, 04:36:19 pm »

Big iron good.

Those were days John when a shade tree and a winch were all you needed. Back in the 60's everything ran fast and a good cam, high rise manifold, dumps, traction bars, and a Holly were all you needed. We raced every Saturday night either in Lowell, MA or behind the Watertown Arsenal, literally blocking off the street. I still remember my BOSS 302 and the absolute piss my pants thrill I got the first time I opened it up. Not as powerful as, but way faster than my 64 Galaxie 500 with the 429 in it. Please god, make me young again.
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Bob Leonard

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Re: Have you checked your tire pressure lately??
« Reply #58 on: November 15, 2013, 04:45:19 pm »

This past weekend I let my garage talk me into using a new brand of tire for the winter. 20" "Tractionwhore 5000" was the name. I had to bring them back because they kept going down on me.
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dick rees

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