Robert61

I didn't post a pic of 1.5". As you can see at 1.5" it starts exposing the hole. Everything I've posted in this thread requires the engine to be in good condition with proper bearing clearances. If it has excess clearance then a stock pump might not produce enough volume to make the pressure increase at idle. But I feel like that isn't the case with this instance, could be wrong.

W Guy

We never had any problems with the tires Michael, but I did have to change the cam followers and the cam. It was a '71.

Verne

Critter1

Copied from the net..... And I think Johnny Carson did something on his show about Pintos with Firestone tires too.

"Ford, Firestone faced much worse in '78 The 1978 editorial cartoon still is remembered by a few veteran automotive journalists: Two cops stand next to a burned-out Ford Pinto with four flat tires. "The guy was driving a Pinto with Firestone 500 tires," one cop says to the other. "We ruled it a suicide."

It was a very bad year for Ford Motor Co. and Firestone Corp.

Early in 1978 a jury made a $128 million judgment against Ford (quickly knocked down on appeal to $6 million) in a case where a man was burned when his Pinto caught fire after being hit from behind. With Pintos linked to more than 60 deaths and under pressure from the National Highway Traffic Safety Admin. (NHTSA) Ford agreed to recall 1.4 million of the popular economy cars made from 1971-1976 in June and make fixes to their fuel tanks.

Then on Sept. 12, Ford was indicted on three counts of "reckless homicide" and one count of "criminal recklessness" by an Elkhart County, IN, grand jury after three teenage girls died when their Pinto caught fire after being hit from the rear by a van traveling at high speed. At one point monthly sales of new '78 Pintos - which had redesigned fuel tanks - were down as much as 45% compared with year-earlier totals.

Meanwhile Firestone Tire & Rubber Co. - a major Ford supplier, as it is now - was being pressured by NHTSA to recall Firestone 500 tires that were prone to tread separation problems and linked with dozens of injuries and deaths. It reluctantly agreed late in the year to recall 7.5 million tires - and later millions more".

65tripleblack

To get from 2.2" free length to 1.5" compressed length requires 10 lbf (pounds force). The diameter of the spool valve is .437", which makes it's area exposed to oil pressure .15 sq-in. Therefore in order to exert 10 lbf on a .15 sq-in area requires 66.667 psi fluid pressure.

Force = pressure x area
10 lbf = (x psi) x .15 sq-in

Pressure = 10/.15 = 66.667 psi

Robert61

And your point. That IS a high pressure spring as noted. And it's a 70lb spring so you win a doggie biscuit!

a striper

Looks like at 10 pounds it could correspond to a typical "hi-pressure" spring.

65tripleblack

This is what you previously posted in an effort to justify your argument about how the spring might begin to open at idle in some engines:

" I was able to measure the spring force at 1.5". It is 10lbs. The spring has a free length of 2.2". Keep in mind this is a high pressure spring. At 1.5" the bypass piston is just starting to expose the bypass hole. With the stock spring being considerably weaker it would get to the bypass earlier."

My post will hopefully clear up any misinterpretations that may have been created by your post. The purple spring ("70 pound") begins to bypass at 67.667 psi, NOT "10 pounds") as you have fairly accurately measured the spring force, but not the pressure acting upon it. BIG DIFFERENCE between the two..
Please try to be more civil and less insulting when someone challenges you and clears the smoke for those who may not fully understand.

Robert61

I have no idea how to convert spring force into psi. Also don't care to. but I do know that increasing spring pressure increases cracking pressure. Every motor I've ever increased the spring pressure on has resulted in more oil pressure. But you already know this yourself.

65tripleblack

I just showed you how to do it.

Your theory about how the spring can begin to relieve at 10 psi is hogwash.

Robert61

Now now didn't you just say something about being more civil. Where did I say the piston began bypassing at 10 psi?

MikeM

It looks like you are trying to rebirth another internet legend here.

Firestone 500 tires were not OEM on Ford Pintos. They were however, aftermarket replacements for me on one car and yes, they did fly apart and I wasn't reimbursed or compensated in any way. They failed on my '68 Nova. No crash because I was easily able to control with one hand on the steering wheel.

Don't have it handy and too lazy to look it up. The Ford Pinto was deemed no more unsafe from rear end collsions than other cars of comparable size/weight. I forget who deemed it but they were experts.

The Pinto fire that put the news media spotlight on the Pinto was the one where the three girls were killed after a big van rammed the car in the rear at high speed. Not reported initially and after the headlines blew it all up was the fact that the girls had just gassed up and left the gas cap of the car laying on the gas pump.

This reminds me of the media blitz about the Crown Vic Police cars catching fire after being rammed in the rear end by cars going 100 mph and the media played it up like there was some short coming in the design of the car somehow because they caught fire.

The Pinto was an excellent, well conceived, well designed and great little package. I wish I could buy a new one right now with the latest electronic power train management like today's cars have.

A $2000 car in 1970 that Henry Ford said would cost over $3000 by 1978 due to government regulations. He was exactly right in his predictions.

PS. I had the Firestone 500's fly apart, I had the Firestone 500 replacements fly apart (727?) and some other Firestone steel radial fly apart. No compensation for any of them. No more Firestones for me.

Pss. Except for the Explorer I had With the Firestone tires that ran 90K miles and still had tread left. The Explorer always had good oil pressure though, even at idle.

Critter1

Are you trying to change the subject again? Oh, wait, that was the original subject.

C.T.

As a point of reference, the May '66 Chevrolet Service News says the minimum hot oil pressures for the '65 and '66 396 and 427 are:
500 rpm - Hyd lifters 7 psi
750 " - " " 9 " , mech 9 psi
1000 " - " " 12 " , " 13 "
2000 " - " " 23 ", " 22 "

wmf62

Bill

Westlotorn

When they set the specs that low they never had a warranty due to low oil pressure because they were in spec.

Robert61

Bill would you drive your car if it had 12lbs at 1,000?

fla-buckeye

I worked in the department that spliced the stock for those Firestone 500s. We had continue issues with the calendaring of the rubber and the steel, we knew they were junk at the time. Production would win out over quality control every time!

Nowhere Man

and all other cars with a gauge for oil pressure only had dashes with no numbers to represent what they mean. and if they did that with Corvettes we wouldn't have seven pages of this

wmf62

if it has/had always been that; yes. if it deteriorated to that, I would go looking for the cause....

Bill

Easy Rhino

Keith, change your settings to 100 replies per page and this thread is only 1 page and change.