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Well I just used dragy and did my first 0-60 run. Needless to say, the launch was less than ideal, but the car is clearly underpowered. I will post the data shortly, but 0-60 mph was 7.6 seconds. I was hoping for 5.x....I have a bit of work to do.....
 

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I love your post! So total newb question, when I floor my goat, and after I finally get traction, it seems like it downshifts, but I watch the RPM go over 4,000 and I'm worried it will not shift into the next gear, likely resulting in an explosion of what was once my beautiful engine, so I let off on the gas. Is there a trick here, should i be letting up on the gas to let it shift? Ok, maybe I made 4,500 once.
 

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Discussion Starter #3
I love your post! So total newb question, when I floor my goat, and after I finally get traction, it seems like it downshifts, but I watch the RPM go over 4,000 and I'm worried it will not shift into the next gear, likely resulting in an explosion of what was once my beautiful engine, so I let off on the gas. Is there a trick here, should i be letting up on the gas to let it shift? Ok, maybe I made 4,500 once.
Well my car is a 4 speed manual and I am shifting at ~5000 - 5500 rpm. Your automatic should go above 4500 before shifting if you are going WOT.
 

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The governor of your auto trans can be modified to shift higher or lower. My trans guy rigged his last bracket car to shift about 5200, if I remember correctly. He just launched in drive, & let the trans shift itself.

https://www.hotrod.com/articles/hppp-1203-recalibrating-turbo-400/

https://www.jegs.com/i/JEGS/555/62070/10002/-1

A healthy 400 should be plenty safe to 5500. But, most smaller cams don't make good power to 5500.

Anyhow, if you're afraid you'll over-rev & blow your engine up, you can install a rev limiter, & set it at 4800, 5000, or where ever you want it. I used a rev limiter on all my 455 bracket cars. They saved ALL of those 455's, some several times, when they'd break the trans or rear end.

https://www.ebay.com/itm/MSD-MSD-8728-IGNITION-SOFT-TOUCH-REV-CONTROLLER-NEW-GENUINE-AUTHENTIC-MSD-8728/183301261141?epid=1317783761&_trkparms=ispr=1&hash=item2aad9b4755:g:7RwAAOSwq2pbOXrR&enc=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&checksum=18330126114198e0badaf31c47e8a132862842fdc94d

https://www.amazon.com/PerTronix-600-Digital-REV-Limiter/dp/B000CC9DAY#customerReviews

You can buy from Advance Auto & use an online 25% off code. That makes it the cheapest price for lots of parts. I've saved quite a few bucks with the 25% off deal.

https://shop.advanceautoparts.com/p/pertronix-600-digital-rev-limiter-600/10110711-p?c3ch=PLA&c3nid=10110711-P&adtype=pla_with_promotion&product_channel=online&store_code=&gclid=Cj0KCQjwiILsBRCGARIsAHKQWLPevmABodhCGycsrcr8j-BaueY4wyhkHLSOAUOrSn4kbf3QBo_aTQ0aAvZUEALw_wcB&gclsrc=aw.ds

Pertronix also makes a points replacement & HEI module with built in rev limiter.

https://www.summitracing.com/parts/pnx-d72000/
 

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Discussion Starter #6
BigD - What about gearing ? My 4 speed + 3.55 + tire combo requires that I shift into 3rd gear to hit 60+ mph. Given all the low end grunt, would it not be better to have a taller rear and only have to do a 1-2 shift to hit 60mph and be easier to launch? (Plus added benefit of lower RPM on the freeway.)
 

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BigD - What about gearing ? My 4 speed + 3.55 + tire combo requires that I shift into 3rd gear to hit 60+ mph. Given all the low end grunt, would it not be better to have a taller rear and only have to do a 1-2 shift to hit 60mph and be easier to launch? (Plus added benefit of lower RPM on the freeway.)
As I see it, higher numerical gear ratios have only one main advantage. Straight line acceleration.

Here: are some of the advantages of lower numerical gear ratios:

(1) Lower highway & cruz rpm.

(2) Better gas mileage.

(3) Should give engine a longer life.

Some disadvantages:

(1) Less acceleration.

(2) Might cause more clutch wear, because of more slippage required for getting the car moving.

SO, for street driven cars, the best gear ratio is a compromise. And, it depends on the driving habits & goals of the driver.

(1) If you do LOTS of high speed freeway driving, then ratios between 2.41 & 3.08 might suit you best.

(2) If you prefer lots of acceleration, & don't really care about fuel mileage, then ratios between 3.55 & 3.90 might be better for you.

(3) So, the compromise gears might be 3.23 to 3.42. I think these were the only 2 options for the '78 W72 4-speed Firebirds.

All this is assuming a 1:1 high gear ratio. An overdrive trans changes things.

Taller or shorter rear tires can also change things, slightly.

4-speed manual trans are available with numerically higher 1st gear ratios, which will work better with numerically lower rear gears. My '69 GTO had a 2.20 1st gear ratio, with 3.90 rear gears. I loved it. But gas was lots cheaper back then. I think the most common 4-speed 1st gear ratios were in the 2.50's & 2.60's. I think 2.88, 2.98 & maybe even 3.08 are available.

https://midwestmuncie.com/product/auto-gear-super-case-m22z-rock-crusher-4-speed-perfect-2-73-3-31-rear-end-gears/
 

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Discussion Starter #8
Interesting.....I would have thought the car (with all the low end torque) would benefit from a 3.08 or even lower (taller) as the tires would not just spin and would save you a gear shift (time) from 2-3 in order to get to 60 mph.
 

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Interesting.....I would have thought the car (with all the low end torque) would benefit from a 3.08 or even lower (taller) as the tires would not just spin and would save you a gear shift (time) from 2-3 in order to get to 60 mph.
If you have lots of tire spin, your 0-60 time is not gonna be quick, regardless of what rear gear you have. Back when I raced my '69 GTO with hard street legal tires, I popped the clutch at about 3000 rpm, but i couldn't go to full WOT until just before the tires quit spinning. If I went to WOT any sooner, the tires would just keep spinning for quite a while longer, resulting in a much slower ET.

With a numerically low rear gear, if the tires don't spin much, but rather hook up at low rpm, it might actually "bog" the engine down, til the rpm get up into near the peak torque range. The bog will be worse, if the cam does not provide much low rpm torque. So, the trick is to get just the right amount of tire spin, but not too much, & going to full WOT at exactly the right time.

With the engine in it's peak torque range, and the tires hooked up, acceleration will obviously be better with a numerically higher rear ratio. And, as for the extra shift, with a little practice, the shift only takes a small fraction of second. So, the numerically higher rear gear ratio will more than make up for anything lost to the extra shift
 

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Average times 0-60 in the muscle car era for the GTO ranged from 4.9-7.5 seconds or so, depending on all of the variables covered by Big D. A 4 speed, 3.90 geared tripower '65 was seconds faster than a 2 speed automatic, air conditioned, 3.08 geared 4 barrel GTO of the same year. My '65 came with tripower, 4 speed, gauges, and a 3.55 posi. No power steering, no power brakes, no seat belts, no outside rearview mirror. I didn't mind the 3.55 gears when I got the car almost 40 years ago when the national speed limit was 55 mph. Where I lived, everybody cruised 60.....65 was a guaranteed ticket. When the law got repealed in the '90's, I changed to 3.36 gears and 29" tall rear tires, which allows a comfortable 70 mph cruise just under 3000 rpm. My '67 automatic car had a 3.36 open rear end.....I changed that to a 2.56 posi about 10-12 years ago. 80 MPH cruise is 2450 rpm getting 20-21 mpg.....90 mph is right at 3000 rpm. The engine runs cool as well. I use this car for long trips over open country. 1000 mile weekends are not uncommon. With my lazy gears, I'll bet my 0-60 is about 8 seconds.....but I don't care. My car will hold second gear until 105 mph....which is more than the top speed of many shorter geared cars.
 

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Interesting.....I would have thought the car (with all the low end torque) would benefit from a 3.08 or even lower (taller) as the tires would not just spin and would save you a gear shift (time) from 2-3 in order to get to 60 mph.

Gearing can get lower (actually higher as the ratio number gets lower) with an automatic versus the typical Muncie. bigD covers a number of things in his posts. The first gear on the 4-speed (still talking Muncie) M-20 wide ratio trans was 2.56. The M-21 close ratio was 2.20. The Dearborn HD 3-speed (installations began on 3/1965) was 2.42.

Many of the manual rear axle gears were 3.23's, keeping in mind that the tire height was 26". Once you go with taller tires, like 28", you will drop about 1 axle ratio, so 3.23's will be about 3.08's. The problem then becomes clutch slip. It takes much more slipping of the clutch to get the weight of the car rolling. I can attest that with a factory type 10.5" diaphragm style set-up, and the close ratio M-21, you will burn through a clutch disc in short order with 3.08's out back and a lot of spirited driving. GREAT for smokey burnouts once they break loose and you keep the pedal pegged! :yesnod: Great for top end speeds well past 100MPH! :yesnod: Super on gas mileage with a stock engine when speed limits were 55MPH! :yesnod: But, tire life will be shortened and I got tired of dropping the shifter/bell/trans/driveshaft after the 3rd clutch in about 9 months. Fun, but there is a cost in time & money. So in went an automatic.

My '68 Lemans had the Dearborn 3-speed & 3.23's. I went with taller 28" x 15" tires out back and 14" on the fronts. I used an aftermarket heavy duty diaphragm pressure plate and carbon fiber disc. It took some slipping to get the car rolling, worse on a hill. When I pulled the engine with about 20,000 plus miles, I removed the clutch to inspect. Not a whole lot of disc left before hitting rivets - might have gotten another 10,000 out of it. In my book, really not an issue because the car was not a daily driver and that mileage span was over about 7 years.

I had the '65 Impala with a built 409, 4-speed, 3.08 posi, and some fat M-50 tires. As bigD stated, dump the clutch and tires would go up in smoke from a dead stop until I let off - not good for a street race. Learned the technique of bringing the RPM's up to I think about 2,500, dump the clutch, the tires would spin about 1 or 2 revolutions and bite, then I would nail it and that car would dig in like a rocket. Never any clutch slip as I used the 3-finger Borg & Beck diaphragm with weights that clamped tight. My left leg grew 1 pant's size larger in diameter with the force needed to push the clutch in. LOL

This is right out of a test article on the '64 GTO. With US Royal brand SS-800 Red Streak 7.50 x 14" tires, driving at 60 MPH, the rear axle ratio and engine RPM's were as follows: the 3.08 was 2,380-RPM, 3.23 was 2,500-RPM, 3.55 was 2,740-RPM, and 3.90 was 3,020-RPM.

With 4-speed, that sudden let-off of the clutch loads up the suspension and breaks tires loose - so you have to develop a technique that works best with your combo. This was also a common experience when the magazine test cars were raced at the 1/4 mile. Often tires smoked right off the line - 4-speed or automatic. So techniques had to be tried and air pressures in the tires adjusted to get the best times BEFORE putting on the slicks and dropping exhaust pipes, etc..

A quick dump of the clutch can also produce violent wheel hop, especially with worn out bushings & shocks. Of course several add-on items can be used to help this condition. If you wanted to try anything, try a set of 70-30 shocks up front. They say not to run them on the street. Hmmm. I ran them the whole time on my '68 Lemans and loved them. That nose would rise up under a hard launch putting weight on the rear and off I would go. I thought they rode and handled pretty good.

Other transmissions utilize a lower 1st gear as well as differing ratio spreads between the gears. With a lower 1st gear, you can use a 3.08 rear gear comfortably. Now with a 5-speed (or even 6 speed) manual with the Overdrive 5th & 6th, you want to gear the rear end for the RPM/speed you plan on most driving. With my '68 Lemans, I went with the Ford 9" and 3.89 gearing, which with the OD 5th, will be very comfortable cruising at 70 MPH or so. However, with its low first gear and the 3.89's, I don't figure I'll get much traction on a hard launch and may find myself starting off better in 2nd. If I had 3.08's, it would work real well, until I put it into 5th OD which probably would be around 100MPH and take me up into the 200 MPH club if the engine had enough grunt to do it (which it won't). So it is important to match cruising speed/RPM with trans/rear gearing - and don't forget the tire height you selected.

A car magazine did a 1/4mile test between two GTO's, one a 4-speed, the other the 2-speed automatic. The cars were both equal off the line with the 2-speed keeping pace with the 4-speed. It was not until the 2-speed shifted into it's "drive" that the 4-speed out performed it. But as geeteeohguy stated, only beat it by a couple seconds.

The 1964 GTO had a curb weight of 3,470 while the '65 jumped up to 3,590. '64 0-60MPH was 6.6 seconds with 348HP/4-speed/3.23 gears and weight as tested was 3,800. '65 0-60MPH was 5.8 seconds with 360HP/M21 4-speed/4.11 gears and weight as tested was 3,920 lbs.

Enter the Royal Pontiac Prepped 1965 2+2. Curb weight 4,155. 0-60 MPH was 3.9 seconds with 376HP/421CI, M21 4-speed, 3.42 gears and weight as tested was 4,400 lbs.

Just some food for thought. :thumbsup:
 

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"...1965 2+2. Curb weight 4,155. 0-60 MPH was 3.9 seconds with 376HP/421CI, M21 4-speed, 3.42 gears and weight as tested was 4,400 lbs..."


I don't believe that was possible. That's quicker than a real Shelby Cobra, from the '60's.

https://www.zeroto60times.com/vehicle-make/shelby-0-60-mph-times/fast-slow-0-60/

There were much lighter Musclecars that were not near that quick.

https://www.caranddriver.com/features/g15379640/1960s-fastest-muscle-cars/

Read it an weep. Keep in mind that the 376HP/421 HO got the Bobcat treatment. The car turned a 13.8 @ 106 MPH in the 1/4 mile - and that was with factory pipes with resonators removed and street tires - not slicks. On the 4-lap run of the road course, it covered the course in 2:01.33 to the Ferrari's 2:00.85 which was less than 1/2 second slower. The Ferrari took the advantage in the curves, but the 2+2 ate it up in the straightaways hitting a best speed of 127 MPH. The driver, Walt Hansgen, drove the 2+2 in 4th gear the entire track except one down shift to 3rd in the 55MPH hairpin. It was felt that if he had used 3rd more, his times would have been faster (ie beat the Ferrari).

My favorite part of the article, "When the throttle is suddenly pressed home and all six throats snap open, the effect is a stunning transformation. The noise level rises from a near-silence to a hard, flat roar. The pressure on the nape of the neck and the pit of the stomach is almost unbearable. The acceleration is phenomenal - the car is literally launched from a stand-still to a hundred-miles-per-hour faster than you can absorb the sensations - so fast that you don't even look at the instruments, just listen for the peaking point and slam the lever into each gear as hard and as fast as you can."

In each book, one written by DeLorean and the other Schornack, they both mirrored the test and the results.

It's all about torque and bite at the rear wheels. No doubt the longer wheelbase and additional weight of the 2+2 was a contributing factor. And how much HP/TQ did that Royal prepped engine really have? Bottom line, we will never know for sure, anymore than we can say the 0-60 times for the Shelby cars are correct or can ever be reproduced. :thumbsup:
 

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Believe it if you choose to.

IMO, a 13.8 @ 106 mph 1/4 mile car will not run anywhere near a 3.9 sec 0-60. The math just don't add up. The Royal Bobcat treatment couldn't work that kind of magic.

Hey, the Cobra wouldn't do it even with a 427 @ around 2500 lbs.

https://www.ultimatespecs.com/car-specs/Shelby/15193/Shelby-Cobra-427.html

https://www.topspeed.com/cars/shelby/1966-shelby-cobra-427-super-snake-ar25745.html

https://www.hemmings.com/blog/article/american-icon-1967-shelby-427-cobra/

https://www.supercars.net/blog/1965-shelby-cobra-427-roadster-history-specifications-performance/
 

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Discussion Starter #15
Believe it if you choose to.

IMO, a 13.8 @ 106 mph 1/4 mile car will not run anywhere near a 3.9 sec 0-60. The math just don't add up. The Royal Bobcat treatment couldn't work that kind of magic.

Hey, the Cobra wouldn't do it even with a 427 @ around 2500 lbs.

https://www.ultimatespecs.com/car-specs/Shelby/15193/Shelby-Cobra-427.html

https://www.topspeed.com/cars/shelby/1966-shelby-cobra-427-super-snake-ar25745.html

https://www.hemmings.com/blog/article/american-icon-1967-shelby-427-cobra/

https://www.supercars.net/blog/1965-shelby-cobra-427-roadster-history-specifications-performance/
Agreed BigD, there is no way one could launch a stock 4400 # car on tiny rear wheels of the day and get 3.9 seconds 0-60. There was definitely a lot more going on with that Royal Bobcat. To put that in perspective, my 600 hp + (modified and whp), all wheel drive AMG takes 3.2 seconds to get to 60 seconds and that has been a lot of work. The same car is turning the 1/4 mile in low 11's at 127mph.

Just shifting the gear, 1-2 and 2-3 will add ~0.5 seconds for a very quick shifter (world class), whereas most normal people would be closer to 0.5 seconds for just the 1-2 shift or 1 second for 1-2 and 2-3.
 

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Big D, I have the old magazine road test somewhere on the '65 2+2....it is a rather famous road test, probably on line these days. The 421 Bobcatted 2+2 did in fact clock a 3.9 0-60 time back in the day. I have no idea what ELSE was done to the car or the clocks.....but the test stands, believe it or not. Remember, Jim Wangers had those 2 ringer '64 GTO's for the Road and Track road test in Sept of '63.....those cars had built 421 engines, passed off as 389's. The actual HP of the Super Duty 421 engines in the early '60's was over 500.
 

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"...but the test stands, believe it or not..."

I believe the test was reported. But I absolutely don't believe that they actually managed to get a car that heavy to run 0-60 in under 4 seconds, especially with only 3.42 gears. It just defies all the laws of gravity, math, & mechanics.

In fact, since the light 427 Cobra couldn't do it, I'd like to see exactly what it would take to make a 3500 lb car that quick, much less a 4400 lb car.

Hey, you guys can believe it if you want to. But that don't mean the car was actually that quick.

This blown 707hp/650 torque 8-speed Hellcat only managed a 3.4 sec 0-60 time. Running 0-60 in under 4 sec just ain't that easy to do, in a heavy street car. Takes LOTS of power, gearing, & traction.

https://www.caranddriver.com/reviews/a15100533/2016-dodge-challenger-srt-hellcat-automatic-test-review/

But hey, whatever ! That's all I'm gonna say about it.
 

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Point taken, bigD. And I suspect you are onto something here.....I believe the car was tested with a stop watch, not electronically, so that leaves loads of room for error. No harm, no foul. All of your points are logical and make sense IMO.....
Jeff
 

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Discussion Starter #19
Here is a log I did in my daily driver....a lot more than 600 whp :) and all wheel drive
 

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That would mean your daily driver has about 735 HP at the crank.....MUCH more than any Pontiac on this forum, I'd bet. What are you driving every day that is making that kind of HP?
 
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