What piston for my 383 build?

[33 IMP]

Used a homemade isky tool on some decent deckheight cast pistons, to make room for a .590 purple shaft. Turned out it just needed a little nick for the exhaust valve. Cast pistons, .008 piston to wall, sounded like a diesel at start-up. Went mid elevens in a duster, thirty years ago.

 

[wyrmrider]

remember if you shorten the duration or go to wider LSA you increase your piston clearance around TDC
another reason not to use a longer than necessary cam
UDHarold wrote on this extensively when trying to fit lobes on max superstock builds
developed special asymetrical lobes and reverse asymetrical lobes for the cam (depending on intake or exhaust was the problem)

 

[LowDeck451]

Not necessarily. Look at the alloys. The Speed-Pro pistons aren’t 2618 forgings and as such not as loud. Plus the Speed-Pros have a skirt coating if that helps any? Also, there’s the flat top versus dome piston and the flame travel debate...

On a side note. We weighed the piston pin combos; new Speed-Pro versus original cast. They were almost identical.

Thinking I’ll do a write-up on my 383 restoration build as a reference for anyone interested once I have all the numbers in.

Using a Bob K cam? Hope you do. I’ve wondered what his cam would be like in a 383.

 

[wyrmrider]

What the specs on the bob K cam
I understand he has some good ones for six-packs
does he grind them himself?

 

[CompSyn]

What the specs on the bob K cam
I understand he has some good ones for six-packs
does he grind them himself?

The specs of the Bob K cam aren’t published. They are within 1-2% of Factory Original specs as per PSMCDR rules.

These cams are ground on Mopar lobes by Engle Cams with Bob K provided specs.

Not only are you getting a cam when you buy Bob’s cam, but decades of Mopar specific drag race experience and the tuning tricks Bob learned from his mentor, Ramchargers Tom Hoover, father of the Hemi. That’s why I say stock engine; it’s a no brainer, get the Mr. 6Pack camshaft.

 

[wyrmrider]

I'd never run a stock Magnum Cam in anything especially a low compression motor
Engle does do quality work
now if you have to meet PSMCDR rules go for it

 

[AustinGriggs]

Get the SpeedPros, I have since went back to a 915 head, But FWIW I had them under some out of the box Stealth Heads running through HP manifolds and my 383 went 8.42 in the 1/8 mile. Block was zero decked and used a standard .039 Felpro gasket. The cam was a roller from Hughes with 208/214@50 and .491/.500 lift. This was all on a factory "loosened up" converter and 3.55s in a Super Bee. I have since went with a cam that has around 230@50 and in the 530s lift with zero Piston to valve issue, using 2.08/1.74 valves. Added some headers and a better converter car now post times in the 7.90s. So in short, if you aren't going for track records and just want to have a fun street car.... Get the Speed Pros.

 

[Kern Dog]

What do those times equate to in the 1/4 mile?

 

[33 IMP]

What do those times equate to in the 1/4 mile?

8.40s, around 13.15, 7.90s around 12.30, by the chart I have. Lots of different formulas to get from eighth to quarter.

 

[BSB67]

8.40s, around 13.15, 7.90s around 12.30, by the chart I have. Lots of different formulas to get from eighth to quarter.

and probably 109 mph. For a street car, he runs a better than average 60 ft time, around a 1.7. Typical unmodified street car will 60 ft at 2.0 or so. That makes a 12.80 car

 

[Kern Dog]

My crappy drag racing skills either results in walking out of the hole to avoid wheelspin or blowing the tires off. I don't think I ever beat a 2.0 time for 60'.

 

[33 IMP]

Kern, all you need is a set of cheap wheels and a set of used 9" stock eliminator slicks to put on em. Ive seen a set of slicks be good for a three tenths improvement in 60 ft.(or more). I would have to check wallace, but ill bet three tenths in 60, can be worth six tenths or more in a quarter.

 

[Kern Dog]

In 2002, I went 14.01 @ 101 with a 2.2 sixty foot time. I got 5 runs in that day, all between 99 and 101 mph.
This was with my red car before paint. Stock piston 440, iron heads milled, 280/474 cam, 1 7/8" headers, 750 Holley. Performer RPM intake, 3850 lbs plus me, 727 with stock 11" converter, 3.91 SG and 27" tall street tires

 

[BSB67]

Kern, all you need is a set of cheap wheels and a set of used 9" stock eliminator slicks to put on em. Ive seen a set of slicks be good for a three tenths improvement in 60 ft.(or more). I would have to check wallace, but ill bet three tenths in 60, can be worth six tenths or more in a quarter.

My experience is that simply putting on a set of slicks on a unaltered street suspension and a stock-ish converter gains you little in this power and et range. And it is mostly the converter. I wish I had a dime every time someone either changed to a short gear, or added slick only to be very disappointed.

 

[33 IMP]

Wallace racing calculators (a fun place to visit!) says 101mph should be a 1.83 60 ft. and 13.12 e.t. Mind you, that is a perfect pass number, the BEST that should be possible. Much harder to achieve with a street car.

 

[33 IMP]

My experience is that simply putting on a set of slicks on a unaltered street suspension and a stock-ish converter gains you little in this power and et range. And it is mostly the converter. I wish I had a dime every time someone either changed to a short gear, or added slick only to be very disappointed.

My experience is planning on going to the races and finding one of my slicks flat. A set of shitty L60 Pro Trac street tires turned an eleven second street car into a high thirteen second street car.

 

[Kern Dog]

Wallace racing calculators (a fun place to visit!) says 101mph should be a 1.83 60 ft. and 13.12 e.t. Mind you, that is a perfect pass number, the BEST that should be possible. Much harder to achieve with a street car.

I had smiles thinking that if I had fine tuned my starting line technique, I would have cracked into the 13s ! I mean just a slight improvement in my 60' time would have got me there.

 

[LowDeck451]

Years ago my stock Charger R/T with McCreary G60 15s, 3.55s, auto, ran a best of 13.89 @ 98.6, 2.04 60’. I was happy with the ET, but thought the mph was a little off.

 

[BSB67]

My experience is planning on going to the races and finding one of my slicks flat. A set of shitty L60 Pro Trac street tires turned an eleven second street car into a high thirteen second street car.

That's because you spun. When you spin, the et is always way off the mark. Any car with a 0.09 or greater power to weight ratio with a full stock street trim/street gear will 60 ft around 2.0. If its much worse than that, it's tire spin and driver technique. Once you have the driving technique down, you don't spin and your consistent, and lets call it 2.0, changing only one of the three (converter, tire, gear) will not net much change, about 0.1 in the 60 ft, and 0.15 to 0.20 in et. Changing all three will get you the three tenths in 60 ft and probably 0.5 in et. I would call that a good modified street set up, but still short of the theoretical best, as you pointed out, in the Wallace or any other information source. The only cars that I've seen come to the theoretical et are well though-out race cars.

Generally, the guys that are getting big improvements in 60 ft & et on a tire switch alone are spinning their street tire.

There can be all kinds of exceptions to this, like a guy with 600 hp switching from BFG 225-70-14 to a 10.5 race slick. But I don't think that is in the spirit of this discussion.

 

[33 IMP]

You bet i spun, for about a hundred feet. But that is exactly that we were talking about, what KernDog said his problem was, see post #91. I didn't say HE would pick up three tenths, i said i had seen it . If you count my car, good tires versus bad was worth six tenths in 60 feet. If i just walked it out at one third throttle for 50 feet or so, it only cost four tenths in 60 ft.
Kern says he would be happy in the thirteens, but that he had a lot of wheelspin, and went 14.01. Do you really think he couldn't pick up a tenth with slicks?