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284/484 for stock 383

No, we don't want to scare him off.. But we don't want to feed him wrong info either... The low deck Mopar's are hard to build compression in do to their short stroke and cylinder head design...

The easiest why to do it is with a domed piston but then the flame travel is effected & not in a good way...

So you choose the best flat top you can, mill the crap outta the heads & measure closely to see how much cam you can get away with...

Another thing to keep in mind is with todays fuels if you run iron heads you really don't want to be at 10-1... I guess some areas get better fuel, here in California gasoline & cow piss are interchangeable... so with 91 Octane 9.5 is about the limit...
 
BSB67 said:
But how? The details are very important. You say that the motor has been rebuilt. Because replacement pistons have not been available for about 40 years, almost any 383 that has been "rebuilt" since then is actually much lower in CR.

You need to know piston part numbers, cylinder head casting numbers and chamber cc's before truly knowing actual compression ratio.

Not to be negative Nancy, but 99% of 383s that have been "rebuilt" in the last 40 years have an 8:1 compression ratio.
Click to expand...
66 383 hp came with 10:1 my engine has the original pistons and heads.
 
That's an advertised number. The real number needs to be calculated by measuring the deck height, chamber volume and gasket thickness. It's almost always lower.
 
Ok so I'm guessing the 284 /484 is not a good choice, that's why I'm here... what do you guys recommend? Power is not really an issue, my car runs good. It just sounds super plain at idle. Thanks to all of you for the input. As far as compression... it pings on 87 but not on 91 or above. Reno is at 4800 ft above sea level.
 
My suggestion....
Crower 271HDP, 222/[email protected] .486/.496 lift 112 center
It's a grind that runs well in a 383, enough to have a decent lope but not so much it knocks the bottom of the power curve out..
 
NV64sportfury said:
66 383 hp came with 10:1 my engine has the original pistons and heads.
Click to expand...
Okay. So the motor was rebuilt without an over bore and with the original 53 year old pistons. That tells us a lot.

So the motor is together and running now. If so, what is the cranking cylinder pressure? What was done to the cylinder heads?
 
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1 Wild R/T said:
My suggestion....
Crower 271HDP, 222/[email protected] .486/.496 lift 112 center
It's a grind that runs well in a 383, enough to have a decent lope but not so much it knocks the bottom of the power curve out..
Click to expand...

Considering what the OP just posted, that cam or the MP 272 like someone else suggested earlier would be good, IMO
 
Don Frelier said:
That's an advertised number. The real number needs to be calculated by measuring the deck height, chamber volume and gasket thickness. It's almost always lower.
Click to expand...

Here's the deal, nobody likes finding out Ma Mopar lied to us...

But the reality is all the manufacturers did it... They fudged the numbers knowing that the racers could blueprint their engines to the numbers the manufacturers published...

And very few buyers would notice that thy didn't get all the cylinder pressure they should have....
And if they had they would have had to buy the higher grade fuel anyway... (which was easy to find and only a few cents more) But it saved dealers from having to hear complaints about needing to buy premium fuel..

So when Chrysler claimed 10-1 that means your cylinder heads have a chamber volume of 72cc like they published.. The reality? About 81cc on a 516 or 915... 906/452/346? About 88-90cc

So what does that extra 8-9cc's mean in real world?

On a 383 9cc drops you from 10-1 down to 9.1-1

But on a 440 with it's longer stroke it doesn't have quite as much effect..

On a 440 9cc drops you from 10-1 down to 9.4-1
 
BSB67 said:
Okay. So the motor was rebuilt without an over bore and with the original 53 year old pistons. That tells us a lot.

So the motor is together and running now. If so, what is the cranking cylinder pressure? What was done to the cylinder heads?
Click to expand...
 
The engine had 23,000 original miles. Came out of a wrecked charger. It was stored for 50 years. It was pulled apart re ringed and honed....The heads were cleaned up and the valves were reseated. Crank was polished and put all back together. That's all the info I have. It's all original down to the original date coded Carter AFB. I have not done a compression test. Like I said it runs good just want a little more rumble.
 
NV64sportfury said:
The engine had 23,000 original miles. Came out of a wrecked charger. It was stored for 50 years. It was pulled apart re ringed and honed....The heads were cleaned up and the valves were reseated. Crank was polished and put all back together. That's all the info I have. It's all original down to the original date coded Carter AFB. I have not done a compression test. Like I said it runs good just want a little more rumble.
Click to expand...


Yup, understood.. Nothing wrong with a ring & bearing job on a low mile engine.. We just want you to have the right info to make the right choices... 383's really don't like the wrong cam...

As mentioned that Lunati 702 grind is good.. As is the Crower 271...
 
1 Wild R/T said:
Yup, understood.. Nothing wrong with a ring & bearing job on a low mile engine.. We just want you to have the right info to make the right choices... 383's really don't like the wrong cam...

As mentioned that Lunati 702 grind is good.. As is the Crower 271...
Click to expand...
 
Dose anyone have any of the recommended ones installed that I can listen to? I've searched the videos, cant find anything.
 
Here is one of my Charger with the Mopar .455 / 272 cam.
The last time I ran it with a carb.
Not a direct comparison:
- 906 heads
- 68/69 HP cast iron manifolds
- Magnaflow 3 chamber mufflers with an H-pipe
- This is a actual 9.4:1 compression motor ( I measured everything )

You may want to try different mufflers and play with the idle speed/mixture.
These things will change the sound particularly the mufflers, cheap and pretty easy to change.
 
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