383 "Stock Piston Depth"

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69 Cuda 440

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383 HP {1967 thu 1971}

Some recent Stock Piston Depth Measurements >

...........................................................Factory Minimum...Compression

Block 1 {1967} ........ -.041" Below Deck ........ {-.014"} ...... 10.0
Block 2 {1968}......... -.033" Below Deck ........ {+.021"} ..... 10.0
Block 3 {1969}......... -.029" Below Deck ........ {+.021"} ..... 10.0
Block 4 {1970} ........ -.081" Below Deck ........ {-.004"} ....... 9.5
Block 5 {1971} ........ -.086" Below Deck ........ {-.019"} ..,,... 9.6
 
69 Cuda 440 said:
383 HP {1967 thu 1971}

Some recent Stock Piston Depth Measurements >

Block 1 {1967} ........ -.041" Below Deck
Block 2 {1968}......... -.033" Below Deck
Block 3 {1969}......... -.051" Below Deck
Block 4 {1969}......... -.029" Below Deck
Block 5 {1970} ........ -.081" Below Deck
Block 6 {1971} ........ -.086" Below Deck
Click to expand...


{383 4-Barrel HP Engines}
 
Not what i found. My 68 383HP was zero on 3, between -.001 to .009 on 4 other cyl and one was .014. Driver side was front to back was .000, 000, 000, .003. then when the worker flipped the engine over to deck the other side it was .004, .007, .009, .014. Any little thing could toss off the decking of these engines back then, sloppy workers, worn or dirty machinery. Several other 383HP's i have measured in the past were no more than .020 down in any cyl.
 
The 383 numbers block I just did for my GTS was only .024. I left the deck alone since its a numbers to car match. Even the 383 I did for my RR project was .025. Never know with Ma Mopar.
 
You can't go by the book numbers. The stack ups don't add up....
 
69 Cuda 440 said:
383 HP {1967 thu 1971}

Some recent Stock Piston Depth Measurements >

..................................................Factory Minimum...Compression

Block 1 {1967} .. -.041" Below Deck ..... {-.014"} ...... 10.0
Block 2 {1968}... -.033" Below Deck ..... {+.021"} ..... 10.0
Block 3 {1969}... -.029" Below Deck ..... {+.021"} ..... 10.0
Block 4 {1970}... -.081" Below Deck ..... {-.004"} ....... 9.5
Block 5 {1971} .. -.086" Below Deck ..... {-.019"} ....... 9.6
Click to expand...

A Better Breakdown of 'factory stock'' untouched Engines that
were recently pulled apart.
 
As per the Chrysler Marine & Industrial Tech Department

The 383's were usually assembled with the Deck Height .045" lower in the
Cylinder than the listed 'minimum specifications'.

ie; 1968/1969 '383' 4-Barrel
Was listed with a deck Height of {+.021" ab} above deck.

But, most of the Blocks left the Assembly Plant with the Flat-Top Piston
at a Deck Height of {-.025"} down in the Cylinder.
 
My 1968 383, C-body 2bbl had all pistons .026 below deck with very little variation.
 
Has anybody calculated the actual compression ratio with stock heads on the early 383 hp motors?
 
ir3333 said:
Has anybody calculated the actual compression ratio with stock heads on the early 383 hp motors?
Click to expand...

On early '383' 4-Barrel Engines,

I'm assuming that you are referring to the 1965 thru 1967 Engines that were listed with 10.0-1 Compression.
* Flat Top Pistons
* 2406516 Cylinder Heads {Closed Chamber}

In actuallity, between 9.2 and 9.4

In those 383 Engines that I have pulled apart, the Pistons are usually
found @ .040" to .045" down in the Cylinder, as opposed to the factory
listing of {-.014"}.
 
Factory deck height.


57709339.jpg
 
This from the 1967 Mopar Performance Recommendations

In a completely 'stock' 383 HP engine, with 'as is' factory deck height
and stock cylinder heads {not milled}.

The 383 can handle a Camshaft with a .500" lift and 300* Duration
without any Valve-to-Piston clearance issues.

'1967' Recommended Street/Strip Camshafts

* Chrysler Street Hemi Grind ~ 'Hydraulic'
* 474" Lift ~ 280* Duration {238* @ .050"Lift}
* For 'Street'

* Iskendarian 310-H ~ 'Hydraulic'
* .440" Lift ~ 310* Duration {268* @ .050" Lift}
* For 'Street'

* Race Brown SSH-24 ~ 'Hydraulic'
* .485" Lift ~ 286* Duration {238* @ .050" Lift}
* For 'High-Performance' Street and Strip

* Crower 300 ~ 'Mechanical'
* .477" Lift ~ 300* Duration {252* @ .050" Lift}
* For 'High-Performance' Street and Strip

* Racer Brown ST-23 ~ 'Mechanical'
* .502" Lift ~ 278* Duration {246* @ .050" Lift}
* For Strip 'Moderate Race' {4-Speed Only}
 
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