383 deck clearance

-
8

808 DUSTER

Active Member
Joined
Aug 26, 2013
Messages
35
Reaction score
0
Location
fort bragg
Does anyone know the deck clearance of a 383b block? Casting number is 2468130 7. Reason I'm asking is I'm thinking of a head swap down the line and trying to figure specs. Current it still has flat top pistons. Also current heads are 346s.
 
Do you mean the deck HEIGHT? Deck clearance will depend completely on what piston and rod combo you use. The "specified" deck HEIGHT is 9.980 from the centerline of the crank to the deck surface. However, it is almost always much taller due to Chrysler's "accurate" machining tolerances. <insert eyeroll here>
 
Hmm not sure, the CR programs are asking for clearance. Far as I know it still has the stock components
 
From years of doing engines,the piston to deck spec is normally in the .025-.050 on the performance 383 engines,the lower the compression of the stock motor,the more piston to deck height increases,as the pin center line to piston crown decreases,mrmopartech
 
Mrmopartech said:
From years of doing engines,the piston to deck spec is normally in the .025-.050 on the performance 383 engines,the lower the compression of the stock motor,the more piston to deck height increases,as the pin center line to piston crown decreases,mrmopartech
Click to expand...

I've never found them to be that close. The average is running closer to .060" down in the bore. One was .086. To get to zero deck we had to cut the decks that far... Factory HP pistons were designed to be .020-.030 but the blocks are always much taller than the blueprint deck height - so you have to cut them way down just to get to blueprint distance. Every block is different.
 
Exactly. No matter how hard I try. I just end up givin up.
 
What I got out of this is that I should cut the decks down to blueprint height and either order custom pistons or offset grind the crank...or buy a stroker :)
 
There are several different piston configurations for a stock 383. On top of that, you have no idea of where the deck height is on the block. Suffice it to say that it's tall from the spec. With those two variables alone, there is no way to make a blanket statement regarding deck clearance and I've not even thrown in possible replacement pistons. The only way to be sure about deck clearance is to measure it.

With my 383 I had the rods resized and trued to length. The crank has been indexed. The block has been decked to a predetermined measurement (9.956) for zero deck height, so I already know what my deck clearance will be. I have a good machinist so I know it will assemble right. If anyone throws you out a number for deck clearance, you better take it with a grain of sand, cause it's most likely WRONG.
 
One thing I'll add - if this is for a numbers matching deal - you have to use a shop with the high speed cutter - not a traditional mill. Otherwise it removes the stampings from the engine ID pad on the passenger's side just outside of the distributor. The best way is to bring the block in, tell them what piston you're using, and then have it decked to that measurement. building a good 383 takes attention to detail beyond anyother idsplacement because there are few pistons available with decent compression hieghts and the blocks are always tall. So you have to know what to cut it down to because to zero deck you'll have to go further than blueprint height.
 
Puzackly. Mine was like .024" under blueprinted spec.
 
The only way to know deck clearance is to actually measure the piston down in the hole if it has not been blueprinted.
If you do decide to have the block decked, it needs to be done on a fixture that precisely locates off of the main journals and indexes the crank/cam centerlines, and also gives an accurate referrence for the actual deck height.
100_7866.JPG


Of course, if you are going that far, make sure the block is honed with a torque plate because the bores will move, and if one isnt used the rings will not seal properly.

2011-03-24%2017_24_45.jpg
 
I am really glad you came to our rescue. I never wouldda thought of actually measuring it. <extreme sarcasm>
 
RustyRatRod said:
I am really glad you came to our rescue. I never wouldda thought of actually measuring it. <extreme sarcasm>
Click to expand...

Well, seeing as how he asked about deck clearance, which is not the same as DECK HEIGHT, I thought I might try to add some info to clarify.
I was simply agreeing with you about that it needs to be measured either way, seeing as how there are 4 variables that affect it.
Which of course you already know.:thumblef:
 
He got all kinda deck clearance answers. Thanks for clarifying.
 
You must log in or register to reply here.
-

Back
Top