Safe to bore a 383 60 over?

-
Kern Dog said:
This is bullshit....
View attachment 1716141120

Thin wall castings?
False. The later blocks have been found to be as thick or thicker than earlier blocks. The later blocks did have less nickel in them and were a little softer but they were still fine. Larry Shephard may have put out some good information but the "thin wall" stuff is wrong.
Why do you think you need to go .060 over? Where are you now? If you're at .030, why not take it .040? My '74 440 block is .040 over. Many 440 blocks have gone .060 without trouble, a 383 should too.
As stated before, a sonic check is the way to go. It will determine the thickness of the cylinders before you go any further.
Click to expand...
I have several of his books and all have alot of inaccuracies!

To the OP I know its apples and oranges but my 360 went .060 over with no issues! Like others have mentioned sonic testing is the best way to know for certain!
 
4fortyDemon said:
That's the same cam I'm using. What compression do you think you had that it didn't make a lot of power?
Click to expand...
I have no idea what compression ratio was...I'll guess pretty low. Crap cast pistons with thrown together 906 heads. Maybe 8:1?? It sounded great but never really made much power. I'm also comparing it to the low deck 470 roller cam deal that's in it now so......
 
Dcuda69 said:
I have no idea what compression ratio was...I'll guess pretty low. Crap cast pistons with thrown together 906 heads. Maybe 8:1?? It sounded great but never really made much power. I'm also comparing it to the low deck 470 roller cam deal that's in it now so......
Click to expand...
Definitely not apples to apples..lol. I'm figuring 9 to 1 here
 
MidnightSwinger said:
What pistons did you go with?
Click to expand...
I didn't pick up the engine yet. But they told me that they are using the same ones as what was in but 60 over. I asked them to use a '68 4bbl piston if possible cause the pin height is lower. I'll measure them when I get it assembled next weekend.
 
4fortyDemon said:
I didn't pick up the engine yet. But they told me that they are using the same ones as what was in but 60 over. I asked them to use a '68 4bbl piston if possible cause the pin height is lower. I'll measure them when I get it assembled next weekend.
Click to expand...
A standard bore 72 and later 440 piston will give you a 1.93" compression height, same as 68 383 but it will be .070" over, I machined and built a lot of them and have another I'll be doing soon which will be for sale.
 
I figured I'd keep this thread going being a lot of info was posted on here.... what would you do with this cam bearing? I looked at the 2 other oil holes, they line up... wth. Drill the hole? **** bearing that isn't made correctly? This is a new one for me.

20230930_150432.jpg
 
Gomer Pyle said:
A standard bore 72 and later 440 piston will give you a 1.93" compression height, same as 68 383 but it will be .070" over, I machined and built a lot of them and have another I'll be doing soon which will be for sale.
Click to expand...
:thumbsup::D old school
 
Gomer Pyle said:
A standard bore 72 and later 440 piston will give you a 1.93" compression height, same as 68 383 but it will be .070" over, I machined and built a lot of them and have another I'll be doing soon which will be for sale.
Click to expand...
Do you machine the block for zero deck.
the low compression 440 piston will set at .008 or so bellow deck in a factory block
Doesn't take much to get it above deck for more compression
 
4fortyDemon said:
Never heard of that! Well, it's getting picked up from the machine shop on Fri. It's 60 over now with new pistons, block sonic checked, crank cut to 20 under, cam bearings r&r, hot tanked, rods resized with high strength bolts, all bearings and rings included from the machine shop. Quick turnaround. Looks like I'll have boat anchors lying around in the form of 40 over pistons...lol.
I'll update this weekend.
Click to expand...
What type of piston? Might be interested in them
 
4fortyDemon said:
I figured I'd keep this thread going being a lot of info was posted on here.... what would you do with this cam bearing? I looked at the 2 other oil holes, they line up... wth. Drill the hole? **** bearing that isn't made correctly? This is a new one for me.

View attachment 1716148171
Click to expand...
I have long drill bits I run from the main bearing and head surface to "line up" the holes.
Dress the bearing as nec.
Let the drill bit do the job, gentle pressure on the drill .
Good luck.
 
Last edited:
inertia said:
I have long drill bits I run from the main and head surface to "line up" the holes.
Dress the bearing as nec.
Let the drill bit do the job, gentle pressure on the drill .
Good luck.
Click to expand...
Unfortunately, the hole that didn't line up isn't the feed hole from the main. It's the feed hole to the head on drivers side. I took a drill bit ( initially couldn't get any drill to fit in the confined space) and turned it with my hand to try to get it opened up...lol
Finally, I found my 1/4" snap on electric driver and got the bit to go. It's not as clean as I wanted, but I dressed up the bearing with WD and krokus cloth. The feed hole so much better.
I ended up cleaning the water passages more figuring that I'm going to clean the block more thoroughly anyway.
 
4fortyDemon said:
Unfortunately, the hole that didn't line up isn't the feed hole from the main. It's the feed hole to the head on drivers side. I took a drill bit ( initially couldn't get any drill to fit in the confined space) and turned it with my hand to try to get it opened up...lol
Finally, I found my 1/4" snap on electric driver and got the bit to go. It's not as clean as I wanted, but I dressed up the bearing with WD and krokus cloth. The feed hole so much better.
I ended up cleaning the water passages more figuring that I'm going to clean the block more thoroughly anyway.
Click to expand...
Holes don’t just appear it was drilled by factory
 
fishmens67 said:
Do you machine the block for zero deck.
the low compression 440 piston will set at .008 or so bellow deck in a factory block
Doesn't take much to get it above deck for more compression
Click to expand...
No, they're budget engines I'll sell, I shoot for about 9.7 CR with whatever iron heads I use for it. I have about 10 engines to finish and sell.
 
You must log in or register to reply here.
-

Back
Top