Is this a 383?

[SLDPULR]

So I started to tear down my motor today to get ready to go to the machine shop. I have been trying to read up on motors as much as possible over the past few weeks. I pulled the motor and to my surprise its a 4 bolt main 010 020 block so that is good news. They part that is confusing me is that the 400 crank is externally balanced and my crank had a harmonic balancer on it. So does this mean that it may already be a 383? I have tried to search for this info but I have not had any luck. The motor ran good when I started to tear down the truck but I wanted to go with a 383 over the 350 for a little more torque. I looked and didn't see any spots where the block was ground down to clear the connecting rods. Do they make a externally balanced 350 or is my thought process completely wrong. What do I need to look for? I do not want to pull the main caps if it is already a 383. Please let me know. Thanks!

I pulled off the balancer and pullys before I took this picture.

[69chevytrucker]

do the pistons have 030 on them

[69chevytrucker]

on the top of them

[mgchevyparts]

You don't show the balancer. Is it a 400 external balanced one?(counter weighted) If so it's a 383. No such thing as a external balanced 350

[69chevytrucker]

has to be bored 30 over with a 400 crank to be a 383 and its not real if it doesnt have dished pistons

[69chevytrucker]

64cc heads with 12cc dished pistons or flat top with 70cc head as well

[mgchevyparts]

Originally Posted by 69chevytrucker

has to be bored 30 over with a 400 crank to be a 383 and its not real if it doesnt have dished pistons

ONLY a 400 balancer will work with a 400 crank, no other small block uses a counter weighted balancer. If it has an external balanced dampner it's a 383, now one could make it a few cubic inches different + or - with the bore size but it's unlikely. 383 pistons come in more then one dome size.
Additionally, the flex plate has to be counter weighted also.

[SLDPULR]

I tried to mic the bore but the ride is pretty bad and I could not get a accurate reading. The only markings on the pistons I could find are the letters of the alphabet in order from a through h. Here are some more pictures.

[Greasey Harley]

400/stroker crank will not clear the sides of a 350 block. All 383's have small notches ground to clearance the block so the rod bolts don't strike the block.
Spin the crank, look where the rod bolts come closest to the block.
Has the block been ground so the rod clears the block?--->383
If not--->Standard 350
Also the internal/external balance thing but I can't explain the difference as clearly.
Good luck
https://www.youtube.com/watch?featur...&v=tzG0RLcxW9I

[SLDPULR]

Originally Posted by Greasey Harley

400/stroker crank will not clear the sides of a 350 block. All 383's have small notches ground to clearance the block so the rod bolts don't strike the block.
Spin the crank, look where the rod bolts come closest to the block.
Has the block been ground so the rod clears the block?--->383
If not--->Standard 350
Also the internal/external balance thing but I can't explain the difference as clearly.
Good luck
https://www.youtube.com/watch?featur...&v=tzG0RLcxW9I

See that is what I thought but I remember seeing that someone makes special rods or rod bolts that will clear a factory block. I am still trying to learn all the info on SBC motors so please bear with me. This motor looks like it has been together for a LONG time judging by the amount of sludge built up in the heads.

[mgchevyparts]

That's a 350 balancer.(no counter weights) So proceed with your 383 build. But you won't see that much difference if every thing else is equal between the two (350 vs 383)

[SLDPULR]

Originally Posted by mgchevyparts

That's a 350 balancer.(no counter weights) So proceed with your 383 build. But you won't see that much difference if every thing else is equal between the two (350 vs 383)

Thanks! Thats what I needed to know.

[69chevytrucker]

that balancer looks like post 87

[SLDPULR]

Originally Posted by 69chevytrucker

that balancer looks like post 87

I looked up all the numbers on the block and its a 75

[69chevytrucker]

block might be 75 doesnt meen every thing is
my block is 89 with 69 heads 85 wp etc

[SLDPULR]

Originally Posted by 69chevytrucker

block might be 75 doesnt meen every thing is
my block is 89 with 69 heads 85 wp etc

Oh I agree. There is no telling what has been done to this motor. All I know is that if the same person who built this motor did the wiring and replaced the floor pans it deff needs to be gone through. There was more twist on wire nuts under the hood of this truck than in my house.

[69chevytrucker]

ya i just didnt want you to get your hopes up i have been building chevy engines for 25yrs i know some weird crap can be done thats why i asked about the 030 on the pistons cause thats one thing for it to be 383 would have to be done to a 350 block

[frank69]

looks like a 75 standard bore 350 smog motor

[67 chevelle]

Originally Posted by frank69

looks like a 75 standard bore 350 smog motor

I concur , if you do make a 383 out of it , with any type of performance parts , it should make 2-3 times the horsepower of its former self , and gobs of toque

[mrein3]

Originally Posted by SLDPULR

See that is what I thought but I remember seeing that someone makes special rods or rod bolts that will clear a factory block. I am still trying to learn all the info on SBC motors so please bear with me. This motor looks like it has been together for a LONG time judging by the amount of sludge built up in the heads.

There are all kinds of 383 "kits" out there. I used a stock 400 crank, external balancer, and GM flywheel they used with 400 small blocks.
The rods I used were out of the 350 that I started with.
The pistons were special for this 383 build. They have the wrist pins higher up than stock 350 pistons to accommodate the longer stroke. And like Greasey Harley pointed out, I paid the machine shop guy to notch the block so the rod bolts clear it.

I think the first 383 "kits" used the 400 crank and rods with 30 over 350 pistons.

Now all the stuff comes in a box if you want to make one.

[mcm1209]

I had to take material off of the bottom of the cylinders so the rods would clear.
I started assembling my motor and went to turn to install another piston and the rods would hit the bottom of my cylinder walls.

[SLDPULR]

Originally Posted by mrein3

There are all kinds of 383 "kits" out there. I used a stock 400 crank, external balancer, and GM flywheel they used with 400 small blocks.
The rods I used were out of the 350 that I started with.
The pistons were special for this 383 build. They have the wrist pins higher up than stock 350 pistons to accommodate the longer stroke. And like Greasey Harley pointed out, I paid the machine shop guy to notch the block so the rod bolts clear it.

I think the first 383 "kits" used the 400 crank and rods with 30 over 350 pistons.

Now all the stuff comes in a box if you want to make one.

Yeah I have been shopping around for 383 rotating assembly's. Should I get a 400 crank for a 400 block and machine the mains to fit that crank or should I get a 400 crank for a 383 build that fits in the 350 mains? I am trying to keep the rotating assembly around 1000 bucks so I can still have some money left over for good heads, carb, manifolds, and intake manifold.

[SLDPULR]

Originally Posted by frank69

looks like a 75 standard bore 350 smog motor

What makes it a smog motor?

[haysonj]

Originally Posted by SLDPULR

Yeah I have been shopping around for 383 rotating assembly's. Should I get a 400 crank for a 400 block and machine the mains to fit that crank or should I get a 400 crank for a 383 build that fits in the 350 mains? I am trying to keep the rotating assembly around 1000 bucks so I can still have some money left over for good heads, carb, manifolds, and intake manifold.

Go to Scat and buy the entire rotating assembly already ballanced. If you are careful you can clearance the block yourself with a dremal or die grinder You need about .050 where the rod bolts go by the rails and the bottom of the bores will need some touch up as well. The 400 crank is old school and not a good way to go.

[SLDPULR]

Originally Posted by haysonj

Go to Scat and buy the entire rotating assembly already ballanced. If you are careful you can clearance the block yourself with a dremal or die grinder You need about .050 where the rod bolts go by the rails and the bottom of the bores will need some touch up as well. The 400 crank is old school and not a good way to go.

Was I correct that the crank journals on the 400 crank are different than that of a 350? I have read so much in the past few days that its all starting to blend together.