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Discussion Starter #1
My 66 sedan sat for a few years before I got it, it has its original 283, which was leaking oil from every seal and not running right.pulled the valve cover to find a bent push rod and a rocker stud hlaf pulled out of the head. So have decided to do a slight build. I’m going with 0.030 over sized pistons, the machince shop is suggesting I deck the block but this will erase the date code and suffix on the pad in front of passenger side head, the block is original to the car and a 194 casting. I really don’t want to loose the date code and suffix so what’s everyone thought or options you can suggest.
 

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Discussion Starter #3
Don't they have a machine that stops before the end of the block?

Dave
It an old machine shop, been oround for decades and I think the machinery is just as old. Here in the Midwest machine shops are getting hard to find with everyone buying crate engines.
 

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Have the machine shop check to see if the block does needs decked, if not then I wouldn't deck it.Unless they have a machine like what was mentioned.
X2....don't do it unless the block really needs it. Spend the money somewhere else where you will "FEEL" what was spent. Put screw in studs and better push rods in the heads. Fel-pro gaskets for all the leaks and a rear main seal while your at it.

Dave
 

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Discussion Starter #6 (Edited)
X2....don't do it unless the block really needs it. Spend the money somewhere else where you will "FEEL" what was spent. Put screw in studs and better push rods in the heads. Fel-pro gaskets for all the leaks and a rear main seal while your at it.

Dave
I am doing a total rebuild, so I’m boring .030 over and stroking with a small journal 327 crank to make the motor 311 cubic inches, 062 L31 vortec heads, eldebrock vortec performer intake. The shop suggested the mill because most aftermarket pistons are .02 shorter than OEM. I am not convinced it is worth it, also vortec pistons are usually dish a little to help with squish, mine are flat top with valve reliefs, so this is why I am questioning the mill along with the possibility of removing the date code and suffix which match the vehicle.

The more I think about it I’m just going to run 300 or 400 wet/dry sandpaper around a straight piece of square tube with some oil or wd40 across the top or the cylinder to clean up the surface, use a good Fel-Pro gasket and spend the money elsewhere.
 

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The aftermarket pistons will likely have a different pin location than the OEM. One needs to be installed at TDC and measure its distance from the deck and then deck the block to achieve the correct quench. The thickness of the head gasket will be factored in as well.
 

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I would just use a straight edge to check if the mating surfaced is smooth or not. if they are there is no need to deck them. I was wondering if you need custom pistons to work with the longer stroke?
 

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Discussion Starter #9 (Edited)
Use 307 0.030 over flat top with valve reliefs, A 307 is a 283 bore with a 327 3.25” stroke crank and was the replacement for the 283 as a base motor in 1968. The one thing you have to verify is the 283 crank is a cast crank and not steel or forged. A cast crank has the larger counter weights which allows the use of a forged 327 crank. Most of the 283s that have a cast crank were produce from 1965 to 1967 for cars
 

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Use 307 0.030 over flat top with valve reliefs, A 307 is a 283 bore with a 327 3.25” stroke crank and was the replacement for the 283 as a base motor in 1968. The one thing you have to verify is the 283 crank is a cast crank and not steel or forged. A cast crank has the larger counter weights which allows the use of a forged 327 crank. Most of the 283s that have a cast crank were produce from 1965 to 1967 for cars
Sounds like a pretty cool little engine build. What cam are you goin with?
 

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283 Chevy II Block

64-67 Chevy II blocks have thick main bearing and lifter area webbing. Look for a machine shop that has a Rottler or Sunnen honing machine. Have them deck block. You should consider having shop use deck plates before honing. 64 -67 Chevy II 283 blocks will accept 327 cranks with no machining of webbing area. Good Luck.
 

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Discussion Starter #12
Sounds like a pretty cool little engine build. What cam are you goin with?
From everything I have found the factory cam will do quite well in this engine so I am looking for one that is close to stock with a little more lift. I am running with vortec heads so a valve lift of 0.450 right in there sweet spot, they flow best with low lift cams, that is what they were designed for.

Factory specs
Including ramps, 300 degree duration both intake & exhaust 78 degrees of overlap and 114 degrees @ lobe centerline
Excluding ramps 250 degrees, 0.398 lift @ valve

I have found a Melling cam is really close with a little more lift and may go with 1.6 or 1.65 rocker to get that extra lift
 

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Discussion Starter #13
64-67 Chevy II blocks have thick main bearing and lifter area webbing. Look for a machine shop that has a Rottler or Sunnen honing machine. Have them deck block. You should consider having shop use deck plates before honing. 64 -67 283 blocks will accept 327 cranks with no machining of webbing area. Good Luck.
Not all 283s will work, many of the ones with forged cranks don’t have the clearance for a 327 crank, the bottom of the cylinders were not scalloped to clear a cast crank or a forged 327 crank so you have to selective with your blocks and cranks to do this type of a setup.

I am using what i have to build this engine otherwise you could start with a 307, this is going in a 4dr sedan so its not meant to be a pavement pounder just a cruiser, when I am done it should pump out no less than 410hp at fly wheeler
 

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The shop suggested the mill because most aftermarket pistons are .02 shorter than OEM.
This is a key fact and something you need to fret over.

The cheap "rebuilder" pistons with .020" short deck height are going to kill your compression ratio and at the same time increase the quench distance (causing premature detonation/pinging), meaning you either need to deck the block .020" or forget those pistons and get some that have true stock deck height. Otherwise you lose power from low compression and lose some more due to having to retard the ignition timing.

If your block needs decking anyway, then those .020" down pistons work out for you. If it doesn't need it, seek out some better pistons. They will cost more.
 

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It sounds like for the amount you are modifying it I would do what was required for a sound engine and not worry about numbers.
 

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Discussion Starter #17
This is a key fact and something you need to fret over.

The cheap "rebuilder" pistons with .020" short deck height are going to kill your compression ratio and at the same time increase the quench distance (causing premature detonation/pinging), meaning you either need to deck the block .020" or forget those pistons and get some that have true stock deck height. Otherwise you lose power from low compression and lose some more due to having to retard the ignition timing.

If your block needs decking anyway, then those .020" down pistons work out for you. If it doesn't need it, seek out some better pistons. They will cost more.
There aren’t many companies making pistons for the old 307 anymore, many people have disguarded the 307 as junk. So not many people looking for parts for them, it’s even getting hard to find aftermarket pistons or cranks for an original 265 or 283. As I have stated in other forums, 307 was designed has a high mpg smog motor with less than ideal compression due large open chamber heads and badly designed cams many went flat due to incorrect design or installation, but like any sbc place some good free flowing small chamber heads and good cam and watch what happens. It will produce 1hp per cube as will any sbc with the same prep or parts.
The 307 has a pin height/compression height of 1.66, the pistons I have are 1.655, both Keith black and sealed power shown pin height of 1.655 so I believe I have the best I can get for a replacement piston. Mine are the seal power, like I said this is a weekend cruiser not a daily driver or a pavement pounding street machine.

I have verified the pin height by use of a micrometer, it is 1.655 so I don’t think I need to deck the block, if I do I will need different pistons or mill the pistons too.

From what I understand my squish/quench needs to be between .02 to .04 to keep from having premature detonation.
 

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DBV, you have stated you are doing a "total rebuild". That would include the basics; cyl honing, align honing the mains, squaring the deck to the crank and correcting the piston/deck clearance. I'm thinking your machine shop has already had this discussion with you.
That block is at least 60 years old.....who knows where the deck is at this point. There is more involved here than gasket seal.
No lecture intended.......it's your money do what you want but I'm kinda wondering why you asked the decking question in the first place.
 

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Discussion Starter #19
DBV, you have stated you are doing a "total rebuild". That would include the basics; cyl honing, align honing the mains, squaring the deck to the crank and correcting the piston/deck clearance. I'm thinking your machine shop has already had this discussion with you.
That block is at least 60 years old.....who knows where the deck is at this point. There is more involved here than gasket seal.
No lecture intended.......it's your money do what you want but I'm kinda wondering why you asked the decking question in the first place.
I know where this block has been, car was bought by my uncle 12-24-65, as a Christmas gift to my aunt, it is the original engine and it has never been rebuilt. Everything is original including the cam, oil pan, water pump, everything has has the correct dates for castings and build in November of 1965, The vehicle only has 59,000 on it. My aunt was Norwegian and rarely drove it. You know the old story about the little old lady only drove it to the store and the cleaners, well I think they were talking about my aunt because she only drove it when my uncle wasn’t there to take her where she needed to go.
 

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Decking

Check out 'Auto/Race Tec'. They have piston 'blanks' and will finish the piston with any compression height you want. Your machine shop will still 'deck' the block a minimum amount to ensure it is straight , true, parallel, etc.
 
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