Dart little m block...some input is needed.

Old 06-17-2010, 07:13 PM
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Default Dart little m block...some input is needed.

I bought a little m block and the papers state it needs finish bore to piston fit,some deburring and it will need to be decked to match my old motor. I call a machine shop and they also want to charge me for checking align bore and lifter bores. I called dart and they said if the block is new it is good to go besides the first few items i listed are the machine shops trying to get extra money from me? Any input or advice would be greatly appreciated. Thanks in advance,Mike
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Old 06-18-2010, 05:15 AM
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Finish bore to piston fit - YES
Deburring - your call but I would say YES
Decked - Unless you have extremely accurate measuring tools, you need to assemble to determine what you deck height is anyway. Don't cut if if you can juggle with head gasket thickness.
Align bore - OK as is
Lifter bores - OK as is

Just me opinion - Hink can probable add input...

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Old 06-18-2010, 09:36 AM
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Why would you NOT want to check the align bore and lifter bores? Different lifter manufacturers make there lifters different diameters so you need to check the clearance. Machinists make mistakes, (I know I run a shop). Not saying anything bad about Dart, I just check it no matter who did the work. I would double check everything I could. JMO

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Old 06-18-2010, 03:55 PM
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We machine a lot of Dart blocks and we do what we think need to be machined every thing has to be checked

Here is a list to what we do to a Little-M block when we machine one


We machine alot of Dart blocks for engines builders and other shops.

95% of the time most guys want main studs installed and after installing the studs in some cases we see the housing bores tighten up, So we line hone the main line on the 400 blocks to 2.8415

The blocks come with a 9.025 decks and most piston, rods and cranks require a 9.000 deck for zero deck.

Lifter bores we make sure they are to the GM tolerance of .8438 to .8443 but again most of the time most guys are asking for .904 lifter bores now.

The cylinder do come on your block appox. 4.120 and do need to be plate honed using the same gasket and hardware you will be using in your build.

Freeze plug and rear cam plug holes need to be chamfered.

Bottom of the cylinders should be camfered.

All the pipe plug hole should be taped deeper

Rear main bearing area needs to be deburred.

Water holes in the decks need to be matched to the head gasket.

On the 400 main line blocks fit up your oil pump and oil pump shaft and distributor to make sure that you don't need to any extra clearancing.

Thats pretty much what we do to the Little-M blocks.

And we charge for the block and the machine work 2695.00

When building a performace engine everything has to be checked and clearanced to the builders specs.

Dart blocks are great foundation to start with but everything needs to be checked before assembled. I MEAN EVERYTHING
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Old 06-18-2010, 05:59 PM
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I don't mean to be a smart azz, but let your machine shop do what he wants to do. I don't mean that directly about the guy you talked to, but just in general. If you're on a budget make him give you a list of things he wants to do and a firm estimate. Have another machine shop do the same.
I guess what I'm saying is find a machine shop you trust and let them do what they're suppose to do and that is build you a motor that will last!!
BTW there can big a huge difference in $ from one shop to another.
I've used two different machinist over the last 5 years. Both did really good work, but there was a BIG difference in $.
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Old 06-22-2010, 10:43 AM
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Originally Posted by TheRabbit
BTW there can big a huge difference in $ from one shop to another.
I've used two different machinist over the last 5 years. Both did really good work, but there was a BIG difference in $.
X2. One machine shop quoted me $1200 for a set of pushrods and the other told me just over $600.....for the EXACT same pushrod.
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Old 06-22-2010, 03:42 PM
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Machine the blocks as needed. This is a new block but it's also a production block, they are not perfect.

We align hone every block, deck, bore and hone, and if using a flat tapped camshaft, you must hone the lifter bore to size.
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Old 07-02-2010, 07:08 PM
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Default dart little m

dart tells u everything is ok but i can tell u the decks may not be even i checked mine with a bhj block tru and it was off .013 and the lifters were off as well with the bhj lifter bore kit all the extra work may be needed
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Old 07-02-2010, 08:01 PM
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Originally Posted by tcarda

X2. One machine shop quoted me $1200 for a set of pushrods and the other told me just over $600.....for the EXACT same pushrod.

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