BLUE PRINT MACHINING A BLOCK

[CNC BLOCKS]

I have been emailed several times asking what it takes to do the job correctly.

First we start with the main line add caps if needed line bore and finish with a line hone.

This is a pic of a 010/020 block with 2482 center caps being line honed.


Next we blue print bore the cam tunnel for over size bearings or roller bearings as this fixture locates center to center distance of the main line and cam center line and keeps the cam tunnel in line with the main line.

This is a pic of a Dart Aluminum block with a .391 raised cam tunnel that we bored out for 55MM cam shaft.


From ther we install it in our CNC machine and index it in the machine. And before we do any machine work we probe the block for deck heights, Cylinder locations in X and Y and cylinder size as it tells us how far its of to blue print.

This is a pick of a Dart Little-M block being probed out.


From there we machine the decks 45 degrees from the crank and cam center lines.

SORRY NO PIC AVAILABLE AS I WILL UP DATE TOMORROW

Next we blue print bore the cylinders or on some of the older 010 blocks that are out of blue print we can bore to the preprobed location

Dart block being bore to blue print.

Once bore we can chamfer the tops of the cylinders yo a desired depth

NO PIC AVAILABLE YET.

Next we blue print bore the lifter bores to .875 or .904 or bush back to standard.

Dart Little-M block being machined for .875 lifter bores.


From there we install the block in our Sunnen Hone intall the torque plate and hone the cylinders to the desired size.

Dart Little-M block being honed


Finished products.

Dart Little-M block


This is a pic of a blower engine our engine shop builds for a pulling team.


Comments are welcome and I will have other pics for this post tomorrow.

[k-star]

On an average how much do you find the cam tunnels to be out of parallel with the mains on the stock blocks?????

Do you do the line hone on your 616 or do you have a seperate tank for that??? I am thinking hard about buying the equipment to do line bores and hones since there really is no place around me that does it well.

Keith

[CNC BLOCKS]

On an average how much do you find the cam tunnels to be out of parallel with the mains on the stock blocks?????

Do you do the line hone on your 616 or do you have a seperate tank for that??? I am thinking hard about buying the equipment to do line bores and hones since there really is no place around me that does it well.

Keith

Keith
We have 2 line hone tables one in the 616 and we have a Sunnen line hone table just for line honing and line boring at the CNC shop.

On the stock blocks GM line bores the cam tunnels and then installs the cam bearings and line bores them with the bearings in place and thats why some times you go to install a camshaft and it don't fit and what I am getting at the cam tunnels maybe alright with the factory cam bearings in place but we have seen them up to .007 out of parallel with the mains and the center to center distances are off as well.

The after market blocks seem to be well within .003

We were doing them in a Tobin Arp but we were going off the exsiting locations in which your not correcting nothing just making it bigger as on the roller cam engines its important to have the center to center distances correct so the lifter can be 90 degrees to the cam as you will see less tracking if everything is square and parallel. And the timing chains and the belt systems fit alot better.

We had the BHJ cam tunnel tool for 5 months before we used it because when we got it we found a few problems with it as we have access to a CMM machine and demensions were not check out correctly but we worked with Bryan at BHJ and got ever thing sorted out and I am very happy with the fixture and we have done both cast iron and aluminum blocks they both require differnt cutters and there is line honing required when you are finished.