Any Old School Machinists Here?

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72DMag

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Have a big block 440 looking to get built but I am installing after market main caps, main cap studs and girdle. I need an align bore and hone done. Local machine shop said they r 8 months behind. Friend with a boring bar that has bored cylinder walls for me in the past said he could do it with a boring bar.

I've never heard of using a boring bar for main caps? If this can be done would the mains need honed after bored? Is there any advantage to wait and have it done by a professional machine? Didn't want to wait 8 months but maybe boring bar for main caps is something that has been done for years and I'm just not aware of it
 
I wouldn't. Machining operations need to be done with the proper tools.
 
As long as the base of the boring bar is perpendicular there's no harm in setting it up and indicating the front main and the last one to see if the bar travels as it should. Again indicating BEFORE cutting will take some extra time. Do you know someone that works in a machine shop with a boring mill ? That would be perfect. Did you check with Billy Kell near you in W.Virginia ? There's also a guy named John in Youngstown, contact Dave @ Woodruff Carb in Glenmore, he's on this site as an advertiser
 
Wait or find someone with an automotive line boring machine, preferably a newer machine. This is something you don’t want to mess up. Nothing against your friend, but I ran a boring bar for 30 years. You need special tooling, like a boring tool that has support at the opposite end of the spindle. A big boring tool with a diameter of 2inches that sticks out 2 feet on a horizontal boring machine will sag due to gravity if its not supported on the opposite end of the spindle. Its not that it can’t be done, but the time involved would be stupid and nerve racking. Thats why line line bores are purposely designed specialty machines.

And yes I would have it align honed for size accuracy.

I would let an automotive machinist with less than 10 years experience touch my engine.
 
I would wait. That's an incredibly specific job that needs a specific piece of equipment. As mentioned, the center line of the crank bore must be placed exactly right and as far as I know, an align hone/bore machine is the only one capable.
 
Call Valley Performance in Michigan they are Mopar oriented machine shop. They are 3 to 5 weeks on their stuff. P.M. if you want contact info.
 
Hold your horses, everybody. Wasn't there a guy here who claimed to be cutting down his pistons with a bandsaw? So why can't he align bore his mains with a boring bar on a mill?
 
Pittsburghracer/ John may be able to steer you to a machine shop.
 
I would first verify that it actually NEEDS it. It's actually kinda rare for them to be off. Some people have it done "just because".
 
72DMag said:
Have a big block 440 looking to get built but I am installing after market main caps, main cap studs and girdle. I need an align bore and hone done. Local machine shop said they r 8 months behind. Friend with a boring bar that has bored cylinder walls for me in the past said he could do it with a boring bar.

I've never heard of using a boring bar for main caps? If this can be done would the mains need honed after bored? Is there any advantage to wait and have it done by a professional machine? Didn't want to wait 8 months but maybe boring bar for main caps is something that has been done for years and I'm just not aware of it
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Nick at Nick's Garage had a 383 come into his shop because of a rear seal leak that seemed to never go away. Found out the customer had the block line bored. Doing that changed how much pressure was being put on the rear main seal. Nick fixed it by using an old style rope seal. He did say that it is rare to need to line bore a big block Mopar.
 
If you need billet caps and a girdle you must be at the limit of the block. Buy aluminum.
 
The thing being missed is the O/P wants to use aftermarket main caps.... So the need to line bore is real... The trick is to barely touch the top of the bore.....

Not sure what caps are being used but some brands need a lot of material removed to get the bore diameter where it needs to be...

If your removing material from the block while correcting the cap your gonna create problems..

A friend was recently trying to fit billet caps to a Hemi block & the mismatch was bad enough they used a junk 440 block to act as a jig while they did 90% of the roughing before moving the caps to the Hemi block.... And yes, that required milling out the junk 440 block to accept the cross bolt bosses.. It was more work than it was worth but there was already to much work done to the Hemi block to stop....
 
I absolutely can not see using a boring bar as a viable option to do anything but 1 hole at a time.
I am old school and I am a machinist but I'm not an old school machinist but I know that will not work.
 
Also I don't know what the limits are for a factory big block Mopar but I'm pretty close to 700 hp with mine and I just run arp studs and factory main caps. I am not worried about it.
 
I would suppose you could bore the main caps with a deck mounted boring bar if you are careful.

You‘d have to get the boring head indicated in and perpendicular to the bore axis.

Then you’d have to be careful once you get past the second main because the bar is hanging further out of the housing. Of course, if you leave the mains .004-.005 undersized any misalignment if it’s fairly close can be honed out.

You could do it, but you better be detail oriented or the mainline will be all over the place.
 
Newbomb Turk said:
I would suppose you could bore the main caps with a deck mounted boring bar if you are careful.

You‘d have to get the boring head indicated in and perpendicular to the bore axis.

Then you’d have to be careful once you get past the second main because the bar is hanging further out of the housing. Of course, if you leave the mains .004-.005 undersized any misalignment if it’s fairly close can be honed out.

You could do it, but you better be detail oriented or the mainline will be all over the place.
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Better be a well, very well maintained boring bar too if it is going to be anywhere near accurate.
 
Old school boring bars bolt to the deck of the block using that as the reference plane... Plus they are designed to bore maybe a 12 inch max travel...

The main bearing saddle doesn't have a machined plane to bolt to at either end of the block.... Timing chain cavity at the front & flywheel cavity at the rear.... What are you going to rig as your reference plane...

Then realize the only way your going to bore the full length of the main saddle with a machine with a 12" travel is to work from both ends.... Talk about a recipe for disaster...
 
1WildRT said:
Old school boring bars bolt to the deck of the block using that as the reference plane... Plus they are designed to bore maybe a 12 inch max travel...

The main bearing saddle doesn't have a machined plane to bolt to at either end of the block.... Timing chain cavity at the front & flywheel cavity at the rear.... What are you going to rig as your reference plane...

Then realize the only way your going to bore the full length of the main saddle with a machine with a 12" travel is to work from both ends.... Talk about a recipe for disaster...
Click to expand...
Yikes, yeah I guess if a fixture could be made it could be easier but that sounds like a pain in the butt
 
1WildRT said:
Old school boring bars bolt to the deck of the block using that as the reference plane... Plus they are designed to bore maybe a 12 inch max travel...

The main bearing saddle doesn't have a machined plane to bolt to at either end of the block.... Timing chain cavity at the front & flywheel cavity at the rear.... What are you going to rig as your reference plane...

Then realize the only way your going to bore the full length of the main saddle with a machine with a 12" travel is to work from both ends.... Talk about a recipe for disaster...
Click to expand...

There are boring bars that have over 12 inches of travel.

Its not hard to make a mounting plate for the bar to sit on.

It can be done if you think outside the box just a little. It’s a boring bar, that’s what it does. Bore holes.
 
MOPARMAGA said:
Yikes, yeah I guess if a fixture could be made it could be easier but that sounds like a pain in the butt
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A small block Chrysler won’t need a plate for the timing cover end. And you can probably use the timing cover mount for almost any V8.

Same for the bellhousing end. Make a plate. That’s what machinists do. Make **** and use the tooling you have to get the job done.

Many a shop has gone broke buying tooling.
 
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