Block Prep

Razor

Forum tech Advisor
Staff member
Joined
Jul 31, 2001
Those been there and done that..
The question is the line hone and line bore. I have read articles where they say to do it with the heads TQ'd down, I have seen shops simply do it with bare block? Which is right or wrong?

The article from Merkel drilling out the 3rd mains to get more oil.. thoughts?

And is it common practice to simply loosen up the mains on clearance when the line hone may be suspect. Factory clearances are like .001 and I know most motors get built at .002-.0025. Is the increase due to the possibility of line bore/line hone?
 
On drilling out that 3rd main hole--seems to me that the hole in the main bearing will be the choke point...
 
On drilling out that 3rd main hole--seems to me that the hole in the main bearing will be the choke point...
Its like a guy with a stock turbo putting a 70 mm TB. The choke point is the outlet on the turbo
 
Razor, I will give you my comments on what we do with a block when prepping it for assembly.

Either line hone or line bore is done on the bare block. When doing the final cylinder hone, we have torque plates installed, and it will take almost a day to complete this operation as the block need to cool down between honing sessions which is done in steps,

We would NEVER bore out the main bearing supply holes on the saddle as you will kill oil pressure as well a reduce oil flow? Cooling is a major factor in oil flow especially in the bottom end.

A couple owners who drilled out their oil supply to the mains had to scrap their build as they could never get proper oil pressure?

Forget the published factory bearing clearances as these are for the economy V-6 carbed engines. What you stated is where we go and that is confirmed in the Buick Power Source manual for the turbo builds.

Good luck, and if you have other questions, I will be glad to help! :)
 
I remember seeing this article years ago. I don't know of any builders other than Merkel that do it that way-(with the heads on)-but I'm sure other members will chime in here.
 
Its like a guy with a stock turbo putting a 70 mm TB. The choke point is the outlet on the turbo


Yep. But in this case the choke point can be taken care of with a Dremel and 10 seconds of time. And the net result is a positive.



I drill out my center mains. Then port match the main bearings to match the hole. (obviously the bearings have to be labelled after that as they are married to the bore they are matched to). Then radius the bearing hole in the direction of the crank turning to aid in 'dragging' the oil into the hydrodynamic wedge.

I radius the oil hole at the front of the block to help direct the incoming oil towards the cam bearing. And install the front cam bearing 'wrong' to keep from dumping a lot of the incoming oil and to inject the oil at 4:30 instead of 9:00.

Tap the front galley plugs to accept pipe plugs. BE CAREFUL here. The PS plug has to LIGHTLY tapped to keep the pipe plug from protruding into the main oil feed galley. Some times the top needs to be trimmed if a shallow plug can't be found.


Drilling out the center main feeds WILL NOT lower your oil pressure. It is a waste of time to enlarge them if the bearing isn't opened up match as all it will do is expose more of the back side of the shell to pressurized oil.


Needless to say all these mods have to be done with a clean bare block that hasn't had a final cleaning yet.
 
My time spent w/ Jim Ruggles covered the topic of line honing.
He used a process that he, and the Sunnen tech rep, came up with.
Due to the short length from the ft to the rear main, the hone was seen to be "wobbling" at the end bores, causing an oor condition. They had a process wherein the rough hone was done, and as the finish dimension was approached, they reduced torque on the ft and rear main caps.
Don't know if reducing the amt of hone pressure wouldn't do the same thing...Never saw that done.
My first 109 was done that way.. No brg issues that I found.
 
Chris, What line hone equipment are you or your machinist using? .....................and how are you fixturing the block?

I'm using a Sunnen CH-100 and it is nearly impossible to do this job with the heads or torque plates installed. In my machine, the block sits upside down in a precision V cradle and is held down by a bar thru the cam tunnel.

As far as the "Ruggles" line hone method goes. Here is what my Sunnen rep told me to do: The standard line hone mandrel has a row of 10 stones and two rows of 10 aluminum shoes. He told me to effectively shorten the mandrel by remove 2 stones and 4 shoes to accomodate the shorter block. He told me to hone it like everything else. It is common practice to loosen up a cap or two when one bore is growing too fast, although Sunnen does not recommend this.

I bought a complete set of stones and shoes specifically to use doing the BV6 block. It is a pain to reconfigure the mandrel to switch back and forth between V8 and V6, but thats what I do.

You have to ask yourself how much the head bolt torque is going to affect the main bearing bulkheads? I've never measured the mains on a BV6 with/without the heads torqued in place. My guess is that it won't matter much, but I'll try it the next chance I get.
 
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Chris, What line hone equipment are you or your machinist using? .....................and how are you fixturing the block?

I'm using a Sunnen CH-100 and it is nearly impossible to do this job with the heads or torque plates installed. In my machine, the block sits upside down in a precision V cradle and is held down by a bar thru the cam tunnel.

As far as the "Ruggles" line hone method goes. Here is what my Sunnen rep told me to do: The standard line hone mandrel has a row of 10 stones and two rows of 10 aluminum shoes. He told me to effectively shorten the mandrel by remove 2 stones and 4 shoes to accomodate the shorter block. He told me to hone it like everything else. It is common practice to loosen up a cap or two when one bore is growing too fast, although Sunnen does not recommend this.

I bought a complete set of stones and shoes specifically to use doing the BV6 block. It is a pain to reconfigure the mandrel to switch back and forth between V8 and V6, but thats what I do.

You have to ask yourself how much the head bolt torque is going to affect the main bearing bulkheads? I've never measured the mains on a BV6 with/without the heads torqued in place. My guess is that it won't matter much, but I'll try it the next chance I get.
I made A set of V blocks to do it with Tq plates on the block. I also made A fixture for Aluminum blocks that the block sets right side up for line honing.
 
Nice! Have you measured with and without the plates? How much variation in the mains have you measured?
I have two deck plates and I could hone them like that too......just never really thought about using torque plates while align honing.
 
Chris,

As an opinion question and hopefully not too far from the subject when you're installing a girdle do you machine the pan rail square to the main registers and install the girdle with all the associated hardware prior to align honing the block?

Neal
 
Chris,

As an opinion question and hopefully not too far from the subject when you're installing a girdle do you machine the pan rail square to the main registers and install the girdle with all the associated hardware prior to align honing the block?

Neal
Yes.
 
Neal, When I have installed girdles, I machined the caps flat, then machined pan rails .003 below the installed caps. This allows the elimination of the shims. Then align hone with everything torqued in place. Lots of labor involved with this setup. PITA!!
 
Neal, When I have installed girdles, I machined the caps flat, then machined pan rails .003 below the installed caps. This allows the elimination of the shims. Then align hone with everything torqued in place. Lots of labor involved with this setup. PITA!!

But worth it in the end.
 
I make the first cut on the caps with them Tq down on the block. When you nock the caps in the block it distorts the cap in the middle. So just cutting the cap flat when you nock it back in it's not flat anymore.
 
I've played around with girdle machining in the past and I know you have to go to great lengths to get it right. I haven't done one without shims but more often than not I wasn't happy with how it set up even when I thought the machining had been done right. Suffice it to say most girdles aren't installed correctly. Thanks for the responses.

Neal
 
What about the taper on the registers. I know ultimately one wants zero.. but as the stones go back and forth doesn't that crown it a bit? And when using steel caps procedures as the materials are different. Especially when line boring as the cap is harder than the block.Or for locking down the caps so they can't move when using studs..

Years ago when I had a girdle done to my TTA, the machinist I used instead of using the shims made the spacers. As the shims would "squish".

Glad I posted this thread. Extremely interesting. Thanks guys for the replies.
 
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