[RSSS1967]

I'm having a 489 built on a Gen VI block. I dropped off a bare block with my engine builder last week, and they have the stroker kit on order - pistons, rods, rings, bearings, etc. Today I get a call telling me that the rear mains look "tight" and he is concerned about clearances ending up on the tight side, especially on the rear main. He said it could go either way, but if I elect not to align bore it then if I have problems down the road he might not be willing to stand behind it. I could have easily gone back to the core shop and selected another block, but it has already been bored and tanked. He wants $250 to do this.

I feel a little bit like I'm being shook down here. Am I being overly suspicious here? My suspicion was aroused because at this point they don't even have a crank or pistons to check clearances from. Can you tell just by measuring the main bearing saddles if the tolerances are going to be tight? If so, couldn't this be cleaned up by just line honing instead of taking material off the caps and going all the way to a line bore?

This is a reputable shop, and maybe I am being overly suspicious, but it just seems like there would be no way to know without measuring the crank and bearings when they get here.

Thoughts?

 

[BillK]

Tom,
To be perfectly honest with you, practically every engine that I build myself is going to get align honed. That is the only way to know it is right. GM's factory tolerances are pretty loose and they make up for it with select fit bearings, sometimes several different sizes in one engine. When you try to put it back together with standard replacement bearings, sometimes it just does not work out. By align honing the block, you can assure it is correct. Same goes with milling the decks square and to the same height on both sides.

Also, believe it or not, even at $250, he really is not going to make much money off the align hone

 

[RB69SS396Conv]

I agree w Bill.

If the shop is generally trustworthy in your previous experience, believe them. It's SUPER eeeeeezy to put a bore gauge in the journals and check them for size and round, and lay a straightedge in them and check for straight. You don't need the other parts to do that. If you're still suspicious, go visit and ask them to show you how far off it is, tell em you want to see it and then make up your mind; you'll see what the deal is, no problems, with your own eyes. Whether it's the block or the shop, it'll be obvious. So obvious in fact, that I can hardly imagine a shop with a reputation, tring to pull a fast one that way.

$250 is not a bad price, so he's not gouging you on that.

 

[RSSS1967]

Thanks for putting my mind at ease, guys. I guess like everything else, the labor for machining operations has gone up in the 12 years since I had my last engine built. It would have been nice to have known before it was bored, but as Bill said, I would probably be chasing my tail trying to find a block that didn't have SOMETHING wrong with it.

BTW, what is the going rate to bore notch the top of the bores for valve clearance? I will be runninng 2.25 valves on a 4.280 bore, and I have heard that this might be worth a few ponies. Should I do this on the intakes only, or exhausts too?

 

[35845]

WOW,, $250 just for align bore??? in my area thats high.. but these prices vary greatly across the country...


edit: here my block work for everything done to the block and i mean everything is round $400...

 

[Busted Knuckles]

Yeah, an align hone runs about $150 here.
Notches in the top of the bores is $5/cylinder. Definitely worth it, IMHO.

 

[Tom Mobley]

is he selling you an align bore or align hone? they're different operations with different possible outcomes. You shouldn't need an align bore unless the block had a spun bearing or had a cap or all the caps changed. If it's a minor size deal it should be align honed to finish size, not align bored. Align boring moves the crank up in the block changing the deck height and timing chain fit. ALighn honing usually doesn't change that stuff much.

Try this: look around in his shop, see if he has only an align bore machine and no align hone. If so, he's trying (IMHO) to sell you services you may not need based on what machines he has available.

Me, I'd avoid align boring unless actually needed for damage repair or different main caps.

 

[RSSS1967]

Tom, the way he put it to me on the phone, he was going to take a very small amount of material off the face of the main caps and then align bore it. He said that small of an amount should not affect the fit of the timing chain.

 

[RATtyCamino]

You shouldn't need an align bore unless the block had a spun bearing or had a cap or all the caps changed..

What he said!

To add to Tom's coments above; I've only had that done once....and it was because of a spun bearing in a 400. Prices vary widely across the country but in Lubbock Texas 10 years ago it was $150. I'd consider that on the low end of the price scale and now a days $250 sounds actually competative considering the cost of those tools, set up time and overhead.

If your guy is known to put out good work...I'm sure he's shooting straight with you.

Bill

 

[sleeper]

Torque the mains down and mike the inside diameters and see if they are in specs. If tight align hone, if loose cut the caps and either align bore or hone.

If the first name of the guy telling you this "Rob"? In Lexington?

 

[RSSS1967]

If the first name of the guy telling you this "Rob"? In Lexington?

Nope.

 

[GRN69CHV]

JMHO, align hone, deck and bore/hone with torque plates should be considered SOP for any build. I don't even consider a line hone as an option anymore. Thing is, as I understand it, line hone comes first, then set the decks off the corrected mains. Once everything is squared up, then it's bore and hone. That way, everything is done right off the mains and squared up.

 

[RAT454]

Are line hone and line boring machines different? My 454 block is in the shop, the owner said he only knew of one line hone machine in the local area, not his. He suggested the bore job probably won't change the cam to crank centerline distance enough to worry about.

 

[RSSS1967]

Just for clarification, he is doing an align hone, not bore. He is using a mill to take a very small amount off the cap seating surface, then performing the align hone.

Grn69, what you are saying makes sense, particularly when decking the block to square things up. For whatever reason, he chose to bore and deck before the align hone. He is going to hone to final bore size with torque plates after it is align honed. Need the pistons to hone for correct clearance, then file fit the rings.

Block is coming home with me today - I am going to spend the weekend bore notching the tops of the bores to unshroud the intakes. Have heard varying opinions on this - some say 15-20 HP is hiding here, others say gains will be negligible. Oh well, couldn't hurt much, and it's my elbow grease.

 

[CNC BLOCKS N/E]

is he selling you an align bore or align hone? they're different operations with different possible outcomes. You shouldn't need an align bore unless the block had a spun bearing or had a cap or all the caps changed. If it's a minor size deal it should be align honed to finish size, not align bored. Align boring moves the crank up in the block changing the deck height and timing chain fit. ALighn honing usually doesn't change that stuff much.

Try this: look around in his shop, see if he has only an align bore machine and no align hone. If so, he's trying (IMHO) to sell you services you may not need based on what machines he has available.

Me, I'd avoid align boring unless actually needed for damage repair or different main caps.

We have line bored alot of blocks over the years but have always finished with a line hone and so far when we have line bored we have never moved the crank to cam center lines as we never cut the block side of he housing bore.

When we line hone we cut the caps appox. .003 and in a perfect world you are only moving the cneter line .0015

Most line boring machines can't line bore all the journals all one shot but require 3 set ups to do the job.

I would not dare to use a GM block with out line honing housing bore size may be fine but some times the alignment stinks.

 

[GRN69CHV]

Just for clarification, he is doing an align hone, not bore. He is using a mill to take a very small amount off the cap seating surface, then performing the align hone.

Grn69, what you are saying makes sense, particularly when decking the block to square things up. For whatever reason, he chose to bore and deck before the align hone. He is going to hone to final bore size with torque plates after it is align honed. Need the pistons to hone for correct clearance, then file fit the rings.

Block is coming home with me today - I am going to spend the weekend bore notching the tops of the bores to unshroud the intakes. Have heard varying opinions on this - some say 15-20 HP is hiding here, others say gains will be negligible. Oh well, couldn't hurt much, and it's my elbow grease.

Your good. Line hone is akin to final hone in the bores. Definitely want to finish line hone prior to final hone in bores, want the mains torqued down just as they will be ran. With the notching, don't need to get too aggressive, just scribe the gasket and ease a relief.

 

[big_orange]

Block is coming home with me today - I am going to spend the weekend bore notching the tops of the bores to unshroud the intakes. Have heard varying opinions on this - some say 15-20 HP is hiding here, others say gains will be negligible. Oh well, couldn't hurt much, and it's my elbow grease.

dunno if it helps much either, but I do every big block that comes through the shop- even the mild ones. seems like the smaller the bore, the more it would help, but youll still be taking plenty out of a 4.28-4.31 bore as well. Just dont get too far down the bores and go below the top ring.
as you said, its free, just a little elbow grease........and it looks cool, too:beers:

 

[Tom Mobley]

mark the deck using the head gasket, but allow a little so the gasket bead is not flush with hanging out into the bore. look at your pistons, measure down from the deck of the piston to the top of the top ring. subtract at least .100 from that, scribe a line on the cylinder wall, don't go below that.

 

[rustbucket79]

I like to set the head on the block and use an angled scribe, reaching up from the crankcase side. This way the cylinder matches the combustion chamber shape, size and location perfectly. Also protects against the guy who uses a gasket for a 4.500 bore size on a block that is 4.280 and creating a block to head missmatch inverse of what he had before the modification. I too go a little conservative, .080" to .100" above the top of the top ring at TDC.

 

[Calculated Risk]

If your going to have it line honed you might as well switch to ARP main studs or bolts at this time.